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1

Exploration Activity: Global Cloud Patterns  

NSDL National Science Digital Library

In this activity, students characterize some global patterns of deep, cold-topped clouds visible on global infrared satellite images. They will apply these characterizations to answer questions about local and global patterns of precipitation. The questions concern what clouds are and how they form, atmospheric cooling, rising air, precipitation, and the use of remote satellite imagery to see precipitation-producing clouds and storms. They will also create animated global infrared satellite images and answer some questions concerning them.

Dempsey, Dave

2005-03-10

2

An Application of Fractal Box Dimension to the Recognition of Mesoscale Cloud Patterns in Infrared Satellite Images.  

NASA Astrophysics Data System (ADS)

Mesoscale cloud patterns are analyzed through the application of fractal box dimensions. Verification of fractal properties in satellite infrared images is carried out by computing box dimensions with two different methods and by computing the fraction of cloudy pixels for two sets of images: 174 are considered the `control series,' and 178 (for verification) are considered the `test series.' The main instabilities in the behavior of such dimensions are investigated from the simulation of circles filling space in several spatial distributions. It is shown that the box dimensions are sensitive to the increase of the area covered and to the spatial organization-that is, the number of cells, the spatial clustering, and the isotropy of the distribution of pixels. From a principal components analysis, the authors find six main patterns in the cloudiness for the control series. The three main patterns related to enhanced convection are the massive noncircular spread cloudiness, the highly isotropic distribution of cloud in several cells, and the most circular pattern associated with mesoscale convective complexes. The six patterns are separated into a cluster analysis, and the properties of each cluster are averaged and verified for the test series. This method is a simple and skillful procedure to recognize mesoscale cloud patterns in satellite infrared images.

Carvalho, Leila M. V.; Silva Dias, Maria A. F.

1998-10-01

3

Patterns in High Cloud Coverage  

NSDL National Science Digital Library

Clouds are a collection of water droplets and small ice crystals that are suspended in an atmosphere. Clouds form when moisture rises, cools, and changes to water or ice. It is important to take into consideration exactly how clouds affect the world around us. Clouds are an important determining factor in climate in any region around the globe. In this lesson, students will plot and analyze data for high cloud coverage from a specified location and determine whether or not a pattern exists.

4

The Research of Satellite Cloud Image Recognition Base on Variational Method and Texture Feature Analysis  

Microsoft Academic Search

Recently, the development of satellite cloud image processing technology has become very quick; the research aspects concentrate on judge the cloud type and classify the cloud mainly. These image processing methods relate to the subject category like image processing and pattern recognition etc; it has become one of the fields of most quickly development in the research of satellite image

Wei Shangguan; Yanling Hao; Zhizhong Lu; Peng Wu

2007-01-01

5

Identifying Cloud computing usage patterns  

Microsoft Academic Search

The current end-users who are developing Cloud-based applications are struggling with multiple solutions for application programming interfaces (APIs) coming from different providers. This fact is partially a consequence of the focus of these APIs on the service provider expectations not on the end-user requirements. In the design of a generic API for Cloud application development, the first step should be

Dana Petcu

2010-01-01

6

Biomedical image analysis and processing in clouds  

NASA Astrophysics Data System (ADS)

Cloud-based Image Analysis and Processing Toolbox project runs on the Australian National eResearch Collaboration Tools and Resources (NeCTAR) cloud infrastructure and allows access to biomedical image processing and analysis services to researchers via remotely accessible user interfaces. By providing user-friendly access to cloud computing resources and new workflow-based interfaces, our solution enables researchers to carry out various challenging image analysis and reconstruction tasks. Several case studies will be presented during the conference.

Bednarz, Tomasz; Szul, Piotr; Arzhaeva, Yulia; Wang, Dadong; Burdett, Neil; Khassapov, Alex; Chen, Shiping; Vallotton, Pascal; Lagerstrom, Ryan; Gureyev, Tim; Taylor, John

2013-10-01

7

Jupiter's Great Red Spot: Fine-scale matches of model vorticity patterns to prevailing cloud patterns  

NASA Astrophysics Data System (ADS)

We report on a set of six new matches between fine-scale features in the vorticity field of a three-dimensional (3D), primitive-equation, finite-difference model of Jupiter's Great Red Spot that includes no clouds or cloud physics, and quasi-permanent structures in reflected visible-band images of the clouds. These add to similar success by Cho et al. (Cho, J., de la Torre Juárez, M., Ingersoll, A.P., Dritschel, D.G. [2001]. J. Geophys. Res. 106, 5099-5106), who earlier captured four characteristic features of the GRS, also reproduced here, using a 3D quasi-geostrophic, cloud-free contour-dynamics model. In that study and this, the key enabling model attribute is sufficient horizontal resolution, rather than the moist-convective and cloud-microphysics processes often required to match the patterns of clouds in terrestrial hurricanes. The only significant feature that these dry models do not capture is the episodic moist-convective plumes seen in the northwest quadrant adjacent to the GRS. We initialize with Jupiter's averaged zonal winds plus an approximately balanced, smooth 3D ellipsoidal anticyclone. The threshold horizontal grid-resolution to obtain the fine-scale matches is approximately ?y/Ld ? 0.15, where ?y ? 300 km is the meridional grid spacing and Ld ˜ 2000 km the Rossby deformation length. For models with this or finer horizontal resolution, the best correspondence with observations is reached after about six vortex turnaround times from initialization (˜30 Earth days), but good facsimiles of nearly all the studied features appear after only 1.5 turnaround times (˜7-8 days). We conclude that in images of Jupiter, it is not accurate to associate clouds with upward motion, since these dry models reproduce the observed cloud patterns without this association, and indeed the synoptic-scale vertical motions in the model, as well as those deduced from observations, do not at all correspond to the observed cloud patterns. Instead, Jupiter's cloud-top patterns indicate the effects of local shear in the manner of passive-tracer fields. As a corollary, the water clouds on Jupiter, which lie unseen below its visible clouds, are the only ones on the planet likely to correlate with upwelling in the manner that clouds do on Earth. The next step is to extend studies such as this past the reflected visible band, for example to include the GRS's 5-?m emission bright collar, which may require the inclusion of cloud physics to enable the successful simulation of large voids.

Morales-Juberías, Raúl; Dowling, Timothy E.

2013-07-01

8

Inhomogeneous cloud removing from remote sensing image  

NASA Astrophysics Data System (ADS)

Cloud is the common phenomenon in the obtaining and application of the visible-light remote sensing image, and these images are usually degraded by the turbid medium (e.g., fog, cloud) in the atmosphere. This article researched the defogging techniques of the single satellite remote sensing image on the basis of the dark channel prior and the imaging model of the cloud images, and proposed a new approach to calculate the airlight in view of problems of asymmetric thickness of cloud in the satellite remote sensing images and unreasonable estimation of the airlight in the existing defogging algorithms. In my approach, cloud thickness information was added to effectively avoid the phenomenon of 'over-treatment' and 'under-treatment'. Finally, the feature of scientific and effective were validated by the successful testament of respectively using medium-resolution and high-resolution satellite remote sensing data.

Zhou, Liya; Qin, Zhiyuan; Lin, Qing; Shang, Wei

2011-11-01

9

Satellite Cloud Image Enhancement by Genetic Algorithm with Fuzzy Technique  

Microsoft Academic Search

In order to efficiently enhance contrast of the satellite cloud image, an efficient satellite cloud image enhancing method is proposed. Most of existing satellite cloud image enhancing methods do not consider uncertainties of the image, that is to say, fuzziness in the satellite cloud image processing. A new kind of image measure function is proposed by combing fuzzy theory with

Changjiang Zhang; Juan Lu

2009-01-01

10

Infrared cloud imaging for diurnal remote sensing of cloud statistics including cloud type  

NASA Astrophysics Data System (ADS)

Clouds are a critical component in determining weather and climate. Spatial and temporal statistics of cloudiness are needed in applications ranging from climate research to precision agriculture. Ground-based cloud remote sensing is particularly useful in applications requiring high spatial and temporal resolution. Thermal infrared imaging allows continuous detection of clouds from their thermal emission, with no interruption during sunrise, sunset, or night. In addition to detecting clouds continually during day and night,the third-generation Infrared Cloud Imager (ICI-3) is capable of classifying thin clouds according to their optical depth. This added capability is provided by a rigorous radiometric calibration and compensation of atmospheric emission from the infrared sky images. Data are shown that illustrate the importance of cloud- type classification in determining the radiative effect of variable cloudiness.

Shaw, J. A.; Nugent, P. W.; Simpson, K.; Johnson, J.; Staal, B.

2008-12-01

11

Image processing for weather satellite cloud segmentation  

Microsoft Academic Search

Image segmentation of weather satellite imagery is an important first step in an automated weather forecasting system. Accurate cloud extraction is also important in the determination of solar radiative transfer in atmospheric research, where satellite observations are used as inputs to global climate models to predict climatic change. Most of the current cloud extraction algorithms tend to be quite complicated

I. J. H. Leung; J. E. Jordan

1995-01-01

12

Image Transformations of Satellite Cloud Photography.  

National Technical Information Service (NTIS)

The report describes a study program which was concerned with the investigation of photographic image transformations. Samples of cloud photographs were digitized using a programmable light source (a computer controlled CRT scanner). The digitized data we...

R. L. Peters

1970-01-01

13

Automatically locating the typhoon center based on satellite cloud image  

Microsoft Academic Search

An automatic locating algorithm is presented for typhoon center locating using cloud motion wind vectors derived from the satellite cloud images. The cloud motion wind vectors are obtained by implementing template matching to a pair of interrelated satellite cloud images with stated time interval. The template matching is a process to find the child image that corresponds to the given

Zhengguang Liu; Juntao Xue; Yuanfei Yu; Bing Wu; Gary Shen

2004-01-01

14

Wide angle infrared cloud imaging for measuring cloud statistics in support of earth space optical communication  

Microsoft Academic Search

Previous research at Montana State University led to the development of the Infrared Cloud Imager (ICI) for measuring downwelling cloud and sky thermal emission for producing cloud coverage statistics using radiometrically calibrated images of the sky. This technique, that was developed primarily for detection of clouds for studies of arctic climate, provides benefits over commonly used systems by producing localized

Paul W. Nugent; Joseph A. Shaw; Sabino Piazzolla

2007-01-01

15

Wide Angle Infrared Cloud Imaging for Measuring Cloud Statistics in support of Earth Space Optical Communication  

Microsoft Academic Search

Previous research at Montana State University led to the development of the Infrared Cloud Imager (ICI) for measuring downwelling cloud and sky thermal emission for producing cloud coverage statistics using radiometrically calibrated images of the sky. This technique, that was developed primarily for detection of clouds for studies of arctic climate, provides benefits over commonly used systems by producing localized

Paul W. Nugent; Joseph A. Shaw; Sabino Piazzolla

2007-01-01

16

Tracking remotely sensed cloud images in time and space  

Microsoft Academic Search

Temporal and spatial analysis has been applied to a sequence of cloud top pressure (CTP) images and cloud optical thickness (TAU) images stored in the International Satellite Cloud Climatology Project D1 database located at the NASA Goddard Institute for Space Studies. Each pixel in the D1 data set has a resolution of 2.5 degrees or 280 kilometers. These images were

John S. DaPonte; Joseph N. Vitale; Jo Ann Parikh; George Tselioudis

2001-01-01

17

Recognizing and estimating rainfall using cloud images  

Microsoft Academic Search

Water is elixir of life. So rainfall becomes the inevitable part of every nation which decides the prosperity and economic scenario of a country. In this fast moving world, estimation of rainfall has become a necessity especially when the global heat levels are soaring. The proposed approach here is to use the digital cloud images to predict rainfall. Considering the

S. Oswalt Mano; V. Kavitha; J. P. Ananth; J. SahayaAru

2010-01-01

18

Cloud Ozone Dust Imager (CODI), Volume 1.  

National Technical Information Service (NTIS)

The Cloud Ozone Dust Imager (CODI) is proposed to investigate the current climatic balance of the Mars atmosphere, with particular emphasis on the important but poorly understood roles which dust and water ice aerosols play in this balance. The large atmo...

R. T. Clancy P. Dusenbery M. Wolff P. James M. Allen J. Goguen R. Kahn R. Gladstone J. Murphy

1995-01-01

19

Contented-Based Satellite Cloud Image Processing and Information Retrieval  

Microsoft Academic Search

Satellite cloud image is a kind of useful image which includes abundant information, for acquired this information, the image\\u000a processing and character extraction method adapt to satellite cloud image has to be used. Content-based satellite cloud image\\u000a processing and information retrieval (CBIPIR) is a very important problem in image processing and analysis field. The basic\\u000a character, like color, texture, edge

Yanling Hao; Wei Shangguan; Yi Zhu; Yanhong Tang

2007-01-01

20

10 Learning Patterns in Images  

Microsoft Academic Search

This chapter concerns problems of learning patterns in images and image se- quences, and using the obtained patterns for interpreting new images. The chap- ter concentrates on three problem areas: (i) semantic interpretation of color im- ages of outdoor scenes, (ii) detection of blasting caps in x-ray images of luggage, and (iii) recognizing actions in video image sequences. It discusses

Ryszard Michalski; Azriel Rosenfeld; Zoran Duric; Marcus Maloof; Qi Zhang

1998-01-01

21

Clouds  

NSDL National Science Digital Library

First, the Project Atmosphere Canada offers a module to educate primary and secondary students about cloud formation and characteristics (1). The website outlines key points and offers a more in-depth discussion of water vapor, cloud formation, convection, air motion, severe weather, and more. The second website, by Scholastic, supplies many pdf documents of activities and lesson plans for all types of weather phenomena including clouds (2). Students can learn about condensation, discover what makes up a cloud, and find a key identifying the cloud types. Next, USA Today offers an online tutorial of the differing characteristics of clouds (3). Users can learn about Mammatus clouds, contrails, cloud seeding, and other cloud-related topics. At the fourth website, visitors can view meteorologist Dan Satterfield's amazing cloud photographs (4). Educators may find useful materials to supplement their lectures. Next, NASA's Climate and Radiation Branch furnishes "information on the fantastic variety of cloud forms and structures, and their implications for climate" (5). While the website is still being constructed, users can find useful information about the Bounded Cascades Fractal Cloud model, animations, and definitions of inhomogeneous cloud terminology. The sixth website, created by the National Center for Atmospheric Research and the University Corporation for Atmospheric Research, addresses how clouds impact our lives, how they cause chaos, and how they form (6). The enlightening descriptions are packed with colorful images and short quizzes. Next, The Australian Government's Bureau of Meteorology describes the useful of clouds as an indicator of weather conditions (7). After learning how moist air can form clouds, individuals can view images of the ten most common cloud types. Lastly, Enchanted Learning offers a table of the cloud types with their abbreviation, appearance, composition, and altitude along with explanations of cloud formation and the atmosphere (8). Educators can find simple activities dealing with cloud types and the water cycle.

22

Polar mesospheric cloud structures observed from the cloud imaging and particle size experiment on the Aeronomy of Ice in the Mesosphere spacecraft: Atmospheric gravity waves as drivers for longitudinal variability in polar mesospheric cloud occurrence  

Microsoft Academic Search

The cloud imaging and particle size (CIPS) experiment is one of three instruments on board the Aeronomy of Ice in the Mesosphere (AIM) spacecraft that was launched into a 600 km Sun-synchronous orbit on 25 April 2007. CIPS images have shown distinct wave patterns and structures in polar mesospheric clouds (PMCs), around the summertime mesopause region, which are qualitatively similar

A. Chandran; D. W. Rusch; A. W. Merkel; S. E. Palo; G. E. Thomas; M. J. Taylor; S. M. Bailey; J. M. Russell

2010-01-01

23

Cloud motion detection from infrared satellite images  

NASA Astrophysics Data System (ADS)

The estimation of cloud motion from a sequence of satellite images can be considered a challenging task due to the complexity of phenomena implied. Being a non-rigid motion and implying non-linear events, most motion models are not suitable and new algorithms have to be developed. We propose a novel technique, combining a Block Matching Algorithm (BMA) and a best candidate block search along with a vector median regularisation.

Brad, Remus; Letia, Ioan A.

2002-07-01

24

A cloud-based medical image repository  

NASA Astrophysics Data System (ADS)

Many widely used digital medical image collections have been established but these are generally used as raw data sources without related image analysis toolsets. Providing associated functionality to allow specific types of operations to be performed on these images has proved beneficial in some cases (e.g. brain image registration and atlases). However, toolset development to provide generic image analysis functions on medical images has tended to be ad hoc, with Open Source options proliferating (e.g. ITK). Our Automated Medical Image Collection Annotation (AMICA) system is both an image repository, to which the research community can contribute image datasets, and a search/retrieval system that uses automated image annotation. AMICA was designed for the Windows Azure platform to leverage the flexibility and scalability of the cloud. It is intended that AMICA will expand beyond its initial pilot implementation (for brain CT, MR images) to accommodate a wide range of modalities and anatomical regions. This initiative aims to contribute to advances in clinical research by permitting a broader use and reuse of medical image data than is currently attainable. For example, cohort studies for cases with particular physiological or phenotypical profiles will be able to source and include enough cases to provide high statistical power, allowing more individualised risk factors to be assessed and thus allowing screening and staging processes to be optimised. Also, education, training and credentialing of clinicians in image interpretation, will be more effective because it will be possible to select instances of images with specific visual aspects, or correspond to types of cases where reading performance improvement is desirable.

Maeder, Anthony J.; Planitz, Birgit M.; El Rifai, Diaa

2012-02-01

25

A novel nonlinear algorithm for typhoon cloud image enhancement  

Microsoft Academic Search

A novel nonlinear gray transform method is proposed to enhance the contrast of a typhoon cloud image. Generally, the typhoon\\u000a cloud image obtained by a satellite cannot be directly used to make an accurate prediction of the typhoon’s center or intensity\\u000a because the contrast of the received typhoon cloud image may be bad. Our aim is to extrude the typhoon’s

Chang-Jiang Zhang; Bo Yang

2011-01-01

26

High-performance isotherm extraction for infrared satellite cloud image  

Microsoft Academic Search

The isotherm is an important feature of infrared satellite cloud images (ISCI), which can directly reveal substantial information of cloud systems. The isotherm extraction of ISCI can remove the redundant information and therefore helps to compress the information of ISCI. In this paper, an isotherm extraction method is presented. The main aggregate of clouds can be segmented based on mathematical

Zhengguang Liu; Bing Wu; Yong Liu; Yuan Liu

2001-01-01

27

Self-adaptive segmentation for infrared satellite cloud image  

Microsoft Academic Search

It is difficult to segment cloud images because of the complicated and various shapes and blurry edges of cloud. In this paper, we present an idea and a set of realizable design about self-adaptive segmentation by means of mathematical morphology. Created models can show some characteristics of clouds such as shapes, scales and temperature exactly. Some practices show that the

Ping Wang; Juntao Xue; Zhengguang Liu; Huanzhu Liu; Guisheng Tang

2001-01-01

28

Automated production of cloud-free and cloud shadow-free image mosaics from cloudy satellite imagery  

Microsoft Academic Search

The humid tropical region is always under partial or complete cloud covers. As a result, optical remote sensing images of this region always encounter the problem of cloud covers and associated shadows. In this paper, an operational system for producing cloud-free and cloud shadow-free image mosaics from cloudy optical satellite imagery is presented. The inputs are several cloudy images of

Min LI; Soo Chin LIEW; Leong Keong KWOH

2004-01-01

29

Synthesized images for pattern recognition  

Microsoft Academic Search

Since there is no generic procedure for machine pattern recognition due to its complexity, ad hoc computer algorithms have been developed for each class of problems. In visual pattern recognition, depending on the area of investigation, it is difficult to obtain test images with the desired characteristics. Capturing the original images in the first place may require special and\\/or expensive

Mario Miyojim; Heng-da Cheng

1995-01-01

30

Male pattern baldness (image)  

MedlinePLUS

Male pattern baldness is a sex-linked characteristic that is passed from mother to child. A man can more accurately predict his chances of developing male pattern baldness by observing his mother's father than by looking ...

31

Satellite cloud image retrieval based on deformable circle model  

Microsoft Academic Search

In order to build a content-based cloud image retrieval system, a deformable circle model is proposed to represent cloud shape. After a description of the model and shape decomposition process, a hierarchical similarity rule is presented. Then comparative experiments with some conventional contented-based image retrieval methods are carried out, which leads to a finding that the retrieval performance of our

Yuan-Xiang Li; Yan-Bing Li; Zhong-Liang Jing

2007-01-01

32

Capturing and analyzing wheelchair maneuvering patterns with mobile cloud computing.  

PubMed

Power wheelchairs have been widely used to provide independent mobility to people with disabilities. Despite great advancements in power wheelchair technology, research shows that wheelchair related accidents occur frequently. To ensure safe maneuverability, capturing wheelchair maneuvering patterns is fundamental to enable other research, such as safe robotic assistance for wheelchair users. In this study, we propose to record, store, and analyze wheelchair maneuvering data by means of mobile cloud computing. Specifically, the accelerometer and gyroscope sensors in smart phones are used to record wheelchair maneuvering data in real-time. Then, the recorded data are periodically transmitted to the cloud for storage and analysis. The analyzed results are then made available to various types of users, such as mobile phone users, traditional desktop users, etc. The combination of mobile computing and cloud computing leverages the advantages of both techniques and extends the smart phone's capabilities of computing and data storage via the Internet. We performed a case study to implement the mobile cloud computing framework using Android smart phones and Google App Engine, a popular cloud computing platform. Experimental results demonstrated the feasibility of the proposed mobile cloud computing framework. PMID:24110214

Fu, Jicheng; Hao, Wei; White, Travis; Yan, Yuqing; Jones, Maria; Jan, Yih-Kuen

2013-07-01

33

Dynamics of artificial plasma clouds in 'Spolokh' experiments - Movement pattern  

NASA Astrophysics Data System (ADS)

Attention is given to the space location and movement data obtained for the high density barium clouds injected during the Spolokh-1 and -2 shaped charge experiments in the midlatitude ionosphere. Initially, the neutral and ionized components move together at the neutral wind speed, and an ion outflow in the form of a stratified tail was observed whose movement is presently interpreted as a drift in the (Eo x B) fields. Agreement is noted between the artificial plasma cloud evolution pattern and the qualitative scheme presently described.

Dzubenko, N. I.; Molotai, A. A.; Zhilinskii, A. P.; Rozhanskii, V. A.; Tsendin, L. D.; Zhulin, I. A.; Ruzhin, Iu. Ia.; Skomarovskii, V. S.; Ivchenko, I. S.

1983-08-01

34

Cloud level winds from the Venus Express Monitoring Camera imaging  

NASA Astrophysics Data System (ADS)

Six years of continuous monitoring of Venus by European Space Agency's Venus Express orbiter provides an opportunity to study dynamics of the atmosphere our neighbor planet. Venus Monitoring Camera (VMC) on-board the orbiter has acquired the longest and the most complete so far set of ultra violet images of Venus. These images enable a study the cloud level circulation by tracking motion of the cloud features. The highly elliptical polar orbit of Venus Express provides optimal conditions for observations of the Southern hemisphere at varying spatial resolution. Out of the 2300 orbits of Venus Express over which the images used in the study cover about 10 Venus years. Out of these, we tracked cloud features in images obtained in 127 orbits by a manual cloud tracking technique and by a digital correlation method in 576 orbits. Total number of wind vectors derived in this work is 45,600 for the manual tracking and 391,600 for the digital method. This allowed us to determine the mean circulation, its long-term and diurnal trends, orbit-to-orbit variations and periodicities. We also present the first results of tracking features in the VMC near-IR images. In low latitudes the mean zonal wind at cloud tops (67 ± 2 km following: Rossow, W.B., Del Genio, A.T., Eichler, T. [1990]. J. Atmos. Sci. 47, 2053-2084) is about 90 m/s with a maximum of about 100 m/s at 40-50°S. Poleward of 50°S the average zonal wind speed decreases with latitude. The corresponding atmospheric rotation period at cloud tops has a maximum of about 5 days at equator, decreases to approximately 3 days in middle latitudes and stays almost constant poleward from 50°S. The mean poleward meridional wind slowly increases from zero value at the equator to about 10 m/s at 50°S and then decreases to zero at the pole. The error of an individual measurement is 7.5-30 m/s. Wind speeds of 70-80 m/s were derived from near-IR images at low latitudes. The VMC observations indicate a long term trend for the zonal wind speed at low latitudes to increase from 85 m/s in the beginning of the mission to 110 m/s by the middle of 2012. VMC UV observations also showed significant short term variations of the mean flow. The velocity difference between consecutive orbits in the region of mid-latitude jet could reach 30 m/s that likely indicates vacillation of the mean flow between jet-like regime and quasi-solid body rotation at mid-latitudes. Fourier analysis revealed periodicities in the zonal circulation at low latitudes. Within the equatorial region, up to 35°S, the zonal wind show an oscillation with a period of 4.1-5 days (4.83 days on average) that is close to the super-rotation period at the equator. The wave amplitude is 4-17 m/s and decreases with latitude, a feature of the Kelvin wave. The VMC observations showed a clear diurnal signature. A minimum in the zonal speed was found close to the noon (11-14 h) and maxima in the morning (8-9 h) and in the evening (16-17 h). The meridional component peaks in the early afternoon (13-15 h) at around 50°S latitude. The minimum of the meridional component is located at low latitudes in the morning (8-11 h). The horizontal divergence of the mean cloud motions associated with the diurnal pattern suggests upwelling motions in the morning at low latitudes and downwelling flow in the afternoon in the cold collar region.

Khatuntsev, I. V.; Patsaeva, M. V.; Titov, D. V.; Ignatiev, N. I.; Turin, A. V.; Limaye, S. S.; Markiewicz, W. J.; Almeida, M.; Roatsch, Th.; Moissl, R.

2013-09-01

35

Data and image fusion for geometrical cloud characterization  

SciTech Connect

Clouds have a strong influence on the Earth`s climate and therefore on climate change. An important step in improving the accuracy of models that predict global climate change, general circulation models, is improving the parameterization of clouds and cloud-radiation interactions. Improvements in the next generation models will likely include the effect of cloud geometry on the cloud-radiation parameterizations. We have developed and report here methods for characterizing the geometrical features and three-dimensional properties of clouds that could be of significant value in developing these new parameterizations. We developed and report here a means of generating and imaging synthetic clouds which we used to test our characterization algorithms; a method for using Taylor`s hypotheses to infer spatial averages from temporal averages of cloud properties; a computer method for automatically classifying cloud types in an image; and a method for producing numerical three-dimensional renderings of cloud fields based on the fusion of ground-based and satellite images together with meteorological data.

Thorne, L.R.; Buch, K.A.; Sun, Chen-Hui; Diegert, C.

1997-04-01

36

Satellite cloud image texture feature extraction based on Gabor wavelet  

Microsoft Academic Search

In recent years, multi-resolution, multi-channel texture analysis algorithm get extensive attention, and become the important development direction of the texture analysis. According to the satellite cloud images, this paper put forward the cloud classification method based on texture feature of 2D-Gabor wavelet. Experiments show that the 2D-Gabor wavelet texture features can achieve better classification of clouds, take this method compared

Desheng Fu; Lijuan Xu

2011-01-01

37

Structure and Nonrigid Motion Analysis of Satellite Cloud Images  

Microsoft Academic Search

This paper proposes a new method for recoveringnonrigid motion and structure of clouds under affineconstraints using time-varying cloud images obtainedfrom meteorological satellites. This problem is challengingnot only due to the correspondence problembut also due to the lack of depth cues in the 2D cloudimages (scaled orthographic projection). In this paper,affine motion is chosen as a suitable model forsmall local cloud

Lin Zhou; Chandra Kambhamettu

1998-01-01

38

Operational Cloud-Motion Winds from Meteosat Infrared Images  

Microsoft Academic Search

The displacement of clouds in successive satellite images reflects the atmospheric circulation at various scales. The main application of the satellite-derived cloud-motion vectors is their use as winds in the data analysis for numerical weather prediction. At low latitudes in particular they constitute an indispensible data source for numerical weather prediction.This paper describes the operational method of deriving cloud-motion winds

Johannes Schmetz; Kenneth Holmlund; Joel Hoffman; Bernard Strauss; Brian Mason; Volker Gaertner; Arno Koch; Leo van de Berg

1993-01-01

39

CLIM: A cloud imager to provide sounders with agile sighting  

Microsoft Academic Search

The CLIM (Cloud Imager) infrared camera, currently being defined, has same channels as AVHRR and has been designed to assist sounders by spotting areas of clear sky from a satellite. The article outlines a simulation of CLIM, based on real data, and presents its estimated performances for different spectral band configurations associated with a cloud detection algorithm. The study shows

Thierry L. Trémas; Sarah Guibert; Bruno Lafrance

2009-01-01

40

Cloud-tracked winds from Pioneer Venus OCPP images  

NASA Astrophysics Data System (ADS)

Results are presented on the analysis of the Pioneer Venus Orbiter Cloud Photopolarimeter (OCPP) UV images, covering 80-day periods from 1979 to 1985. The analysis provides a method for determining wind speeds at the cloud level, from the motions of cloud UV features. Data used for tracking the cloud feature motions are described along with the analysis method. The results identified four wave modes: a diurnal solar tide, a semidiurnal solar tide, a '4-day equatorial' wave, and a '5-day midlatitude' wave. The features of these wave modes are described.

Rossow, William B.; del Genio, Anthony D.; Eichler, Timothy

1990-09-01

41

Cloud Image Resolution Enhancement Method Using Loss Information Estimation  

Microsoft Academic Search

\\u000a Image resolution enhancement techniques are required in various multimedia systems for image generation and processing. The\\u000a main problem is an artifact such as blurring in image resolution enhancement techniques. Specially, cloud image have important\\u000a information which need resolution enhancement technique without image quality degradation. To solve the problem, we propose\\u000a error estimation and image resolution enhancement algorithm using low level

Won-Hee Kim; Jong-Nam Kim

2010-01-01

42

Extraction of cloud statistics from whole sky imaging cameras.  

National Technical Information Service (NTIS)

Computer codes have been developed to extract basic cloud statistics from whole sky imaging (WSI) cameras. This report documents, on an algorithmic level, the steps and processes underlying these codes. Appendices comment on code details and on how to ada...

W. P. Kegelmeyer

1994-01-01

43

Hazardous cloud imaging: a new way of using passive infrared  

NASA Astrophysics Data System (ADS)

A modeling and simulation study of the limits of remote detection by passive IR has led to a new concept for the remote detection of hazardous clouds. A passive IR signature model was developed with the Edgewood Research, Development, and Engineering Center IR spectral data bases used as input for chemicals and biologicals and with the atmospheric transmittance model used for Modtran . The cloud travel and dispersion model, VLStrack , was used to simulate chemical and biological clouds. An easily applied spectral discrimination technique was developed with a standard Mathematica version of linear programming. All these were melded with Mathematica to produce images of three threat clouds: Sarin, mustard, and an unnamed biological. The hazardous cloud imager is a spatially scanning Fourier transform IR on the same level of complexity as conventional remote detectors, but is capable of greater sensitivity and moving operation.

Flanigan, Dennis F.

1997-09-01

44

Uneven cloud and fog removing for satellite remote sensing image  

Microsoft Academic Search

Haze is an important influence factor of visible light RS data's obtaining and using. Based on dark channel prior and haze image model, this paper studies the dehaze technology from a single satellite RS image. Aim at the characteristic of uneven cloud in satellite RS image and the problem of the unreasonable estimate for airlight in dehaze method, this paper

Liya Zhou; Zhiyuan Qin

2011-01-01

45

The research on DMSP nighttime cloud image segmentation  

Microsoft Academic Search

In this paper we employ the Integrated Active Contour (IAC) model of vector-value image segmentation and C-V model based on PDE in the segmentation of two channels DMSP nighttime satellite cloud images. The results of segmentation show that the IAC model can integrate the information of each channel throughout the segmentation and can be employed in the image with uneven

Kai Liu; Zheng Kou

2011-01-01

46

Hazardous cloud imaging: a new way of using passive IR  

NASA Astrophysics Data System (ADS)

A Modeling and Simulation study of the limits of remote detection by passive IR has led to a new concept for the remote detection of hazardous clouds. A passive IR signature model was developed using as input the ERDEC IR spectral data bases for chemicals and biologicals, and the atmospheric transmittance model MODTRAN (MODerate resolution TRANSmittance). The cloud travel and dispersion model VLSTRACK (Vapor, Liquid, and Solid TRACKing) was used to simulate chemical and biological clouds. An easily applied spectral discrimination technique was developed using Linear Programming. All of these were melded with MATHEMATICA to produce images of 3 threat clouds: Sarin, mustard and an unnamed biological. (For reasons of space only Sarin is discussed here.) The HAZCI (HAZarous Cloud Imager) is a unique configuration of a spatially scanning Fourier Transform IR on the same level of complexity as the M21, but capable of orders-of-magnitude greater sensitivity and moving operation. The concept provides for automatic detection and operator assisted discrimination for chemical clouds and biological clouds at ranges greater than 50 kms. Both chemical and biological clouds can generally be discriminated from other known battlefield contaminants and from all materials (including biologicals) that are uniformly distributed in the atmosphere; but, specific detection of pathogenic biologicals is not projected at this time.

Flanigan, Dennis F.

1997-07-01

47

Imprints of Molecular Clouds in Radio Continuum Images  

NASA Astrophysics Data System (ADS)

We show radio continuum images of several molecular complexes in the inner Galaxy and report the presence of dark features that coincide with dense molecular clouds. Unlike infrared dark clouds, these features which we call "radio dark clouds" are produced by a deficiency in radio continuum emission from molecular clouds that are embedded in a bath of UV radiation field or synchrotron emitting cosmic-ray particles. The contribution of the continuum emission along different path lengths results in dark features that trace embedded molecular clouds. The new technique of identifying cold clouds can place constraints on the depth and the magnetic field of molecular clouds when compared to those of the surrounding hot plasma radiating at radio wavelengths. The study of five molecular complexes in the inner Galaxy, Sgr A, Sgr B2, radio Arc, the Snake filament, and G359.75-0.13 demonstrates an anti-correlation between the distributions of radio continuum and molecular line and dust emission. Radio dark clouds are identified in Green Bank Telescope maps and Very Large Array images taken with uniform sampling of uv coverage. The level at which the continuum flux is suppressed in these sources suggests that the depth of the molecular cloud is similar to the size of the continuum emission within a factor of two. These examples suggest that high-resolution, high-dynamic-range continuum images can be powerful probes of interacting molecular clouds with massive stars and supernova remnants in regions where the kinematic distance estimates are ambiguous as well as in the nuclei of active galaxies.

Yusef-Zadeh, F.

2012-11-01

48

Imaging Spectroscopy of Magellanic Cloud Planetary Nebulae  

NASA Astrophysics Data System (ADS)

We present an initial analysis of images and slitless spectroscopy of a large sample of LMC and SMC planetary nebulae (PNs), which were obtained in three SNAP surveys with the Space Telescope Imaging Spectrograph over the past 3 years. These surveys have increased the number of Magellanic Cloud PNe that have been imaged with HST by a factor of more than four. The data permit us to determine the nebular dimensions and morphology in the monochromatic light of several emission lines, including those that have traditionally been used for morphological studies in the Galaxy (H-alpha, [N II] 6583 and [O III] 5007), plus others of varying ionization, such as [O I], He I, and [S II]. We find the decline in surface brightness with nebular radius for the aggragate sample can be well characterized by an R-3 law for all observed emission lines, and for both the LMC and SMC PNs. Thus, this relationship holds some promise for constructing a useful distance scale for Galactic PNs. The differing metallicity of the host galaxies makes our comparative study of these PN samples well suited to illuminating the question of Population effects on nebular and stellar evolution. Interestingly, the incidence of asymmetric PNs (which is an indicator of Population I ancestry) in the SMC ( 30%) is significantly lower than that found in the LMC ( 50%), but is more comparible with the fraction found in the Galaxy (26%). The ionized gas in the SMC PNs in our sample are on average denser by a factor of 1.5, and more massive by nearly that same factor than the LMC PNs, which is at least broadly consistent with a slower evolution for SMC PNs. Finally, we examine the curious tendency of I([O III] 5007)/I(H-beta) for PNs in the LMC to exceed that of the SMC by about 65%. One might naively expect the ratio to be reversed, owing to the lower average chemical abundances (and therefore higher average Te) in the SMC PNs. Photoionization modelling suggests that other emission lines, such as C IV 1550, may provide the dominant cooling mechanism for these nebulae, which would then allow for a lower emissivity in 5007. Support for this work was provided by NASA through grants GO-08271, GO-08663, and GO-09077 from ST ScI.

Shaw, R. A.; Stanghellini, L.; Mutchler, M.; Balick, B.; Blades, J. C.; Villaver, E.

2002-12-01

49

Cloud properties observed by Global Imager (GLI)  

NASA Astrophysics Data System (ADS)

The data analyses of the ADEOS-II (Midori-II) GLI data have started. The optical and microphysical properties of warm water and cold ice clouds were retrieved by use of originally developed GLI data analysis algorithms. On the one-month mean results of warm water cloud in April 2003, very thick cloud optical thickness appeared in the east coast of the North America, the East Europe, and the South-East Asia. The moderately optically thick area spread over the Atlantic Ocean and West to Middle Pacific oceans. The effective radius was smaller on the continents and coastal area than ocean area. Especially, the South-East Asia to the middle pacific area where often covered with aerosols coming from continent in April, is the region of the smaller cloud effective particles. For the cirrus clouds, the smaller effective radii and larger effective radii can be obtained in low-to-mid and mid-to-high latitude area, respectively. Very low cloud top temperatures around 210K were often observed in the tropics. Warmer cloud top temperatures ranging from 220 to 240K were widely seen both over continental and oceanic area in mid-to-high latitude area.

Nakajima, Takashi Y.; Nakajima, Teruyuki; Katagiri, Shuichiro; Takamura, Tamio; Okada, Itaru

2004-11-01

50

Automatic tracking and characterization of multiple moving clouds in satellite images  

Microsoft Academic Search

Investigating the characteristics of mesoscale convective clouds based on satellite infrared images is very important for strong precipitation forecast. This paper proposes a new method for cloud identification, tracking and characterization using time-varying satellite infrared cloud image sequences. After clouds are identified using image processing techniques, a couple of features are extracted as their representations, based on which feature correspondences

Yubin Yang; Hui Lin; Zhongyang Guo; Zhaobao Fang; Jixi Jiang

2004-01-01

51

Cloud statistics measured with a ground-based Infrared Cloud Imager  

Microsoft Academic Search

The Infrared Cloud Imager (ICI) is a ground-based instrument for measuring spatial cloud statistics. ICI uses an uncooled microbolometer detector array to record downwelling infrared atmospheric emission in the 8-14 mum spectral band with 320times240 pixels. The ICI system has been deployed at Poker Flat Research Range near Fairbanks, Alaska, at Barrow, Alaska, and in central Oklahoma. With a water

Joseph A. Shaw; Brentha Thurairajah; Kohei Mizutani

2004-01-01

52

Low level cloud motion vectors from Kalpana-1 visible images  

NASA Astrophysics Data System (ADS)

Till now low-level winds were retrieved using Kalpana-1 infrared (IR) images only. In this paper, an attempt has been made to retrieve low-level cloud motion vectors using Kalpana-1 visible (VIS) images at every half an hour. The VIS channel provides better detection of low level clouds, which remain obscure in thermal IR images due to poor thermal contrast. The tracers are taken to be 15 × 15 pixel templates and hence each wind corresponds to about 120 km × 120 km at sub-satellite point. Multiplet based wind retrieval technique is followed for VIS wind derivation. However, for height assignment of VIS winds, collocated IR image is used. Due to better contrast between cloud and ocean surface, the low level atmospheric flow is captured better as compared to IR winds. The validation of the derived VIS winds is done with Global Forecast System (GFS) model winds and Oceansat-II scatterometer (OSCAT) winds.

Kaur, Inderpreet; Deb, S. K.; Kishtawal, C. M.; Pal, P. K.; Kumar, Raj

2013-08-01

53

Non-Linear Prediction Algorithm of Satellite Cloud Images  

Microsoft Academic Search

In order to solve the problem of low prediction accuracy of conventional prediction algorithm of satellite cloud images. The spectrum-space reconstruction and phase-space prediction algorithm are proposed, the algorithm takes full account of that the cloud moves, grows and dissipates in the non-linear and nonstationary process, the mathematical principles of the algorithm and the process of numerical realization is given.

Jiang Zhuhui

2009-01-01

54

The radiative consistency of Atmospheric Infrared Sounder and Moderate Resolution Imaging Spectroradiometer cloud retrievals  

NASA Astrophysics Data System (ADS)

The consistency of cloud top temperature (TC) and effective cloud fraction (f) retrieved by the Atmospheric Infrared Sounder (AIRS)/Advanced Microwave Sounding Unit (AMSU) observation suite and the Moderate Resolution Imaging Spectroradiometer (MODIS) on the EOS-Aqua platform are investigated. Collocated AIRS and MODIS TC and f are compared via an "effective scene brightness temperature" (Tb,e). Tb,e is calculated with partial field of view (FOV) contributions from TC and surface temperature (TS), weighted by f and 1-f, respectively. AIRS reports up to two cloud layers while MODIS reports up to one. However, MODIS reports TC, TS, and f at a higher spatial resolution than AIRS. As a result, pixel-scale comparisons of TC and f are difficult to interpret, demonstrating the need for alternatives such as Tb,e. AIRS-MODIS Tb,e differences (?Tb,e) for identical observing scenes are useful as a diagnostic for cloud quantity comparisons. The smallest values of ?Tb,e are for high and opaque clouds, with increasing scatter in ?Tb,e for clouds of smaller opacity and lower altitude. A persistent positive bias in ?Tb,e is observed in warmer and low-latitude scenes, characterized by a mixture of MODIS CO2 slicing and 11-?m window retrievals. These scenes contain heterogeneous cloud cover, including mixtures of multilayered cloudiness and misplaced MODIS cloud top pressure. The spatial patterns of ?Tb,e are systematic and do not correlate well with collocated AIRS-MODIS radiance differences, which are more random in nature and smaller in magnitude than ?Tb,e. This suggests that the observed inconsistencies in AIRS and MODIS cloud fields are dominated by retrieval algorithm differences, instead of differences in the observed radiances. The results presented here have implications for the validation of cloudy satellite retrieval algorithms, and use of cloud products in quantitative analyses.

Kahn, Brian H.; Fishbein, Evan; Nasiri, Shaima L.; Eldering, Annmarie; Fetzer, Eric J.; Garay, Michael J.; Lee, Sung-Yung

2007-05-01

55

Segmentation for Satellite Cloud Image by Combining Fractal Features and Continuous Wavelet Transform  

Microsoft Academic Search

A kind of algorithm to segment typhoon cloud image is proposed. First, fractal feature of typhoon cloud image is used to recognize center dense cloud region so that an initial segmentation region (ISR) including typhoon cloud series can be determined. Morphological operator and median filter are used to reduce latitude lines and amplitude lines in the ISR so as to

Changjiang Zhang; Juan Lu; Sufang Shu

2009-01-01

56

Describing the NPOESS Preparatory Project Visible/Infrared Imaging Radiometer Suite (VIIRS) Cloud Environmental Data Records  

NASA Astrophysics Data System (ADS)

The Visible/Infrared Imaging Radiometer Suite (VIIRS) is one of the instruments that make up the suite of sensors on the NPOESS Preparatory Project (NPP) scheduled to launch in 2010. VIIRS will produce seven Environmental Data Records (EDRs) describing cloud properties. The VIIRS Cloud EDRs include the Cloud Optical Thickness (COT), Cloud Effective Particle Size Parameter (CEPS), Cloud Top Pressure (CTP), Cloud Top Height (CTH), Cloud Top Temperature (CTT), Cloud Cover/Layers (CCL), and Cloud Base Height (CBH). This paper will describe the VIIRS algorithms used to generate these EDRs and provide a current estimate of performance based on pre-Launch test data.

Hoffman, C.; Guenther, B.; Kilcoyne, H.; Mineart, G.; St. Germain, K.; Reed, B.

2008-12-01

57

Climatic shift in patterns of shallow clouds over the Amazon  

NASA Astrophysics Data System (ADS)

The Amazon rain forest has experienced dramatic changes in the past 50 years due to active deforestation. As of 2001, 15% of the 4,000,000 km2 Brazilian Amazon has been deforested [Instituto Nacional de Pesquisas Espaciais (INPE), 2003]; each year, agricultural exploitation claims an estimated 13,000 km2 of tropical forest [Achard et al., 2002]. In this paper we investigate the climatic effects caused by the observed change of the physical characteristics of the land surface (i.e., increased surface albedo, decreased root-zone depth, decreased surface roughness and decreased leaf-area index). More precisely, we examine the spatial correspondence of shallow cumulus clouds with deforestation. Through the creation of an 8-year record of thrice daily shallow cumulus cloud cover at 1 km resolution from multi-spectral satellite imagery, we quantitatively show the existence of a significant climatic shift in shallow cloudiness patterns associated with deforestation. This shift manifests itself as an enhancement of shallow cumuli over deforested patches, and has potentially important climatic, hydrologic and ecological implications.

Chagnon, F. J. F.; Bras, R. L.; Wang, J.

2004-12-01

58

Cloud detection with the Earth Polychromatic Imaging Camera (EPIC)  

NASA Astrophysics Data System (ADS)

The Earth Polychromatic Imaging Camera (EPIC) on board the Deep Space Climate Observatory (DSCOVR) would provide a unique opportunity for Earth and atmospheric research due not only to its Lagrange point sun-synchronous orbit, but also to the potential for synergistic use of spectral channels in both the UV and visible spectrum. As a prerequisite for most applications, the ability to detect the presence of clouds in a given field of view, known as cloud masking, is of utmost importance. It serves to determine both the potential for cloud contamination in clear-sky applications (e.g., land surface products and aerosol retrievals) and clear-sky contamination in cloud applications (e.g., cloud height and property retrievals). To this end, a preliminary cloud mask algorithm has been developed for EPIC that applies thresholds to reflected UV and visible radiances, as well as to reflected radiance ratios. This algorithm has been tested with simulated EPIC radiances over both land and ocean scenes, with satisfactory results. These test results, as well as algorithm sensitivity to potential instrument uncertainties, will be presented.

Meyer, K.; Marshak, A.; Lyapustin, A.; Torres, O.; Wang, Y.

2011-12-01

59

Segmentation for Main Body of Typhoon from Satellite Cloud Image by Genetic Algorithm in Contourlet Domain  

Microsoft Academic Search

A single-threshold algorithm to segment typhoon cloud image is proposed based on contourlet transform and Bezier histogram. In order to enhance the contrast and reduce noise of the original typhoon cloud image, discrete contourlet transform is done to the original typhoon cloud image. The contrast is enhanced in the low frequency components based on non-linear transform in the contourlet domain.

Changjiang Zhang; Xiaoqin Lu; Juan Lu; Jianping Xu

2008-01-01

60

Locating the Typhoon Center from the IR Satellite Cloud Images  

Microsoft Academic Search

The typhoon center location is important for weather forecast and typhoon analysis. However, the appearance of the typhoon center as viewed from the IR satellite cloud image will have different shape and size at different time. At the genesis stage, the center of a typhoon is quite ambiguous. When it reached to certain strength, there will be an eye appeared

Tsang-Long Pao; Jun-Heng Yeh; Min-Yen Liu; Yung-Chang Hsu

2006-01-01

61

Solar energy mapping by using cloud images received from GMS  

Microsoft Academic Search

Solar energy maps that indicate the wide-ranging spatial distribution of solar irradiation are required by the researchers of the solar power systems. However, the irradiation measurement networks at ground level are not enough to obtain reliable information of the solar energy distribution in the world. On the other hand, geostationary meteorological satellites (GMS) have provided the images of cloud fields

Kenji Otani; Tadashi Saitoh; I. Tsuda; K. Kurokawa

1994-01-01

62

Infrared Spectral Imaging of Martian Clouds and Ices  

Microsoft Academic Search

Multispectral images of Mars, taken at the NASA Infrared Telescope Facility (IRTF) near and at the 1995 opposition, are used to identify and track its atmospheric clouds and ground ices. Band depth mapping is used to help distinguish between the composition of volatiles and provide a check for the techniques of principal components analysis (PCA) and linear mixture modeling (LMM).

David R. Klassen; James F. Bell; Robert R. Howell; Paul E. Johnson; William Golisch; Charles D. Kaminski; David Griep

1999-01-01

63

Extraction of cloud statistics from whole sky imaging cameras  

SciTech Connect

Computer codes have been developed to extract basic cloud statistics from whole sky imaging (WSI) cameras. This report documents, on an algorithmic level, the steps and processes underlying these codes. Appendices comment on code details and on how to adapt to future changes in either the source camera or the host computer.

Kegelmeyer, W.P. Jr.

1994-03-01

64

Objective Quality Assessment Measurement for Typhoon Cloud Image Enhancement  

Microsoft Academic Search

There are kinds of enhancement methods for satellite image, however, visual quality of them are basically assessed by human\\u000a eyes. This can result in wrong identification. This will result in wrong prediction for center and intensity of the typhoon.\\u000a It is necessary to find an objective measure to evaluate the visual quality for enhanced typhoon cloud image. In order to

Changjiang Zhang; Juan Lu; Jinshan Wang

2009-01-01

65

Enhanced IR imagery of cloud top temperatures, heights, cloud types and organizational patterns  

NSDL National Science Digital Library

Dorothea Ivanova, Embry-Riddle Aeronautical University Summary The object of this activity is to find enhanced IR imagery, to interpret cloud top temperatures and heights and to identify cloud types and ...

Ivanova, Dorothea

66

Images of the Cyanopolyyne Emission in the Taurus Molecular Cloud  

NASA Astrophysics Data System (ADS)

We present images of the Cyanopolyyne Peak in the Taurus Molecular Cloud, in which the structure and composition of the cloud are visible. Cyanopolyynes are long organic molecules that are formed in abundance within the TMC, and we have modeled their intensities through observations with the Green Bank Telescope. The particular molecules we display are HC5N, HC7N, and HC9N. In measuring their properties, we have been able to deduce the temperature of the cloud to be 5.5K +/- 0.5K at the location of peak emission. This is important to the field of astrochemistry and astrobiology, as these long hydrocarbons are important precursors to the molecules that form life.

Woolard, Kyle D.; Langston, G.; Mennicke, C.

2010-05-01

67

The Research and Application of Content-Based Satellite Cloud Image Retrieval  

Microsoft Academic Search

Content-based satellite cloud image retrieval is a very important problem in image processing and analysis field. Traditional image retrieval method has some limitation, for realized image retrieval accurately and quickly, the CBIR method is an adaptive method. For achieved good retrieval result, some of the pretreatment method of the satellite cloud image was used, and the experiment effect was shown.

Wei ShangGuan; YanLing Hao; YanHong Tang; Yi Zhu

2007-01-01

68

Images of optically thick artificial aerosol clouds in the near-Earth space  

NASA Astrophysics Data System (ADS)

The images were constructed for three aerosol cloud distribution types: uniform, one with a cavity in the center (shell) and one with a dense core (core with 'wings'). Differences between images of optically thich and optically thin clouds for these three distribution types of particles and various view angles are discussed. Calculated results are compared with experimental data from aerosol clouds observations.

Belikov, Yu. E.; Gurvich, A. V.

1995-04-01

69

Estimating cloud top height and spatial displacement from scan-synchronous GOES images using simplified IR-based stereoscopic analysis  

Microsoft Academic Search

An efficient method for estimating cloud top heights and correcting cloud image spatial displacements was developed. The method applies stereoscopic analysis to a pair of scan-synchronous infrared cloud images received from two GOES satellites using a piecewise linear approximation of the relationship between height and infrared brightness temperature of top of the cloud element. The algorithm solves for cloud top

Shayesteh E. Mahani; Xiaogang Gao; Soroosh Sorooshian; Bisher Imam

2000-01-01

70

Flux Calibration Of Images Of The Large Magellanic Cloud  

NASA Astrophysics Data System (ADS)

The Magellanic Cloud Emission Line Survey (MCELS) is a survey of two of our nearest neighboring galaxies, the Large and Small Magellanic Clouds (LMC and SMC, respectively). Data has been obtained in the emission-lines of [O III] 5007A, H-alpha 6563A, and [S II] 6724A, as well as green and red continuum filters. These data will allow us to investigate the physical properties of the interstellar medium (ISM) in these galaxies. To this end, there are 1250 images (250/filter) in a 9degx9deg field toward the LMC. These data have overscan-corrected, trimmed, zero-subtracted, and flat-fielded. This project involves determining astrometric solutions for all fields, sky-subtraction, flux-calibration, continuum subtraction, and mosaicking the data into 1 image per filter.

Bryant, Mark A.; Points, S.

2011-01-01

71

Typhoon Cloud Image Enhancement by Differential Evolution Algorithm and Arc-Tangent Transformation  

Microsoft Academic Search

\\u000a This paper proposed an image enhancement method based on the differential evolution algorithm (DEA) and arc tangent transformation\\u000a for typhoon cloud images. Because of the effect of sensors or other factors, the contrast of the satellite cloud images received\\u000a directly by satellite was not acceptable. In view of the features of typhoon cloud images, especially the feature of gray\\u000a level

Bo Yang; Changjiang Zhang

2010-01-01

72

Operational cloud-motion winds from Meteosat infrared images  

SciTech Connect

The displacements of clouds in successive satellite images reflects the atmospheric circulation at various scales. The main application of the satellite-derived cloud-motion vectors is their use as winds in the data analysis for numerical weather prediction. At low latitudes in particular they constitute an indispensible data source for numerical weather prediction. This paper describes the operational method of deriving cloud-motion winds (CMW) from the IR images (10.5-12.5 [mu]m) of the European geostationary Meteosat satellites. The method is automatic, that is, the cloud tracking uses cross correlation and the height assignment is based on satellite observed brightness temperature and a forecast temperature profile. Semitransparent clouds undergo a height correction based on radiative forward calculations and simultaneous radiance observations in both the IR and water vapor (5.7-7.1 [mu]m) channel. Cloud-motion winds are subject to various quality checks that include manual quality controls as the last step. Typically about 3000 wind vectors are produced per day over four production cycles. This paper documents algorithm changes and improvements made to the operational CMWs over the last five years. The improvements are shown by long-term comparisons with both collocated radiosondes and the first guess of the forecast model of the European Centre for Medium-Range Weather Forecasts. In particular, the height assignment of a wind vector and radiance filtering techniques preceding the cloud tracking have ameliorated the errors in Meteosat winds. The slow speed bias of high-level CMWs (<400 hPa) in comparison to radiosonde winds has been reduced from about 4 to 1.3 m s[sup [minus]1] for a mean wind speed of 24 m s[sup [minus]1]. Correspondingly, the rms vector error of Meteosat high-level CMWs decreased from about 7.8 to 5 m s[sup [minus]1]. Medium-and low-level CMWs were also significantly improved. 56 refs., 12 figs., 2 tabs.

Schmetz, J.; Holmlund, K.; Mason, B.; Gaertner, V.; Koch, A.; Van De Berg, L. (European Space Agency, Darmstadt (Germany)); Hoffman, J. (METEO France, Toulouse (France)); Strauss, B. (European Centre for Medium-Range Weather Forecasts, Berkshire (United Kingdom))

1993-07-01

73

A Spitzer Imaging Survey of the Entire Taurus Molecular Cloud  

NASA Astrophysics Data System (ADS)

The star-forming clouds nearest to our Sun are located 140 pc away in Taurus. Lacking young stellar clusters and luminous OB stars, Taurus hosts a distributed mode of star formation that has proven particularly amenable to observational and theoretical study. Yet despite its importance to the past two decades of star formation research, only fragments of the Taurus clouds are currently planned for mapping with the Spitzer Space Telescope. We propose to make a comprehensive, unbiased map of the TMC using MIPS and IRAC, covering an area of 28 square degrees. Achieving sensitivities 20 times better than ISOCAM at 8 microns, and 200 times better than IRAS at 24 microns, these maps will reveal the lowest luminosity members of the young stellar population: collapsing protostars, young substellar objects, and edge-on disks. Due to the importance of this dataset in establishing new objects for followup with Spitzer and HST, we will waive our proprietary rights to the data and make the images and source catalogs available to the community upon completion of the survey. This survey will be a central and crucial part of a multiwavelength study of the Taurus cloud complex that we are already conducting using XMM and CFHT. The 5 - 7 photometry data points we will obtain from Spitzer will allow us to characterize the circumstellar environment of each object, and, in conjunction with NIR photometry, construct a complete luminosity function for the cloud members that will place constraints on the initial mass function.

Padgett, Deborah; Allen, Lori; Audard, Marc; Bouvier, Jerome; Brooke, Tim; Carey, Sean; Dougados, Catherine; Evans, Neal; Grosso, Nicolas; Guedel, Manuel; Harvey, Paul; Hillenbrand, Lynne; Hines, Dean; Keene, Jocelyn; Latter, Bill; Lonsdale, Carol; Menard, Francois; Myers, Phil; Noreiga-Crespo, Alberto; Rebull, Luisa; Shupe, David; Skinner, Steve; Stapelfeldt, Karl; Strom, Steve; Wolf, Sebastian

2004-09-01

74

High Quality Typhoon Cloud Image Restoration by Combining Genetic Algorithm with Contourlet Transform  

SciTech Connect

An efficient typhoon cloud image restoration algorithm is proposed. Having implemented contourlet transform to a typhoon cloud image, noise is reduced in the high sub-bands. Weight median value filter is used to reduce the noise in the contourlet domain. Inverse contourlet transform is done to obtain the de-noising image. In order to enhance the global contrast of the typhoon cloud image, in-complete Beta transform (IBT) is used to determine non-linear gray transform curve so as to enhance global contrast for the de-noising typhoon cloud image. Genetic algorithm is used to obtain the optimal gray transform curve. Information entropy is used as the fitness function of the genetic algorithm. Experimental results show that the new algorithm is able to well enhance the global for the typhoon cloud image while well reducing the noises in the typhoon cloud image.

Zhang Changjiang; Wang Xiaodong [College of Mathematics, Physics and Information Engineering, Zhejiang Normal University, Jinhua (China)

2008-11-06

75

Analysis of gravity waves structures visible in noctilucent cloud images  

NASA Astrophysics Data System (ADS)

The noctilucent clouds (NLC) are high-altitude bright cloud formations visible under certain conditions from high-latitude places during the summer months. Even if the exact nature of these clouds still remains a mystery, they are an efficient tracer of the dynamic processes at their level, particularly the gravity waves propagating from the stratosphere through the mesopause layer. In this paper, we describe a technique developed to analyze the structures visible in the NLC images taken every summer night since 2004 from Stockholm, Sweden (59.4°N). The parameters of 30 short-period gravity wave events have been measured and compared with older datasets obtained mostly from low and mid-latitude sites, using airglow imaging techniques. The horizontal wavelengths are in good agreement with previous results while the observed horizontal phase speeds exhibit smaller values than for other sites. The directionality of the waves presents strong poleward preference, traditionally observed during the summer season. This anisotropy and the difference in the phase speed distribution cannot be explained by the filtering due to the background wind field but more probably by the position of the gravity waves sources, located to the south of the observation site.

Pautet, P.-D.; Stegman, J.; Wrasse, C. M.; Nielsen, K.; Takahashi, H.; Taylor, M. J.; Hoppel, K. W.; Eckermann, S. D.

2011-09-01

76

Image processing and pattern recognition in textiles  

Microsoft Academic Search

Image processing and pattern recognition have been successfully applied in many textile related areas. For example, they have been used in defect detection of cotton fibers and various fabrics. In this work, the application of image processing into animal fiber classification is discussed. Integrated into\\/with artificial neural networks, the image processing technique has provided a useful tool to solve complex

Lingxue Kong; F. H. She

2001-01-01

77

Cloud Cover/Layers. Visible/Infrared Imager/Radiometer Suite Algorithm Theoretical Basis Document. Version 5, Revision 1.  

National Technical Information Service (NTIS)

Total cloud cover and layered cloud structure are basic components of an image analysis procedure called 'nephanalysis'. Many operational users of cloud data require analysis of the extent, type, and physical characteristics of vertically distributed clou...

H. L. Huang R. Slonaker H. M. Woolf R. L. Solomon

2002-01-01

78

Edge features extraction from 3D laser point cloud based on corresponding images  

NASA Astrophysics Data System (ADS)

An extraction method of edge features from 3D laser point cloud based on corresponding images was proposed. After the registration of point cloud and corresponding image, the sub-pixel edge can be extracted from the image using gray moment algorithm. Then project the sub-pixel edge to the point cloud in fitting scan-lines. At last the edge features were achieved by linking the crossing points. The experimental results demonstrate that the method guarantees accurate fine extraction.

Li, Xin-feng; Zhao, Zi-ming; Xu, Guo-qing; Geng, Yan-long

2013-09-01

79

Application of Principal Component Extraction technique in processing cloud images from Chinese FY1 satellite  

Microsoft Academic Search

Principal component extraction technique is employed to process cloud images from 10-channel radiometer onboard the Chinese FY-1 polar-orbiting meteorological satellites. The results suggest that the consensus technique can concentrate the prominent distribution features of the grey shades of the targets, including clouds, landform and oceans shown on the 10 channel images into a single image which can be then used

Zhenhui Wang; Xiaofang Pei

2009-01-01

80

Cloud Thickness and Satellite Images (title provided or enhanced by cataloger)  

NSDL National Science Digital Library

This applet explores how the thickness of a cloud changes the way it looks from a satellite. The image is in the visible part of the spectrum, and the radiant energy is a function of not just temperature, as in the case of infrared images. The cloud thickness, its effective brightness, and the surface temperature can be modified while observing the satellite image.

Whittaker, Tom; Ackerman, Steve

81

Image normalization for pattern recognition  

Microsoft Academic Search

In general, there are four basic forms of distortion in the recognition of planar patterns: translation, rotation, scaling and skew. In this paper, a normalization algorithm has been developed which transforms pattern into its normal form such that it is invariant to translation, rotation, scaling and skew. After normalization, the recognition can be performed by a simple matching method. In

Soo-chang Pei; Chao-nan Lin

1995-01-01

82

Finding Patterns in Image Databases  

Microsoft Academic Search

\\u000a Image is one of the most widely used media in the world. Many real-life applications have been designed to process and analyze\\u000a large number of images. For example, in the terrain matching applications, we have thousands of images that are returned by\\u000a the satellite which need to be processed and mapped; in the archaeology domain, all ancient artifacts are photographed

Wynne Hsu; Mong Li Lee; Jing Dai

83

Distortion of the HBT images by meson clouds  

NASA Astrophysics Data System (ADS)

We study the effects of mesonic final state interactions on the Hanbury Brown and Twiss intensity interferometry in ultra-relativistic heavy ion collisions. Modification of the one-body amplitude of emitted mesons while traversing a cloud of other mesons is estimated adopting the semiclassical approximation. The difference of the phase shifts causes a distortion of the images reflecting the two particle interference. Many body interaction due to the strong interaction among a particle and the rest of the system except for baryons is modeled with a optical potential which incorporates both coherent forward scattering and the absorption due to the incoherent scattering in the clouds. We found distortion of the images in the direction of both outward and sideward due to the real part of optical potential. Repulsive potential elongate the images in the outward direction, and attractive potential stretches in the sideward direction. However, the surface-dominated emission in the existence of the imaginary part of optical potential weakens the effect of the real part. The distortion is effective below around 100 MeV and weakens at high momentum regime. K. Hattori, T. Matsui, nucl-th/0905.3210

Hattori, Koichi; Matsui, Tetsuo

2009-10-01

84

Imaging Spatial Correlations of Rydberg Excitations in Cold Atom Clouds  

SciTech Connect

We use direct spatial imaging of cold {sup 85}Rb Rydberg atom clouds to measure the Rydberg-Rydberg correlation function. The results are in qualitative agreement with theoretical predictions [F. Robicheaux and J. V. Hernandez, Phys. Rev. A 72, 063403 (2005)]. We determine the blockade radius for states 44D{sub 5/2}, 60D{sub 5/2}, and 70D{sub 5/2} and investigate the dependence of the correlation behavior on excitation conditions and detection delay. Experimental data hint at the existence of long-range order.

Schwarzkopf, A.; Sapiro, R. E.; Raithel, G. [FOCUS Center, Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2011-09-02

85

Multiscale image enhancement of chromosome banding patterns  

Microsoft Academic Search

Visual examination of chromosome banding patterns is an important means of chromosome analysis. Cytogeneticists compare their patient's chromosome image against the prototype normal\\/abnormal human chromosome banding patterns. Automated chromosome analysis instruments facilitate this by digitally enhancing the chromosome images. Currently available systems employing traditional highpass\\/bandpass filtering and\\/or histogram equalization are approximately equivalent to photomicroscopy in their ability to support the

Qiang Wu; Kenneth R. Castleman

1996-01-01

86

Image Recognition Based on Biometric Pattern Recognition  

NASA Astrophysics Data System (ADS)

A new method, biomimetric pattern recognition, is mentioned to recognize images. At first, the image is pretreatment and feature extraction, then a high vector is got. A biomimetric pattern recognition model is designed. The judgment function is used to discriminate the classification of the samples. It is showed that the method is effective for little samples by experiment. It would be useful in many fields in future.

Sun, Shuliang; Chen, Zhong; Liu, Chenglian; Guo, Yongning; Lin, Xueyun

2011-09-01

87

WFC3 Imaging of Protostars in the Orion Molecular Clouds  

NASA Astrophysics Data System (ADS)

The Orion molecular clouds contain the largest sample of protostars within 500 pc of the Sun. We present results from HST/WFC3 imaging of 124 fields in Orion containing previously identified protostars. Combined with imaging from the HST/NICMOS camera, these data provide high resolution 1.6 micron images of 260 protostars. These data are being combined with Spitzer and Herschel imaging and spectra to construct complete spectral energy distributions from 1.6 to 160 microns for the entire sample of protostars. We present a search for companions to the protostars using the WFC3/NICMOS imaging, which has the capability to identify objects at separations as small as 100 AU. We present here the mean surface density of sources as a function of distance from the protostars and use this to identify candidate companions. The 1.6 micron photometry is combined with 3.6 micron data from Spitzer and the IRTF to measure the colors of the candidate companions and determine whether they are protostars. We demonstrate that the longer wavelength observations are essential for identifying the most deeply embedded companions. We also discuss the incidence of scattered light nebulae surrounding the protostars, as detected in the WFC3/NICMOS images. These nebulae, which often show a bipolar morphology, are created by light scattered from the infalling envelope.

Kounkel, Marina; Megeath, T.; Fischer, W.; Poteet, C.

2012-01-01

88

Fringe pattern denoising via image decomposition.  

PubMed

Filtering off noise from a fringe pattern is one of the key tasks in optical interferometry. In this Letter, using some suitable function spaces to model different components of a fringe pattern, we propose a new fringe pattern denoising method based on image decomposition. In our method, a fringe image is divided into three parts: low-frequency fringe, high-frequency fringe, and noise, which are processed in different spaces. An adaptive threshold in wavelet shrinkage involved in this algorithm improves its denoising performance. Simulation and experimental results show that our algorithm obtains smooth and clean fringes with different frequencies while preserving fringe features effectively. PMID:22297373

Fu, Shujun; Zhang, Caiming

2012-02-01

89

The benefit of limb cloud imaging for infrared limb sounding of tropospheric trace gases  

Microsoft Academic Search

Advances in detector technology enable a new generation of infrared limb sounders to measure 2-D images of the atmosphere. A proposed limb cloud imager (LCI) mode will detect clouds with a spatial resolution unprecedented for limb sounding. For the inference of temperature and trace gas distributions, detector pixels of the LCI have to be combined into super-pixels which provide the

S. Adams; R. Spang; P. Preusse; G. Heinemann

2009-01-01

90

A Structural-Stochastic Model for the Analysis and Synthesis of Cloud Images  

Microsoft Academic Search

A structural-stochastic image model is developed for the analysis and synthesis of cloud images. The ability of the model to characterize the visual appearance of cloud fields observed by satellite with a limited number of parameters is demonstrated. The model merges structural and stochastic information, the stochastic model acting as a local statistical operator applied to the output of the

Louis Garand; James A. Weinman

1986-01-01

91

Image processing methods for predicting the time of cloud shadow arrivals to photovoltaic systems  

Microsoft Academic Search

This document presents a combination of image processing tools used for detecting clouds from sky images and for predicting the arrival time of cloud shadows to an area of interest, for example an area of solar panels. Solar panels are used to produce energy from the sun in areas without access to electricity from central power plants and are increasingly

Yazmin Najera; Doug R. Reed; W. Mack Grady

2011-01-01

92

Textural analysis for the detection of dust clouds from infrared satellite images  

NASA Astrophysics Data System (ADS)

The remote sensing constitutes a vast field of study whose repercussions are many and varied on environmental management. The phenomenon of dust clouds is a major climatic event in Africa. But the observation means of this phenomenon are still too much limited. The development of an approach consisting in the detection of dust clouds from satellite images can be a solution. In this work, we present a new approach for dust clouds detection in the infrared images coming from the METEOSAT satellite. It is then proved necessary of finding automatic or semi-automatic analysis methods to assist their detection and interpretation. Thus we are interested in image fusion methods for detection structures in the images. In this paper, we present some statistical methods which enable to extract texture features from the images. Then, we describe the method used for selection the best attributes for the images segmentation into three classes: "water clouds", "ocean" and "continent". We then use a method which enable us to segment the class "continent" of the image for dust clouds detection. Finally, we compare our results with another one which shows the zone of presence or absence of dust clouds. This comparison shows that we are in concord because visually, we have a good analogy of shape on the dust clouds zone as well as on the part without dust clouds.

Diop, Oumar; Kpalma, Kidiyo; Ronsin, Joseph

2006-11-01

93

Motion segmentation and cloud tracking on noisy infrared image sequences  

Microsoft Academic Search

Aerial surveillance is an issue of key importance for warship protection. In addition to radar systems, infrared surveillance sensors represent an interesting alternative for remote observation. In this paper, we study such a system and an original approach to the tracking of complex cloudy patterns in noisy infrared image sequences is proposed. We have paid particular attention to robustness with

Ronan Fablet; Philippe Rostaing; Christophe Collet

1998-01-01

94

An assessment of Multiangle Imaging Spectroradiometer (MISR) stereo-derived cloud top heights and cloud top winds using ground-based radar, lidar, and microwave radiometers  

Microsoft Academic Search

(1) In this article stereoscopically derived cloud top heights and cloud winds estimated from the Multiangle Imaging Spectroradiometer (MISR) are assessed. MISR is one of five instruments on board the NASATerra satellite. The cloud top height assessment is based on a comparison of more than 4 years of MISR retrievals with that derived from ground-based radar and lidar systems operated

Roger T. Marchand; Thomas P. Ackerman; Catherine Moroney

2007-01-01

95

An assessment of Multiangle Imaging Spectroradiometer (MISR) stereo-derived cloud top heights and cloud top winds using ground-based radar, lidar, and microwave radiometers  

Microsoft Academic Search

In this article stereoscopically derived cloud top heights and cloud winds estimated from the Multiangle Imaging Spectroradiometer (MISR) are assessed. MISR is one of five instruments on board the NASA Terra satellite. The cloud top height assessment is based on a comparison of more than 4 years of MISR retrievals with that derived from ground-based radar and lidar systems operated

Roger T. Marchand; Thomas P. Ackerman; Catherine Moroney

2007-01-01

96

Aerosol patterns and aerosol-cloud-interactions off the West African Coast based on the A-train formation  

NASA Astrophysics Data System (ADS)

In this study, spatial and temporal aerosol patterns off the Western African coast are characterized and related to cloud properties, based on satellite data Atmospheric aerosols play a key role in atmospheric processes and influence our environmental system in a complex way. Their identification, characterization, transport patterns as well as their interactions with clouds pose major challenges. Especially the last aspect reveals major uncertainties in terms of the Earth's radiation budget as reported in the IPCC's Fourth Assessment Report (IPCC, 2007). Western and Southern Africa are dominated by two well-known source types of atmospheric aerosols. First, the Saharan Desert is the world's largest aeolian dust emitting source region. Second, biomass burning aerosol is commonly transported off-shore further south (Kaufman et al., 2005). Both aerosol types influence Earth's climate in different manners and can be detected by the MODIS (MODerate resolution Imaging Spectrometer) sensor onboard the EOS platforms as they propagate to the Central and Southern Atlantic. The motivation of this study was to reveal the seasonal pattern of the Saharan dust transport based on an observation period of 11 years and trying to explain the meteorological mechanisms. North African dust plumes are transported along a latitude of 19°N in July and 6°N in January. The seasonally fluctuating intensities adapt to the annual cycle of wind and precipitation regimes. A strong relationship is found between the spatial shift of the Azores High and the Saharan dust load over the middle Atlantic Ocean. Monthly Aerosol Optical Thickness products of Terra MODIS and NCEP-DOE (National Centers for Environmental Predictions) Reanalysis II data are used for this purpose. The relationship between aerosol and cloud droplet parameters is blurred by high sensitivities to aerosol size and composition (Feingold, 2003; McFiggans et al., 2006) as well as meteorological context (Ackerman et al., 2004). Satellite data from the A-train formation, including the Aqua, CloudSat and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) are used to analyze aerosol-cloud-interactions in detail, along with re-analysis data to constrain by meteorological conditions. Information about the vertical and geographical distribution of different aerosol types and cloud parameters will lead to a process-oriented understanding of these issues on a regional scale. Ackerman, A., Kirkpatrick, M., Stevens, D., & Toon, O. (2004). The impact of humidity above stratiform clouds on indirect aerosol climate forcing. Nature, 432(December), 1014-1017. doi:10.1038/nature03137.1. Feingold, G. (2003). First measurements of the Twomey indirect effect using ground-based remote sensors. Geophysical Research Letters, 30(6), 1287. doi:10.1029/2002GL016633 IPCC. (2007). Climate Change 2007: The Physical Science Basis. Contribution of Working group I to the Fourth Assessment Report of the Interfovernmental Panel on climate Change. Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Kaufman, Y. J., Koren, I., Remer, L. A., Tanré, D., Ginoux, P., & Fan, S. (2005). Dust transport and deposition observed from the Terra-Moderate Resolution Imaging Spectroradiometer (MODIS) spacecraft over the Atlantic Ocean. Journal of Geophysical Research, 110(D10), 1-16. doi:10.1029/2003JD004436 McFiggans, G., Artaxo, P., Baltensperger, U., Coe, H., Facchini, M. C., Feingold, G., Fuzzi, S., et al. (2006). The effect of physical and chemical aerosol properties on warm cloud droplet activation. Atmospheric Chemistry and Physics, 6(9), 2593-2649. doi:10.5194/acp-6-2593-2006

Fuchs, Julia; Bendix, Jörg; Cermak, Jan

2013-04-01

97

Multiscale image enhancement of chromosome banding patterns  

NASA Astrophysics Data System (ADS)

Visual examination of chromosome banding patterns is an important means of chromosome analysis. Cytogeneticists compare their patient's chromosome image against the prototype normal/abnormal human chromosome banding patterns. Automated chromosome analysis instruments facilitate this by digitally enhancing the chromosome images. Currently available systems employing traditional highpass/bandpass filtering and/or histogram equalization are approximately equivalent to photomicroscopy in their ability to support the detection of band pattern alterations. Improvements in chromosome image display quality, particularly in the detail of the banding pattern, would significantly increase the cost-effectiveness of these systems. In this paper we present our work on the use of multiscale transform and derivative filtering for image enhancement of chromosome banding patterns. A steerable pyramid representation of the chromosome image is generated by a multiscale transform. The derivative filters are designed to detect the bands of a chromosome, and the steerable pyramid transform is chosen based on its desirable properties of shift and rotation invariance. By processing the transform coefficients that correspond to the bands of the chromosome in the pyramid representation, contrast enhancement of the chromosome bands can be achieved with designed flexibility in scale, orientation and location. Compared with existing chromosome image enhancement techniques, this new approach offers the advantage of selective chromosome banding pattern enhancement that allows designated detail analysis. Experimental results indicate improved enhancement capabilities and promise more effective visual aid to comparison of chromosomes to the prototypes and to each other. This will increase the ability of automated chromosome analysis instruments to assist the evaluation of chromosome abnormalities in clinical samples.

Wu, Qiang; Castleman, Kenneth R.

1996-10-01

98

Decomposition of satellite-derived images for the distinction of cloud types' features  

NASA Astrophysics Data System (ADS)

Linear filtering methods using convolution techniques are applied in computer vision, to detect spatial discontinuities in the intensity of luminance of photograph images. These techniques are based on the following principal: a pixel's neighborhood contains information about its intensity. The variation of this intensity provides some information about the distribution and the possible decomposition of the image in various features. This decomposition relies on the relative position of the pixel (edge or not) on the image. These principals, integrated into remote sensing analyses, are applied in this study to differentiate cloud morphological features representing cloud types from a thermal image product (the Cloud top temperatures) derived from polar orbit satellites' observations. This approach contrast with that of other techniques commonly used in satellite cloud classification, and based on optical or thermodynamic properties of the clouds. The interpretation of the distribution of these cloud morphological features, and their frequency is evaluated against another cloud classification method relying on cloud optical properties. The results show a relatively good match between the two classifications. Implications of these results, on the estimation of the impact of cloud shapes' variations on the recent climate are discussed.

Dim, Jules R.; Murakami, Hiroshi

2013-02-01

99

Methodology for estimating availability of cloud-free image composites: A case study for southern Canada  

NASA Astrophysics Data System (ADS)

Image composites are often used for earth surface phenomena studies at regional or national level. The compromise between residual clouds and the length of compositing period is a necessary corollary to the choice of satellite optical data for monitoring earth surface phenomena dynamics. This paper introduced a methodology for estimating availability of cloud-free image composites for optical sensors with various revisiting intervals, using MODIS MOD06 L2 cloud fraction product in the period of 2000-2008. The methodology starts with downscaling of the cloud fraction product to 1 km × 1 km cloud cover binary images. The binary images are then used for the exploration of spatial and temporal characteristics of cloud dynamics, and subsequently for the simulation of cloud-free composite availability with various revisiting intervals of optical sensors. Using Canada's southern provinces as an application case, the study explored several factors important for the design of environmental monitoring system using optical sensors of earth observation, in particular, cloud dynamics and its inter-annual variability, sensors' revisiting intervals, and cloud-free threshold for targeting composites. While the cloud images used in the analysis are at 1 km × 1 km resolution, our analysis suggests that the simulated availabilities of cloud-free image composites may also provide reasonable estimates for optical sensors with higher than 1 km × 1 km resolution, though the closer to 1 km × 1 km resolution the optical sensor, the more pertinent the application. Also, the methodology can be parameterised to different temporal period and different spatial region, depending on applications.

Zhou, Fuqun; Zhang, Aining

2013-04-01

100

A novel technique for extracting clouds base height using ground based imaging  

NASA Astrophysics Data System (ADS)

The height of a cloud in the atmospheric column is a key parameter in its characterization. Several remote sensing techniques (passive and active, either ground-based or on space-borne platforms) and in-situ measurements are routinely used in order to estimate top and base heights of clouds. In this article we present a novel method that combines thermal imaging from the ground and sounded wind profile in order to derive the cloud base height. This method is independent of cloud types, making it efficient for both low boundary layer and high clouds. In addition, using thermal imaging ensures extraction of clouds' features during daytime as well as at nighttime. The proposed technique was validated by comparison to active sounding by ceilometers (which is a standard ground based method), to lifted condensation level (LCL) calculations, and to MODIS products obtained from space. As all passive remote sensing techniques, the proposed method extracts only the height of the lowest cloud layer, thus upper cloud layers are not detected. Nevertheless, the information derived from this method can be complementary to space-borne cloud top measurements when deep-convective clouds are present. Unlike techniques such as LCL, this method is not limited to boundary layer clouds, and can extract the cloud base height at any level, as long as sufficient thermal contrast exists between the radiative temperatures of the cloud and its surrounding air parcel. Another advantage of the proposed method is its simplicity and modest power needs, making it particularly suitable for field measurements and deployment at remote locations. Our method can be further simplified for use with visible CCD or CMOS camera (although nighttime clouds will not be observed).

Hirsch, E.; Agassi, E.; Koren, I.

2011-01-01

101

A novel technique for extracting clouds base height using ground based imaging  

NASA Astrophysics Data System (ADS)

The height of a cloud in the atmospheric column is a key parameter in its characterization. Several remote sensing techniques (passive and active, either ground-based or on space-borne platforms) and in-situ measurements are routinely used in order to estimate top and base heights of clouds. In this article we present a novel method that combines thermal imaging from the ground and sounded wind profile in order to derive the cloud base height. This method is independent of cloud types, making it efficient for both low boundary layer and high clouds. In addition, using thermal imaging ensures extraction of clouds' features during daytime as well as at nighttime. The proposed technique was validated by comparison to active sounding by ceilometers (which is a standard ground based method), to lifted condensation level (LCL) calculations, and to MODIS products obtained from space. As all passive remote sensing techniques, the proposed method extracts only the height of the lowest cloud layer, thus upper cloud layers are not detected. Nevertheless, the information derived from this method can be complementary to space-borne cloud top measurements when deep-convective clouds are present. Unlike techniques such as LCL, this method is not limited to boundary layer clouds, and can extract the cloud base height at any level, as long as sufficient thermal contrast exists between the radiative temperatures of the cloud and its surrounding air parcel. Another advantage of the proposed method is its simplicity and modest power needs, making it particularly suitable for field measurements and deployment at remote locations. Our method can be further simplified for use with visible CCD or CMOS camera (although nighttime clouds will not be observed).

Hirsch, E.; Agassi, E.; Koren, I.

2010-10-01

102

Fluid Structure and Motion Analysis from Multi-spectrum 2D Cloud Image Sequences  

Microsoft Academic Search

In this paper we present a novel approach to estimateand analyze 3D fluid structure and motion ofclouds from multi-spectrum 2D cloud image sequences.Accurate cloud-top structure and motion are very importantfor a host of meteorological and climate applications.However, due to the extremely complex natureof cloud fluid motion, classical nonrigid motion analysismethods will be insufficient to solve this particularproblem. In this paper,

Lin Zhou; Chandra Kambhamettu; Dmitry B. Goldgof

2000-01-01

103

Distribution of cloud-free Landsat images in the Barents region  

Microsoft Academic Search

The utility of optical satellites depends heavily on latitude and cloud cover. In the north-eastern corner of the Fenno-Scandinavian landmass, extreme seasonal variations in sunlight and the clashing of weather fronts severely limit the season for optical satellites. In this paper, we examine the distribution of cloud-free Landsat images of the Barents Region during 1984-93. Based on cloud-cover data from

Tore Tollefsen

1994-01-01

104

Typhoon cloud system segmentation with multichannel images using vector-valued Chan-Vese model  

NASA Astrophysics Data System (ADS)

Cloud segmentation is an important step and a very difficult problem in typhoon image processing. There are many works on cloud image segmentation, but few are carried out on typhoon primary cloud system (galaxy) segmentation. Typhoon satellite images are always multiple channels whose properties are very different, so that the appearances of these channels are different as well. In order to segment out primary cloud systems accurately, multiple channel images are employed in this paper. The image data is from MERSI (short for MEdium Resolution Spectral Imager) of Chinese FY- 3A meteorological satellite launched on March, 2008. The scalar multiphase Chan-Vese (CV) model is extended for the vector-valued images, so as to partition out typhoon cloud systems. The experiment results show that the multi-channel segmentation is more accurate, more complete and more effective than that of usually using only one image, with multiple channel images being treated as a vector one input into the CV model. The multi-channel segmentation integrates the distribution information of cloud systems in all channels, so information fusion of multiple channels are realized when segmenting.

Wei, Kun; Li, Yuanxiang; Jing, Zhongliang; Shi, Chunxiang

2009-10-01

105

Radar Imaging of Ocean Surface Patterns  

Microsoft Academic Search

Radar imagery of ocean surface patterns is presented and discussed. The imaging radar detects changes in ocean surface backscatter and yields imagery of deepwater gravity waves, oil slicks, island shadows, internal waves, coastal waves, and other features. The results of several observations suggest that the surface irregularities behave as iostropic scatterers for a radar wavelength of 25 cm. The popular

W. E. Brown; C. Elachi; T. W. Thompson

1976-01-01

106

Color pattern selection using linguistic image scales  

NASA Astrophysics Data System (ADS)

In this paper, we propose a novel scheme to construct the color pattern retrieval system, which can recommend color patterns of the desired human feeling. The desired feeling is represented as a 9D vector in linguistic image scales. That means a component value of the vector is the degree of the feeling in the corresponding linguistic image scale. Then the system recommends color patterns of desired feeling after it compares the given query vector with emotional features of stored color patterns. In order to construct the system, the emotional features are taken from outputs of the neural network which has inputs as the physical features extracted from color patterns. To make indexing system, the hierarchical clustering method with fuzzy c-mean algorithm is used. To verify our scheme, a set of 368 color images for textile design is selected and experimented. Using the proposed retrieval scheme, we could obtain a promising results even though several problems are still remained. We believe this pilot system can be improved to find corresponding textile designs, wall papers, or pictures in a gallery for linguistic queries of human feelings.

Lee, Joon-Whoan; Um, Jinsub

1998-08-01

107

Design patterns in medical imaging information systems  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to introduce a new and important conceptual framework of software design for the medical imaging community using design patterns. Use cases are created to summarize operational scenarios of clinicians using the system to complete certain tasks such as image segmentation. During design the Unified Modeling Language is used to translate the use cases into modeling diagrams that describe how the system functions. Next, design patterns are applied to build models that describe how software components interoperate to deliver that functionality. The software components are implemented using the Java language, CORBA architecture, and other web technologies. The biomedical image information system is used in epilepsy neurosurgical planning and diagnosis. This article proposes the use of proven software design models for solving medical imaging informatics design problems. Design patterns provide an excellent vehicle to leverage design solutions that have worked in the past to solve the problems we face in building user-friendly, reliable, and efficient information systems. This work introduces this new technology for building increasing complex medical image information systems. The rigorous application of software design techniques is essential in building information systems that are easy to use, rich in functionality, maintainable, reliable, and updatable.

Hoo, Kent S.; Wong, Stephen T.; Laxer, Kenneth D.; Knowlton, Robert C.; Ching, Wan

2000-05-01

108

Video imaging of debris clouds following penetration of lightweight spacecraft materials  

Microsoft Academic Search

The structure of debris clouds following hypervelocity penetration of thin materials is of special interest to spacecraft designers--it forms the basis for damage equations from meteoroids, orbital debris, and other kinetic energy threats. Today, video imaging offers the experimenter a new view into the structure and development of debris clouds following penetration of these thin materials. This technique is of

Joel Williamsen; Eric Howard

2001-01-01

109

Application of genetic algorithm in tracking convective cloud images from Chinese FY2C satellite  

Microsoft Academic Search

It is significance to identify and track convective clouds using satellite data in nowcasting and severe weather warning. This article uses genetic algorithm to match and track convection clouds identified from infrared channel images of FY - 2C satellite. The preliminary results suggest that the genetic algorithm need set up enough group size & genetic algebra, and can select appropriate

Xiaofang Pei; Nan Li; Yating Zhan

2010-01-01

110

Polar mesospheric cloud structures observed from the cloud imaging and particle size experiment on the Aeronomy of Ice in the Mesosphere spacecraft: Atmospheric gravity waves as drivers for longitudinal variability in polar mesospheric cloud occurrence  

NASA Astrophysics Data System (ADS)

The cloud imaging and particle size (CIPS) experiment is one of three instruments on board the Aeronomy of Ice in the Mesosphere (AIM) spacecraft that was launched into a 600 km Sun-synchronous orbit on 25 April 2007. CIPS images have shown distinct wave patterns and structures in polar mesospheric clouds (PMCs), around the summertime mesopause region, which are qualitatively similar to structures seen in noctilucent clouds (NLCs) from ground-based photographs. The structures in PMC are generally considered to be manifestations of upward propagating atmospheric gravity waves (AGWs). Variability of AGW effects on PMC reported at several lidar sites has led to the notion of longitudinal differences in this relationship. This study compares the longitudinal variability in the CIPS-observed wave occurrence frequency with CIPS-measured PMC occurrence frequency and albedo along with mesospheric temperatures measured by the sounding of the atmosphere using broadband emission radiometry instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics spacecraft. Our results for the latitude ranges between 70° and 80° show a distinct anticorrelation of wave structures with cloud occurrence frequency and correlations with temperature perturbations for at least two of the four seasons analyzed, supporting the idea of gravity wave-induced cloud sublimation. The locations of the observed wave events show regions of high wave activity in both hemispheres. In the Northern Hemisphere, while the longitudinal variability in observed wave structures show changes from the 2007-2008 seasons, there exist regions of both low and high wave activities common to the two seasons. These persistent features may explain some of the observed differences in PMC activity reported by ground-based lidar instruments distributed at different longitudes. The statistical distribution of horizontal scales increases with wavelength up to at least 250 km. We also discuss the possibility of atmospheric tides, especially the nonmigrating semidiurnal tide, aliasing our observations and affecting the results presented in this analysis.

Chandran, A.; Rusch, D. W.; Merkel, A. W.; Palo, S. E.; Thomas, G. E.; Taylor, M. J.; Bailey, S. M.; Russell, J. M.

2010-07-01

111

Polar Mesospheric Cloud properties derived from the Cloud Imaging and Particle Size Experiment on the Aeronomy of Ice in the Mesosphere Mission  

Microsoft Academic Search

The Cloud Imaging and Particle Size Experiment (CIPS) is a four-camera nadir pointing imager with a bandpass centered at 265 nm and a field of view of 80 by 120 degrees. CIPS observes Polar Mesospheric Clouds (PMCs) against the sunlit Rayleigh scattered background. The observations cover five PMC seasons, three in the North (2007, 2008, and 2009) and two in

D. W. Rusch; G. E. Thomas; W. E. McClintock; A. W. Merkel; J. D. Lumpe; S. Benze; S. Bailey; C. E. Randall; J. M. Russell

2009-01-01

112

Global Images of Polar Mesospheric Clouds From the SNOE Spacecraft  

NASA Astrophysics Data System (ADS)

Polar Mesospheric Clouds (PMC) have been observed from several spacecraft over the last three decades. These experiments have shown the seasonal behavior of PMCs and have provided some morphological information. The Student Nitric Oxide Explorer (SNOE) has been observing PMCs since 1998 and has successfully measured six PMC seasons. SNOE is a spinning satellite in a sun-synchronous near-polar orbit at 10:30 am/pm local time. SNOE has a significant advantage over its predecessors in that it is able to observe PMCs globally each day. In the summer seasons, the Ultraviolet Spectrometer (UVS) limb measurements include detections of PMCs around 83 km. Because SNOE orbits the earth 15 times a day, it obtains global coverage of the mesosphere. By combining the 15 orbits, we can produce daily global images of PMC observation frequency and UV scattering ratio. The SNOE measurements show that PMCs start to form at high latitudes (75 degrees and higher) in the beginning of the PMC season, three weeks before summer solstice. By the middle of the season, PMCs form globally down to 50 degrees in latitude and then recede back to higher latitudes in the latter part of the season. The daily images, shown in a movie format, show the day-to-day variability in latitude and longitude of the PMC occurrences. The images suggest the influence of dynamics on the creation and destruction of PMCs. Case studies of several 5-10 day periods show a westward movement of PMC formation with the suggestion of wave structure.

Merkel, A. W.; Thomas, G. E.; Bailey, S. M.; Barth, C. A.

2001-05-01

113

The effects of orography in indochina on wind, cloud, and rainfall patterns during Typhoon Ketsana (2009)  

NASA Astrophysics Data System (ADS)

The objective of this study is to i) investigate the effects of orography on the rainfall, wind, and cloud systems of the Typhoon Ketsana (2009) in Indochina, ii) determine rainfall distribution patterns and which parts of Indochina were most affected during Typhoon Ketsana, iii) identify trends in the cloud and rainfall distribution patterns and wind flow patterns in the synoptic scale on orographic effects during Typhoon Ketsana. Remote sensing techniques have been used to study the impacts of TCs. Using data from the remote sensing data such as Fengyun 2D (FY-2D) satellite, Global Digital Elevation Model (GDEM) from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite, wind information from the Navy Operational Global Atmospheric Prediction System (NOGAPS), and radiosonde data were applied in this study to determine the relationship of the typhoon with the orographic effect. This study provides examples of how the orographic effect is important to weather forecasters, as high mountain ranges were able to influence the distribution of the cloud, rainfall and even wind flow patterns during the typhoon season. This remote sensing technique allows tropical cyclones to be forecasted and their impacts to be defined, and it allows disaster zones to be determined.

Tan, Fuyi; Lim, H. S.; Abdullah, K.

2012-08-01

114

Far field subwavelength imaging of magnetic patterns  

NASA Astrophysics Data System (ADS)

Far field imaging of subwavelength magnetic objects in real time is a very challenging issue. We propose an original solution based on a planar array of closely spaced split ring resonators. Hybridization between the resonators of such metalens induces subwavelength modes with different frequencies. Thanks to these high Q resonating modes, Purcell like effect allows an evanescent source, close to the metalens, to emit waves that can be collected efficiently in the far field. We present the first microwave experimental demonstration of such metalens to image of a subwavelength magnetic pattern. Numerical simulation shows that this approach is still valid at THz frequencies.

Ourir, Abdelwaheb; Lerosey, Geoffroy; Lemoult, Fabrice; Fink, Mathias; de Rosny, Julien

2012-09-01

115

Application of Ant Colony Algorithm in Tracking Convective Cloud Images from Chinese FY2C Satellite  

Microsoft Academic Search

\\u000a It is significance to identify and track convective clouds using satellite images in nowcasting and severe weather warning.\\u000a This article applies ant colony algorithm to match and track convection clouds identified from infrared channel images of\\u000a FY - 2C satellite. The preliminary results suggest that ant colony algorithm is simple and effective to gain satisfactory\\u000a results with adjustable features. The

Xiaofang Pei; Nan Li; Miaoying Li; Luan Li

116

The benefit of limb cloud imaging for tropospheric infrared limb sounding  

Microsoft Academic Search

Advances in detector technology enable a new generation of infrared limb sounders to measure 2-D images of the atmosphere. A proposed limb cloud imager (LCI) mode will measure clouds with very high spatial resolution. For the inference of temperature and trace gas distributions, detector pixels of the LCI have to be combined into super-pixels which provide the required signal-to-noise ratio

S. Adams; R. Spang; P. Preusse; G. Heinemann

2009-01-01

117

Flow Analysis of Cloud Images from Geostationary Satellites  

Microsoft Academic Search

Geostationary satellites are a valuable source of rain- fall information due to the availability of a global view of clouds at an acceptable spatial and temporal resolution. However to retrieve the information from the satellite im- ages is a significant challenge. For example, precipita- tion peaks while the cloud area is rapidly growing and reduces at the time of maximum

Aimamorn Suvichakorn; Adrian R. Tatnall

118

Neural network system for cloud classification from satellite images  

Microsoft Academic Search

Highly accurate, automated cloud detection and classification methods are essential for processing multispectral meteorological satellite in an operational environment and providing data for meteorological and climatological studies. They help to discover hazardous meteorological phenomena such as hail storms developing on tops of clouds, hurricanes and cyclones. Weather prediction and rainfall estimation systems are enhanced substantially by having access to information

I. S. Torsum; E. Kwiatkowska

1999-01-01

119

Estimation of cloud optical thickness by processing SEVIRI images and implementing a semi analytical cloud property retrieval algorithm  

NASA Astrophysics Data System (ADS)

Clouds play a very important role in the Earth's climate system, as they form an intermediate layer between Sun and the Earth. Satellite remote sensing systems are the only means to provide information about clouds on large scales. The geostationary satellite, Meteosat Second Generation (MSG) has onboard an imaging radiometer, the Spinning Enhanced Visible and Infrared Imager (SEVIRI). SEVIRI is a 12 channel imager, with 11 channels observing the earth's full disk with a temporal resolution of 15 min and spatial resolution of 3 km at nadir, and a high resolution visible (HRV) channel. The visible channels (0.6 µm and 0.81 µm) and near infrared channel (1.6µm) of SEVIRI are being used to retrieve the cloud optical thickness (COT). The study domain is over Europe covering the region between 35°N - 70°N and 10°W - 30°E. SEVIRI level 1.5 images over this domain are being acquired from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) archive. The processing of this imagery, involves a number of steps before estimating the COT. The steps involved in pre-processing are as follows. First, the digital count number is acquired from the imagery. Image geo-coding is performed in order to relate the pixel positions to the corresponding longitude and latitude. Solar zenith angle is determined as a function of latitude and time. The radiometric conversion is done using the values of offsets and slopes of each band. The values of radiance obtained are then used to calculate the reflectance for channels in the visible spectrum using the information of solar zenith angle. An attempt is made to estimate the COT from the observed radiances. A semi analytical algorithm [Kokhanovsky et al., 2003] is implemented for the estimation of cloud optical thickness from the visible spectrum of light intensity reflected from clouds. The asymptotical solution of the radiative transfer equation, for clouds with large optical thickness, is the basis of this algorithm. The two visible channels of SEVIRI are used to find the COT and the near infra red channel to estimate the effective radius of droplets. Estimation of COT using a semi analytical scheme, which doesn't involve the conventional look-up table approach, is the aim of this work and henceforth, vertically integrated liquid water (w) or ice water content will be retrieved. The COT estimated and w obtained, will be compared with the values obtained from other approaches and will be validated with in situ measurements. Corresponding author address: Praveen Pandey, VITO - Flemish Institute for Technological Research, Boeretang 200, B 2400, Mol, Belgium. E-mail: praveen.pandey@vito.be

Pandey, P.; De Ridder, K.; van Lipzig, N.

2009-04-01

120

Patterns and connections between aerosols, clouds and vegetation in the Amazon as seen by the twin MODIS sensors aboard Terra and Aqua  

NASA Astrophysics Data System (ADS)

In this study, twin Moderate Resolution Imaging Spectroradiometer (MODIS) sensors aboard NASA's Terra and Aqua satellites are used for characterization of cloud development and identification of processes affecting cloud formation. We find that much of the development of microphysical properties of water clouds over the Brazilian Legal Amazon can be characterized by the simple difference between those properties observed at the two times of MODIS overpass, only 3 hours apart. The time window is small enough that observed differences in cloud properties are primarily associated with the local events; therefore, it is ideal for exploring the effects of plant transpiration, biomass burning and Secondary Organic Aerosol (SOA) formation on regional cloud properties. In this region we find that the effective cloud droplet radius observed in the afternoon by Aqua-MODIS is systematically higher than the effective radii observed in the morning by Terra-MODIS. The difference corresponds to the invigoration of convection in the afternoon with the corresponding growth of droplet size. The monthly mean difference is 1 to 2 um, depending on season, but the overall pattern of the difference prevails throughout the Amazon, is repeated over other tropical rain forest regions globally, and is strikingly different from other types of cloud systems around the globe. Furthermore, we find that the effective radius difference found in the Amazon is inversely correlated to measures of evapotranspiration and all-sky solar radiation at the surface, but is not well-correlated to precipitation. The picture that emerges is a complex one that intertwines a light- limited forest, aerosols (both biogenic and anthropogenic) and cloud development.

Meskhidze, N.; Negrón Juárez, R.; Remer, L.; Platnick, S.; Aiyyer, A.

2007-12-01

121

Discrete plane segmentation and estimation from a point cloud using local geometric patterns  

Microsoft Academic Search

This paper presents a method for segmenting a 3D point cloud into planar surfaces using recently obtained discrete-geometry\\u000a results. In discrete geometry, a discrete plane is defined as a set of grid points lying between two parallel planes with\\u000a a small distance, called thickness. In contrast to the continuous case, there exist a finite number of local geometric patterns\\u000a (LGPs)

Yukiko Kenmochi; Lilian Buzer; Akihiro Sugimoto; Ikuko Shimizu

2008-01-01

122

Weekly cycle of lightning and associated patterns of rainfall, cloud, and aerosols over Korea and adjacent oceans during boreal summer  

NASA Astrophysics Data System (ADS)

In this study, we analyze the weekly cycle of lightning over Korea and adjacent oceans and associated variations of aerosols, clouds, precipitation, and atmospheric circulations, using aerosol optical depth (AOD) from the NASA Moderate resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpectroRadiometer (MISR), cloud properties from MODIS, precipitation and storm height from Tropical Rainfall Measuring Mission (TRMM) satellite, and lightning data from the Korean Lightning Detection Network (KLDN) during 9-year from 2002 to 2010. Lightning data was divided into three approximately equal areas, land area of Korea, and two adjacent oceans, Yellow Sea and South Sea. Preliminary results show that the number of lightning increases during the middle of the week over land area. AOD data also shows moderately significant midweek increase at about the same time as lightning peaks. These results are consistent with the recent studies showing the invigoration of storms with more ice hydrometeors by aerosols, and subsequently wash out of aerosols by rainfall. Frequency of lightning strokes tend to peak at weekend in coastal area and over South Sea, indicating local weekly anomalous circulation between land and adjacent ocean. On the other hand, lightning frequency over Yellow Sea appears to have very strong weekly cycle with midweek peak on around Wednesday. It is speculated that the midweek peak of lightning over Yellow Sea was related with aerosol transport from adjacent land area. AOD data also suggests midweek peak over Yellow Sea, however, the weekly cycle of AOD was not statistically significant. Changes in weekly cycle of lightning from pre-monsoon to monsoon season, as well as associated clouds and circulation patterns are also discussed.

Kim, J.; Kim, K.

2011-12-01

123

The computation of cloud base height from paired whole-sky imaging cameras  

SciTech Connect

A major goal for global change studies is to improve the accuracy of general circulation models (GCMs) capable of predicting the timing and magnitude of greenhouse gas-induced global warming. Research has shown that cloud radiative feedback is the single most important effect determining the magnitude of possible climate responses to human activity. Of particular value to reducing the uncertainties associated with cloud-radiation interactions is the measurement of cloud base height (CBH), both because it is a dominant factor in determining the infrared radiative properties of clouds with respect to the earth`s surface and lower atmosphere and because CBHs are essential to measuring cloud cover fraction. We have developed a novel approach to the extraction of cloud base height from pairs of whole sky imaging (WSI) cameras. The core problem is to spatially register cloud fields from widely separated WSI cameras; this complete, triangulation provides the CBH measurements. The wide camera separation (necessary to cover the desired observation area) and the self-similarity of clouds defeats all standard matching algorithms when applied to static views of the sky. To address this, our approach is based on optical flow methods that exploit the fact that modern WSIs provide sequences of images. We will describe the algorithm and present its performance as evaluated both on real data validated by ceilometer measurements and on a variety of simulated cases.

Allmen, M.C.; Kegelmeyer, W.P. Jr.

1994-03-01

124

Statistical pattern recognition algorithms for autofluorescence imaging  

NASA Astrophysics Data System (ADS)

In cancer diagnostics the most important problems are the early identification and estimation of the tumor growth and spread in order to determine the area to be operated. The aim of the work was to design of statistical algorithms helping doctors to objectively estimate pathologically changed areas and to assess the disease advancement. In the research, algorithms for classifying endoscopic autofluorescence images of larynx and intestine were used. The results show that the statistical pattern recognition offers new possibilities for endoscopic diagnostics and can be of a tremendous help in assessing the area of the pathological changes.

Kulas, Zbigniew; Bere?-Pawlik, El?bieta; Wierzbicki, Jaros?aw

2009-02-01

125

Cloud Coverage Based on All-Sky Imaging and Its Impact on Surface Solar Irradiance  

SciTech Connect

In Lauder, Central Otago, two all-sky imaging systems have been operated for more than one year measuring the total, opaque, and thin cloud fraction as well as an indicator of whether the sun is obscured by clouds. The data provide a basis for investigating the impact of clouds on the surface radiation field. We aligned the all-sky cloud parameters with measurements of global, direct and diffuse surface solar irradiance over the spectral interval from 0.3 to 3 mm. Here we describe results of ongoing analysis of this data set. As a reference for the magnitude of the cloud influence, clear sky irradiance values are estimated as a simple function of solar zenith angle and Earth-Sun distance. The function is derived from a least-square fit to measurements taken when available cloud images show clear sky situations. Averaged over a longer time period, such as a month, cloud fraction and surface irradiance are clearly negatively correlated. Monthly means in the ratio of the measured surface irradiance to the clear-sky value had a correlation coefficient of about -0.9 with means of cloud fraction for the months July 2000 to June 2001. In the present work we analyze reductions in the surface irradiance and also situations where clouds cause radiation values to exceed the expected clear sky amount. Over one year of observations, 1-minute-average radiation measurements exceeding the expected clear sky value by more than 10% were observed with a frequency of 5%. In contrast, a reduction of more than 10% below estimated clear sky values occurred in 66% of the cases, while clear sky irradiances (measured irradiance within {+-}10% of estimated clear sky value) were observed 29% of the time. Low cloud fractions frequently lead to moderate enhancement, as the sun is often unobscured and the clouds are brighter than the sky that they hide. As cloud fraction increases the sun is likely to be obscured, causing irradiance values to fall well below clear sky values. However, in case of unobscured sun, there is a tendency for strongest enhancements when cloud fractions are highest. Enhancements, especially at high solar zenith angle, are also often observed in association with thin clouds.

Pfister, G.; McKenzie, R. L.; Liley, J. B.; Thomas, A.; Forgan, B. W.; Long, Charles N.

2003-10-31

126

Always up-to-date: scalable offline patching of VM images in a compute cloud  

Microsoft Academic Search

Patching is a critical security service that keeps computer systems up to date and defends against security threats. Existing patching systems all require running systems. With the increasing adoption of virtualization and cloud computing services, there is a growing number of dormant virtual machine (VM) images. Such VM images cannot benefit from existing patching systems, and thus are often left

Wu Zhou; Peng Ning; Xiaolan Zhang; Glenn Ammons; Ruowen Wang; Vasanth Bala

2010-01-01

127

Satellite Cloud Image Segmentation Based on the Improved Normalized Cuts Model  

Microsoft Academic Search

We propose a novel approach for satellite cloud image segmentation based on the improved Normalized Cuts Model. We extracted three important features from the multi-channel grayscale information and the texture features of satellite image, by the statistical analyses of the surface observation. Having set up the weight matrix by those features, we use the spectral graph theoretic framework of normalized

Fei Wenlong; Lv Hong; Wei Zhihui

2009-01-01

128

Tracking Nonrigid Motion and Structure from 2D Satellite Cloud Images without Correspondences  

Microsoft Academic Search

Tracking both structure and motion of nonrigid objects from monocular images is an important problem in vision. In this paper, a hierarchical method which integrates local analysis (that recovers small details) and global analysis (that appropriately limits possible nonrigid behaviors) is developed to recover dense depth values and nonrigid motion from a sequence of 2D satellite cloud images without any

Lin Zhou; Chandra Kambhamettu; Dmitry B. Goldgof; Kannappan Palaniappan; Frederick Hasler

2001-01-01

129

Venus cloud top winds from tracking UV features in Venus Monitoring Camera images  

Microsoft Academic Search

To date dynamical observations of the Venus clouds have delivered mainly either only short-term or long-term averaged results. With the Venus Monitoring Camera (VMC) it finally became possible to investigate the global dynamics with a relatively high resolution in space and time on a long-term basis. Our findings from manual cloud feature wind tracking in VMC UV image sequences so

R. Moissl; I. Khatuntsev; S. S. Limaye; D. V. Titov; W. J. Markiewicz; N. I. Ignatiev; T. Roatsch; K.-D. Matz; R. Jaumann; M. Almeida; G. Portyankina; T. Behnke; S. F. Hviid

2009-01-01

130

The radiative consistency of Atmospheric Infrared Sounder and Moderate Resolution Imaging Spectroradiometer cloud retrievals  

Microsoft Academic Search

The consistency of cloud top temperature (T C) and effective cloud fraction (f) retrieved by the Atmospheric Infrared Sounder (AIRS)\\/Advanced Microwave Sounding Unit (AMSU) observation suite and the Moderate Resolution Imaging Spectroradiometer (MODIS) on the EOS-Aqua platform are investigated. Collocated AIRS and MODIS T C and f are compared via an ``effective scene brightness temperature'' (T b,e). T b,e is

Brian H. Kahn; Evan Fishbein; Shaima L. Nasiri; Annmarie Eldering; Eric J. Fetzer; Michael J. Garay; Sung-Yung Lee

2007-01-01

131

The radiative consistency of Atmospheric Infrared Sounder and Moderate Resolution Imaging Spectroradiometer cloud retrievals  

Microsoft Academic Search

The consistency of cloud top temperature (TC) and effective cloud fraction (f) retrieved by the Atmospheric Infrared Sounder (AIRS)\\/Advanced Microwave Sounding Unit (AMSU) observation suite and the Moderate Resolution Imaging Spectroradiometer (MODIS) on the EOS-Aqua platform are investigated. Collocated AIRS and MODIS TC and f are compared via an “effective scene brightness temperature” (Tb,e). Tb,e is calculated with partial field

Brian H. Kahn; Evan Fishbein; Shaima L. Nasiri; Annmarie Eldering; Eric J. Fetzer; Michael J. Garay; Sung-Yung Lee

2007-01-01

132

Wide-angle imaging LIDAR (WAIL): a ground-based instrument for monitoring the thickness and density of optically thick clouds.  

SciTech Connect

Traditional lidar provides little information on dense clouds beyond the range to their base (ceilometry), due to their extreme opacity. At most optical wavelengths, however, laser photons are not absorbed but merely scattered out of the beam, and thus eventually escape the cloud via multiple scattering, producing distinctive extended space- and time-dependent patterns which are, in essence, the cloud's radiative Green functions. These Green functions, essentially 'movies' of the time evolution of the spatial distribution of escaping light, are the primary data products of a new type of lidar: Wide Angle Imaging Lidar (WAIL). WAIL data can be used to infer both optical depth and physical thickness of clouds, and hence the cloud liquid water content. The instrumental challenge is to accommodate a radiance field varying over many orders of magnitude and changing over widely varying time-scales. Our implementation uses a high-speed microchannel plate/crossed delay line imaging detector system with a 60-degree full-angle field of view, and a 532 nm doubled Nd:YAG laser. Nighttime field experiments testing various solutions to this problem show excellent agreement with diffusion theory, and retrievals yield plausible values for the optical and geometrical parameters of the observed cloud decks.

Love, Steven P.; Davis, A. B. (Anthony B.); Rohde, C. A. (Charles A.); Ho, Cheng,

2001-01-01

133

Cloud detection and classification with the use of whole-sky ground-based images  

NASA Astrophysics Data System (ADS)

A simple whole sky imaging system, based on a commercial digital camera with a fish-eye lens and a hemispheric dome, is used for the automatic estimation of total cloud coverage and classification. For the first time, a multi color criterion is applied on sky images, in order to improve the accuracy in detection of broken and overcast clouds under large solar zenith angles. The performance of the cloud detection algorithm is successfully compared with ground based weather observations. A simple method is presented for the detection of raindrops standing on the perimeter of hemispheric dome. Based on previous works on cloud classification, an improved k-Nearest-Neighbor algorithm is presented, based not only on statistical color and textural features, but taking also into account the solar zenith angle, the cloud coverage, the visible fraction of solar disk and the existence of raindrops in sky images. The successful detection percentage of the classifier ranges between 78 and 95% for seven cloud types.

Kazantzidis, A.; Tzoumanikas, P.; Bais, A. F.; Fotopoulos, S.; Economou, G.

2012-09-01

134

Image draping for planar surfaces extracted from point clouds  

NASA Astrophysics Data System (ADS)

This paper presents an algorithm for aligning 2D video to 3D point clouds. The paper is a vignette of on-going research in the area of 3D Urban Environment Modelling. The aim of this research is to produce accurate, fast and useable 3D maps of the dynamic urban environment. Paper presents development of the algorithm followed by the processing and implementation procedure to produce a realistic 3D model of an urban environment model from 3D point cloud and RGB video collected by the system. To allow further discussion the paper concludes with the results of draping 2D video frames to a solid surface developed from 3D point clouds.

Mahmood, Asher; Christy, Mark; Hughes, Steve; Tudor, Philip M.

2008-10-01

135

Improvements in Near-Terminator and Nocturnal Cloud Masks using Satellite Imager Data over the Atmospheric Radiation Measurement Sites  

SciTech Connect

Cloud detection using satellite measurements presents a big challenge near the terminator where the visible (VIS; 0.65 {micro}m) channel becomes less reliable and the reflected solar component of the solar infrared 3.9-{micro}m channel reaches very low signal-to-noise ratio levels. As a result, clouds are underestimated near the terminator and at night over land and ocean in previous Atmospheric Radiation Measurement (ARM) Program cloud retrievals using Geostationary Operational Environmental Satellite (GOES) imager data. Cloud detection near the terminator has always been a challenge. For example, comparisons between the CLAVR-x (Clouds from Advanced Very High Resolution Radiometer [AVHRR]) cloud coverage and Geoscience Laser Altimeter System (GLAS) measurements north of 60{sup o}N indicate significant amounts of missing clouds from AVHRR because this part of the world was near the day/night terminator viewed by AVHRR. Comparisons between MODIS cloud products and GLAS at the same regions also shows the same difficulty in the MODIS cloud retrieval (Pavolonis and Heidinger 2005). Consistent detection of clouds at all times of day is needed to provide reliable cloud and radiation products for ARM and other research efforts involving the modeling of clouds and their interaction with the radiation budget. To minimize inconsistencies between daytime and nighttime retrievals, this paper develops an improved twilight and nighttime cloud mask using GOES-9, 10, and 12 imager data over the ARM sites and the continental United States (CONUS).

Trepte, Q.Z.; Minnis, P.; Heck, P.W.; Palikonda, R.

2005-03-18

136

Improved Cloud and Surface Properties By Combining Conventional and L-1 Satellite Imager Data  

NASA Astrophysics Data System (ADS)

Imagers on geostationary (GEOSat) and low-earth orbiting (LEOSat) satellites are often used to derive information about clouds and the surface, but are limited in their angular coverage of a given scene by their particular orbits. A GEOSat views an area through its entire diurnal cycle covering the full range of solar zenith angles (SZAs) while viewing from a constant viewing zenith angle (VZA) and varying relative azimuth angle (RAA). Most polar-orbiting satellites are sun-synchronous and view a given area at one time of day from various VZAs and RAAs, but a over a small SZA range. A few imagers such as MISR or AATSR are on LEOSats and can provide views over a greater range of RAA and VZA, but are still constrained by SZA. The Deep Space Climate Observatory (DSCOVR) will orbit at the L-1 position in a near backscatter angle (~168°) relative to the Earth and sun. It carries an imager, EPIC, that has several UV, visible, and near-infrared channels measuring radiances at a nadir 10-km resolution. Because it views most of the sunlit Earth at high frequency, it can provide unprecedented coverage of the daylight portion of the diurnal cycle for a given area at over the full range of SZAs and VZAs at a nearly constant RAA. Because of this coverage, pixels from the EPIC can be matched with those from any other satellite passing over the sunlit hemisphere. Although cloud information such as cloud amount, optical depth, and height can be derived from the EPIC channels, the combination of EPIC data with that from higher resolution GEOSats and LEOSats will be more useful than either by itself. Because of its low resolution and lack of infrared data, broken and scattered and cirrus cloud fields are likely to be misinterpreted using the EPIC data alone. Matching the more conventional satellite data and associated cloud products with the EPIC data will enhance the information from the EPIC as its field of view increases as 1/cos(VZA). The cloud heights derived from oxygen A and B bands will be improved by knowing the cloud fraction and type more accurately. Multiangle views from the matched satellite data will provide information about cirrus cloud particle habit, multilayer cloud conditions, and, possibly, the width of the droplet size spectrum. Better definition of clear areas and cloud conditions within the EPIC fields of view will be realized by inclusion of matched data, so that retrievals of other parameters such as leaf area index can be determined more accurately, without cloud contamination. This paper will explore these and other potential uses of combining real-time NASA Langley cloud data from LEOSats and GEOSats.

Minnis, P.; Doelling, D.; Nguyen, L.; Palikonda, R.; Spangenberg, D. A.; Hong, G.; Yi, Y.

2011-12-01

137

Pattern Recognition and Image Processing of Infrared Astronomical Satellite Images  

NASA Astrophysics Data System (ADS)

The Infrared Astronomical Satellite (IRAS) images with wavelengths of 60 mu m and 100 mu m contain mainly information on both extra-galactic sources and low-temperature interstellar media. The low-temperature interstellar media in the Milky Way impose a "cirrus" screen of IRAS images, especially in images with 100 mu m wavelength. This dissertation deals with the techniques of removing the "cirrus" clouds from the 100 mu m band in order to achieve accurate determinations of point sources and their intensities (fluxes). We employ an image filtering process which utilizes mathematical morphology and wavelet analysis as the key tools in removing the "cirrus" foreground emission. The filtering process consists of extraction and classification of the size information, and then using the classification results in removal of the cirrus component from each pixel of the image. Extraction of size information is the most important step in this process. It is achieved by either mathematical morphology or wavelet analysis. In the mathematical morphological method, extraction of size information is done using the "sieving" process. In the wavelet method, multi-resolution techniques are employed instead. The classification of size information distinguishes extra-galactic sources from cirrus using their averaged size information. The cirrus component for each pixel is then removed by using the averaged cirrus size information. The filtered image contains much less cirrus. Intensity alteration for extra-galactic sources in the filtered image are discussed. It is possible to retain the fluxes of the point sources when we weigh the cirrus component differently pixel by pixel. The importance of the uni-directional size information extractions are addressed in this dissertation. Such uni-directional extractions are achieved by constraining the structuring elements, or by constraining the sieving process to be sequential. The generalizations of mathematical morphology operations based on the dynamic hit-or-miss transform are presented in this dissertation. The generalized erosion (gamma-erosion) bridges traditional erosion and dilation. It also enriches the morphological operators available in the field of signal and image processing. Traditional closing is generalized into gamma -closing, which bridges traditional closing and opening. Properties of gamma-erosion and gamma -closing are discussed. The sieving process is generalized based on gamma-closing, and is bi-directional, with the polarity directly related to the parameter gamma. The size information extractors of morphological methods and wavelet methods are justified quantitatively using a prototype peak with fixed slope. The non-linearity of the sieving process is analyzed. It is shown that the sieving process can approach an approximate linearity at positions where the input signal has sharp peaks (i.e., the slopes are large). The spatial discriminating properties of the size information extractors are also very important.

He, Lun Xiong

1996-01-01

138

Low clouds and fog along the South-Western African coast — Satellite-based retrieval and spatial patterns  

NASA Astrophysics Data System (ADS)

The spatial and temporal patterns of fog and low clouds along the South-Western African coast are characterized based on an evaluation of Meteosat SEVIRI satellite data. A technique for the detection of fog/low clouds in the region is introduced, and validated using 1 year of CALIOP cloud lidar products, showing reliable performance. The frequency of fog and low cloud in the study area is analyzed by systematic application of the technique to all available Meteosat SEVIRI scenes from 2004 to 2009, for 7:00 UTC and 14:00 UTC. The highest frequencies are encountered in the area around Walvis Bay, with a peak in the summer months. Fog and low clouds clear by 14:00 UTC almost everywhere over land. Supplementary data are available at doi:10.1594/PANGAEA.755427.

Cermak, Jan

2012-10-01

139

Distinct muscle imaging patterns in myofibrillar myopathies  

PubMed Central

Objective: To compare muscle imaging findings in different subtypes of myofibrillar myopathies (MFM) in order to identify characteristic patterns of muscle alterations that may be helpful to separate these genetic heterogeneous muscular disorders. Methods: Muscle imaging and clinical findings of 46 patients with MFM were evaluated (19 desminopathy, 12 myotilinopathy, 11 filaminopathy, 1 ?B-crystallinopathy, and 3 ZASPopathy). The data were collected retrospectively in 43 patients and prospectively in 3 patients. Results: In patients with desminopathy, the semitendinosus was at least equally affected as the biceps femoris, and the peroneal muscles were never less involved than the tibialis anterior (sensitivity of these imaging criteria to detect desminopathy in our cohort 100%, specificity 95%). In most of the patients with myotilinopathy, the adductor magnus showed more alterations than the gracilis muscle, and the sartorius was at least equally affected as the semitendinosus (sensitivity 90%, specificity 93%). In filaminopathy, the biceps femoris and semitendinosus were at least equally affected as the sartorius muscle, and the medial gastrocnemius was more affected than the lateral gastrocnemius. The semimembranosus mostly showed more alterations than the adductor magnus (sensitivity 88%, specificity 96%). Early adult onset and cardiac involvement was most often associated with desminopathy. In patients with filaminopathy, muscle weakness typically beginning in the 5th decade of life was mostly pronounced proximally, while late adult onset (>50 years) with distal weakness was more often present in myotilinopathy. Conclusions: Muscle imaging in combination with clinical data may be helpful for separation of distinct myofibrillar myopathy subtypes and in scheduling of genetic analysis.

Fischer, D.; Kley, R. A.; Strach, K.; Meyer, C.; Sommer, T.; Eger, K.; Rolfs, A.; Meyer, W.; Pou, A.; Pradas, J.; Heyer, C. M.; Grossmann, A.; Huebner, A.; Kress, W.; Reimann, J.; Schroder, R.; Eymard, B.; Fardeau, M.; Udd, B.; Goldfarb, L.; Vorgerd, M.; Olive, M.

2008-01-01

140

Automatic registration of multi-view 3D laser point cloud based on image registration and ameliorated ICP Algorithm  

NASA Astrophysics Data System (ADS)

In the process of the registration of multi-view point cloud, it's difficult to extract the feature points at present. In view of this condition, the article advances a new automatic registration method of multi-view point cloud based on Image Registration and ICP Algorithm. After the registration of point cloud and corresponding image, the feather can be extracted from the image that has plenty of textures compared with the point cloud. And it's beneficial to improve the precision and efficiency for the next registration. The experimental results demonstrate that the new method guarantees accurate fine registration.

Zhao, Ziming; Hao, Xiangyang; Zhao, Song; Su, Yintai

2011-06-01

141

An Association Rule Mining Approach for Satellite Cloud Images and Rainfall  

Microsoft Academic Search

This paper aims at discovering useful knowledge from a large collection of satellite cloud images and rainfall data using\\u000a image mining. The paper illustrates how important the data conversion is in building an accurate data mining architecture.\\u000a Most of data about image features and rainfall data are values or vectors, which are not fit for mining directly. We present\\u000a two

Xu Lai; Guo-hui Li; Ya-li Gan; Ze-gang Ye

2006-01-01

142

Active probing of cloud thickness and optical depth using wide-angle imaging LIDAR.  

SciTech Connect

At most optical wavelengths, laser light in a cloud lidar experiment is not absorbed but merely scattered out of the beam, eventually escaping the cloud via multiple scattering. There is much information available in this light scattered far from the input beam, information ignored by traditional 'on-beam' lidar. Monitoring these off-beam returns in a fully space- and time-resolved manner is the essence of our unique instrument, Wide Angle Imaging Lidar (WAIL). In effect, WAIL produces wide-field (60{sup o} full-angle) 'movies' of the scattering process and records the cloud's radiative Green functions. A direct data product of WAIL is the distribution of photon path lengths resulting from multiple scattering in the cloud. Following insights from diffusion theory, we can use the measured Green functions to infer the physical thickness and optical depth of the cloud layer. WAIL is notable in that it is applicable to optically thick clouds, a regime in which traditional lidar is reduced to ceilometry. Section 2 covers the up-to-date evolution of the nighttime WAIL instrument at LANL. Section 3 reports our progress towards daytime capability for WAIL, an important extension to full diurnal cycle monitoring by means of an ultra-narrow magneto-optic atomic line filter. Section 4 describes briefly how the important cloud properties can be inferred from WAIL signals.

Love, Steven P.; Davis, A. B. (Anthony B.); Rohde, C. A. (Charles A.); Tellier, L. L. (Larry L.); Ho, Cheng,

2002-01-01

143

Color image segmentation considering human sensitivity for color pattern variations  

Microsoft Academic Search

Color image segmentation plays an important role in the computer vision and image processing area. In this paper, we propose a novel color image segmentation algorithm in consideration of human visual sensitivity for color pattern variations by generalizing K-means clustering. Human visual system has different color perception sensitivity according to the spatial color pattern variation. To reflect this effect, we

Kuk-Jin Yoon; In-So Kweon

2001-01-01

144

Orientation of Airborne Laser Scanning Point Clouds with Multi-View, Multi-Scale Image Blocks  

PubMed Central

Comprehensive 3D modeling of our environment requires integration of terrestrial and airborne data, which is collected, preferably, using laser scanning and photogrammetric methods. However, integration of these multi-source data requires accurate relative orientations. In this article, two methods for solving relative orientation problems are presented. The first method includes registration by minimizing the distances between of an airborne laser point cloud and a 3D model. The 3D model was derived from photogrammetric measurements and terrestrial laser scanning points. The first method was used as a reference and for validation. Having completed registration in the object space, the relative orientation between images and laser point cloud is known. The second method utilizes an interactive orientation method between a multi-scale image block and a laser point cloud. The multi-scale image block includes both aerial and terrestrial images. Experiments with the multi-scale image block revealed that the accuracy of a relative orientation increased when more images were included in the block. The orientations of the first and second methods were compared. The comparison showed that correct rotations were the most difficult to detect accurately by using the interactive method. Because the interactive method forces laser scanning data to fit with the images, inaccurate rotations cause corresponding shifts to image positions. However, in a test case, in which the orientation differences included only shifts, the interactive method could solve the relative orientation of an aerial image and airborne laser scanning data repeatedly within a couple of centimeters.

Ronnholm, Petri; Hyyppa, Hannu; Hyyppa, Juha; Haggren, Henrik

2009-01-01

145

Detection and tracking of gas clouds in an urban area by imaging infrared spectroscopy  

NASA Astrophysics Data System (ADS)

The release of toxic industrial compounds in urban areas is a threat for the population and the environment. In order to supply emergency response forces with information about the released compounds after accidents or terrorist attacks, monitoring systems such as the scanning imaging spectrometer SIGIS 2 or the hyperspectral imager HI 90 were developed. Both systems are based on the method of infrared spectroscopy. The systems were deployed to monitor gas clouds released in the harbor area of Hamburg. The gas clouds were identified, visualized and quantified from a distance in real time. Using data of two systems it was possible to identify contaminated areas and to determine the source location.

Sabbah, Samer; Rusch, Peter; Gerhard, Jörn-Hinnrich; Harig, Roland

2013-05-01

146

On the camparability of cloud fractions derived from whole sky imager and ceilometer data  

SciTech Connect

The Atmospheric Radiation Measurement (ARM) Program`s most heavily instrumented site is its central facility in Lamont, OK. With respect to cloud observations, the instrumentation included a whole sky imager, ceilometers, lidar, millimeter cloud radar, microwave profilers, and radiosondes. Data from three of these instrument--the Whole Sky Imager (WSI), Belfort Laser Ceilometer (BLC) and Micropulse Lidar (MPL)-- are used in this study primarily to investigate the utility of using ceilometers, now strategically emplaced at four additional locations along the perimeter of the site.

Rodriguez, D.

1998-01-30

147

Direct imaging of a massive dust cloud around R Coronae Borealis  

NASA Astrophysics Data System (ADS)

We present recent polarimetric images of the highly variable star R CrB using ExPo and archival WFPC2 images from the HST. We observed R CrB during its current dramatic minimum where it decreased more than 9 mag due to the formation of an obscuring dust cloud. Since the dust cloud is only in the line-of-sight, it mimics a coronograph allowing the imaging of the star's circumstellar environment. Our polarimetric observations surprisingly show another scattering dust cloud at approximately 1.3'' or 2000 AU from the star. We find that to obtain a decrease in the stellar light of 9 mag and with 30% of the light being reemitted at infrared wavelengths (from R CrB's SED) the grains in R CrB's circumstellar environment must have a very low albedo of approximately 0.07%. We show that the properties of the dust clouds formed around R CrB are best fitted using a combination of two distinct populations of grains size. The first are the extremely small 5 nm grains, formed in the low density continuous wind, and the second population of large grains (~0.14 ?m) which are found in the ejected dust clouds. The observed scattering cloud, not only contains such large grains, but is exceptionally massive compared to the average cloud. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

Jeffers, S. V.; Min, M.; Waters, L. B. F. M.; Canovas, H.; Rodenhuis, M.; de Juan Ovelar, M.; Chies-Santos, A. L.; Keller, C. U.

2012-03-01

148

Clouds and Solar Radiation  

NSDL National Science Digital Library

Most people are aware that clouds impact the amount of solar energy that is received at the ground. This lesson examines qualitative and quantitative aspects of how clouds affect incoming solar radiation. Students will be given a visible satellite image, and asked to describe where clouds are located in the state. Given a map of Mesonet solar radiation measurements, the students will be asked to determine regions of relatively high and low values of solar radiation. This lesson also enables students to practice analyzing different types of data sets and compare patterns between two types of data.

149

Optical processing of speckle images with bacteriorhodopsin for pattern recognition  

Microsoft Academic Search

Logarithmic processing of images with multiplicative noise characteristics can be utilized to transform an image into one with an additive noise distribution. This simplifies subsequent image processing steps for applications such as image restoration or correlation for pattern recognition. One particularly common form of multiplicative noise is speckle, for which the logarithmic operation not only produces additive noise, but also

John D. Downie

1995-01-01

150

Elimination Technology for Labele d Objects of Satellite Cloud Images Based on Total Variation Algorithm  

Microsoft Academic Search

(Abstract)The paper proposes to use the Total Variation(TV) algorithm to eliminate the labeled objects in the satellite cloud images. The shapes of labeled objects are often long and narrow. The main effort focuses on improving the process of discreteness for the total variation algorithm through introducing different weights. The improved algorithm fulfills that it only fills the eliminating areas according

LAI Xu; ZHU Wei; LI GUO-hui

2009-01-01

151

The study of a linear optimal location the typhoon center automatic from IR satellite cloud image  

Microsoft Academic Search

The typhoon center location is important for forecast typhoon path and harmful weather. However, the appearance of the typhoon from satellite cloud images was very complex and stochastic. Some location methods were short of robustness and oneness. In order to locate the typhoon center automatically and accurately, we propose a linear optimal location technique based on the feature of typhoon

Yan Li; Xi Chen; Shu-Ming Fei; Ke-Feng Mao; Kai Zhou

2011-01-01

152

Fluorescence Imaging for Visualization of the Ion Cloud in a Quadrupole Ion Trap Mass Spectrometer  

NASA Astrophysics Data System (ADS)

Laser-induced fluorescence is used to visualize populations of gaseous ions stored in a quadrupole ion trap (QIT) mass spectrometer. Presented images include the first fluorescence image of molecular ions collected under conditions typically used in mass spectrometry experiments. Under these "normal" mass spectrometry conditions, the radial (r) and axial (z) full-width at half maxima (FWHM) of the detected ion cloud are 615 and 214 ?m, respectively, corresponding to ~6 % of r 0 and ~3 % of z 0 for the QIT used. The effects on the shape and size of the ion cloud caused by varying the pressure of helium bath gas, the number of trapped ions, and the Mathieu parameter q z are visualized and discussed. When a "tickle voltage" is applied to the exit end-cap electrode, as is done in collisionally activated dissociation, a significant elongation in the axial, but not the radial, dimension of the ion cloud is apparent. Finally, using spectroscopically distinguishable fluorophores of two different m/z values, images are presented that illustrate stratification of the ion cloud; ions of lower m/z (higher q z ) are located in the center of the trapping region, effectively excluding higher m/z (lower q z ) ions, which form a surrounding layer. Fluorescence images such as those presented here provide a useful reference for better understanding the collective behavior of ions in radio frequency (rf) trapping devices and how phenomena such as collisions and space-charge affect ion distribution.

Talbot, Francis O.; Sciuto, Stephen V.; Jockusch, Rebecca A.

2013-10-01

153

The Investigation of Cloud-Computing-based Image Mining Mechanism in Mobile Communication WEB on Android  

Microsoft Academic Search

With the development of 3G network technology, the rapid upgrading of mobile phone hardware, and the refined requirements for mobile phones by mobile phone users, it is essential for mobile phones to be able to promptly and accurately process images. A mobile phone terminal sends the service requests to cloud computer system which then processes the requests and sends the

Cai-Dong Gu; Kan Lu; Jian-Ping Wu; Ying-li Fu; Jing-xiang Li; Chang-shui Xiao; Mao-xin Si; Zhao-bin Liu

2010-01-01

154

Landmark image classification using 3D point clouds  

Microsoft Academic Search

Most of the existing approaches for landmark image classification utilize either holistic features or interest of points in the whole image to train the classification model, which may lead to unsatisfactory result due to involvement of much information non-located on the landmark in the training process. In this paper, we propose a novel approach to improve landmark image classification result

Xian Xiao; Changsheng Xu; Jinqiao Wang

2010-01-01

155

The cloud imaging and particle size experiment on the aeronomy of ice in the mesosphere mission: Cloud morphology for the northern 2007 season  

NASA Astrophysics Data System (ADS)

The Aeronomy of Ice in the Mesosphere (AIM) mission was launched from Vandenberg Air Force Base in California at 4:26:03 EDT on April 25, 2007, becoming the first satellite mission dedicated to the study of noctilucent clouds (NLCs), also known as polar mesospheric clouds (PMC) when viewed from space. We present the first results from one of the three instruments on board the satellite, the Cloud Imaging and Particle Size (CIPS) instrument. CIPS has produced detailed morphology of the Northern 2007 PMC and Southern 2007/2008 seasons with 5 km horizontal spatial resolution. CIPS, with its very large angular field of view, images cloud structures at multiple scattering angles within a narrow spectral bandpass centered at 265 nm. Spatial coverage is 100% above about 70° latitude, where camera views overlap from orbit to orbit, and terminates at about 82°. Spatial coverage decreases to about 50% at the lowest latitudes where data are collected (35°). Cloud structures have for the first time been mapped out over nearly the entire summertime polar region. These structures include [`]ice rings', spatially small but bright clouds, and large regions ([`]ice-free regions') in the heart of the cloud season essentially devoid of ice particles. The ice rings bear a close resemblance to tropospheric convective outflow events, suggesting a point source of mesospheric convection. These rings (often circular arcs) are most likely Type IV NLC ([`]whirls' in the standard World Meteorological Organization (WMO) nomenclature).

Rusch, D. W.; Thomas, G. E.; McClintock, W.; Merkel, A. W.; Bailey, S. M.; Russell, J. M., III; Randall, C. E.; Jeppesen, C.; Callan, M.

2009-03-01

156

Effects of baroclinicity on the cloud pattern and structure of polar lows: A high-resolution numerical experiment  

NASA Astrophysics Data System (ADS)

High-resolution numerical experiments using a three-dimensional non-hydrostatic model with horizontal grid size of 5 or 2 km are performed to clarify what determines the structure and cloud pattern of polar lows. An axisymmetric initial vortex is imposed in a baroclinic basic state for which thermal wind balance holds. It is found that when the baroclinicity is absent, a hurricane-like vortex with spiral cloud bands, a cloud-free eye, and a warm core develops. When the baroclinicity is strong, on the other hand, a vortex with a comma-shaped cloud and slightly larger horizontal scale develops. The former appears to develop due to CISK/WISHE mechanism, while the latter due to baroclinic instability modified by latent heating.

Yanase, W.; Niino, H.

2005-01-01

157

The effects of orography on cloud and rainfall patterns during typhoon Ketsana (2009)  

NASA Astrophysics Data System (ADS)

The objective of this study is to investigate the effects of orography on the rainfall, wind, and cloud systems of the TCs in Malaysia and Indochina. To determine the relationship of the typhoon with the orographic effect, remote sensing techniques such as the Global Digital Elevation Model (GDEM) from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite, rainfall data from the Fengyun 2D (FY-2D), and radiosonde data were applied in this study. From this study, the following conclusions can be drawn: 1) rainfall tends to be distributed over high mountain regions; 2) wind flow will change its direction upon encountering any restrictions, especially those of high terrain regions; and 3) cloud patterns are deformed by high mountains and tend to flow with the mountains' structure because of the orographic effects. The regions most affected by Typhoon Ketsana in the study area were Vietnam in Indochina, Sabah in East Malaysia (EM), Kelantan and Terengganu in Peninsular Malaysia (PM). From the comparison among the study areas, it was found that Indochina had the most significant results for the orographic effects on typhoon activity, followed by the tail effects in EM. This phenomenon was found in PM, although it was not as significant as the other study areas. This remote sensing technique allows tropical cyclones to be forecasted and their impacts to be defined, and it allows disaster zones to be determined.

Fuyi, Tan; MatJafri, Mohd Zubir; Lim, Hwee-San; Abdullah, Khiruddin

2012-10-01

158

Reconstruction of typhoon path and cloud image from descriptors  

Microsoft Academic Search

In this paper, we propose a novel method to reconstruct the path and contour of a typhoon in a satellite image using mathematical morphology and descriptors. Generally, it is hard to depict the contour and path of a typhoon by a simple way in the satellite images. Especially, if we would like to track changes of a typhoon in the

Jun-heng Yeh; Tsang-long Pao; Chung-lang Lee; Wei-ta Lai

2007-01-01

159

Cumulus Cloud Field Morphology and Spatial Patterns Derived from High Spatial Resolution Landsat Imagery.  

NASA Astrophysics Data System (ADS)

Detailed observations of cumulus cloud scales and processes are an essential ingredient in models that deal with (i) high spatial resolution cumulus ensembles; and (ii) parameterization of cloud radiative processes. The present investigation focuses on three aspects of the morphology of cumulus clouds: 1) the inhomogeneity as represented by the size distribution of clouds and cloud `holes,' 2) the nearest-neighbor relationships regarding their sizes and mutual distances, and 3) the scales of their clustering.Distributionwise, cloud size can best be represented by a mixture of two power laws. Clouds of diameter below 1 km have the slope parameter ranging from about 1.4 to 2.3, while larger clouds have slopes ranging from 2.1 to 4.75. Furthermore, these clouds are bifractal in nature. The break in power law and fractal dimension occurs at a size critical to the cloud-scale processes in the following sense. First, this is the cloud size that makes the largest contribution to the extent of cloud cover. Second, there are indications that this is the size at which clouds begin to modify their environment.Cloud inhomogeneities have significant impact on radiative fluxes. The size distribution of holes in the cumulus clouds studied here have a single slope power law with estimated slopes close to 3; these holes have single fractal dimensions. Furthermore, the results suggest that as the cloud field matures, there is an increase in the number and size of the inhomogeneities along with increasing cloud size.Nearest-neighbor relationships are studied from two different perspectives. First, the nearest-neighbor separation distance is modeled by four probability distributions: lognormal, gamma, extreme-value and Weibull. Lognormal appears to provide the best fit. Second, the nearest-neighbor pair sizes and the associated separation distance are studied using a co-occurrence frequency approach of spatial point processes using second-order statistics. The largest frequency of nearest-neighbor pairs occurs at a distance of 200-300 m, with the largest absolute differences in cloud size found at separations of about 500 m. At larger separations, there is a tendency for the larger clouds to be closer to other large clouds, apparently through the modification of the environment. Nonlinear dependence between the sizes of nearest-neighbor cloud pairs increases with increasing cloud size.Cumulus cloud clustering scales are determined by using the classical Greig-Smith quadrat analysis technique. Clustering scales of about 15, 29, and 59 km are found for most of the ten cloud fields studied.

Sengupta, S. K.; Welch, R. M.; Navar, M. S.; Berendes, T. A.; Chen, D. W.

1990-12-01

160

Elucidating the Spatial Scaling Behavior of Cloud Embedded Convection and Rainfall Patterns in Complex Terrain Using Idealized WRF Simulations  

NASA Astrophysics Data System (ADS)

It is often observed a situation where a stratiform orographic cloud develops shallow embedded convective structures, which change the rainfall pattern and amounts considerably and can lead to localized extreme values of rainfall. These localized extremes are responsible for mountain hazards including landslides, debris flows and flashfloods. Although the basic mechanism responsible for orographic precipitation is well known, the triggering and dynamics of embedded convective structures is still poorly understood. An interesting idea is that the development of these cloud embedded convective structures results from the unstable growth of small scale disturbances inside the cloud, with upstream lee wave generation by small scale topography being a very important source of such disturbances. Linear stability analysis has been used previously with promising results to gain insight on the dominant spatial scales of the convective structures when a wide range of disturbance modes are present, as it is expected in the atmosphere. But the ability of such models to explain more realistic situations is still unclear and there is no consensus on the governing physics. These issues are assessed using a population of idealized cloud resolving high resolution simulations performed with the Weather Research and Forecasting (WRF) model for various configurations of small scale terrain. Here, we report on the relationships among the spatial scaling behavior of cloud embedded convective structures and associated precipitation patterns, small scale terrain features, and dynamical regimes described by moist stability, advective time scale, mean wind intensity and mean wind shear.

Nogueira, M.; Barros, A. P.; Miranda, P. M.

2010-12-01

161

Accelerating statistical image reconstruction algorithms for fan-beam x-ray CT using cloud computing  

NASA Astrophysics Data System (ADS)

Statistical image reconstruction algorithms potentially offer many advantages to x-ray computed tomography (CT), e.g. lower radiation dose. But, their adoption in practical CT scanners requires extra computation power, which is traditionally provided by incorporating additional computing hardware (e.g. CPU-clusters, GPUs, FPGAs etc.) into a scanner. An alternative solution is to access the required computation power over the internet from a cloud computing service, which is orders-of-magnitude more cost-effective. This is because users only pay a small pay-as-you-go fee for the computation resources used (i.e. CPU time, storage etc.), and completely avoid purchase, maintenance and upgrade costs. In this paper, we investigate the benefits and shortcomings of using cloud computing for statistical image reconstruction. We parallelized the most time-consuming parts of our application, the forward and back projectors, using MapReduce, the standard parallelization library on clouds. From preliminary investigations, we found that a large speedup is possible at a very low cost. But, communication overheads inside MapReduce can limit the maximum speedup, and a better MapReduce implementation might become necessary in the future. All the experiments for this paper, including development and testing, were completed on the Amazon Elastic Compute Cloud (EC2) for less than $20.

Srivastava, Somesh; Rao, A. Ravishankar; Sheinin, Vadim

2011-03-01

162

A multispectral spatio-temporal approach for cloud screening of remotely sensed images  

NASA Astrophysics Data System (ADS)

Information extraction from remotely sensed images acquired in the visible and near-infrared (VNIR) frequency range strongly depends on an accurate cloud pixel screening. Indeed, many remote sensing applications require a preliminary cloud detection phase to obtain profitable results. In this paper we propose to integrate the potential of the MAP-MRF methodology with the multispectral approach for augmenting the capability of the algorithm to detect cloudy pixels. In particular the proposed technique combines information from some SEVIRI sensor channels (in particular the channels 0.64?m, 1.6?m, 3.9?m, 7.3?m and 10.8?m) with the classification obtained by the MAP-MRF method in the 0.8?m channel in order to discriminate between snowy and cloudy pixels. The validation is performed on challenging images of Alps mountains acquired by the SEVIRI sensor during winter months. Results show significant improvements with respect to existing methods. In particular we highlight a more precise classification at the cloud borders and a considerable reduction of unsolicited holes inside the cloud masses.u

Addesso, Paolo; Conte, Roberto; Longo, Maurizio; Restaino, Rocco; Vivone, Gemine

2011-10-01

163

Pattern recognition software and techniques for biological image analysis.  

PubMed

The increasing prevalence of automated image acquisition systems is enabling new types of microscopy experiments that generate large image datasets. However, there is a perceived lack of robust image analysis systems required to process these diverse datasets. Most automated image analysis systems are tailored for specific types of microscopy, contrast methods, probes, and even cell types. This imposes significant constraints on experimental design, limiting their application to the narrow set of imaging methods for which they were designed. One of the approaches to address these limitations is pattern recognition, which was originally developed for remote sensing, and is increasingly being applied to the biology domain. This approach relies on training a computer to recognize patterns in images rather than developing algorithms or tuning parameters for specific image processing tasks. The generality of this approach promises to enable data mining in extensive image repositories, and provide objective and quantitative imaging assays for routine use. Here, we provide a brief overview of the technologies behind pattern recognition and its use in computer vision for biological and biomedical imaging. We list available software tools that can be used by biologists and suggest practical experimental considerations to make the best use of pattern recognition techniques for imaging assays. PMID:21124870

Shamir, Lior; Delaney, John D; Orlov, Nikita; Eckley, D Mark; Goldberg, Ilya G

2010-11-24

164

Pattern Recognition Software and Techniques for Biological Image Analysis  

PubMed Central

The increasing prevalence of automated image acquisition systems is enabling new types of microscopy experiments that generate large image datasets. However, there is a perceived lack of robust image analysis systems required to process these diverse datasets. Most automated image analysis systems are tailored for specific types of microscopy, contrast methods, probes, and even cell types. This imposes significant constraints on experimental design, limiting their application to the narrow set of imaging methods for which they were designed. One of the approaches to address these limitations is pattern recognition, which was originally developed for remote sensing, and is increasingly being applied to the biology domain. This approach relies on training a computer to recognize patterns in images rather than developing algorithms or tuning parameters for specific image processing tasks. The generality of this approach promises to enable data mining in extensive image repositories, and provide objective and quantitative imaging assays for routine use. Here, we provide a brief overview of the technologies behind pattern recognition and its use in computer vision for biological and biomedical imaging. We list available software tools that can be used by biologists and suggest practical experimental considerations to make the best use of pattern recognition techniques for imaging assays.

Shamir, Lior; Delaney, John D.; Orlov, Nikita; Eckley, D. Mark; Goldberg, Ilya G.

2010-01-01

165

Infrared Cloud Imager Development for Atmospheric Optical Communication Characterization, and Measurements at the JPL Table Mountain Facility  

NASA Astrophysics Data System (ADS)

The continuous demand for high data return in deep space and near-Earth satellite missions has led NASA and international institutions to consider alternative technologies for high-data-rate communications. One solution is the establishment of wide-bandwidth Earth-space optical communication links, which require (among other things) a nearly obstruction-free atmospheric path. Considering the atmospheric channel, the most common and most apparent impairments on Earth-space optical communication paths arise from clouds. Therefore, the characterization of the statistical behavior of cloud coverage for optical communication ground station candidate sites is of vital importance. In this article, we describe the development and deployment of a ground-based, long-wavelength infrared cloud imaging system able to monitor and characterize the cloud coverage. This system is based on a commercially available camera with a 62-deg diagonal field of view. A novel internal-shutter-based calibration technique allows radiometric calibration of the camera, which operates without a thermoelectric cooler. This cloud imaging system provides continuous day-night cloud detection with constant sensitivity. The cloud imaging system also includes data-processing algorithms that calculate and remove atmospheric emission to isolate cloud signatures, and enable classification of clouds according to their optical attenuation. Measurements of long-wavelength infrared cloud radiance are used to retrieve the optical attenuation (cloud optical depth due to absorption and scattering) in the wavelength range of interest from visible to near-infrared, where the cloud attenuation is quite constant. This article addresses the specifics of the operation, calibration, and data processing of the imaging system that was deployed at the NASA/JPL Table Mountain Facility (TMF) in California. Data are reported from July 2008 to July 2010. These data describe seasonal variability in cloud cover at the TMF site, with cloud amount (percentage of cloudy pixels) peaking at just over 51 percent during February, of which more than 60 percent had optical attenuation exceeding 12 dB at wavelengths in the range from the visible to the near-infrared. The lowest cloud amount was found during August, averaging 19.6 percent, and these clouds were mostly optically thin, with low attenuation.

Nugent, P. W.; Shaw, J. A.; Piazzolla, S.

2013-02-01

166

Retrieval of Cloud Phase Using the Moderate Resolution Imaging Spectroradiometer Data during the Mixed-Phase Arctic Cloud Experiment  

SciTech Connect

Improving climate model predictions over Earth's polar regions requires a comprehensive knowledge of polar cloud microphysics. Over the Arctic, there is minimal contrast between the clouds and background snow surface, making it difficult to detect clouds and retrieve their phase from space. Snow and ice cover, temperature inversions, and the predominance of mixed-phase clouds make it even more difficult to determine cloud phase. Also, since determining cloud phase is the first step toward analyzing cloud optical depth, particle size, and water content, it is vital that the phase be correct in order to obtain accurate microphysical and bulk properties. Changes in these cloud properties will, in turn, affect the Arctic climate since clouds are expected to play a critical role in the sea ice albedo feedback. In this paper, the IR trispectral technique (IRTST) is used as a starting point for a WV and 11-{micro}m brightness temperature (T11) parameterization (WVT11P) of cloud phase using MODIS data. In addition to its ability to detect mixed-phase clouds, the WVT11P also has the capability to identify thin cirrus clouds overlying mixed or liquid phase clouds (multiphase ice). Results from the Atmospheric Radiation Measurement (ARM) MODIS phase model (AMPHM) are compared to the surface-based cloud phase retrievals over the ARM North Slope of Alaska (NSA) Barrow site and to in-situ data taken from University of North Dakota Citation (CIT) aircraft which flew during the Mixed-Phase Arctic Cloud Experiment (MPACE). It will be shown that the IRTST and WVT11P combined to form the AMPHM can achieve a relative high accuracy of phase discrimination compared to the surface-based retrievals. Since it only uses MODIS WV and IR channels, the AMPHM is robust in the sense that it can be applied to daytime, twilight, and nighttime scenes with no discontinuities in the output phase.

Spangenberg, D.; Minnis, P.; Shupe, M.; Uttal, T.; Poellot, M.

2005-03-18

167

Spatially resolved cloud structure on Uranus: Implications of near-IR adaptive optics imaging  

NASA Astrophysics Data System (ADS)

Seven-band near-IR adaptive optics imaging of Uranus by the Keck II telescope during 2004, with the assistance of selected Hubble Space Telescope images, provides new constraints on the uranian vertical cloud structure and CH 4 mixing ratio, after tuned deconvolutions are applied to remove significant limb darkening distortions. The most strongly absorbing bands approximately agree with the stratospheric haze model of Rages et al. [Rages, K., Pollack, J.B., Tomasko, M.G., Doose, L.R., 1991. Icarus 89, 359-376]. The next most absorbing bands suggest a CH 4 relative humidity of 50-60% above the 1.2-bar condensation level. Window channels imply effective cloud pressures at 12° S that vary from 9 to 3.5 bars, and reflectivity values that vary from 7 to 4%, as the assumed CH 4 mixing ratio varies from 0.75 to 4%. The shape of the center-to-limb radiance profile is in best agreement with the deep cloud being translucent, with relatively low optical depth, and is most consistent with low methane mixing ratios (0.75-1%) if the cloud particles are conservative. Non-conservative particles provide good fits over a wide range of mixing ratios. If C and S are enhanced by the same factor over solar mixing ratios, then the cloud pressures inferred from near-IR observations would be less than H 2S condensation pressures for methane mixing ratios of ˜1.3% or greater. The bright band at 45° S must be partly produced by increased particulate scattering at pressures ˜2 bars to be consistent with its absence in 1.9-?m images and its presence in 0.619-?m images. The reflectivity of the lower clouds declines to nearly negligible values in the northern hemisphere, where I/F observations beyond 50° N are nearly those of a clear atmosphere. The most surprising result is the general lack of scattering originating from the 1.2-bar region where methane is expected to condense. Exceptions occur for discrete features. A large and long-lived discrete feature at 34° S is associated with particulates near 700 mb and ˜4.5 bars. The highest discrete feature, near 26° N, reached pressures ˜200 mb and was eleven times brighter than the background atmosphere in K images.

Sromovsky, L. A.; Fry, P. M.

2007-12-01

168

Typhoon Locating and Reconstruction from the Infrared Satellite Cloud Image  

Microsoft Academic Search

Typhoon inflicts terrible damage due to thunderstorms, violent winds, torrential rain, floo ding and extreme high tides. Improving the early typhoon forecast capability is important for the disaster prevention . In recent years, many scholars have made efforts in typhoon center location, typhoon intensity estimation and moving path prediction from the satellite images. Moreover, it may be useful to transfer

Tsang-long Pao; Jun-heng Yeh

2008-01-01

169

Clouds as Seen by Satellite Sounders (3I) and Imagers (ISCCP). Part I: Evaluation of Cloud Parameters.  

NASA Astrophysics Data System (ADS)

The improved initialization inversion (3I) algorithms convert TIROS-N Operational Vertical Sounder observations from the National Oceanic and Atmospheric Administration (NOAA) polar-orbiting environmental satellites into atmospheric temperature and water vapor profiles, together with cloud and surface properties. Their relatively good spectral resolution and coverage make IR sounders a very useful tool for the determination of cloud properties both day and night. The iterative process of detailed comparisons between cloud parameters obtained from this global dataset, which is available in the framework of the NOAA-National Aeronautics and Space Administration Pathfinder Program, with time-space-collocated observations of clouds from the recently reprocessed International Satellite Cloud Climatology Project (ISCCP) dataset has led to an improved 3I cloud analysis scheme based on a weighted-2 method described in the second article of this series. This process also provides a first evaluation of the ISCCP reanalysis. The new 3I cloud scheme obtains cloud properties very similar to those from ISCCP for homogeneous cloud scenes. Improvement is especially notable in the stratocumulus regimes where the new 3I scheme detects much more of the low-level cloudiness. Remaining discrepancies in cloud classification can now be explained by differences in cloud detection sensitivity, differences in temperature profiles used, and inhomogeneous or partly cloudy fields. Cirrus cloud identification during the daytime in the recent ISCCP dataset is improved relative to the first version of ISCCP, but is still an underestimate. At night only multispectral IR analyses like 3I can provide cirrus information. The reprocessed ISCCP dataset also shows considerable improvement in cloud cover at higher latitudes. Differences in 3I and ISCCP summertime cloud cover over deserts may be caused by different sensitivities to dust storms.

Stubenrauch, C. J.; Rossow, W. B.; Chéruy, F.; Chédin, A.; Scott, N. A.

1999-08-01

170

Geometrically robust image watermarking using star patterns  

Microsoft Academic Search

Digital copyright protection has become increasingly important in recent times due to the rapid growth of the Inter- net and the proliferation of P2P technologies. Copyright protection of digital images and videos are of particular interest since they can easily be pirated and distributed illegally across networks. Existing watermarking methods can embed a signature into a digital image and tend

John R. Zhang; Jon G. Rokne

2007-01-01

171

Implementation of MapReduce-based image conversion module in cloud computing environment  

Microsoft Academic Search

In recent years, the rapid advancement of the Internet and the growing number of people using social networking services (SNSs) have facilitated the sharing of multimedia data. However, multimedia data processing techniques such as transcoding and transmoding impose a considerable burden on the computing infrastructure as the amount of data increases. Therefore, we propose a MapReduce-based image-conversion module in cloud

Hyeokju Lee; Myoungjin Kim; Joon Her; Hanku Lee

2012-01-01

172

Retrieval of cloud liquid water using the special sensor microwave imager (SSM\\/I)  

Microsoft Academic Search

The special sensor microwave imager (SSM\\/I) is a microwave radiometer having dual-polarized channels at 19.35, 37, and 85.5 GHz and a vertically polarized channel at 22.235 GHz. The measurements at these frequencies are used to retrieve the liquid water path in precipitating and nonprecipitating clouds over oceans. Three separate algorithms, each accurate for different ranges of liquid water, are combined

Fuzhong Weng; Norman C. Grody

1994-01-01

173

Estimating cloud top height and spatial displacement from scan-synchronous GOES images using simplified IR-based stereoscopic analysis  

NASA Astrophysics Data System (ADS)

An efficient method for estimating cloud top heights and correcting cloud image spatial displacements was developed. The method applies stereoscopic analysis to a pair of scan-synchronous infrared cloud images received from two GOES satellites using a piecewise linear approximation of the relationship between height and infrared brightness temperature of top of the cloud element. The algorithm solves for cloud top heights and subsequently calculates the spatial displacements of cloud images. Optimal parameterization of the piecewise linear approximation is achieved using the shuffled complex evolution (SCE) algorithm. Because the proposed method simplifies the stereoscopic analysis, it allows for an easy implementation of stereoscopic technique on desktop computers. When compared to the standard isotherm matching approaches, the proposed method yielded higher correlation between GOES 8 and GOES 9 scan-simultaneous images after the parallax adjustment. The validity of the linear approximation was tested against temperature profiles obtained from the multiple ground sounding measurements from the Tropical Rainfall Measuring Mission/Texas and Florida Underflights (TRMM/TEFLUN) experiments. The results of this comparison demonstrated good fit, particularly within the troposphere, between the optimized relationship and atmospheric sounding measurements. The data produced by this method, including cloud top temperatures and heights, atmospheric temperature profiles for cloudy sky areas, and spatial displacement-adjusted cloud images, can be useful for weather/climate and atmospheric studies. In particular, the displacement-adjusted cloud images can be critical to develop high-resolution satellite rainfall estimates, which are urgently needed by mesoscale atmospheric modeling and studies, severe weather monitoring, and heavy precipitation and flash flood forecasting. Limitations of the proposed method are also identified and discussed.

Mahani, Shayesteh E.; Gao, Xiaogang; Sorooshian, Soroosh; Imam, Bisher

2000-06-01

174

Vehicle detection at night using image processing and pattern recognition  

Microsoft Academic Search

We present a methodology to detect vehicles at night using image processing and pattern recognition. The using of mathematical morphology, the techniques of pattern recognition and the studying of perspective influences are the major innovations of our method. First, we present an initialisation phase that involves a road modelling. Afterwards, we present methodologies to detect vehicles on highways. We also

R. Taktak; M. Dufaut; R. Husson

1994-01-01

175

Thin Photo-Patterned Micropolarizer Array for CMOS Image Sensors  

Microsoft Academic Search

We fabricated and characterized a thin photo-patterned micropolarizer array for complementary metal-oxide-semiconductor (CMOS) image sensors. The proposed micropolarizer fabrication technology completely removes the need for complex selective etching. Instead, it uses the well-controlled process of ultraviolet photolithography to define micropolarizer orientation patterns on a spin-coated azo-dye-1 film. The patterned polymer film micropolarizer (10 mum x 10 mum) exhibits submicron thickness

Xiaojin Zhao; Farid Boussaid; Amine Bermak; Vladimir G. Chigrinov

2009-01-01

176

Body image boundaries and patterns of body perception  

Microsoft Academic Search

4 studies were undertaken to test hypotheses concerning the relationship of the definitness of the body image boundary to patterns of sensation from exterior and interior body regions. The measure of boundary definiteness utilized was the barrier score which is derived from responses to inkblots. It was found that the more definite an S's body image boundary the more likely

Seymour Fisher; Rhoda L. Fisher

1964-01-01

177

Watershed image segmentation and cloud classification from multispectral MSG-SEVIRI imagery  

NASA Astrophysics Data System (ADS)

In this work a technique for cloud detection and classification from MSG-SEVIRI (Meteosat Second Generation-Spinning Enhanced Visible and Infra-red Imager) imagery is presented. It is based on the segmentation of the multispectral images using order-invariant watershed algorithms, which are applied to the corresponding gradient images, computed by a multi-dimensional morphological operator. To reduce the over-segmentation produced by the watershed method, a RAG (Region Adjacency Graph) based region merging technique is applied, using region dissimilarity functions. Once the objects present in the image have been segmented, they are classified using a multi-threshold method based on physical considerations that takes into account the statistical parameters inside each region.

González, Albano; Pérez, Juan C.; Muñoz, Jonathan; Méndez, Zebensui; Armas, Montserrat

2012-01-01

178

Cassini imaging of Titan's high-latitude lakes, clouds, and south-polar surface changes  

NASA Astrophysics Data System (ADS)

Cassini's Imaging Science Subsystem (ISS) has been observing Titan since April 2004, compiling a nearly global surface map and monitoring the surface and atmosphere for activity. Early images of the south-polar region revealed numerous dark surface features and contemporaneous convective cloud systems, suggesting the presence of hydrocarbon lakes similar to those later detected at Titan's North Pole. Intriguingly, repeated south-polar imaging by ISS revealed differences consistent with ponding of hydrocarbon liquids on the surface due to precipitation from a large storm. More recent ISS images of high northern latitudes illustrate the full extents (>500,000 km2) of hydrocarbon seas, sections of which have been observed by Cassini's RADAR. These observations demonstrate dynamic processes at work on Titan and that the poles harbor liquid-hydrocarbon reservoirs, the extents of which differ from pole to pole and which may be coupled to seasonally varying circulation.

Turtle, E. P.; Perry, J. E.; McEwen, A. S.; Del Genio, A. D.; Barbara, J.; West, R. A.; Dawson, D. D.; Porco, C. C.

2009-01-01

179

Multi Spectral Pushbroom Imaging Radiometer (MPIR) for remote sensing cloud studies  

SciTech Connect

A Multi Spectral Pushbroom Imaging Radiometer (MPIR) has been developed as are relatively inexpensive ({approximately}$IM/copy), well-calibrated,imaging radiometer for aircraft studies of cloud properties. The instrument is designed to fly on an Unmanned Aerospace Vehicle (UAV) platform at altitudes from the surface up to 20 km. MPIR is being developed to support the Unmanned Aerospace Vehicle portion of the Department of Energy`s Atmospheric Radiation Measurements program (ARM/UAV). Radiation-cloud interactions are the dominant uncertainty in the current General Circulation Models used for atmospheric climate studies. Reduction of this uncertainty is a top scientific priority of the US Global Change Research Program and the ARM program. While the DOE`s ARM program measures a num-ber of parameters from the ground-based Clouds and Radiation Testbed sites, it was recognized from the outset that other key parameters are best measured by sustained airborne data taking. These measurements are critical in our understanding of global change issues as well as for improved atmospheric and near space weather forecasting applications.

Phipps, G.S.; Grotbeck, C.L.

1995-10-01

180

Day/night whole sky imagers for 24-h cloud and sky assessment: history and overview.  

PubMed

A family of fully automated digital whole sky imagers (WSIs) has been developed at the Marine Physical Laboratory over many years, for a variety of research and military applications. The most advanced of these, the day/night whole sky imagers (D/N WSIs), acquire digital imagery of the full sky down to the horizon under all conditions from full sunlight to starlight. Cloud algorithms process the imagery to automatically detect the locations of cloud for both day and night. The instruments can provide absolute radiance distribution over the full radiance range from starlight through daylight. The WSIs were fielded in 1984, followed by the D/N WSIs in 1992. These many years of experience and development have resulted in very capable instruments and algorithms that remain unique. This article discusses the history of the development of the D/N WSIs, system design, algorithms, and data products. The paper cites many reports with more detailed technical documentation. Further details of calibration, day and night algorithms, and cloud free line-of-sight results will be discussed in future articles. PMID:23478763

Shields, Janet E; Karr, Monette E; Johnson, Richard W; Burden, Art R

2013-03-10

181

Horizontal structure of planetary-scale waves at the cloud top of Venus deduced from Galileo SSI images with an improved cloud-tracking technique  

NASA Astrophysics Data System (ADS)

An improved cloud tracking method for deriving wind velocities from successive planetary images was developed. The new method incorporates into the traditional cross-correlation method an algorithm that corrects for erroneous cloud motion vectors by re-determining the most plausible correlation peak among all of the local maxima on the correlation surface by comparing each vector with its neighboring vectors. The newly developed method was applied to the Venusian violet images obtained by the Solid State Imaging system (SSI) onboard the Galileo spacecraft during its Venus flyby. Although the results may be biased by the choice of spatial scale of atmospheric features, the cloud tracking is the most practical mean of estimating the wind velocities with extensive spatial and temporal coverage. The two-dimensional distribution of the horizontal wind vector field over 5 days was obtained. It was found from these wind maps that the solar-fixed component in 1990 was similar to that in 1982 obtained by the Pioneer Venus orbiter. The deviation of the instantaneous zonal wind field from the solar-fixed component shows a distinct wavenumber-1 structure in the equatorial region. On the assumption that this structure is a manifestation of an equatorial Kelvin wave, the phase relationship between the zonal wind and the cloud brightness suggests a short photochemical lifetime of the violet absorber. The momentum deposition by this Kelvin wave, which is subject to radiative damping, would induce a westward mean-wind acceleration of ˜0.3 m s -1 per Earth day.

Kouyama, Toru; Imamura, Takeshi; Nakamura, Masato; Satoh, Takehiko; Futaana, Yoshihumi

2012-01-01

182

Color image zooming on the Bayer pattern  

Microsoft Academic Search

A zooming framework suitable for single-sensor dig- ital cameras is introduced and analyzed in this paper. The pro- posed framework is capable of zooming and enlarging data ac- quired by single-sensor cameras that employ the Bayer pattern as a color filter array (CFA). The approach allows for operations on noise-free data at the hardware level. Complexity and cost imple- mentation

Rastislav Lukac; Konstantinos N. Plataniotis; Dimitrios Hatzinakos

2005-01-01

183

Imaging of the CCS 22.3 GHz Emission in the Taurus Molecular Cloud Complex  

NASA Astrophysics Data System (ADS)

Thioxoethenylidene (CCS) is an abundant interstellar molecule and a good tracer of high density and evolutionary stage of dense molecular clouds. It is also a suitable candidate for Zeeman splitting observations for its high splitting factor and narrow thermal line widths. We report here Expanded Very Large Array 22.3 GHz observations of three dense molecular cores TMC-1, TMC-1C, and L1521B in the Taurus molecular cloud complex to image the CCS 21-10 transition. For all three sources, the clumpy CCS emission is most likely tracing the starless cores. However, these compact structures account for only ~1%-13% of the integrated emission detected in single-dish observations, indicating the presence of significant large-scale diffuse emission in favorable conditions for producing CCS.

Roy, Nirupam; Datta, Abhirup; Momjian, Emmanuel; Sarma, Anuj P.

2011-09-01

184

The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI): a new tool for aerosol and cloud remote sensing  

NASA Astrophysics Data System (ADS)

The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) is an eight-band (355, 380, 445, 470, 555, 660, 865, 935 nm) pushbroom camera, measuring polarization in the 470, 660, and 865 nm bands, mounted on a gimbal to acquire multiangular observations over a ±67° along-track range. The instrument has been flying aboard the NASA ER-2 high altitude aircraft since October 2010. AirMSPI employs a photoelastic modulator-based polarimetric imaging technique to enable accurate measurements of the degree and angle of linear polarization in addition to spectral intensity. A description of the AirMSPI instrument and ground data processing approach is presented. Example images of clear, hazy, and cloudy scenes over the Pacific Ocean and California land targets obtained during flights between 2010 and 2012 are shown, and quantitative interpretations of the data using vector radiative transfer theory and scene models are provided to highlight the instrument's capabilities for determining aerosol and cloud microphysical properties and cloud 3-D spatial distributions. Sensitivity to parameters such as aerosol particle size distribution, ocean surface wind speed and direction, cloud-top and cloud-base height, and cloud droplet size is discussed. AirMSPI represents a major step toward realization of the type of imaging polarimeter envisioned to fly on NASA's Aerosol-Cloud-Ecosystem (ACE) mission in the next decade.

Diner, D. J.; Xu, F.; Garay, M. J.; Martonchik, J. V.; Rheingans, B. E.; Geier, S.; Davis, A.; Hancock, B. R.; Jovanovic, V. M.; Bull, M. A.; Capraro, K.; Chipman, R. A.; McClain, S. C.

2013-08-01

185

Continuous image writer with improved image quality for high-accuracy optical patterning  

Microsoft Academic Search

We report on the development of a production tool for fast optical maskless patterning. The Continuous Image Writer (CIW) combines the advantages of direct writing by using a programmable mask with the advantages of conventional optical lithography by using the same lithographic process for image formation in photoresist. An electronically programmable Spatial Light Modulator (SLM) is imaged into the substrate

Joerg Paufler; Stefan Brunn; Tim Koerner

2001-01-01

186

Using Geotags to Derive Rich Tag-Clouds for Image Annotation  

NASA Astrophysics Data System (ADS)

Geotagging has become popular for many multimedia applications. In this chapter, we present an integrated and intuitive system for location-driven tag suggestion, in the form of tag-clouds, for geotagged photos. Potential tags from multiple sources are extracted and weighted. Sources include points of interest (POI) tags from a public Geographic Names Information System (GNIS) database, community tags from Flickr® pictures, and personal tags shared through users' own, family, and friends' photo collections. To increase the effectiveness of GNIS POI tags, bags of place-name tags are first retrieved, clustered, and then re-ranked using a combined tf-idf and spatial distance criteria. The community tags from photos taken in the vicinity of the input geotagged photo are ranked according to distance and visual similarity to the input photo. Personal tags from other personally related photos inherently carry a significant weight due more to their high relevance than to both the generic place-name tags and community tags, and are ranked by weights that decay over time and distance differences. Finally, a rich set of the most relevant location-driven tags is presented to the user in the form of individual tag clouds under the three mentioned source categories. The tag clouds act as intuitive suggestions for tagging an input image. We also discuss quantitative and qualitative findings from a user study that we conducted. Evaluation has revealed the respective benefits of the three categories toward the effectiveness of the integrated tag suggestion system.

Joshi, Dhiraj; Luo, Jiebo; Yu, Jie; Lei, Phoury; Gallagher, Andrew

187

Frequency hopping patterns for simultaneous multiple-beam sonar imaging  

Microsoft Academic Search

This paper describes the design of frequency-hopped signals for a multi-beam imaging system. A frequency hopping pattern is a frequency-coded uniform pulse train. The signal is divided into M time intervals, with each interval assigned a different frequency chosen from a set of N frequencies. A set of N patterns composed of N-1 frequencies can be generated using first-order Reed-Solomon

Philippe M. Cassereau; Jules S. Jaffe

1987-01-01

188

Automatic Pattern Extraction and Classification for Chromosome Images  

NASA Astrophysics Data System (ADS)

Chromosome image analysis and pattern classification is one of the essential tasks in genetic syndrome diagnoses. An automatic procedure is introduced for chromosome image analysis. The pale-path algorithm is proposed to segment touching and overlapping chromosomes. Medial axis is extracted by the middle point algorithm. Chromosome band is enhanced by the algorithm based on multiscale wavelets Bi-spline, and extracted by average gray profile, gradient profile and shape profile. The multilayer classifier is used to classify the chromosome pattern calculated by weighted density distribution algorithm. Experiment results demonstrate that the algorithms perform well.

Ming, Delie; Tian, Jinwen

2010-07-01

189

Image analysis of dye stained patterns in soils  

NASA Astrophysics Data System (ADS)

Quality of surface water and groundwater is directly affected by flow processes in the unsaturated zone. In general, it is difficult to measure or model water flow. Indeed, parametrization of hydrological models is problematic and often no unique solution exists. To visualise flow patterns in soils directly dye tracer studies can be done. These experiments provide images of stained soil profiles and their evaluation demands knowledge in hydrology as well as in image analysis and statistics. First, these photographs are converted to binary images classifying the pixels in dye stained and non-stained ones. Then, some feature extraction is necessary to discern relevant hydrological information. In our study we propose to use several index functions to extract different (ideally complementary) features. We associate each image row with a feature vector (i.e. a certain number of image function values) and use these features to cluster the image rows to identify similar image areas. Because images of stained profiles might have different reasonable clusterings, we calculate multiple consensus clusterings. An expert can explore these different solutions and base his/her interpretation of predominant flow mechanisms on quantitative (objective) criteria. The complete workflow from reading-in binary images to final clusterings has been implemented in the free R system, a language and environment for statistical computing. The calculation of image indices is part of our own package Indigo, manipulation of binary images, clustering and visualization of results are done using either build-in facilities in R, additional R packages or the LATEX system.

Bogner, Christina; Trancón y Widemann, Baltasar; Lange, Holger

2013-04-01

190

Forecasting for Grid and Cloud Computing On-Demand Resources Based on Pattern Matching  

Microsoft Academic Search

Abstract: The Cloud phenomenon,brings along the cost-saving benefit of dynamic scaling. Knowledge in advance is necessary as the virtual resources that Cloud computing uses have a setup time that is not negligible. We propose a new approach to the problem of workload prediction based on identifying similar past occurrences to the current short-term workload history. We present in detail the

Eddy Caron; Frédéric Desprez; Adrian Muresan

2010-01-01

191

Analysis of Breathing Air Flow Patterns in Thermal Imaging  

Microsoft Academic Search

We introduce a novel methodology to characterize breathing patterns based on thermal infrared imaging. We have retrofitted a Mid-Wave Infra-Red (MWIR) imaging system with a narrow band-pass filter in the CO2 absorption band (4130 - 4427 nm). We use this system to record the radiation information from within the breathing flow region. Based on this information we compute the mean

Jin Fei; Ioannis Pavlidis

2006-01-01

192

Automatic Pattern Extraction and Classification for Chromosome Images  

Microsoft Academic Search

Chromosome image analysis and pattern classification is one of the essential tasks in genetic syndrome diagnoses. An automatic\\u000a procedure is introduced for chromosome image analysis. The pale-path algorithm is proposed to segment touching and overlapping\\u000a chromosomes. Medial axis is extracted by the middle point algorithm. Chromosome band is enhanced by the algorithm based on\\u000a multiscale wavelets Bi-spline, and extracted by

Delie Ming; Jinwen Tian

2010-01-01

193

Edge patterns extracted from natural images and their statistics for reduced-reference image quality assessment  

NASA Astrophysics Data System (ADS)

Image quality assessment (IQA) aims to predict perceived image quality consistently with the corresponding subjective perceptual quality. Searching for features efficiently representing natural images and investigating their statistics are the fundamentals in the task of IQA models design. In this context, we have proposed previously a novel reduced reference (RR) IQA model in which groups of the named edge patterns are good to represent the local distribution of the zero-crossings both for natural images and their distorted counterpart, and then proposed a RR IQA model. In this paper, we focus on the issue of the interesting edge patterns related to natural images, i.e., what are the edge patterns good at representing ZC distribution of natural images? And how should we do to use them for IQA model design? Along those ideas, we extract 39 groups of edge patterns from 110 natural pictures by a defined curvature rule. Combined with error tolerance, the 39 groups of edge patterns can well represent the ZC distribution of both the reference and distortion images. Based on them, a RR IQA model is built on the statistical analysis of the selected edge patterns. Experimental results show that the proposed model works fairly good compared to its competitor.

Shao, Wenting; Mou, Xuanqin

2013-01-01

194

Imaging open-path Fourier transform infrared spectrometer for 3D cloud profiling  

NASA Astrophysics Data System (ADS)

An imaging open-path Fourier transform infrared (I-OP-FTIR) spectrometer is being developed for real-time three-dimensional cloud profiling. The system employs a single modulator and a novel optical configuration which projects an array of angularly dispersed IR beams, each of which exhibits comparable throughput to a single channel OP-FTIR, to an array of respective retroreflector arrays remotely located at the opposite side of the test grid. The return light from each retroreflector array is imaged onto respective detectors that record the spatially-resolved interferograms which are subsequently transformed and analyzed for molecular content via advanced multicomponent algorithms. The result is a capability to sensitively, quantitatively, and simultaneously measure the molecular absorbance and associated concentration-pathlength of an open release plume over a spatial region. Use of two or more I-OP-FTIR sensors around the perimeter of the release allows for tomographic reconstruction of the concentration map of each molecular species contained in the plume. This approach realizes the high sensitivity of an OP-FTIR spectrometer without adding the expense and logistical difficulties associated with installing a large number of spectrometer units required for the cloud profiling application. In addition, the active spectral measurement supports detection in zero temperature contrast conditions where the plume is the same temperature as the background. A further reduction in cost and weight is achieved through the use of low-cost plastic press molded retroreflector arrays to return the spatially dispersed open path beams.

Dupuis, Julia R.; Mansur, David J.; Engel, James R.; Vaillancourt, Robert; Todd, Lori; Mottus, Kathleen

2007-10-01

195

PSC Meteorology Program Cloud Boutique  

NSDL National Science Digital Library

Plymouth State College (PSC) provides the PSC Meteorology Program Cloud Boutique Website to "provide explanations of and access to detailed pictures of some basic cloud forms." Spectacular images and brief descriptions of high clouds (cirrus, cirrocumulus, and cirrostratus), middle clouds (altocumulus and altostratus), low clouds (cumulus, stratocumulus, stratus, and fog), multi-layer clouds (nimbostratus and cumulonimbus), and orographic clouds (lenticular and cap), among others are included. The site is an excellent general cloud reference.

196

Harmonic models of shape transformations in digital images and patterns  

Microsoft Academic Search

A harmonic model of shape transformations is presented. In this model, harmonic functions are governed by the Laplace equation. This model can convert all image or a pattern to another with arbitrary shapes. The transformation process is harmonic, without abruptness and discontinuity. This model can be used to generate and recognize handwritten Roman letters and Chinese characters, fingerprints, and other

Z. C. Li; C. Y. Suen; T. D. Bui; Q. L. Gu

1990-01-01

197

Symbolic document image compression based on pattern matching techniques  

Microsoft Academic Search

In this paper, a novel compression algorithm for Chinese document images is proposed. Initially, documents are segmented into readable components such as characters and punctuation marks. Similar patterns within the text are found by shape context matching and grouped to form a set of prototype symbols. Text redundancies can be removed by replacing repeated symbols by their corresponding prototype symbols.

Chwan-Yi Shiah; Yun-Sheng Yen

2011-01-01

198

Three Dimensional Measurement using Color Structured Patterns and Imaging Spectrograph  

Microsoft Academic Search

In this paper, we propose a simultaneous measurement system of spectral reflectance and shape of an object with the use of color gray code structured patterns and an imaging spectrograph. Color and shape information are very important for its to recognize objects. Therefore, we have proposed an earlier system which is able to measure spectral reflectance and shape simultaneously by

Yoshitsugu Manabe; Jussi Parkkinen; Timo Jaaskelainen; Kunihiro Chihara

2002-01-01

199

Thermodynamics of Bose-Einstein-condensed clouds using phase-contrast imaging  

SciTech Connect

Phase contrast imaging is used to observe Bose-Einstein condensates at finite temperature in situ. The imaging technique is used to accurately derive the absolute phase shift of a probe laser beam due to both the condensate and the thermal cloud. The accuracy of the method is enhanced by using the periodicity of the intensity signal as a function of the accumulated phase. The measured density profiles can be described using a two-relevant-parameter fit, in which only the chemical potential and the temperature are to be determined. This allows us to directly compare the measured density profiles to different mean-field models in which the interaction between the condensed and the thermal atoms is taken into account to various degrees.

Meppelink, R.; Rozendaal, R. A.; Koller, S. B.; Vogels, J. M.; Straten, P. van der [Atom Optics and Ultrafast Dynamics, Utrecht University, Post Office Box 80000, NL-3508 TA Utrecht (Netherlands)

2010-05-15

200

CCD camera response to diffraction patterns simulating particle images.  

PubMed

We present a statistical study of CCD (or CMOS) camera response to small images. Diffraction patterns simulating particle images of a size around 2-3 pixels were experimentally generated and characterized using three-point Gaussian peak fitting, currently used in particle image velocimetry (PIV) for accurate location estimation. Based on this peak-fitting technique, the bias and RMS error between locations of simulated and real images were accurately calculated by using a homemade program. The influence of the intensity variation of the simulated particle images on the response of the CCD camera was studied. The experimental results show that the accuracy of the position determination is very good and brings attention to superresolution PIV algorithms. Some tracks are proposed in the conclusion to enlarge and improve the study. PMID:23842270

Stanislas, M; Abdelsalam, D G; Coudert, S

2013-07-01

201

Directional binary wavelet patterns for biomedical image indexing and retrieval.  

PubMed

A new algorithm for medical image retrieval is presented in the paper. An 8-bit grayscale image is divided into eight binary bit-planes, and then binary wavelet transform (BWT) which is similar to the lifting scheme in real wavelet transform (RWT) is performed on each bitplane to extract the multi-resolution binary images. The local binary pattern (LBP) features are extracted from the resultant BWT sub-bands. Three experiments have been carried out for proving the effectiveness of the proposed algorithm. Out of which two are meant for medical image retrieval and one for face retrieval. It is further mentioned that the database considered for three experiments are OASIS magnetic resonance imaging (MRI) database, NEMA computer tomography (CT) database and PolyU-NIRFD face database. The results after investigation shows a significant improvement in terms of their evaluation measures as compared to LBP and LBP with Gabor transform. PMID:21822675

Murala, Subrahmanyam; Maheshwari, R P; Balasubramanian, R

2011-08-06

202

Cloud patterns and mixing properties in shallow moist Rayleigh-Bénard convection  

NASA Astrophysics Data System (ADS)

Three-dimensional direct numerical simulations of idealized moist turbulent Rayleigh-Bénard convection are presented. The thermodynamics of moist air is linearized close to the phase boundary between water vapor and liquid water. This formulation allows for a simplified saturation condition for the cloud formation, but omits supersaturation and rain. The sensitivity of this problem to changes of the Rayleigh number, the aspect ratio of the convection layer and the water vapor concentration is studied. The Rayleigh number is found to impact the behavior of the system in multiple ways. First, the relaxation time toward a well-mixed turbulent state increases with the Rayleigh number. Similarly, the flow exhibits a higher spatial and temporal intermittency at higher Rayleigh number. This is in line with an enhanced intermittency of the upward buoyancy flux, which we quantify by a multifractal analysis. In addition, phase transition introduces an asymmetry in the distribution of the thermodynamic properties of the well-mixed state. This asymmetry is most pronounced in layers where clouds are partially present. Furthermore, the geometrical properties of the cloud formations averaged with respect to the height of the layer are studied. Similar to isocontours in scalar mixing, the boundaries of isolated clouds show no strict (mono-)fractal behavior. The results of the perimeter-area analysis of the largest isolated clouds agree well with those of large eddy simulations of cumulus convection. This perimeter-area scaling is also similar to that of percolation processes in a plane.

Weidauer, Thomas; Pauluis, Olivier; Schumacher, Jörg

2010-10-01

203

Systemic and Internal motions of the Magellanic Clouds: Third Epoch Images  

NASA Astrophysics Data System (ADS)

In Cycles 11 and 13 we obtained two epochs of ACS/HRC data for fields in the Magellanic Clouds centered on background quasars. We used these data to determine the proper motions of the LMC and SMC to better than 5% and 15% respectively. These are by far the best determinations of the proper motions of these two galaxies. The results have a number of unexpected implications for the Milky Way-LMC-SMC system. The implied three-dimensional velocities are larger than previously believed, and are not much less than the escape velocity in a standard 10^12 solar mass Milky Way dark halo. Orbit calculations suggest the Clouds may not be bound to the Milky Way or may just be on their first passage, both of which would be unexpected in view of traditional interpretations of the Magellanic Stream. Alternatively, the Milky Way dark halo may be a factor of two more massive than previously believed, which would be surprising in view of other observational constraints. Also, the relative velocity between the LMC and SMC is larger than expected, leaving open the possibility that the Clouds may not be bound to each other. To further verify and refine our results we now request an epoch of WFPC2/PC data for the fields centered on 40 quasars that have at least one epoch of ACS imaging. We request execution in snapshot mode, as in our previous programs, to ensure the most efficient use of HST resources. A third epoch of data of these fields will provide crucial information to verify that there are no residual systematic effects in our previous measurements. More importantly, it will increase the time baseline from 2 to 5 yrs and will increase the number of fields with at least two epochs of data. This will reduce our uncertainties correspondingly, so that we can better address whether the Clouds are indeed bound to each other and to the Milky Way. It will also allow us to constrain the internal motions of various populations within the Clouds, and will allow us to determine a distance to the LMC using rotational parallax.;

Kallivayalil, Nitya

2007-07-01

204

Coordinated Imaging and Lidar measurements of Noctilucent Cloud Dynamics over Poker Flat, Alaska, August 2005.  

NASA Astrophysics Data System (ADS)

In conjunction with the 2005 Polar Aeronomy and Radio Science (PARS) Summer School coordinated observations of noctilucent clouds (NLC) were made from central Alaska during August 2005 using imaging and lidar instrumentation. The image measurements was made from a field site near Donnelly Dome (63° N, 145° W) to record NLC over the lidar facility located at Poker Flat Research Range (PFRR) approximately 160 km to the north. A combination of two low-light digital color video cameras and several digital SLR cameras were used to image the NLC field over PFRR using wide and narrow field optics. At the same time NLC observations were made using the NICT Rayleigh lidar to investigate their altitude, structure and backscatter strength. Strong NLC were imaged from Donnelly Dome on three consecutive nights (August 8-10). These events were extensive, filling the northern twilight sky and were observed for over 4 hours. In particular the display of August 9 was very bright and was observed to extend well to the south of PFRR. The lidar measurements on this night were the strongest NLC signal yet recorded at PFRR. In this talk we will present a comparison between the imaging and lidar data focusing on August 9 display which was highly dynamic and observed to split into two distinct layers separated by approximately 1 km after local midnight. The two data sets will be used to study the dynamics of this display.

Nielsen, K.; Taylor, M. J.; Jensen, P. F.; Collins, R. L.; Su, L.; Thurairajah, B.; McDonald, J. G.; Marlow, Z. J.

2005-12-01

205

Global pattern analysis and classification of dermoscopic images using textons  

NASA Astrophysics Data System (ADS)

Detecting and classifying global dermoscopic patterns are crucial steps for detecting melanocytic lesions from non-melanocytic ones. An important stage of melanoma diagnosis uses pattern analysis methods such as 7-point check list, Menzies method etc. In this paper, we present a novel approach to investigate texture analysis and classification of 5 classes of global lesion patterns (reticular, globular, cobblestone, homogeneous, and parallel pattern) in dermoscopic images. Our statistical approach models the texture by the joint probability distribution of filter responses using a comprehensive set of the state of the art filter banks. This distribution is represented by the frequency histogram of filter response cluster centers called textons. We have also examined other two methods: Joint Distribution of Intensities (JDI) and Convolutional Restricted Boltzmann Machine (CRBM) to learn the pattern specific features to be used for textons. The classification performance is compared over the Leung and Malik filters (LM), Root Filter Set (RFS), Maximum Response Filters (MR8), Schmid, Laws and our proposed filter set as well as CRBM and JDI. We analyzed 375 images of the 5 classes of the patterns. Our experiments show that the joint distribution of color (JDC) in the L*a*b* color space outperforms the other color spaces with a correct classification rate of 86.8%.

Sadeghi, Maryam; Lee, Tim K.; McLean, David; Lui, Harvey; Atkins, M. Stella

2012-02-01

206

GROUND-BASED CLOUD IMAGES AND SKY RADIANCES IN THE VISIBLE AND NEAR INFRARED REGION FROM WHOLE SKY IMAGER MEASUREMENTS  

Microsoft Academic Search

Automatic cloud documentation from the ground is one of the basic tools to set up cloud climatologies with high resolution in space and time. Ground-based cloud data are of specific importance to study the role of clouds on the radiation balance of the earth's surface and the lower atmosphere. They can also provide ground-truth information for satellite-retrieved cloud parameters. A

Uwe Feister; Janet Shields; Monette Karr; Richard Johnson; Klaus Dehne; Michael Woldt

207

Efficient rate-distortion compression of dynamic point cloud for grid-pattern-based 3D scanning systems  

NASA Astrophysics Data System (ADS)

Recently 3D scanning systems are capable of modeling entire dense shapes that evolve over time with a single scan ( a.k.a. one-shot scan). In particular, structured-light-based systems have emerged as one-shot shape reconstruction methods that project a static grid pattern onto the object surface. This pattern allows the scanning of moving objects while still maintaining dense reconstruction. One-shot scanning systems are then capable of producing 3D+t ( a.k.a. 4D) spatio-temporal models with millions of points. As a consequence, effective 4D geometry compression schemes are required to face the need to store or transmit the huge amount of data, in addition to classical static 3D data. In this paper, we propose a 4D spatiotemporal rate-distortion (RD) optimized point cloud encoder via a curve-based representation of the point cloud, particularly well-suited for one-shot scanning systems. The object surface is naturally sampled in a series of curves, due to the grid pattern. This motivates our choice to leverage a curve-based representation to remove the spatial and temporal correlation of the sampled point along the scanning directions through a competitive-based predictive encoder that includes different spatio-temporal prediction modes through an RD cost computation control. Experimental results show the significant gain obtained with the proposed method. [Figure not available: see fulltext.

Daribo, Ismael; Furukawa, Ryo; Sagawa, Ryusuke; Kawasaki, Hiroshi; Hiura, Shinsaku; Asada, Naoki

2012-03-01

208

Evaluating EUV mask pattern imaging with two EUV microscopes  

SciTech Connect

Aerial image measurement plays a key role in the development of patterned reticles for each generation of lithography. Studying the field transmitted (reflected) from EUV masks provides detailed information about potential disruptions caused by mask defects, and the performance of defect repair strategies, without the complications of photoresist imaging. Furthermore, by measuring the continuously varying intensity distribution instead of a thresholded, binary resist image, aerial image measurement can be used as feedback to improve mask and lithography system modeling methods. Interest in EUV, at-wavelength, aerial image measurement lead to the creation of several research tools worldwide. These tools are used in advanced mask development work, and in the evaluation of the need for commercial at-wavelength inspection tools. They describe performance measurements of two such tools, inspecting the same EUV mask in a series of benchmarking tests that includes brightfield and darkfield patterns. One tool is the SEMATECH Berkeley Actinic Inspection Tool (AIT) operating on a bending magnet beamline at Lawrence Berkeley National Laboratory's Advanced Light Source. The AIT features an EUV Fresnel zoneplate microscope that emulates the numerical aperture of a 0.25-NA stepper, and projects the aerial image directly onto a CCD camera, with 700x magnification. The second tool is an EUV microscope (EUVM) operating at the NewSUBARU synchrotron in Hyogo, Japan. The NewSUBARU tool projects the aerial image using a reflective, 30x Schwarzschild objective lens, followed by a 10-200x x-ray zooming tube. The illumination conditions and the imaging etendue are different for the two tools. The benchmarking measurements were used to determine many imaging and performance properties of the tools, including resolution, modulation transfer function (MTF), aberration magnitude, aberration field-dependence (including focal-plane tilt), illumination uniformity, line-edge roughness, and flare. These measurements reveal the current state of the art in at-wavelength inspection performance, and will be a useful reference as performance improves over time.

Goldberg, Kenneth A.; Takase, Kei; Naulleau, Patrick P.; Han, Hakseung; Barty, Anton; Kinoshita, Hiroo; Hamamoto, Kazuhiro

2008-02-26

209

MR Imaging of Spinal Nerve Roots:Techniques, Enhancement Patterns, and Imaging Findings  

Microsoft Academic Search

The purpose of this report was to review the MR techniques, contrast enhancement patterns, and MR imaging findings for the spinal nerve roots. The phenomenon of contrast enhance- ment of the nerve roots and its relationship to disk disease and failed-back-surgery syndrome are discussed. The MR imaging findings for various inflammatory and neoplastic disorders affecting the spinal nerve roots are

Bassem A. Georgy; Ruth D. Snow; John R. HesSelink

210

Mitigating illumination gradients in a SAR image based on the image data and antenna beam pattern  

DOEpatents

Illumination gradients in a synthetic aperture radar (SAR) image of a target can be mitigated by determining a correction for pixel values associated with the SAR image. This correction is determined based on information indicative of a beam pattern used by a SAR antenna apparatus to illuminate the target, and also based on the pixel values associated with the SAR image. The correction is applied to the pixel values associated with the SAR image to produce corrected pixel values that define a corrected SAR image.

Doerry, Armin W.

2013-04-30

211

Continuous image writer with improved image quality for high-accuracy optical patterning  

NASA Astrophysics Data System (ADS)

We report on the development of a production tool for fast optical maskless patterning. The Continuous Image Writer (CIW) combines the advantages of direct writing by using a programmable mask with the advantages of conventional optical lithography by using the same lithographic process for image formation in photoresist. An electronically programmable Spatial Light Modulator (SLM) is imaged into the substrate by passing a demagnifying Fourier optics. The use of short pulses of a KrF excimer laser allows the imaging of the extended image field of the SLM without stopping the substrate carrying stage during exposure. This results in short writing times. Based on the experiences with a production-like prototype of the CIW we have investigated the various contributions to image quality such as address grid, stitching errors, and SLM quality. This paper describes a method for achieving a critical dimension performance well suited for the generation of photomask and wafer patterns for present and future technology nodes.

Paufler, Joerg; Brunn, Stefan; Koerner, Tim

2001-04-01

212

Holographic images reconstructed from GMR-based fringe pattern  

NASA Astrophysics Data System (ADS)

We have developed a magneto-optical spatial light modulator (MOSLM) using giant magneto-resistance (GMR) structures for realizing a holographic three-dimensional (3D) display. For practical applications, reconstructed image of hologram consisting of GMR structures should be investigated in order to study the feasibility of the MOSLM. In this study, we fabricated a hologram with GMR based fringe-pattern and demonstrated a reconstructed image. A fringe-pattern convolving a crossshaped image was calculated by a conventional binary computer generated hologram (CGH) technique. The CGH-pattern has 2,048 × 2,048 with 5 ?m pixel pitch. The GMR stack consists of a Tb-Fe-Co/CoFe pinned layer, a Ag spacer, a Gd-Fe free layer for light modulation, and a Ru capping layer, was deposited by dc-magnetron sputtering. The GMR hologram was formed using photo-lithography and Krion milling processes, followed by the deposition of a Tb-Fe-Co reference layer with large coercivity and the same Kerr-rotation angle compared to the free layer, and a lift-off process. The reconstructed image of the ON-state was clearly observed and successfully distinguished from the OFF-state by switching the magnetization direction of the free-layer with an external magnetic field. These results indicate the possibility of realizing a holographic 3D display by the MOSLM using the GMR structures.

Kato, Daisuke; Aoshima, Kenichi; Machida, Kenji; Emoto, Akira; Kinjo, Hidekazu; Kuga, Kiyoshi; Ono, Hiroshi; Ishibashi, Takayuki; Kikuchi, Hiroshi; Shimidzu, Naoki

2013-01-01

213

Displacement fields from point cloud data: Application of particle imaging velocimetry to landslide geodesy  

NASA Astrophysics Data System (ADS)

Acquiring spatially continuous ground-surface displacement fields from Terrestrial Laser Scanners (TLS) will allow better understanding of the physical processes governing landslide motion at detailed spatial and temporal scales. Problems arise, however, when estimating continuous displacement fields from TLS point-clouds because reflecting points from sequential scans of moving ground are not defined uniquely, thus repeat TLS surveys typically do not track individual reflectors. Here, we implemented the cross-correlation-based Particle Image Velocimetry (PIV) method to derive a surface deformation field using TLS point-cloud data. We estimated associated errors using the shape of the cross-correlation function and tested the method's performance with synthetic displacements applied to a TLS point cloud. We applied the method to the toe of the episodically active Cleveland Corral Landslide in northern California using TLS data acquired in June 2005-January 2007 and January-May 2010. Estimated displacements ranged from decimeters to several meters and they agreed well with independent measurements at better than 9% root mean squared (RMS) error. For each of the time periods, the method provided a smooth, nearly continuous displacement field that coincides with independently mapped boundaries of the slide and permits further kinematic and mechanical inference. For the 2010 data set, for instance, the PIV-derived displacement field identified a diffuse zone of displacement that preceded by over a month the development of a new lateral shear zone. Additionally, the upslope and downslope displacement gradients delineated by the dense PIV field elucidated the non-rigid behavior of the slide.

Aryal, Arjun; Brooks, Benjamin A.; Reid, Mark E.; Bawden, Gerald W.; Pawlak, Geno R.

2012-03-01

214

A Time-Series Pattern Based Noise Generation Strategy for Privacy Protection in Cloud Computing  

Microsoft Academic Search

Cloud computing promises an open environment where customers can deploy IT services in a pay-as-you-go fashion while saving huge capital investment in their own IT infrastructure. Due to the openness, various malicious service providers may exist. Such service providers may record service information in a service process from a customer and then collectively deduce the customer's private information. Therefore, from

Gaofeng Zhang; Yun Yang; Xiao Liu; Jinjun Chen

2012-01-01

215

Pattern masking estimation in image with structural uncertainty.  

PubMed

A model of visual masking, which reveals the visibility of stimuli in the human visual system (HVS), is useful in perceptual based image/video processing. The existing visual masking function mainly considers luminance contrast, which always overestimates the visibility threshold of the edge region and underestimates that of the texture region. Recent research on visual perception indicates that the HVS is sensitive to orderly regions that possess regular structures and insensitive to disorderly regions that possess uncertain structures. Therefore, structural uncertainty is another determining factor on visual masking. In this paper, we introduce a novel pattern masking function based on both luminance contrast and structural uncertainty. Through mimicking the internal generative mechanism of the HVS, a prediction model is firstly employed to separate out the unpredictable uncertainty from an input image. In addition, an improved local binary pattern is introduced to compute the structural uncertainty. Finally, combining luminance contrast with structural uncertainty, the pattern masking function is deduced. Experimental result demonstrates that the proposed pattern masking function outperforms the existing visual masking function. Furthermore, we extend the pattern masking function to just noticeable difference (JND) estimation and introduce a novel pixel domain JND model. Subjective viewing test confirms that the proposed JND model is more consistent with the HVS than the existing JND models. PMID:24001999

Wu, Jinjian; Lin, Weisi; Shi, Guangming; Wang, Xiaotian; Li, Fu

2013-08-30

216

Pattern recognition of magnetic resonance images with application to atherosclerosis  

SciTech Connect

Magnetic resonance imaging provides excellent soft tissue contrast enabling the non-invasive visualization of soft tissue diseases. The quantification of tissues visible in MR images would significantly increase the diagnostic information available. While tissue selection methods exist for CT images, those same methods do not work with MR images. This dissertation focuses on the application of image processing and pattern recognition techniques to MR images for the identification and quantification of soft tissues, atherosclerosis in particular. Atherosclerosis is a chronic disease of human arteries responsible for significant mortality and medical expense. Current diagnostic methods are invasive and carry significant risk. Supervised pattern recognition methods were investigated for tissue identification in MR images. The classifiers were trained A Fisher linear classifier successfully identified the tissues of interest from MR images of excised arteries, performing better than a minimum distance to the means classifier. Quantitative measures of the disease state were computed from the results and 3-D displays were generated of the diseased anatomy. For tissue in vivo, adequate histology can be difficult to collect, increasing the difficulty of training the classifiers and making the results less accurate. Cluster analysis was used in this dissertation to generate the training information. A new cluster analysis method was developed. ISODATA was modified to use hierarchical stopping rules. The new method was tested in a Monte Carlo study and with real world data sets. Comparisons were made with published methods using the same data. An information theoretic criterion, the CAIC, was found to be an excellent criteria for hierarchical stopping rules.

Carman, C.S.

1989-01-01

217

Visual simulation of clouds  

Microsoft Academic Search

Clouds present serious problems to standard computer image generation techniques because clouds do not have well-defined surfaces and boundaries. In addition, clouds contain varying degrees of translucence, and their amorphous structure can change with time. Although several approaches to cloud simulation have produced impressive results, they have relied on complex mathematical models which produce high computation costs for a single

Geoffrey Y. Gardner

1985-01-01

218

Point cloud generation from aerial image data acquired by a quadrocopter type micro unmanned aerial vehicle and a digital still camera.  

PubMed

The objective of this investigation was to develop and investigate methods for point cloud generation by image matching using aerial image data collected by quadrocopter type micro unmanned aerial vehicle (UAV) imaging systems. Automatic generation of high-quality, dense point clouds from digital images by image matching is a recent, cutting-edge step forward in digital photogrammetric technology. The major components of the system for point cloud generation are a UAV imaging system, an image data collection process using high image overlaps, and post-processing with image orientation and point cloud generation. Two post-processing approaches were developed: one of the methods is based on Bae Systems' SOCET SET classical commercial photogrammetric software and another is built using Microsoft(®)'s Photosynth™ service available in the Internet. Empirical testing was carried out in two test areas. Photosynth processing showed that it is possible to orient the images and generate point clouds fully automatically without any a priori orientation information or interactive work. The photogrammetric processing line provided dense and accurate point clouds that followed the theoretical principles of photogrammetry, but also some artifacts were detected. The point clouds from the Photosynth processing were sparser and noisier, which is to a large extent due to the fact that the method is not optimized for dense point cloud generation. Careful photogrammetric processing with self-calibration is required to achieve the highest accuracy. Our results demonstrate the high performance potential of the approach and that with rigorous processing it is possible to reach results that are consistent with theory. We also point out several further research topics. Based on theoretical and empirical results, we give recommendations for properties of imaging sensor, data collection and processing of UAV image data to ensure accurate point cloud generation. PMID:22368479

Rosnell, Tomi; Honkavaara, Eija

2012-01-04

219

Component pattern analysis of chemicals using multispectral THz imaging system  

NASA Astrophysics Data System (ADS)

We have developed a novel basic technology for terahertz (THz) imaging, which allows detection and identification of chemicals by introducing the component spatial pattern analysis. The spatial distributions of the chemicals were obtained from terahertz multispectral transillumination images, using absorption spectra previously measured with a widely tunable THz-wave parametric oscillator. Further we have applied this technique to the detection and identification of illicit drugs concealed in envelopes. The samples we used were methamphetamine and MDMA, two of the most widely consumed illegal drugs in Japan, and aspirin as a reference.

Kawase, Kodo; Ogawa, Yuichi; Watanabe, Yuki

2004-04-01

220

Etiology of the obstructive pattern in hepatobiliary imaging  

SciTech Connect

The records of all patients undergoing hepatobiliary imaging with technetion radioisotopes at our hospital from January 1980 to March 1983 were reviewed and 29 scans met the criteria for a pattern consistent with complete biliary tract obstruction. Biliary tract obstruction (due to choledocholithiasis, primary or secondary carcinoma involving the common bile duct, and pancreatitis) was documented in 24 of these patients. However, the remaining five patients had a patent common bile duct, and the etiologic factor was intrahepatic cholestasis secondary to sepsis in four and peritonitis in one. A classification of altered biliary dynamics in hepatobiliary imaging, which is based on the classification of jaundice, is proposed.

Hughes, K.S.; Marrangoni, A.G.; Turbiner, E.

1984-04-01

221

Pattern recognition of transillumination images for diagnosis of rheumatoid arthritis  

NASA Astrophysics Data System (ADS)

In this work the statistical pattern recognition methods were applied for evaluation of transillumination images of interphalangeal joints of patients suffering from rheumatoid arthritis. Special portable apparatus was constructed for performing the transillumination examination. It consisted of He-Ne laser with optics for collimated illumination, special holder for placing the finger (perpendicular to optical axis, dorsal site towards camera), and CCD camera with memory stick. 20 ill patients and 20 healthy volunteers were examined. The captured images with 1152x864 resolution were converted into the gray level pictures and analyzed by means of statistical pattern recognition method. Principal Component Analysis (PCA) and cluster analysis by use of 1-NN method (1 Nearest Neighbour) were applied for classification. The recognition system was able to differentiate correctly between healthy and ill subjects with 72.35% accuracy in case the data base composed of 40 persons.

Bauer, Joanna; Boerner, Ewa; Podbielska, Halina; Suchwalko, Artur

2005-09-01

222

Graph Matching Iris Image Blocks with Local Binary Pattern  

Microsoft Academic Search

Abstract. Iris-based personal identification has attracted much ,attention in re- cent years. Almost all the state-of-the-art iris recognition algorithms are based onstatistical classifier and local image features, which are noise sensitive and hardly to deliver perfect recognition performance. In this paper, we propose a novel iris recognition method, using the histogram of local binary pattern for global iris texture representation

Zhenan Sun; Tieniu Tan; Xianchao Qiu

2006-01-01

223

A Near-Infrared Imaging Survey of the rho Ophiuchi Cloud Core  

NASA Astrophysics Data System (ADS)

We report results of a JHK imaging survey of the central square degree of the rho Ophiuchi star-forming cloud core, the largest such survey to date. We catalog nearly 4500 sources, the vast majority being background stars. Our 90%, 10sigma completeness limits are J=15.0, H=14.5, and K=14.0. Our derived positions for these sources are good to ~ 1.2('') , derived from comparison with HST guide stars. We have also cross-identified our sources with all existing published near-infrared surveys, resulting in one or more identifications for 449 sources. Of these, 79 sources have four or more independent magnitude measurements at K. Using rather strict criteria (sigma_K >= 0.4 mag, sigma_ {J,H} >= 0.2), we identify thirteen variable sources. Follow-up work on newly identified cluster members is in progress (see abstract presented by Casement, Barsony & Ressler elsewhere at this Meeting).

Barsony, M.; Kenyon, S. J.; Lada, E. A.; Teuben, P. J.

1996-12-01

224

Pattern recognition via multispectral, hyperspectral, and polarization-based imaging  

NASA Astrophysics Data System (ADS)

Pattern recognition deals with the detection and identification of a specific target in an unknown input scene. Target features such as shape, color, surface dynamics, and material characteristics are common target attributes used for identification and detection purposes. Pattern recognition using multispectral (MS), hyperspectral (HS), and polarization-based spectral (PS) imaging can be effectively exploited to highlight one or more of these attributes for more efficient target identification and detection. In general, pattern recognition involves two steps: gathering target information from sensor data and identifying and detecting the desired target from sensor data in the presence of noise, clutter, and other artifacts. Multispectral and hyperspectral imaging (MSI/HSI) provide both spectral and spatial information about the target. As the reflection or emission spectral signatures depend on the elemental composition of objects residing within the scene, the polarization state of radiation is sensitive to the surface features such as relative smoothness or roughness, surface material, shapes and edges, etc. Therefore, polarization information imparted by surface reflections of the target yields unique and discriminatory signatures which could be used to augment spectral target detection techniques, through the fusion of sensor data. Sensor data fusion is currently being used to effectively recognize and detect one or more of the target attributes. However, variations between sensors and temporal changes within sensors can introduce noise in the measurements, contributing to additional target variability that hinders the detection process. This paper provides a quick overview of target identification and detection using MSI/HSI, highlighting the advantages and disadvantages of each. It then discusses the effectiveness of using polarization-based imaging in highlighting some of the target attributes at single and multiple spectral bands using polarization spectral imaging (PSI), known as spectropolarimetry imaging.

El-Saba, Aed; Alam, Mohammad S.; Sakla, Wesam A.

2010-04-01

225

A 10-year climatology of Northern Hemisphere tropical cloud plumes and their composite flow patterns  

SciTech Connect

A 10-year cool season climatology of tropical cloud plumes in the Northern Hemisphere was generated by visual inspection of infrared satellite imagery. The sample included 1062 plume events during the months of October to May for the years 1974 to 1984. The results show that the westerly ducts of the tropical eastern Pacific and central Atlantic are preferred regions for tropical cloud plume development. Composite fields of streamfunction and outgoing longwave radiation for eastern Pacific plumes indicate that both low-latitude westerlies in the planetary-scale basic-state flow and the presence of synoptic-scale transients appear to be favorable for plume formation. With a knowledge of these features, some of the interannual and intraannual variability shown in the climatology can be explained. 14 refs., 6 figs.

Iskenderian, H. [State Univ. of New York, Albany, NY (United States)

1995-06-01

226

An Efficient Pattern Substitution Watermarking Method for Binary Images  

NASA Astrophysics Data System (ADS)

In this paper, a method to decrease the size of location map for non-overlapping pattern substitution method is presented. Original pattern substitution (PS) method has been proposed by Ho et al.[1] as a reversible watermarking scheme for binary images. They use a pair of two patterns to embed data. Unfortunately, their location map is huge in size. In our method, we propose an efficient mechanism which can decrease the size of location map considerably for un-overlapping version of the PS method. Experiment results show that our method works well on decreasing the size of location map. Comparison results with the original PS method demonstrate that the proposed method achieves more embedding capacity and higher PSNR value due to the reduced size of the location map.

Dong, Keming; Kim, Hyoung-Joong

227

Analysis of breathing air flow patterns in thermal imaging.  

PubMed

We introduce a novel methodology to characterize breathing patterns based on thermal infrared imaging. We have retrofitted a Mid-Wave Infra-Red (MWIR) imaging system with a narrow band-pass filter in the CO(2) absorption band (4130 - 4427 nm). We use this system to record the radiation information from within the breathing flow region. Based on this information we compute the mean dynamic thermal signal of breath. The breath signal is quasi-periodic due to the interleaving of high and low intensities corresponding to expirations and inspirations respectively. We sample the signal at a constant rate and then filter the high frequency noise due to tracking instability. We detect the breathing cycles through zero cross thresholding, which is insensitive to noise around the zero line. We normalize the breathing cycles and align them at the transition point from inhalation to exhalation. Then, we compute the mean breathing cycle. We use the first eight (8) harmonic components of the mean cycle to characterize the breathing pattern. The harmonic analysis highlights the intra-individual similarity of breathing patterns. Our method opens the way for desktop, unobtrusive monitoring of human respiration and may find widespread applications in clinical studies of chronic ailments. It also brings up the intriguing possibility of using breathing patterns as a novel biometric. PMID:17945610

Fei, Jin; Pavlidis, Ioannis

2006-01-01

228

Buildup of electron cloud with different bunch pattern in thepresence of solenoid field  

SciTech Connect

We have augmented the code POSINST to include solenoidfields, and used it to simulate the build up of electron cloud due toelectron multipacting in the PEP-II positron ring. We find that thedistribution of electrons is strongly affected by the resonancesassociated with the cyclotron period and bunch spacing. In addition, wediscover a threshold beyond which the electron density growsexponentially until it reaches the space charge limit. The threshold doesnot depend on the bunch spacing but does depend on the positron bunchpopulation.

Cai, Y.; Pivi (SLAC), M.; Furman (LBNL), M.A.

2003-05-01

229

Symbolic document image compression based on pattern matching techniques  

NASA Astrophysics Data System (ADS)

In this paper, a novel compression algorithm for Chinese document images is proposed. Initially, documents are segmented into readable components such as characters and punctuation marks. Similar patterns within the text are found by shape context matching and grouped to form a set of prototype symbols. Text redundancies can be removed by replacing repeated symbols by their corresponding prototype symbols. To keep the compression visually lossless, we use a multi-stage symbol clustering procedure to group similar symbols and to ensure that there is no visible error in the decompressed image. In the encoding phase, the resulting data streams are encoded by adaptive arithmetic coding. Our results show that the average compression ratio is better than the international standard JBIG2 and the compressed form of a document image is suitable for a content-based keyword searching operation.

Shiah, Chwan-Yi; Yen, Yun-Sheng

2011-10-01

230

CERES Cloud Property Retrievals from Imagers on TRMM Terra and Aqua  

Microsoft Academic Search

ABSTRACT The micro- and macrophysical,properties of clouds,play a crucial role in Earth’s radiation budget. The NASA Clouds and Earth’s Radiant Energy System (CERES) is providing simultaneous measurements,of the radiation and cloud fields on a global basis to improve the understanding and modeling,of the interaction between clouds and radiation at the top ofthe atmosphere, at the surface, and within the atmosphere.

Patrick Minnis; David Young; Sunny Sun-mack; Patrick W. Heck; David R. Doelling; Qing Z. Trepte

231

Coordinated optical and radar image measurements of noctilucent clouds and polar mesospheric summer echoes  

NASA Astrophysics Data System (ADS)

Novel coincident 3-D radar, lidar and optical image measurements of dynamical structures in polar mesosphere summer echoes (PMSE) and noctilucent clouds (NLC) are presented. Common volume mesospheric measurements were made over central Alaska using the new Poker Flat Incoherent Scatter Radar (PFISR), a co-located Rayleigh lidar and remote, two-station digital image observations, enabling the first detailed investigation of the horizontal and vertical structures of NLC and PMSE. Coincident measurements were made of an unusual NLC display recorded on 10-11 August 2007, characterized by a broad luminous band that contained several prominent wave forms. Concurrent lidar and image measurements established the presence of NLC within the radar volume from ~09:00 UT (01:00 LT), when the solar depression angle was 10.4°, until dawn. Strong but intermittent PMSE were detected by PFISR, with distinct patchy structures that exhibited a similar southward motion as the NLC. Detailed comparison of the 3-D PMSE structures and the NLC lidar and image data have revealed striking similarities when account was taken of the NLC layer altitude, suggesting a direct link between their small-scale spatial signatures (within the current resolution of the radar measurements). At the same time, the lidar detected a sustained increase in the backscatter signal, while the imagers revealed the development of copious short horizontal wavelength (4.9 km) billow waves. We conclude that strong wind shears associated with the Kelvin-Helmholtz billow instabilities played a key role in the development of a neutral turbulence layer in close proximity to the NLC layer resulting in the strong but intermittent PMSE detected at 450 MHz on this occasion.

Taylor, M. J.; Zhao, Y.; Pautet, P.-D.; Nicolls, M. J.; Collins, R. L.; Barker-Tvedtnes, J.; Burton, C. D.; Thurairajah, B.; Reimuller, J.; Varney, R. H.; Heinselman, C. J.; Mizutani, K.

2009-05-01

232

Cloud Imaging from Meteorological Satellites and its Application to Robotic Observing  

Microsoft Academic Search

Satellite cloud imagery is a standard tool of meteorology, and also of ground-based observational astronomy. Fast access to cloud imagery through the Internet now permits more accurate prediction of local cloud cover than was formerly the case. This is particularly useful for automatic and remotely operated telescopes, where an observer may be at a considerable distance from the telescope itself.

Andre Phillips; Michael C. B. Ashley

2005-01-01

233

A new method of three-dimensional visualization of satellite cloud image  

Microsoft Academic Search

To solve the problems on 3D visualization of satellite data, such as the inaccuracy of cloud mask, ignorance of visual affect of gray, transparency and orientation, this paper brings forward a series of methods. Through radiation background to detect cloud mask and cloud top inversion etc, can obtain high precision application data, moreover, advances the revised model on aspects of

Ji-Ping Guan; Zhi-Quan Yin; Zhu-Hui Jiang

2010-01-01

234

Precipitation water path and rainfall rate estimates over oceans using special sensor microwave imager and International Satellite Cloud Climatology Project data  

Microsoft Academic Search

The liquid\\/ice water paths (LWP\\/IWP) and the rainfall rate (RR) of precipitation systems over oceans are estimated using a combination of data from the special sensor microwave\\/imager (SSM\\/I) and the International Satellite Cloud Climatology Project (ISCCP). The retrieval scheme is based on microwave radiative transfer simulations. Collocated ISCCP cloud top temperatures are used to separate warm from cold precipitating clouds:

Bing Lin; William B. Rossow

1997-01-01

235

CERES CLoud Effects  

NSDL National Science Digital Library

This computer-generated animation depicts the Clouds and the Earth's Radiant Energy System (CERES) instrument in operation. CERES measures the energy at the top of the atmosphere and estimates energy levels in the atmosphere and at the Earth's surface. Using information from very high resolution cloud-imaging instruments on the same spacecraft, CERES also will determine cloud properties, including cloud amount, altitude, thickness, and the size of the cloud particles.

1997-06-06

236

Build up of electron cloud with different bunch pattern in the presence of solenoidal field  

SciTech Connect

We have augmented the code POSINST to include solenoid fields, and used it to simulate the build up of electron cloud due to electron multipacting in the PEP-II positron ring. We find that the distribution of electrons is strongly affected by the resonances associated with the cyclotron period and bunch spacing. In addition, we discover a threshold beyond which the electron density grows exponentially until it reaches the space charge limit. The threshold does not depend on the bunch spacing but does depend on the positron bunch population.

Cai, Y.; Furman, M.A.; Pivi, M.

2004-04-01

237

Infrared Imaging of the Large Magellanic Cloud Star-forming Region Henize 206  

NASA Astrophysics Data System (ADS)

Henize 206 is a region of star formation in the Large Magellanic Cloud of the approximate scale of the Orion belt and sword. Our Spitzer Space Telescope infrared images and Cerro Tololo Inter-American Observatory (CTIO) optical images show that the region is experiencing very energetic star formation. The radiation from young stars has excited strong polycyclic aromatic hydrocarbon (PAH) emission throughout Henize 206, except on the side of the nebula with the prominent young supernova remnant. As is also seen in early Spitzer observations of M81, star formation rates calculated from H? for Henize 206 may miss the deeply embedded young stars, compared with star formation rates calculated from far infrared emission. For one of the highest surface brightness regions of Henize 206, we obtained snapshot exposures with the Thermal-Region Camera Spectrograph on Gemini South to explore the complex structure. A few percent of the total flux from this brightest region in Henize 206 emanates from infrared peaks of subparsec scale.

Gorjian, V.; Werner, M. W.; Mould, J. R.; Gordon, K. D.; Muzzerole, J.; Morrison, J.; Surace, J. M.; Rebull, L. M.; Hurt, R. L.; Smith, R. C.; Points, S. D.; Aguilera, C.; De Buizer, J. M.; Packham, C.

2004-09-01

238

An adaptive OPD and dislocation prediction used characteristic of interference pattern for interference hyperspectral image compression  

Microsoft Academic Search

According to the imaging principle and characteristic of LASIS (Large Aperture Static Interference Imaging Spectrometer), we discovered that the 3D (three dimensional) image sequences formed by different interference pattern frames, which were formed in the imaging process of LASIS Interference hyperspectral image, had much stronger correlation than the original interference hyperspectral image sequences, either in 2D (two dimensional) spatial domain

Jia Wen; Caiwen Ma; Penglang Shui

2011-01-01

239

Object tracking in video pictures based on image segmentation and pattern matching  

Microsoft Academic Search

We propose a novel algorithm for object tracking in video pictures, based on image segmentation and pattern matching. With image segmentation, we can detect all objects in images, whether they are moving or not. Using the image segmentation results of successive frames, we exploit pattern matching in a simple feature space for tracking the objects. Consequently, the proposed algorithm can

Takashi Morimoto; Osamu Kiriyama; Yohmei Harada; Hidekazu Adachi; Tetsushi Koide; Hans Jürgen Mattausch

2005-01-01

240

Comparison of simulated cloud cover with satellite observations over the western United States  

SciTech Connect

Satellite image datasets and regional climate model results are intercompared for evaluation of model accuracy in the simulation of cloud cover. Both monthly average and individual simulation times are analyzed. To provide a consistent comparison, satellite data are first mapped into the model`s geographic projection, grid domain, and resolution. It is found that September 1988 monthly average cloud fraction results from the model simulations correspond to observations, in both spatial pattern and magnitude, with bias less than {plus_minus}% cloud fraction over the entire inland West. Agreement in the pattern of cloud fraction also is evident for monthly average cloud fraction in July, but there is a negative bias of 10%-30% cloud fraction in the model diagnosis of cloud cover. Correlations between the spatial distributions of model-derived and observed cloud fractions are found to exceed 0.80 for certain geographic regions of the West, and these correlations are largest over mountainous areas during summer. Case studies of a series of daily cloud cover demonstrate the ability of the model to simulate the effects of frontal passage on cloud distribution. The ability of the RegCM1 to simulate daily cloud fraction and diurnal cloud evolution is somewhat weak for the summer convective season. It is anticipated that a more recent version of the regional climate model may improve the simulation of summer season cloud cover, through changes in cloud parameterization and improvements in model resolution. 21 refs., 22 figs.

Wetzel, M.A. [Desert Research Institute, Reno, NV (United States); Bates, G.T. [National Center for Atmospheric Research, Boulder, CO (United States)

1995-02-01

241

Imaging of Flow Patterns with Fluorescent Molecular Rotors  

PubMed Central

Molecular rotors are a group of fluorescent molecules that form twisted intramolecular charge transfer states (TICT) upon photoexcitation. Some classes of molecular rotors, among them those that are built on the benzylidene malononitrile motif, return to the ground state either by nonradiative intramolecular rotation or by fluorescence emission. In low-viscosity solvents, intramolecular rotation dominates, and the fluorescence quantum yield is low. Higher solvent viscosities reduce the intramolecular rotation rate, thus increasing the quantum yield. We recently described a different mechanism whereby the fluorescence quantum yield of the molecular rotor also depends on the shear stress of the solvent. In this study, we examined a possible application for shear-sensitive molecular rotors for imaging flow patterns in fluidic chambers. Flow chambers with different geometries were constructed from polycarbonate or acrylic. Solutions of molecular rotors in ethylene glycol were injected into the chamber under controlled flow rates. LED-induced fluorescence (LIF) images of the flow chambers were taken with a digital camera, and the intensity difference between flow and no-flow images was visualized and compared to computed fluid dynamics (CFD) simulations. Intensity differences were detectable with average flow rates as low as 0.1 mm/s, and an exponential association between flow rate and intensity increase was found. Furthermore, a good qualitative match to computed fluid dynamics simulations was seen. On the other hand, prolonged exposure to light reduced the emission intensity. With its high sensitivity and high spatial and temporal resolution, imaging of flow patterns with molecular rotors may become a useful tool in microfluidics, flow measurement, and control.

Mustafic, Adnan; Huang, Hsuan-Ming; Theodorakis, Emmanuel A.

2010-01-01

242

Saturn's cloud structure and temporal evolution from ten years of Hubble Space Telescope images (1994 2003)  

NASA Astrophysics Data System (ADS)

We present a study of the vertical structure of clouds and hazes in the upper atmosphere of Saturn's Southern Hemisphere during 1994-2003, about one third of a Saturn year, based on Hubble Space Telescope images. The photometrically calibrated WFPC2 images cover the spectral region between the near-UV (218-255 nm) and the near-IR (953-1042 nm), including the 890 nm methane band. Using a radiative transfer code, we have reproduced the observed center-to-limb variations in absolute reflectivity at selected latitudes which allowed us to characterize the vertical structure of the entire hemisphere during this period. A model atmosphere with two haze layers has been used to study the variation of hazes with latitude and to characterize their temporal changes. Both hazes are located above a thick cloud, putatively composed of ammonia ice. An upper thin haze in the stratosphere (between 1 and 10 mbar) is found to be persistent and formed by small particles (radii ˜0.2 ?m). The lower thicker haze close to the tropopause level shows a strong latitudinal dependence in its optical thickness (typically ?˜20-40 at the equator but ?˜5 at the pole, at 814 nm). This tropospheric haze is blue-absorbent and extends from 50 to 100 mbar to about ˜400 mbar. Both hazes show temporal variability, but at different time-scales. First, there is a tendency for the optical thickness of the stratospheric haze to increase at all latitudes as insolation increases. Second, the tropospheric haze shows mid-term changes (over time scales from months to 1-2 years) in its optical thickness (typically by a factor of 2). Such changes always occur within a rather narrow latitude band (width ˜5-10°), affecting almost all latitudes but at different times. Third, we detected a long-term (˜10 year) decrease in the blue single-scattering albedo of the tropospheric haze particles, most intense in the equatorial and polar areas. Long-term changes follow seasonal insolation variations smoothly without any apparent delay, suggesting photochemical processes that affect the particles optical properties as well as their size. In contrast, mid-term changes are sudden and show various time-scales, pointing to a dynamical origin.

Pérez-Hoyos, S.; Sánchez-Lavega, A.; French, R. G.; Rojas, J. F.

2005-07-01

243

Longitudinal distribution and temperature influence on the seasonal distribution of Polar Mesospheric Clouds in the 2007 Northern season from the Cloud Imaging and Particle Size (CIPS) experiment and SABER  

Microsoft Academic Search

PMC imaging data from the Cloud Imaging and Particle Size (CIPS) experiment on the Aeronomy of Ice in the Mesosphere (AIM) mission and temperature data from the SABER on the TIMED satellite are used to demonstrate the inter-dependence of temperature and PMC occurrence. The measured CIPS PMC occurrence is seen to be anti-correlated with SABER temperatures. In the middle of

A. W. Merkel; D. W. Rusch; G. E. Thomas; W. McClintock; J. M. Russell; S. M. Bailey

2008-01-01

244

Satellite Cloud Image DeNoising and Enhancement by Fuzzy Wavelet Neural Network and Genetic Algorithm in Curvelet Domain  

Microsoft Academic Search

A satellite cloud image is decomposed by discrete curvelet transform (DCT). In-complete Beta transform (IBT) is used to obtain\\u000a non-linear gray transform curve so as to enhance the coefficients in the coarse scale in the DCT domain. GA determines optimal\\u000a gray transform parameters. Information entropy is used as fitness function of GA. In order to calculate IBT in the coarse

Xingcai Zhang; Changjiang Zhang

2007-01-01

245

Investigation of the complex dynamics and structure of the 2010 Eyjafjallajökull volcanic ash cloud using multispectral images and numerical simulations  

NASA Astrophysics Data System (ADS)

investigated the structure and evolution of the 2010 Eyjafjallajökull volcanic cloud and its dispersal over Iceland and Europe integrating satellite multispectral images and numerical simulations. Data acquired by Medium Resolution Imaging Spectrometer (MERIS) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) have been analyzed to quantify the cloud extent and composition. The VOL-CALPUFF dispersal code was applied to reconstruct the transient and 3-D evolution of the cloud. Source parameters estimated on the base of available a posteriori volcanological data sets have been used. Quantitative comparisons between satellite retrievals and modeling results were performed for two selected instants of time during the first and third eruptive phases on a regional scale. Sensitivity of the model to initial volcanological conditions has been analyzed at continental scale. Several complex non intuitive features of cloud dynamics have been highlighted and strengths and limitations of the adopted methods identified. The main findings are: the level of quantitative agreement between satellite observations and numerical results depends on ash cloud composition (particle sizes and concentration) with better agreement for smaller particles and higher concentrations; the agreement between observations and modeling outcomes also depends on the temporal stability of volcanological conditions and the complexity of the meteorological wind field; the irregular dispersion of ash, as reconstructed from satellite data and numerical modeling, can be well explained by the different response of particle sizes to strong vertical wind-shear, and by resuspension processes acting at ground level; eruptive source conditions are the main source of uncertainty in modeling, especially during an ongoing crisis and at long-range scales.

Spinetti, C.; Barsotti, S.; Neri, A.; Buongiorno, M. F.; Doumaz, F.; Nannipieri, L.

2013-05-01

246

A new method of 3D reconstruction using the point cloud and distance images of laser radar  

NASA Astrophysics Data System (ADS)

As for the characteristic of the data acquired by laser radar and the three dimentional point cloud in disorder, and by combining the abundant in three dimentional information of point cloud with the specific textural information of distance images, we raised a new algorithm on the reconstruction of laser radar based on simplified point cloud and distance images. In this article, we take advantage of the feature that Delaunay triangulation have to raise a simplified algorithm to achieve the model network. In this algorithm, at first we build up the Delaunay triangulation, then comfirm the vector by calculating the distance that every vertex in the network from the adjacency vertex, and then calculate the intersection angle that the vector with triangle around; at the same time set the angular threshold in order to generate the new Delaunay triangulation. Experimental results show that this algorithm can accomplish the simplication of triangulation without affecting the accuracy of the modeling, along with the detailed, textural and shading information, we can achieve 3D reconstruction of the target images effectively.

Lan, Jinhui; Li, Jiehui; Zheng, Liujiang; Wu, Yang; Li, Xisheng

2012-05-01

247

Algorithms for pattern recognition in images of cell cultures  

NASA Astrophysics Data System (ADS)

Several applications of silicon microstructures in areas such as neurobiology and electrophysiology have been stimulating the development of microsystems with the objective of mechanical support to monitor and control several parameters in cell cultures. In this work a multi-microelectrode arrays was fabricated over a glass plate to obtain the growth of neuronal cell monitoring their behavior during cell development. To identify the neuron core and axon an approach for implementation of edge detectors algorithms associated to images is described. The necessity of efficient and reliable algorithms for image processing and interpretation is justified by its large field of applications in several areas as well as medicine, robotics, cellular biology, computational vision and pattern recognition. In this work, it is investigated the adequacy of some edge detectors algorithms such as Canny, Marr-Hildreth. Some alterations in those methods are propose to improve the identification of both cell core and axonal growth measure. We compare the operator to edge detector proposed by Canny, Marr-Hildreth operator and application of Hough Transform. For evaluation of algorithms adaptations, we developed a method for automatic cell segmentation and measurement. Our goal is to find a set of parameters defining the location of the objects to compare the original and processed images.

Mendes, Joyce M.; Peixoto, Nathalia L.; Ramirez-Fernandez, Francisco J.

2001-06-01

248

Study of the relations between cloud properties and atmospheric conditions using ground-based digital images  

Microsoft Academic Search

The aerosol constituents of the earth atmosphere are of great significance for the radiation budget and global climate of the planet. They are the precursors of clouds that in turn play an essential role in these processes and in the hydrological cycle of the Earth. Understanding the complex aerosol-cloud interactions requires a detailed knowledge of the dynamical processes moving the

Kalinka Bakalova

2008-01-01

249

Cloud screening and quality control algorithm for star photometer data: assessment with lidar measurements and with all-sky images  

NASA Astrophysics Data System (ADS)

This paper presents the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. These algorithms are necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, ?Ae(?), and precipitable water vapor content, W, at nighttime. This cloud screening procedure consists of calculating moving averages of ?Ae(?) and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable ?Ae(?) and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16° N, 3.60° W, 680 m a.s.l.; South-East of Spain) for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

Pérez-Ramírez, D.; Lyamani, H.; Olmo, F. J.; Whiteman, D. N.; Navas-Guzmán, F.; Alados-Arboledas, L.

2012-07-01

250

Cloud screening and quality control algorithm for star photometer data: assessment with lidar measurements and with all-sky-images  

NASA Astrophysics Data System (ADS)

This paper present the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. This kind of algorithms is necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, ?Ae(?), and precipitable water vapor content, W, at night-time. This cloud screening procedure consists of calculating moving averages of ?Ae(?) and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable ?Ae(?) and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16° N, 3.60° W, 680 m a.s.l.; South-East of Spain) for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

Pérez-Ramírez, D.; Lyamani, H.; Olmo, F. J.; Whiteman, D. N.; Navas-Guzman, F.; Alados-Arboledas, L.

2012-02-01

251

Measurements of cathode pattern drifts using high-speed imaging in SSPX  

Microsoft Academic Search

A specially designed high-speed imaging system that can take up to two images for every plasma shot has been installed at the Sustained Spheromak Physics Experiment (SSPX). The imaging system has revealed the existence of bright patterns close to the electrodes during current sustainment and ramp-down. In particular, circular patterns are seen on the end face of the cylindrically shaped

C. A. Romero-Talamãs; P. M. Bellan

2004-01-01

252

A novel method of intelligent analysis of weave pattern based on image processing technology  

Microsoft Academic Search

This paper proposed a new method based on image processing and pattern recognition technology to recognize the pattern of woven fabric. The method disposed the information of both the top and bottom fabric images. The result of analyzing the regularity of the intensity variation of the horizontal and vertical direction of image can be used to determine the interlacing position

Xinxing Tu; Ping Zhong; Binjie Xin; Shile Wang

2011-01-01

253

Fragmentary area repairing on the edge of 3D laser point cloud based on edge extracting of images and LS-SVM  

NASA Astrophysics Data System (ADS)

In the process of hole-repairing in point cloud, it's difficult to repair by the indeterminate boundary of fragmentary area in the edge of point cloud. In view of this condition, the article advances a method of Fragmentary area repairing on the edge of point cloud based on edge extracting of image and LS-SVM. After the registration of point cloud and corresponding image, the sub-pixel edge can be extracted from the image. Then project the training points and sub-pixel edge to the characteristic plane that has being constructed to confirm the bound and position for re-sampling. At last get the equation of fragmentary area to accomplish the repairing by Least-Squares Support Vector Machines. The experimental results demonstrate that the method guarantees accurate fine repairing.

Zhao, Ziming; Hao, Xiangyang; Liu, Songlin; Zhao, Song

2011-06-01

254

Sensitivity of Satellite-Retrieved Cloud Properties to the Effective Variance of Cloud Droplet Size Distribution  

SciTech Connect

Cloud reflectance models currently used in cloud property retrievals from satellites have been developed using size distributions defined by a set of fixed effective radii with a fixed effective variance. The satellite retrievals used for the Atmospheric Radiation Measurement (ARM) program assume droplet size distributions with an effective variance value of 0.10 (Minnis et al. 1998); the International Satellite Cloud Climatology Project uses 0.15 (Rossow and Schiffer 1999); and the Moderate Resolution Imaging Spectroradiometer (MODIS) team uses 0.13 (Nakajima and King 1990). These distributions are not necessarily representative of the actual sizes present in the clouds being observed. Because the assumed distributions can affect the reflectance patterns and near-infrared absorption, even for the same droplet effective radius reff, it is desirable to use the optimal size distributions in satellite retrievals of cloud properties. Collocated observations of the same clouds from different geostationary satellites, at different viewing angles, indicate that the current models may not be optimal (Ayers et al. 2005). Similarly, hour-to-hour variations in effective radius and optical depth reveal an unexplained dependence on scattering angle. To explore this issue, this paper examines the sensitivity of the cloud reflectance at 0.65 and 3.90-{micro}m to changes in the effective variance, or the spectral dispersion, of the modeled size distributions. The effects on the scattering phase functions and on the cloud reflectances are presented, as well as some resultant effects on the retrieved cloud properties.

Arduini, R.F.; Minnis, P.; Smith, W.L.Jr.; Ayers, J.K.; Khaiyer, M.M.; Heck, P.

2005-03-18

255

Roughness Estimation from Point Clouds - A Comparison of Terrestrial Laser Scanning and Image Matching by Unmanned Aerial Vehicle Acquisitions  

NASA Astrophysics Data System (ADS)

Recently, terrestrial laser scanning (TLS) and matching of images acquired by unmanned arial vehicles (UAV) are operationally used for 3D geodata acquisition in Geoscience applications. However, the two systems cover different application domains in terms of acquisition conditions and data properties i.e. accuracy and line of sight. In this study we investigate the major differences between the two platforms for terrain roughness estimation. Terrain roughness is an important input for various applications such as morphometry studies, geomorphologic mapping, and natural process modeling (e.g. rockfall, avalanche, and hydraulic modeling). Data has been collected simultaneously by TLS using an Optech ILRIS3D and a rotary UAV using an octocopter from twins.nrn for a 900 m² test site located in a riverbed in Tyrol, Austria (Judenbach, Mieming). The TLS point cloud has been acquired from three scan positions. These have been registered using iterative closest point algorithm and a target-based referencing approach. For registration geometric targets (spheres) with a diameter of 20 cm were used. These targets were measured with dGPS for absolute georeferencing. The TLS point cloud has an average point density of 19,000 pts/m², which represents a point spacing of about 5 mm. 15 images where acquired by UAV in a height of 20 m using a calibrated camera with focal length of 18.3 mm. A 3D point cloud containing RGB attributes was derived using APERO/MICMAC software, by a direct georeferencing approach based on the aircraft IMU data. The point cloud is finally co-registered with the TLS data to guarantee an optimal preparation in order to perform the analysis. The UAV point cloud has an average point density of 17,500 pts/m², which represents a point spacing of 7.5 mm. After registration and georeferencing the level of detail of roughness representation in both point clouds have been compared considering elevation differences, roughness and representation of different grain sizes. UAV closes the gap between aerial and terrestrial surveys in terms of resolution and acquisition flexibility. This is also true for the data accuracy. Considering these data collection and data quality properties of both systems they have their merit on its own in terms of scale, data quality, data collection speed and application.

Rutzinger, Martin; Bremer, Magnus; Ragg, Hansjörg

2013-04-01

256

Short range tracking of rainy clouds by multi-image flow processing of X-band radar data  

NASA Astrophysics Data System (ADS)

Two innovative algorithms for motion tracking and monitoring of rainy clouds from radar images are proposed. The methods are generalizations of classical optical flow techniques, including a production term (modelling formation, growth or depletion of clouds) in the model to be fit to the data. Multiple images are processed and different smoothness constraints are introduced. When applied to simulated maps (including additive noise up to 10 dB of SNR) showing formation and propagation of objects with different directions and velocities, the algorithms identified correctly the production and the flow, and were stable to noise when the number of images was sufficiently high (about 10). The average error was about 0.06 pixels (px) per sampling interval (? T) in identifying the modulus of the flow (velocities between 0.25 and 2 px/? T were simulated) and about 1° in detecting its direction (varying between 0° and 90°). An example of application to X-band radar rainfall rate images detected during a stratiform rainfall is shown. Different directions of the flow were detected when investigating short (10 min) or long time ranges (8 h), in line with the chaotic behaviour of the weather condition. The algorithms can be applied to investigate the local stability of meteorological conditions with potential future applications in nowcasting.

Mesin, Luca

2011-12-01

257

Cloud-to-ground lightning and upper-air patterns during bursts and breaks in the southwest monsoon  

SciTech Connect

Convective bursts and breaks in the southwest U.S. monsoon are investigated in a lightning context because cloud-to-ground (CG) lightning is an excellent indicator of deep convection. Bursts and breaks are identified using six years of Bureau of Land Management CG lightning information. Composited upper-air analyses for 12 bursts and 10 breaks are developed to examine the synoptic-scale differences between these two regimes. Anomaly patterns are investigated, and average burst and break regimes are presented. This investigation shows the importance of moisture, the location of the subtropical ridge axis, and the high-plateau thermal low. For the burst, the ridge axis is displaced northward across Arizona and New Mexico and moisture is usually abundant in the southwestern United States. During the break, the ridge retreats southward into northern Mexico, giving way to dry westerly winds across Arizona. The high-plateau thermal low is firmly in place during July and August, and it pulls-low-level moist air upslope into the Great Basin from the Gulf of California through the only opening available, which is the lower desert of Arizona.

Watson, A.I.; Holle, R.L.; Lopez, R.E. [NOAA, Norman, OK (United States)

1994-08-01

258

Reducing the resolution bias in cloud fraction from satellite derived clear-conservative cloud masks  

NASA Astrophysics Data System (ADS)

Clear-conservative satellite cloud detection algorithms overestimate cloud fraction (CF), the degree to which depends on instrument resolution and the spatial distribution of cloud area, with boundary layer cumulus carrying the largest overestimation. This is because in the standard method of computing CF, partially cloudy pixels contribute in the amount of the pixel's area rather than the true cloud area. Development of analytical and pattern recognition techniques to reduce overestimation has been limited by the lack of coincident long-term, large scale, and high-resolution satellite data sets. Such data sets are now available from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Multiangle Imaging SpectroRadiometer (MISR) instruments onboard the satellite, Terra. These data sets are used to determine the resolution required to reduce the CF overestimation to ?0.01 absolute CF using the standard, analytical, and pattern recognition techniques on perfect, clear-conservative cloud masks with future instrument design in mind; investigate the challenges of implementing these techniques on MISR's operational clear-conservative cloud mask; and demonstrate the impact of these techniques on a MISR-derived CF climatology similar to those used to evaluate climate models. Reducing the median CF bias to ?0.01 requires resolutions of <45 m and ?80 m for the standard and analytical techniques, respectively, while the pattern recognition technique has no resolution requirement up to a resolution of 1.2 km. When the pattern recognition technique is applied to 10-year, December, low cloud climatologies over the tropical Western Atlantic (10°N-20°N and 50°W-60°W) derived from MISR, the average CF reduces from 0.50 to 0.20. This is a large reduction in cloud fraction, particularly when considering the climate sensitivity to low clouds and the use of satellite derived CF climatologies for evaluation of climate model CF and radiative budgets.

Jones, Alexandra L.; di Girolamo, Larry; Zhao, Guangyu

2012-06-01

259

Imaging and estimation of human abdominal fat by electrical impedance tomography using multiple voltage measurement patterns.  

PubMed

A measuring device for human abdominal fat from the conductivity image derived by electrical impedance tomography (EIT) is rarely found. This study was aimed to reconstruct precise conductivity images from multiple voltage measurements in different patterns of the combination of current and voltage electrodes. We examined two voltage measuring patterns using electrodes located at upper and lower levels around the abdomen of a subject. In the experiment, after 1024 voltage data were taken from one specified voltage measurement pattern, another 1024 data were also taken continuously using another pattern. The reconstruction of conductivity image was made using entire data. As a result, the tomography image was improved compared with the image obtained from single voltage measurement pattern. We then obtained the histogram of the conductivities and estimated the area of abdominal fat. The present method using multiple voltage measurement patterns would be effective, if the measuring time can be much reduced through future modification of the tomography device. PMID:24110433

Yamaguchi, Tohru F; Katashima, Mitsuhiro; Wang, Li-Qun; Kuriki, Shinya

2013-07-01

260

Vertical stratification of tropical cloud properties as determined from satellite  

Microsoft Academic Search

A new retrieval scheme is developed to infer tropical cloud properties and vertical structure, including liquid and ice water content, cloud top and base, and cloud layering. The retrieval scheme utilizes a cloud classification scheme that uses both International Satellite Cloud Climatology Project (ISCCP) cloud top temperature and a microwave index from the special sensor microwave\\/imager (SSM\\/I). Different cloud classes

Rong-Shyang Sheu; Judith A. Curry; Guosheng Liu

1997-01-01

261

Local binary patterns for stromal area removal in histology images  

NASA Astrophysics Data System (ADS)

Nuclei counting in epithelial cells is an indication for tumor proliferation rate which is useful to rank tumors and select an appropriate treatment schedule for the patient. However, due to the high interand intra- observer variability in nuclei counting, pathologists seek a deterministic proliferation rate estimate. Histology tissue contains epithelial and stromal cells. However, nuclei counting is clinically restricted to epithelial cells because stromal cells do not become cancerous themselves since they remain genetically normal. Counting nuclei existing within the stromal tissue is one of the major causes of the proliferation rate non-deterministic estimation. Digitally removing stromal tissue will eliminate a major cause in pathologist counting variability and bring the clinical pathologist a major step closer toward a deterministic proliferation rate estimation. To that end, we propose a computer aided diagnosis (CAD) system for eliminating stromal cells from digital histology images based on the local binary patterns, entropy measurement, and statistical analysis. We validate our CAD system on a set of fifty Ki-67-stained histology images. Ki-67-stained histology images are among the clinically approved methods for proliferation rate estimation. To test our CAD system, we prove that the manual proliferation rate estimation performed by the expert pathologist does not change before and after stromal removal. Thus, stromal removal does not affect the expert pathologist estimation clinical decision. Hence, the successful elimination of the stromal area highly reduces the false positive nuclei which are the major confusing cause for the less experienced pathologists and thus accounts for the non-determinism in the proliferation rate estimation. Our experimental setting shows statistical insignificance (paired student t-test shows ? = 0.74) in the manual nuclei counting before and after our automated stromal removal. This means that the clinical decision of the expert pathologist is not affected by our CAD system which is what we want to prove. However, the usage of our CAD system substantially account for the reduced inter- and intra- proliferation rate estimation variability and especially for less-experienced pathologists.

Alomari, Raja S.; Ghosh, Subarna; Chaudhary, Vipin; Al-Kadi, Omar

2012-02-01

262

A 4.8 AND 8.6 GHz SURVEY OF THE SMALL MAGELLANIC CLOUD: THE IMAGES  

SciTech Connect

Detailed 4.8 and 8.6 GHz radio images of the entire Small Magellanic Cloud with half-power beamwidths of 35'' at 4.8 GHz and 22'' at 8.6 GHz have been obtained using the Australia Telescope Compact Array. A total of 3564 mosaic positions were used to cover an area of 4.{sup 0}5 on a side. Full polarimetric observations were made. These images have sufficient spatial resolution ({approx}9 and 6 pc, respectively) and sensitivity (3{sigma} of 1.5 mJy beam{sup -1}) to identify most of the individual supernova remnants and H II regions and also, in combination with available data from the Parkes 64 m telescope, the structure of the smooth emission in that galaxy. In addition, limited data using the sixth antenna at 4.5-6 km baselines are available to distinguish bright point sources (< 3 and 2 arcsec, respectively) and to help estimate sizes of individual sources smaller than the resolution of the full survey. The resultant database will be valuable for statistical studies and comparisons with X-ray, optical and infrared surveys of the Small Magellanic Cloud with similar resolution. The images and calibrated uv data are publicly available in FITS format.

Dickel, John R. [Department of Physics and Astronomy, University of New Mexico, MSC 07 4220, Albuquerque, NM 87131 (United States); Gruendl, Robert A. [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); McIntyre, Vincent J.; Amy, Shaun W. [Australia Telescope National Facility, CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia)

2010-11-15

263

Global assessment of AMSR-E and MODIS cloud liquid water path retrievals in warm oceanic clouds  

NASA Astrophysics Data System (ADS)

We compared 1 year of Advanced Microwave Scanning Radiometer-EOS (AMSR-E) Wentz and Moderate Resolution Imaging Spectroradiometer (MODIS) cloud liquid water path estimates in warm marine clouds. In broken scenes AMSR-E increasingly overestimated MODIS, and retrievals became uncorrelated as cloud fraction decreased, while in overcast scenes the techniques showed generally better agreement, but with a MODIS overestimation. We found microwave and visible near-infrared retrievals being most consistent in extensive marine Sc clouds with correlations up to 0.95 and typical RMS differences of 15 g m-2. The overall MODIS high bias in overcast domains could be removed, in a global mean sense, by adiabatic correction; however, large regional differences remained. Most notably, MODIS showed strong overestimations at high latitudes, which we traced to 3-D effects in plane-parallel visible-near-infrared retrievals over heterogeneous clouds at low Sun. In the tropics or subtropics, AMSR-E-MODIS differences also depended on cloud type, with MODIS overestimating in stratiform clouds and underestimating in cumuliform clouds, resulting in large-scale coherent bias patterns where marine Sc transitioned into trade wind Cu. We noted similar geographic variations in Wentz cloud temperature errors and MODIS 1.6-3.7 ?m droplet effective radius differences, suggesting that microwave retrieval errors due to cloud absorption uncertainties, and visible near-infrared retrieval errors due to cloud vertical stratification might have contributed to the observed liquid water path bias patterns. Finally, cloud-rain partitioning was found to introduce a systematic low bias in Wentz retrievals above 180 g m-2 as the microwave algorithm erroneously assigned an increasing portion of the liquid water content of thicker nonprecipitating clouds to rain.

Seethala, C.; HorváTh, ÁKos

2010-07-01

264

Mining Patterns of Change in Remote Sensing Image Databases  

Microsoft Academic Search

Remote sensing image databases are the fastest growing archives of spatial information. However, we still have a limited capacity for extracting information from large remote sensing image databases. There are currently very few techniques for image data mining and information extraction in large image data sets, and thus we are failing to exploit our large remote sensing data archives. This

Marcelino Pereira Dos Santos Silva; Gilberto Câmara; Ricardo Cartaxo Modesto De Souza; Dalton M. Valeriano; Maria Isabel Sobral Escada

2005-01-01

265

Pattern Recognition Software and Techniques for Biological Image Analysis  

Microsoft Academic Search

The increasing prevalence of automated image acquisition systems is enabling new types of microscopy experiments that generate large image datasets. However, there is a perceived lack of robust image analysis systems required to process these diverse datasets. Most automated image analysis systems are tailored for specific types of microscopy, contrast methods, probes, and even cell types. This imposes significant constraints

Lior Shamir; John D. Delaney; Nikita Orlov; D. Mark Eckley; Ilya G. Goldberg

2010-01-01

266

Concerning the Inter-Hemispheric Transfer of Mirror-Image Patterns in Pigeon.  

National Technical Information Service (NTIS)

Pigeons were monocularly trained on a chain DRO VII reinforcement schedule on each of the following discrimination problems: (a) up-down mirror-image patterns; (b) left-right mirror-image patterns; (c) ambiguous figures containing both up-down and left-ri...

N. K. Mello

1966-01-01

267

Range Image Acquisition with a Single Binary-Encoded Light Pattern  

Microsoft Academic Search

The problem of strike identification in range image acquisition systems based on triangulation with periodically structured illumination is discussed. A coding scheme is presented based on a single fixed binary encoded illumination pattern, which contains all the information required to identify the individual strikes visible in the camera image. Every sample point indicated by the light pattern is made identifiable

Piet Vuylsteke; André Oosterlinck

1990-01-01

268

Detecting, grouping, and structure inference for invariant repetitive patterns in images.  

PubMed

The efficient and robust extraction of invariant patterns from an image is a long-standing problem in computer vision. Invariant structures are often related to repetitive or near-repetitive patterns. The perception of repetitive patterns in an image is strongly linked to the visual interpretation and composition of textures. Repetitive patterns are products of both repetitive structures as well as repetitive reflections or color patterns. In other words, patterns that exhibit near-stationary behavior provide rich information about objects, their shapes, and their texture in an image. In this paper, we propose a new algorithm for repetitive pattern detection and grouping. The algorithm follows the classical region growing image segmentation scheme. It utilizes a mean-shift-like dynamic to group local image patches into clusters. It exploits a continuous joint alignment to: 1) match similar patches, and 2) refine the subspace grouping. We also propose an algorithm for inferring the composition structure of the repetitive patterns. The inference algorithm constructs a data-driven structural completion field, which merges the detected repetitive patterns into specific global geometric structures. The result of higher level grouping for image patterns can be used to infer the geometry of objects and estimate the general layout of a crowded scene. PMID:23481858

Cai, Yunliang; Baciu, George

2013-06-01

269

First correlated measurements of the shape and light scattering properties of cloud particles using the new Particle Habit Imaging and Polar Scattering (PHIPS) probe  

NASA Astrophysics Data System (ADS)

Studying the radiative impact of cirrus clouds requires knowledge of the relationship between their microphysics and the single scattering properties of cloud particles. Usually, this relationship is obtained by modeling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. We present here a novel optical sensor (the Particle Habit Imaging and Polar Scattering probe, PHIPS) designed to measure simultaneously the 3-D morphology and the corresponding optical and microphysical parameters of individual cloud particles. Clouds containing particles ranging from a few micrometers to about 800 ?m diameter in size can be characterized systematically with an optical resolution power of 2 ?m and polar scattering resolution of 1° for forward scattering directions (from 1° to 10°) and 8° for side and backscattering directions (from 18° to 170°). The maximum acquisition rates for scattering phase functions and images are 262 KHz and 10 Hz, respectively. Some preliminary results collected in two ice cloud campaigns conducted in the AIDA cloud simulation chamber are presented. PHIPS showed reliability in operation and produced size distributions and images comparable to those given by other certified cloud particles instruments. A 3-D model of a hexagonal ice plate is constructed and the corresponding scattering phase function is compared to that modeled using the Ray Tracing with Diffraction on Facets (RTDF) program. PHIPS is a highly promising novel airborne optical sensor for studying the radiative impact of cirrus clouds and correlating the particle habit-scattering properties which will serve as a reference for other single, or multi-independent, measurement instruments.

Abdelmonem, A.; Schnaiter, M.; Amsler, P.; Hesse, E.; Meyer, J.; Leisner, T.

2011-10-01

270

First correlated measurements of the shape and scattering properties of cloud particles using the new Particle Habit Imaging and Polar Scattering (PHIPS) probe  

NASA Astrophysics Data System (ADS)

Studying the radiative impact of cirrus clouds requires the knowledge of the link between their microphysics and the single scattering properties of the cloud particles. Usually, this link is created by modeling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. We present here a novel optical sensor (the Particle Habit Imaging and Polar Scattering probe, PHIPS) designed to measure the 3-D morphology and the corresponding optical and microphysical parameters of individual cloud particles, simultaneously. Clouds containing particles ranging in size from a few micrometers to about 800 ?m diameter can be systematically characterized with an optical resolution power of 2 ?m and polar scattering resolution of 1° for forward scattering directions (from 1° to 10°) and 8° for side and backscattering directions (from 18° to 170°). The maximum acquisition rates for scattering phase functions and images are 262 KHz and 10 Hz, respectively. Some preliminary results collected in two ice cloud campaigns which were conducted in the AIDA cloud simulation chamber are presented. PHIPS showed reliability in operation and produced comparable size distributions and images to those given by other certified cloud particles instruments. A 3-D model of a hexagonal ice plate is constructed and the corresponding scattering phase function is compared to that modeled using the Ray Tracing with Diffraction on Facets (RTDF) program. PHIPS is candidate to be a novel air borne optical sensor for studying the radiative impact of cirrus clouds and correlating the particle habit-scattering properties which will serve as a reference for other single, or multi-independent, measurements instruments.

Abdelmonem, A.; Schnaiter, M.; Amsler, P.; Hesse, E.; Meyer, J.; Leisner, T.

2011-05-01

271

Introduction to Clouds  

NSDL National Science Digital Library

This site provides the user an opportunity to explore storm clouds and climate change through the use of NASA climate research data obtained through satellite imaging. The user is challenged to investigate actual scientific research data on clouds and storms, and make observations and interpretations available to NASA research scientists for review. Topics addressed by these investigations include the role of clouds in relation to the changing climate of Earth, the role of clouds in warming or cooling the planet, and the major types of clouds produced by storms.

Tselioudis, George; Petersen, Christopher

1997-01-01

272

An image analysis method for determination of spatial colonization patterns of bacteria in plant rhizosphere  

Microsoft Academic Search

A method that allows the rapid visualization of bacterial spatial colonization patterns on roots for the determination of\\u000a general colonization trends was developed. This method, which analyzes images of roots, and bioluminescence-enhanced images\\u000a of bacterial colonization patterns on these roots, was used to study the colonization patterns of seed-applied Enterobacter cloacae strain E6 on 3-day-old cucumber plants. Conventional dilution-plating methods

D. P. Roberts; D. Y. Kobayashi; P. D. Dery; N. M. Short Jr

1999-01-01

273

Cassini Imaging Observations of Lakes and Clouds at Titan's High Latitudes and the Implications of the Changes Therein  

NASA Astrophysics Data System (ADS)

Cassini's Imaging Science Subsystem (ISS) imaged Titan's south polar region in July 2004 and June 2005, revealing convective cloud systems and dark surface features interpreted to be hydrocarbon lakes, e.g. 235- km-long Ontario Lacus (McEwen et al., B.A.A.S. 37, 2005). Recent evidence from Cassini's Visual and Infrared Mapping Spectrometer supports the interpretation that Ontario Lacus contains liquid ethane and methane (Brown et al., Nature 454, 2008). Although diffuse clouds or atmospheric scattering could play a role, differences between the two ISS observations taken a year apart may be due to changes in the lakes as a result of precipitation from a large cloud system observed in Fall 2004 (Schaller et al., Icarus 182, 2006). ISS observations of northern latitudes just emerging from northern winter have revealed much larger dark areas, including Mare Kraken (>1100 km long), as well as myriad smaller dark spots. Many of these features coincide with liquid-filled areas identified by Cassini RADAR (e.g., Lopes et al., EOS 88, 2007). Combined these features cover well over 600,000 km2, ~1% of Titan's surface area; however, as shown by Lorenz et al. (GRL 35, 2008), even if all were filled with liquid, they would not provide enough methane to keep Titan's atmosphere resupplied for a substantial amount of time, unless they are unexpectedly deep or other subsurface reservoirs exist. Intriguingly the surface coverage is unevenly distributed, with more total area and much larger seas occurring around the North (recently winter) Pole. The extents to which this variation depends on the season and/or local geology and its effects on atmospheric circulation may be revealed with the advent of northern spring and summer.

Turtle, E. P.; Perry, J. E.; McEwen, A. S.; Del Genio, A. D.; Barbara, J.; West, R. A.; Dawson, D. D.; Porco, C. C.

2008-12-01

274

Detailed images and distance measurements for eighteen dwarf irregular galaxies in the Canes Venatici cloud  

Microsoft Academic Search

In the Canes Venatici cloud, eighteen dwarf irregular galaxies were observed in B, V bands at the Nordic Optical Telescope under a seeing of one arcsec. Most of the galaxies having radial velocities V_0 < 500 km\\/s have been resolved into stars for the first time. The galaxy distances were derived based on photometry of their brightest blue stars. Distances

L. Makarova; I. Karachentsev; L. O. Takalo; P. Heinaemaeki; M. Valtonen

1998-01-01

275

A bispectral method for the automatic determination of parameters for use in imaging satellite cloud retrievals  

Microsoft Academic Search

Two major problems in deriving cloud amounts and physical properties from satellite imagery are the selection of suitable surface-type discriminators, which may vary as a function of time and place, and the extraction of cloudiness on the subpixel scale. We present a method of retrieving suitable parameters for such discriminations on the local scale, based on the information contained in

C. F. ENGLAND; G. E. HUNT

1985-01-01

276

OVRO High Resoliution Imaging of Dense Molecular Clouds in the Central Three Parsecs of the Galaxy  

NASA Astrophysics Data System (ADS)

Using the Owens Valley Radio Observatory (OVRO) millimeter array, we have obtained the highest spatial (3.3" x 2.4") and spectral resolution HCN maps of the galactic center region. The prominent molecular emission comes from the circumnuclear disk (CND), a ring-like structure surrounding the galactic center at an inner radius of 1-1.5 parsecs. The CND is not a smooth structure, but rather is comprised primarily of 10-20 high density clouds with characteristic sizes of 8-10". From our observations we deduce a typical H2 density within these clouds of a few x 106 cm-3, corresponding to approximately a thousand solar masses of molecular gas in each cloud. The densities within these clouds are not high enough to prevent tidal disruption in the gravitational field of the galactic center (comprising both the massive black hole and the stellar population interior to the CND). Comparing our observed molecular gas emission with the ionized gas emission as seen in the Paschen Alpha NICMOS map from Scoville et al. (2002), there is clear evidence for interplay between the ionized and molecular gas (e.g. the western arc in ionized gas is the photoionized edge of the CND and streamers within the CND spatially and kinematically connect with the Northern Arm of ionized gas). Examining the interaction of the molecular and ionized gas within the central parsecs of the galaxy sheds observational light on conditions near massive black holes, a critical tool for understanding AGN phenomenon.

Christopher, M. H.; Scoville, N. Z.

277

The cloud imaging and particle size experiment on the aeronomy of ice in the mesosphere mission: Cloud morphology for the northern 2007 season  

Microsoft Academic Search

The Aeronomy of Ice in the Mesosphere (AIM) mission was launched from Vandenberg Air Force Base in California at 4:26:03 EDT on April 25, 2007, becoming the first satellite mission dedicated to the study of noctilucent clouds (NLCs), also known as polar mesospheric clouds (PMC) when viewed from space. We present the first results from one of the three instruments

D. W. Rusch; G. E. Thomas; W. McClintock; A. W. Merkel; S. M. Bailey; J. M. Russell III; C. E. Randall; C. Jeppesen; M. Callan

2009-01-01

278

Physical modelling of point-cloud (3D) and full-wave-form (4D) laser imaging  

NASA Astrophysics Data System (ADS)

We compare results issued from a numerical model that simulates the point cloud obtained by 3D laser scanning of a scene and measurements provided by a commercial laser scanner. The model takes into account the temporal and transverse characteristics of the laser pulse, the propagation through turbulent and scattering atmosphere, the interaction with the objects of the scene (which have special optical properties: BRDF...) and the characteristics of the opto-electric detection system. The model derives 4D laser imaging information as temporal laser backscattered intensity (full wave form) is considered here. Experiments and simulations are performed on targets and scenes in order to test the performances of such imager under conditions that could be representative of future applications like Sense and Avoid, Target Recognition and Mapping,...

Anna, G.; Hespel, L.; Riviere, N.; Hamoir, D.; Tanguy, B.

2010-10-01

279

Continuous Image Writer with improved critical dimension performance for high-accuracy maskless optical patterning  

Microsoft Academic Search

We report on the development of a production tool for fast optical maskless patterning. The Continuous Image Writer (CIW) combines the advantages of direct writing by using a programmable mask with the advantages of conventional optical lithography by using the same lithographic process for image formation in photoresist. An electronically programmable spatial light modulator (SLM) is imaged onto the substrate

J. Paufler; St. Brunn; T. Körner; F. Kühling

2001-01-01

280

Pc Imaging for Ultraviolet Spectral Atlas of O Stars in the Milky way and Magellanic Clouds  

Microsoft Academic Search

We will obtain B-band pictures of the 30 Dor region in the Large Magellanic Cloud, which we will combine with existing U and V-band pictures in order to construct a color-magnitude diagram for the region. In later cycles, we will obtain G160M spectra of O stars in the Milky Way in order to carry out a quantitative, non-LTE photospheric analysis.

Sara Heap

1991-01-01

281

Image-Based Network Rendering of Large Meshes for Cloud Computing  

Microsoft Academic Search

Recent advances in sensing and software technologies enable us to obtain large-scale, yet fine 3D mesh models of cultural\\u000a assets. However, such large models cannot be displayed interactively on consumer computers because of the performance limitation\\u000a of the hardware. Cloud computing technology is a solution that can process a very large amount of information without adding\\u000a to each client user’s

Yasuhide Okamoto; Takeshi Oishi; Katsushi Ikeuchi

2011-01-01

282

Automatic center location of non-eyed typhoon in satellite cloud image  

Microsoft Academic Search

Typhoon can be classified into two classes: eyed typhoon and non-eyed typhoon. The center of a non-eyed typhoon with good circularity is the geometric center of the cloud system and the center of a non-eyed typhoon with bad circularity can be located in the high grayness value area near the side of the greater grayness gradient sector. A new mathematical

Zhengguang Liu; Haiming Qiu; Bing Wu; Gary G. Shen

2003-01-01

283

Error Estimation in deriving the Atmospheric Motion Vectors from cloud images  

Microsoft Academic Search

The primary goal of Japan's Venus meteorological satellite mission (Planet-C), which will be launched in 2007, is to reveal the formation and maintenance mechanism of high speed westward winds in the Venusian atmosphere called super-rotation (approximately 100 m\\/s at the altitude of 70 km). The mechanism to keep on transporting momentum from the surface to the cloud-top has been wrapped

T. Murachi; T. Imamura; T. Higuchi; M. Nakamura

2001-01-01

284

Cloud computing platform for GIS image processing in U-city  

Microsoft Academic Search

Ubiquitous city (U-city) is a city with ubiquitous information technology that enables citizens to access the converged information anywhere and anytime. A lot of compute power are required in U-city, because large amount of data should be processed in real-time. Cloud computing enables users to use the abstracted and virtualized computing resources and to process huge amount of information without

Jong Won Park; Chang Ho Yun; Shin-gyu Kim; Heon Y. Yeom; Yong Woo Lee

2011-01-01

285

Laboratory measurements of light scattered by clouds and layers of solid particles using an imaging technique  

Microsoft Academic Search

\\u000a The Optical PRoperties of Astronomical and Atmospheric Grains (PROGRA2) experiment was developed in 1993 to study the light scattered by dust clouds, with an emphasis on its linear polarization.\\u000a The instrument was progressively improved. A short description of the PROGRA2-vis instrument operating in the visible is given in this chapter. In the framework of the experiment, solid particles are\\u000a lifted

E. Hadamcik; J.-B. Renard; A. C. Levasseur-Regourd; J. Lasue

286

Relevance feedback-based image retrieval interface incorporating region and feature saliency patterns as visualizable image similarity criteria  

Microsoft Academic Search

Region and feature saliency pattern (RFSP) is proposed as: (1) a new image similarity model; and (2) a new, visualizable representation of the image similarity criteria. RFSP, coupled with the proposed genetic-algorithm (GA)-based relevance feedback mechanism, is incorporated in the image retrieval interface. By capturing the two fundamental properties of the human visual system-region and feature saliencies-in a context-dependent sense,

Zoran Stejic; Yasufumi Takama; Kaoru Hirota

2003-01-01

287

Application of cloud vertical structure from CloudSat to investigate MODIS-derived cloud properties of cirriform, anvil, and deep convective clouds  

NASA Astrophysics Data System (ADS)

CloudSat cloud vertical structure is combined with the CALIPSO Lidar and Collection-5 Level 2 cloud data from Aqua's Moderate Resolution Imaging Spectroradiometer (MODIS) to investigate the mean properties of high/cirriform, anvil, and deep convective (DC) clouds. Cloud properties are sampled over 30°S-30°N for 1 year and compared to existing results of Collection-4 Aqua MODIS high-level cloud observations where cloud types were categorized using the International Satellite Cloud Climatology Project (ISCCP) cloud classification scheme. Results show high/cirriform sampled in this study have high biases in cloud top pressure and temperature due to CloudSat's sensitivity to thin high clouds. Mean cloud properties of DC show reasonable agreement with existing DC results notwithstanding mean cloud optical thickness which is ~23% higher due to the exclusion of thick cirrus and anvil clouds. Anvil cloud properties are a mix between high/cirriform and DC according to ISCCP cloud optical thickness thresholds whereby ~80% are associated with high/cirriform and the other 20% are associated with DC. The variability of cloud effective particle radii was also evaluated using DC with ?5 dBZ echoes at and above 10 km. No evidence of larger cloud effective particle radii are given despite considering higher reaching echoes. Using ISCCP cloud optical thickness thresholds, ~25% of DC would be classified as cirrostratus clouds. These results provide a basis to evaluate the uncertainty of the ISCCP cloud classification scheme and MODIS-derived cloud properties using active satellite observations.

Young, Alisa H.; Bates, John J.; Curry, Judith A.

2013-05-01

288

Optical parallel pattern recognition of multiple stored images in a persistent spectral holeburning memory  

NASA Astrophysics Data System (ADS)

We propose and demonstrate a novel parallel pattern recognition technique (pulse-correlation technique) to extract a specific pattern directly from multiple stored images in a persistent spectral holeburning (PHB) memory. Multiple recording channels which exist in the same spatial area but in different frequency regions can be accessed simultaneously with a pulsed laser whose frequency linewidth is comparable with an inhomogeneous width of the PHB material. Using the pulsed laser for pattern recognition, we have succeeded in extracting a specific image instantly from multiple stored images in a PHB material.

Sasaki, H.; Karaki, K.

1998-07-01

289

Passive multiangle imaging of clouds, aerosols, and atmospheric dynamics: Broadening our vision from MISR to WindCam and MSPI  

NASA Astrophysics Data System (ADS)

The Multi-angle Imaging SpectroRadiometer (MISR) has been collecting global Earth data from NASA’s Terra satellite since February 2000. With its nine along-track view angles, four visible/near-infrared spectral bands, intrinsic spatial resolution of 275 m, and stable calibration, no instrument that combines MISR’s attributes has previously flown in space, nor is there is a similar capability currently available on any other satellite platform. The MISR data record provides unprecedented opportunities for characterizing long-term variability in aerosol and cloud structure and atmospheric dynamics, including measurements of the vertical distributions of clouds; aerosol (smoke, volcanic, and dust) plume heights and global optical depths and particle properties; and pole-to-pole height-resolved winds. To extend what has been learned during the first decade of MISR observations, we are developing the WindCam and Multiangle SpectroPolarimetric Imager (MSPI) instruments. WindCam will enable MISR-like stereo observations over a broader swath using a much more compact sensor design. MSPI expands MISR capabilities through broader spectral coverage (ultraviolet to shortwave infrared), wider swath (enabling more rapid global coverage), and incorporation of high-accuracy polarimetric imaging, which will provide greater sensitivity to particle microphysics. A ground-based prototype camera (GroundMSPI) with spectral coverage from 355-935 nm has been built and an airborne version (AirMSPI) is ready for flight on NASA’s ER-2 high-altitude aircraft. Algorithm developments and improvements enabled by increases in computational speed since Terra launch are being explored with MISR data, and will be needed to handle the rich information content of these MISR successor instruments.

Diner, D. J.; Wu, D. L.; Chipman, R.; Davis, A.; Misr Science Team

2010-12-01

290

Statistical image recovery from laser speckle patterns with polarization diversity  

NASA Astrophysics Data System (ADS)

This research extends the theory and understanding of the laser speckle imaging technique. This non-traditional imaging technique may be employed to improve space situational awareness and image deep space objects from a ground-based sensor system. The use of this technique is motivated by the ability to overcome aperture size limitations and the distortion effects from Earth's atmosphere. Laser speckle imaging is a lensless, coherent method for forming two-dimensional images from their autocorrelation functions. Phase retrieval from autocorrelation data is an ill-posed problem where multiple solutions exist. This research introduces polarization diversity as a method for obtaining additional information so the structure of the object being reconstructed can be improved. Results show that in some cases the images restored using polarization diversity are superior to those reconstructed without it. This research presents statistical analysis of the observed data, two distinct image recovery algorithms, and a Cramer-Rao Lower Bound on resolution. A mathematical proof is provided to demonstrate the statistical properties of the observed, noisy autocorrelation data. The algorithms are constructed using the Expectation-Maximization approach and a polarization parameter that relates two independently observed data channels. The algorithms are validated with computer simulation and laboratory experiment. Comparison is made to an existing phase-retrieval technique. The theoretical lower bound is developed for comparing theoretical performance with and without polarization diversity. The results demonstrate the laser speckle imaging technique is improved with polarization diversity.

Dixon, Donald B.

291

Optical time-domain analog pattern correlator for high-speed real-time image recognition.  

PubMed

The speed of image processing is limited by image acquisition circuitry. While optical pattern recognition techniques can reduce the computational burden on digital image processing, their image correlation rates are typically low due to the use of spatial optical elements. Here we report a method that overcomes this limitation and enables fast real-time analog image recognition at a record correlation rate of 36.7 MHz--1000 times higher rates than conventional methods. This technique seamlessly performs image acquisition, correlation, and signal integration all optically in the time domain before analog-to-digital conversion by virtue of optical space-to-time mapping. PMID:21263506

Kim, Sang Hyup; Goda, Keisuke; Fard, Ali; Jalali, Bahram

2011-01-15

292

Integrated spatio-spectral method for efficiently suppressing honeycomb pattern artifact in imaging fiber bundle microscopy  

NASA Astrophysics Data System (ADS)

In a fiber bundle, spots of varying intensity occur throughout the fiber structure, and the ensemble of these spots creates the honeycomb pattern image, called a pixelated image. The spatio-spectral method, an integrated suppression method for the honeycomb pattern in the spatial and Fourier (spectral) domains, has demonstrated efficient restoration of microscopic images based on the fiber bundle. The morphological processing in the spatial domain partially interpolated the gaps between the circular patterns of fiber cores, and the selective band-reject filter in the Fourier domain was applied to reduce the honeycomb-shaped artifact. The auto-corrective search for the global peaks in the localized region was employed to apply the notch filter to the exact position of the individual periodic component in the Fourier domain. We found that a closing preprocessing in the spatial domain, combined with a Gaussian notch Fourier domain filter, yields the optimum image quality when eliminating the honeycomb pattern.

Lee, Cheon-Yang; Han, Jae-Ho

2013-10-01

293

Patterned Resonance Plasmonic Microarrays for High-Performance SPR Imaging  

PubMed Central

We report a novel optical platform based on SPR generation and confinement inside a defined 3-dimensional microwell geometry that leads to background resonance-free SPR images. The array shows an exceptionally high signal-to-noise ratio (S/N>80) for imaging analysis and subnanometric thickness resolution. An angular sensitivity of 1 degree/0.01 RIU has been achieved and the signal to background ratio (S/B) improves to 20, one order of magnitude higher than best literature results. The design proves effective for probing supported lipid membrane arrays in real time with a thickness resolution of 0.24 nm and allows for imaging analysis of microfluidic circuits where resonant spots are separated by only one pixel (~ 7 ?m). The high image quality and unique chip geometry open up new avenues for array screening and biomicrofluidics using SPRi detection.

Abbas, Abdennour; Linman, Matthew J.; Cheng, Quan

2011-01-01

294

Image segmentation and pattern matching based FPGA\\/ASIC implementation architecture of real-time object tracking  

Microsoft Academic Search

A novel algorithm for object tracking of video pictures, based on image segmentation and pattern matching as well as its FPGA\\/ASIC implementation architecture are presented. With image segmentation, we can detect all objects in the images no matter whether they are moving or not. Using image segmentation results of successive frames, we exploit pattern matching in a simple object feature

K. Yamaoka; T. Morimoto; H. Adachi; T. Koide; H. J. Mattausch

2006-01-01

295

Image segmentation and pattern matching based FPGA\\/ASIC implementation architecture of real-time object tracking  

Microsoft Academic Search

A novel algorithm for object tracking in video pictures, based on image segmentation and pattern matching, as well as its FPGA\\/ASIC implementation architecture are presented. With image segmentation, we can detect all objects in the images no matter whether they are moving or not. Using image segmentation results of successive frames, we exploit pattern matching in a simple object feature

K. Yamaoka; Takashi Morimoto; Hidekazu Adachi; Tetsushi Koide; Hans Jürgen Mattausch

2006-01-01

296

Mapping of SO2 on Venus within the H2SO4 cloud using ground-based infrared imaging spectroscopy  

NASA Astrophysics Data System (ADS)

Sulfur dioxide and water vapor, two key parameters of Venus' photochemistry, are known to exhibit significant spatial and temporal variations. In particular, ground-based thermal imaging spectroscopy at high resolution, achieved on Venus in January 2012, has shown evidence for strong SO2 variations on timescales shorter than a day (Encrenaz et al. AA 543, 153, 2012). We have continued our observing campaign using the TEXES high-resolution imaging spectrometer at the NASA Infrared Telescope Facility to map sulfur dioxide over the disk of Venus at two different wavelengths, 7 ?m (already used in the previous study) and 19 ?m. The 7 ?m radiation probes the top of the H2SO4 cloud at about 65 km, while the 19 ?m radiation probes at deeper levels within the cloud. Observations took place on October 4 and 5, 2012. The diameter of Venus was 15 arcsec, with an illumination factor of 72%. Data were recorded at 1343-1353 cm-1 during the two first hours of each run and at 529-531 cm-1 during the two last hours. The spectral resolving power and spatial resolution were, respectively, about 70000 and 1 arcsec at 7 ?m, and 60000 and 1.5 arcsec at 19 ?m. The Doppler velocity of Venus was + 12 km/s, corresponding to a Doppler shift of - 0.054 cm-1 at 1350 cm-1 and - 0.021 cm-1 at 530 cm-1. Both HDO and SO2 lines are identified in our 7 ?m spectra and SO2 is also easily identified at 19 ?m; the poor weather and the high water atmospheric content during our observing run limited the quality of the 7 ?m observations. As observed in our previous run, the HDO map is relatively uniform over the disk of Venus. In contrast, the SO2 maps at 19 ?m show intensity variations over the disk, as observed in January 2012 at 7 ?m. In addition, the SO2 map at 19 ?m shows significant changes within a timescale of an hour. The CO2 lines at 7 and 19 ?m will be used to infer the thermal structure within the cloud and to study its latitudinal variations.

Encrenaz, Therese; Greathouse, Thomas; Richter, Matthew; Lacy, John; Bézard, Bruno; Fouchet, Thierry; DeWitt, Curtis; Widemann, Thomas

2013-04-01

297

ISCCP Global Cloud Cover  

NSDL National Science Digital Library

This animated sequence is a one month sample of composited images from cloud cover data collected from a suite of U.S., European, and Japanese geostationary satellites and U.S. polar orbiting meteorological satellites. This data was composited under the auspices of ISCCP, the International Satellite Cloud Climatology Program.

Pape, Dave; Rossow, William; Walker, Alison

1994-03-13

298

Parallax correction in collocating CloudSat and Moderate Resolution Imaging Spectroradiometer (MODIS) observations: Method and application to convection study  

Microsoft Academic Search

Parallax correction is important for spaceborne studies of convective cloudsParallax correction here improves the estimates of cloud top temperatureParallax correction affects relevant statistics in satellite data analysis

Chunpeng Wang; Zhengzhao Johnny Luo; Xianglei Huang

2011-01-01

299

Using semivariogram indices to analyse heterogeneity in spatial patterns in remotely sensed images  

NASA Astrophysics Data System (ADS)

The benchmark problem proposed in this paper is to identify regions in aerial or satellite images with geometric patterns and describe the geometric properties of the constituent elements of the pattern and their spatial distribution. This is a relevant topic in image analysis processes where spatial regular patterns are studied. This paper first presents two approaches based on multi-directional semivariograms for reducing the processing time required to compute omnidirectional semivariograms. A set of parameters for describing the structure of a semivariogram, introduced by Balaguer et al. (2010), is extracted from an experimental semivariogram and analysed to quantify the heterogeneity of the distribution of elements (trees) with periodic patterns in images of orchards. An assessment is made using four image datasets. The first dataset is composed of synthetic images that simulate regularly spaced tree crops and real images, and is used to evaluate the influence that the orientation of elements (regularly spaced trees) in the objects (crop plots) has in the descriptive parameter values. This dataset is also used to compare different semivariogram computational approaches. The other three are also composed of synthetic images and are used to evaluate the semivariogram parameters under different spatial heterogeneity conditions, and are generated by varying patterns and tree characteristics, i.e., existence or absence of faults, regular/irregular distributions, and size of the elements. Finally, the proposed methodology is applied to real aerial orthoimages of orchard plots.

Balaguer-Beser, A.; Ruiz, L. A.; Hermosilla, T.; Recio, J. A.

2013-01-01

300

MR Imaging Findings of Intracranial Dural Arteriovenous Fistulas: Relations with Venous Drainage Patterns  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Venous drainage patterns are a major determinant of clinical outcome in intracranial dural arteriovenous fistula (DAVF) patients. In this study, we sought to identify MR imaging finding differences between DAVF types classified on the basis of venous drainage patterns. METHODS: Twenty-seven patients diagnosed as having DAVFs by conventional angiography were included. Medical records (n 27), and MR

Bae Ju Kwon; Moon Hee Han; Hyun-Seung Kang; Kee-Hyun Chang

301

Extraction of frequent grouped sequential patterns from Satellite Image Time Series  

Microsoft Academic Search

This paper presents an original data mining approach for extracting pixel evolutions and sub-evolutions from Satellite Image Time Series. These patterns, called frequent grouped sequential patterns, represent the (sub-)evolutions of pixels over time, and have to satisfy two constraints: firstly to correspond to at least a given minimum surface and secondly to be shared by pixels that are sufficiently connected.

Andreea Julea; Nicolas Méger; Christophe Rigotti; Marie-Pierre Doin; Cécile Lasserre; Emmanuel Trouvé; Philippe Bolon; Vasile Lazarescu

2010-01-01

302

Hyperspectral simulation of chemical weapon dispersal patterns using DIRSIG  

NASA Astrophysics Data System (ADS)

Fieldable thermal infrared hyperspectral imaging spectrometers has made it possible to design and construct new instruments for better detection of battlefield hazards such as chemical weapon clouds. The availability of spectroscopic measurements of these clouds can be used not only for the detection and identification of specific chemical agents but also to potentially quantify the lethality of the cloud. The simulation of chemical weapon dispersal patterns in a synthetic imaging environment offers significant benefits to sensor designers. Such an environment allows designers to easily develop trade spaces to test detection and quantification algorithms without the need for expensive and dangerous field releases. This paper discusses the implementation of a generic gas dispersion model that has been integrated into the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model. The gas cloud model utilizes a 3D Gaussian distribution and first order dynamics (drift and dispersion) to drive the macro-scale cloud development and movement. The model also attempts to account for turbulence by incorporating fractional Brownian motion techniques to reproduce the micro-scale variances within the cloud. The cloud path length concentrations are then processed by the DIRSIG radiometry sub-model to compute the emission and transmission of the cloud body on a per-pixel basis. Example hyperspectral image cubes containing common agents and release amounts will be presented. Time lapse sequences will also be presented to demonstrate the evolution of the cloud over time.

Arnold, Peter S.; Brown, Scott D.; Schott, John R.

2000-07-01

303

Exploiting structure in fast aerial image computation for integrated circuit patterns  

Microsoft Academic Search

Modeling aerial images has recently become a crucial component of semiconductor manufacturing. As all steppers employ partially coherent illumination, such modeling has been computationally intensive for all but elementary patterns. In this paper we describe a fast computational method for calculating aerial images of integrated circuit masks produced by a partially coherent optical projection system. The method described relies on

Y. C. Pati; Amir Aalam Ghazanfarian; R. Fabian Pease

1997-01-01

304

Modelling, calibration and correction of nonlinear illumination dependent fixed pattern noise in logarithmic CMOS image sensors  

Microsoft Academic Search

At present, most CMOS image sensors use an array of pixels with a linear response. However, logarithmic CMOS sensors are also possible, which are capable of imaging high dynamic range scenes without saturating. Unfortunately, logarithmic sensors suffer from fixed pattern noise (FPN). Work reported in the literature generally assumes the FPN is independent of illumination. This paper develops a nonlinear

Dileepan Joseph; Steve Collins

2001-01-01

305

Genetic Algorithm-Based Relevance Feedback for Image Retrieval Using Local Similarity Patterns.  

ERIC Educational Resources Information Center

|Proposes local similarity pattern (LSP) as a new method for computing digital image similarity. Topics include optimizing similarity computation based on genetic algorithm; relevance feedback; and an evaluation of LSP on five databases that showed an increase in retrieval precision over other methods for computing image similarity. (Author/LRW)|

Stejic, Zoran; Takama, Yasufumi; Hirota, Kaoru

2003-01-01

306

An Application of Automated Inkless Fingerprint Imaging Software in Fingerprint Collection and Pattern Analysis  

Microsoft Academic Search

Fingerprint data collections of 684 Thai subjects using a transparent-adhesive tape technique compared with developed software namely an automated inkless fingerprint image which is able to scan fingertips and face images then arrange them in a portable document format prior to printing. Each fingerprint pattern was characterized as arch, radial loop, ulnar loop, and whorl (including double loop whorl, accidental

Somsong Nanakorn; Pongsakorn Poosankam; Art Nanakorn

2007-01-01

307

Biometric verification using thermal images of palm-dorsa vein patterns  

Microsoft Academic Search

A novel approach to personal verification using the thermal images of palm-dorsa vein patterns is presented in this paper. The characteristics of the proposed method are that no prior knowledge about the objects is necessary and the parameters can be set automatically. In our work, an infrared (IR) camera is adopted as the input device to capture the thermal images

Chih-lung Lin; Kuo-chin Fan

2004-01-01

308

Mask pattern quality assurance based on lithography simulation with fine pixel SEM image  

Microsoft Academic Search

We evaluated the accuracy of the simulation based on mask edge extraction for mask pattern quality assurance. Edge extraction data were obtained from SEM images by use of TOPCON UR-6080 in which high resolution (pixel size of 2nm) and fine pixel SEM image (8000 x 8000 pixels) acquisition is possible. The repeatability of the edge extraction and its impact on

Mitsuyo Kariya; Eiji Yamanaka; Satoshi Tanaka; Takahiro Ikeda; Shinji Yamaguchi; Kohji Hashimoto; Masamitsu Itoh; Hideaki Kobayashi; Tsukasa Kawashima; Shogo Narukawa

2005-01-01

309

Clustering of non-convex patterns for medical imaging  

Microsoft Academic Search

The study treats the problem of partitional clustering of non-convex patterns of arbitrary shape, with no definite analytical description of the data. A new method for calculating the distance is defined, according to a data induced metric principle. Calculation of the distance is carried out using weighted graphs. The new distance is introduced in the fuzzy k-means algorithm, and the

Isak Gath; Anna Smolyak Iskoz

1995-01-01

310

Characterizing cloud cover and satellite revisit with cloud masks in North West England  

Microsoft Academic Search

The aim of this study is to determine the availability of cloud-free images in relation to satellite revisit periods for the UK and in particular for the North West of England. Cloud cover was analysed with cloud masks from AVHRR\\/APOLLO and TERRA\\/MODIS cloud products. Availability of cloud-free images was determined from revisit frequency and the numbers of monthly images from

Ebenezer Yemi Ogunbadewa

2012-01-01

311

Method for characterizing mask defects using image reconstruction from X-ray diffraction patterns  

Microsoft Academic Search

The invention applies techniques for image reconstruction from X-ray diffraction patterns on the three-dimensional imaging of defects in EUVL multilayer films. The reconstructed image gives information about the out-of-plane position and the diffraction strength of the defect. The positional information can be used to select the correct defect repair technique. This invention enables the fabrication of defect-free (since repaired) X-ray

Hau-Riege; Stefan Peter

2007-01-01

312

A Novel Retrieval Refinement and Interaction Pattern by Exploring Result Correlations for Image Retrieval  

Microsoft Academic Search

Efficient retrieval of image database that contains multiple predefined categories (e.g. medical imaging databases, museum\\u000a painting collections) poses significant challenges and commercial prospects. By exploring category correlations of retrieval\\u000a results in such scenario, this paper presents a novel retrieval refinement and feedback framework. It provides users a novel\\u000a perceptual-similar interaction pattern for topic-based image retrieval. Firstly, we adopts Pairwise-Coupling SVM

Rongrong Ji; Hongxun Yao; Shaohui Liu; Jicheng Wang; Pengfei Xu

2007-01-01

313

Direct imaging of periodic subwavelength patterns generated by optical phase masks  

SciTech Connect

We have demonstrated direct imaging of interference fringes of total atomic density with periods {lambda}/4 and {lambda}/2 for optical wavelength {lambda} that have been produced in a de Broglie wave atom interferometer. The imaging was done by means of an 'optical mask' technique, which allowed us to observe subwavelength periodic patterns with a resolution of up to {lambda}/16. In addition, the dependence of the fringe pattern on the recoil phase and pulse area reveals quantum dynamics in the atomic center-of-mass motion. The behavior of the fringe patterns near the interference times distinguishes the effects of phase gratings from those of amplitude gratings.

Tonyushkin, Alexei; Sleator, Tycho [Department of Physics, New York University, 4 Washington Place, New York, New York 10003 (United States)

2006-11-15

314

Identification of psychopathic individuals using pattern classification of MRI images  

Microsoft Academic Search

Background: Psychopathy is a disorder of personality characterized by severe impairments of social conduct, emotional experience, and interpersonal behavior. Psychopaths consistently violate social norms and bring considerable financial, emotional, or physical harm to others and to society as a whole. Recent developments in analysis methods of magnetic resonance imaging (MRI), such as voxel-based-morphometry (VBM), have become major tools to understand

João R. Sato; Ricardo de Oliveira-Souza; Carlos E. Thomaz; Rodrigo Basílio; Ivanei E. Bramati; Edson Amaro Jr; Fernanda Tovar-Moll; Robert D. Hare; Jorge Moll

2011-01-01

315

Discovering Temporal Patterns from Images using Extended PLSA  

Microsoft Academic Search

This paper considers the problem of modelling the topics in a sequence of images with known time stamp. Detecting and tracking of temporal data is an important task in multiple applications, such as finding hot research point from scientific literature, news article series analysis, email surveillance, search query log mining, etc. In contrast to existing works mainly focusing on text

Xiaofeng Liao; Yongji Wang; Liping Ding

2010-01-01

316

Systematic variations of cloud top temperature and precipitation rate with aerosols over the global tropics  

NASA Astrophysics Data System (ADS)

Aerosols may modify cloud properties and precipitation via a variety of mechanisms with varying and contradicting consequences. Using a large ensemble of satellite data acquired by the Moderate Resolution Imaging Spectroradiometer onboard the Earth Observing System's Aqua platform, the CloudSat cloud profiling radar and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite over the tropical oceans, we identified two distinct correlations of clouds and precipitation with aerosol loading. Cloud-top temperatures are significantly negatively correlated with increasing aerosol index (AI) over oceans and aerosol optical depth (AOT) over land for deep mixed-phase clouds with liquid droplets near the warm bases and ice crystals near the cold tops; no significant changes were found for uniformly liquid clouds. Precipitation rates are positively correlated with the AI for mixed-phase clouds, but negatively correlated for liquid clouds. These distinct correlations might be a manifestation of two potential mechanisms: the invigoration effect (which enhances convection and precipitation) and the microphysical effect (which suppresses precipitation). We note that the highly limited information garnered from satellite products cannot unequivocally support the causal relationships between cloud-top temperature/precipitation rate and aerosol loading. But if aerosols are indeed the causes for the observed relationships, they may change the overall distribution of precipitation, leading to a more extreme and unfavorable rainfall pattern of suppressing light rains and fostering heavy rains.

Niu, Feng; Li, Zhanqing

2012-09-01

317

Mapping low- and high-density clouds in astrophysical nebulae by imaging forbidden line emission  

Microsoft Academic Search

Emission line ratios have been essential for determining physical parameters such as gas temperature and density in astrophysical gaseous nebulae. With the advent of panoramic spectroscopic devices, images of regions with emission lines related to these physical parameters can, in principle, also be produced. We show that, with observations from modern instruments, it is possible to transform images taken from

J. E. Steiner; R. B. Menezes; T. V. Ricci; A. S. Oliveira

2009-01-01

318

Learning Sparse Representations for Fruit-Fly Gene Expression Pattern Image Annotation and Retrieval  

PubMed Central

Background Fruit fly embryogenesis is one of the best understood animal development systems, and the spatiotemporal gene expression dynamics in this process are captured by digital images. Analysis of these high-throughput images will provide novel insights into the functions, interactions, and networks of animal genes governing development. To facilitate comparative analysis, web-based interfaces have been developed to conduct image retrieval based on body part keywords and images. Currently, the keyword annotation of spatiotemporal gene expression patterns is conducted manually. However, this manual practice does not scale with the continuously expanding collection of images. In addition, existing image retrieval systems based on the expression patterns may be made more accurate using keywords. Results In this article, we adapt advanced data mining and computer vision techniques to address the key challenges in annotating and retrieving fruit fly gene expression pattern images. To boost the performance of image annotation and retrieval, we propose representations integrating spatial information and sparse features, overcoming the limitations of prior schemes. Conclusions We perform systematic experimental studies to evaluate the proposed schemes in comparison with current methods. Experimental results indicate that the integration of spatial information and sparse features lead to consistent performance improvement in image annotation, while for the task of retrieval, sparse features alone yields better results.

2012-01-01

319

Desktop computer-based image analysis of cell surface fluorescence patterning from a photographic source.  

PubMed

We report the use of standard computer-based image analysis technology to analyze, from a photographic source, individual cell surface receptor site patterns using fluorochrome labeling. The model used in this study was a Strongylocentrotus purpuratus sea urchin embryo labeled with fluorescein isothiocyanate-conjugated wheat germ agglutinin (FITC-WGA) (0.5 mg/ml for 5 min at 15 degrees C incubated with fertilization membrane free embryos). Image capture was performed using desktop-type digital scanning, and the images were imported into Adobe Photoshop for study. All images analyzed were derived from a single photographic negative: 1) the actual micrograph printed from the negative and scanned into a Macintosh IIx computer; 2) the scanned negative itself; and, 3) a high resolution scanning process used with a Kodak Photo CD. Patterns were analyzed using the densitometry feature of Photoshop, and were similar enough from all 3 scanned images to indicate that any of the 3 scanning processes can be used for fluorescence patterning analysis. Adobe Photoshop was also used to highlight, for closer analysis, the fluorescence patterns by producing 3-D effects, border mapping and transition area detailing. The desktop image analysis procedures described here to study fluorescence patterning require no expensive scientific hardware or software. PMID:8863858

Latham, V H; Latham, L E; Oppenheimer, S B

1996-07-01

320

Detailed images and distance measurements for eighteen dwarf irregular galaxies in the Canes Venatici cloud  

NASA Astrophysics Data System (ADS)

In the Canes Venatici cloud, eighteen dwarf irregular galaxies were observed in B, V bands at the Nordic Optical Telescope under a seeing of one arcsec. Most of the galaxies having radial velocities V_0 < 500 km/s have been resolved into stars for the first time. The galaxy distances were derived based on photometry of their brightest blue stars. Distances to some of the galaxies: UGC 6782, UGC 7131 and, probably, K 215, which are located at the CVn southern edge, were estimated to be about 15 Mpc, which is typical of the Virgo cluster outskirts. For two LSB galaxies, K 200 and K 215, the distances may be overestimated, probably because of a lack of young massive stars. For the remaining galaxies: UGC 7559, UGC 7599, UGC 7605, UGC 7639, UGC 7698, UGCA 290, UGCA 292, UGC 7866, UGC 8024, UGC 8638, UGC 8651, UGC 8760, and UGC 8833 the estimated distances range from 2.3 to 8.0 Mpc, indicating their actual membership in the CVn cloud. Several objects studied here (UGC 7605, UGC 7639, UGC 8638, UGC 8833) have a well-resolved bluish core and regular yellow outer parts, which may point to composite (new and old) populations. The galaxy UGCA 292 = CVn dwA has unusual global parameters: (B-V)_T=+0.08, M_T=-11.4, M(HI)/L_B = 6\\ M_sun/L_sun and M(HI)/M_T =0.7, being, perhaps, one of the youngest known objects in the Local Universe. Table 2 to 19 are only available at the CDS via anonymous ftp 130.79.128.5 or via http://cdsweb.u-strasbg.fr/Abstract.html

Makarova, L.; Karachentsev, I.; Takalo, L. O.; Heinaemaeki, P.; Valtonen, M.

1998-03-01

321

Introduction to Clouds  

NSDL National Science Digital Library

This site gives students an opportunity to explore storm clouds and climate change through the use of National Aeronautic and Space Administration (NASA) climate research data obtained through satellite imaging. The challenge is to investigate actual scientific research data on clouds and storms, and make the resulting observations and interpretations available to NASA research scientists for review. The interactive site will allow students to discover what the major types of clouds produced by storms are and whether these clouds help to cool or warm the Earth's surface. Storms are the major producers of clouds in the Earth's atmosphere, so students investigate the relationship between the types of clouds in order to make their conclusions.

322

Genetic Techniques for Pattern Extraction in Particle Boards Images  

Microsoft Academic Search

Time-to-market and high product quality standards are pushing the use of automatic visual inspection systems for defect detection in a wide broad of applications. The defect detection of particle boards requires the identification of all the printed and natural wood defects that can occur. The availability of information about the particle board to inspect (e.g. the pattern used to print

M. Gamassi; V. Piuri; F. Scotti; M. Roveri

2006-01-01

323

Using Time-Series Satellite Imaging Radar Data to Monitor Inundation Patterns and Hydroperiod in Herbaceous Wetlands of Southern Florida  

NASA Astrophysics Data System (ADS)

Knowledge of the components of the hydrologic cycle, including spatial and temporal distribution of water, is critical for regional hydrologic applications. However, at a regional scale, the variations of hydrologic condition are often too great to be easily quantified with ground-based observations alone. We developed methods to use satellite imaging radar data to monitor changes in hydrologic condition of regional scale wetland ecosystems in south Florida. Satellite imaging radar data have been shown to be sensitive to soil moisture variations and to flood conditions in a variety of wetland ecosystems. Initial observations of south Florida imagery from the European Space Agency's C-band microwave sensor onboard the European Remote Sensing Satellite (ERS) showed dynamic variations in backscatter between wet and dry seasons. Further studies revealed how fluctuations in water level influenced ERS radar backscatter for several different herbaceous vegetation cover types. Unfortunately, the C-band wavelength is incapable of penetrating dense forested canopies, thus, our research was focused on the vast herbaceous wetland ecosystems of southern Florida. The ERS synthetic aperture radar (SAR) sensor is a C-band, 5.7 cm wavelength imaging radar with vertical transmit and receive polarization (C-VV). The ERS sensor has a resolution of 30 m and a footprint of 100 by 100 km. SARs have the unique capability to collect data independent of cloud cover and solar illumination. This provides an advantage in areas typically covered by clouds such as tropical and sub-tropical regions like south Florida. In this study, several techniques were developed to utilize SAR data to detect, monitor, and map spatial and temporal changes in wetland hydrology. This study shows that radar imagery can be used to create innundation maps of relative soil moisture and flooding in herbaceous wetlands. Using C-band SAR imagery collected between 1997 and 1999, hydropattern maps were created at approximately bi-monthly periods for the south Florida region. In addition, a methodology for creating hydroperiod (the time period of flooding) maps was developed and examples from wet and dry years are presented. Principal component Analysis (PCA) was the basis of our hydroperiod maps and was linked to rainfall patterns of the south Florida region. Validation of the maps was conducted with in situ data and review by experts in the region.

Bourgeau-Chavez, L. L.; Kasischke, E.

2002-05-01

324

Local affine image matching and synthesis based on structural patterns.  

PubMed

A general purpose block-to-block affine transformation estimator is described. The estimator is based on Fourier slice analysis and Fourier spectral alignment. It shows encouraging performance in terms of both speed and accuracy compared to existing methods. The key elements of its success are attributed to the ability to: 1) locate an arbitrary number of affine invariant points in the spectrum that latch onto significant structural features; 2) match the estimated invariant points with the target spectrum by the slicewise phase-correlation; and 3) use affine invariant points to directly compute all linear parameters of the full affine transform by spectral alignment. Experimental results using a wide range of textures are presented. Potential applications include affine invariant image segmentation, registration, affine symmetric image coding, and motion analysis. PMID:20236890

Park, Heechan; Martin, Graham R; Bhalerao, Abhir

2010-03-15

325

Moiré patterns on STM images of graphite induced by rotations of surface and subsurface layers  

NASA Astrophysics Data System (ADS)

We have observed by means of scanning tunneling microscopy (STM) moiré patterns corresponding to the rotation of one graphene layer on HOPG surface. These moiré patterns were characterized by rotation angle and extension in the plane. Additionally, by identifying border domains and defects we can discriminate between moiré patterns due to rotation on the surface or subsurface layer. For a better understanding of moiré patterns formation, we have studied by first principles arrays of three graphene layers (TGL) and we have calculated their corresponding STM images. Such TLG arrays have a rotated layer (top or middle) around the stacking axis. We compare experimental and theoretical results and we show the strong influence of rotations in both surface layer and subsurface layer for moiré patterns formation in STM images.

Flores, M.; Cisternas, E.; Correa, J. D.; Vargas, P.

2013-09-01

326

Mapping low and high density clouds in astrophysical nebulae by imaging forbidden line emission  

Microsoft Academic Search

Emission line ratios have been essential for determining physical parameters\\u000asuch as gas temperature and density in astrophysical gaseous nebulae. With the\\u000aadvent of panoramic spectroscopic devices, images of regions with emission\\u000alines related to these physical parameters can, in principle, also be produced.\\u000aWe show that, with observations from modern instruments, it is possible to\\u000atransform images taken from

J. E. Steiner; R. B. Menezes; T. V. Ricci; A. S. Oliveira

2009-01-01

327

Local binary pattern texture-based classification of solid masses in ultrasound breast images  

NASA Astrophysics Data System (ADS)

Breast cancer is one of the leading causes of cancer mortality among women. Ultrasound examination can be used to assess breast masses, complementarily to mammography. Ultrasound images reveal tissue information in its echoic patterns. Therefore, pattern recognition techniques can facilitate classification of lesions and thereby reduce the number of unnecessary biopsies. Our hypothesis was that image texture features on the boundary of a lesion and its vicinity can be used to classify masses. We have used intensity-independent and rotation-invariant texture features, known as Local Binary Patterns (LBP). The classifier selected was K-nearest neighbors. Our breast ultrasound image database consisted of 100 patient images (50 benign and 50 malignant cases). The determination of whether the mass was benign or malignant was done through biopsy and pathology assessment. The training set consisted of sixty images, randomly chosen from the database of 100 patients. The testing set consisted of forty images to be classified. The results with a multi-fold cross validation of 100 iterations produced a robust evaluation. The highest performance was observed for feature LBP with 24 symmetrically distributed neighbors over a circle of radius 3 (LBP24,3) with an accuracy rate of 81.0%. We also investigated an approach with a score of malignancy assigned to the images in the test set. This approach provided an ROC curve with Az of 0.803. The analysis of texture features over the boundary of solid masses showed promise for malignancy classification in ultrasound breast images.

Matsumoto, Monica M. S.; Sehgal, Chandra M.; Udupa, Jayaram K.

2012-02-01

328

Cloud Fun  

NSDL National Science Digital Library

Learners complete a series of hands-on and investigative activities to explore cumulus clouds. Learners observe cumulus clouds outside, read a book about how cumulus clouds differ from other clouds, and create a list of words that describe cumulus clouds. Then, learners create their own cumulus cloud out of white paper and complete the Cloud Fun Student Activity sheet that includes a description of the cloud and what the weather was like on the day the cloud was observed. Learners will use their five senses to describe their clouds. Clouds can be displayed in the classroom or assembled into a class book. This lesson guide includes brief background information about cumulus clouds, adaptations for younger and older learners, and extension ideas.

Program, The G.

2006-01-01

329

Diffraction-contrast imaging of cold atoms  

NASA Astrophysics Data System (ADS)

We consider the inverse problem of in-line holography, applied to minimally destructive imaging of cold atom clouds. Absorption imaging near resonance provides a simple, but destructive measurement of atom column density. Imaging off resonance greatly reduces heating, and sequential images may be taken. Under the conditions required for off-resonant imaging, the generally intractable inverse problem may be linearized. A minimally destructive, quantitative and high-resolution image of the atom cloud column density is then retrieved from a single diffraction pattern.

Turner, L. D.; Domen, K. F. E. M.; Scholten, R. E.

2005-09-01

330

Hubble Space Telescope Observations of Planetary Nebulae in the Magellanic Clouds. IV. [O iii] Images and Evolutionary Ages  

NASA Astrophysics Data System (ADS)

The Planetary Camera of the Hubble Space Telescope has been used to obtain images in the [O III] ?5007 line for a sample of 15 planetary nebulae in the Magellanic Clouds chosen to eliminate any selection bias in either excitation class or in flux [for log F(H?) > -13.7 ergs cm^-2^ s^-1^]. These images are used to derive the physical dimensions, the spatial structure, and the kinematic ages of the nebulae. The raw images were deconvolved using the Richardson-Lucy image restoration algorithm, and based on extensive tests of model images, a limit of 100 iterations of the algorithm was adopted. The restored images show clear evidence for size evolution across the H-R diagram. The younger, low-excitation, compact planetary nebulae tend to be systematically smaller than photoionization models based on ground- based data would predict, suggesting that these planetary nebulae have a central reservoir of dense atomic and molecular gas. This gas lies close to the central star and is undergoing ionization and being accelerated into outflow. Planetary nebulae previously classified as nitrogen-rich objects with massive central stars (Peimbert type I) show the bipolar "butterfly" symmetry that is also a characteristic of their Galactic counterparts. The derived kinematic ages range from less than 1000 yr up to almost 5000 yr but show little sign of systematic increase along the evolutionary tracks. The true ages of the larger objects are systematically underestimated because of acceleration of the nebular shell during its lifetime. Using both the empirical fit that we had previously derived for the expansion velocity as a function of the position on the H-R diagram, and the theoretical evolutionary tracks of the central star, we have derived two semiempirical estimates for the evolutionary timescales based upon the nebular size and the measured dynamical age. If these evolutionary timescales are to be consistent with the evolutionary age derived from theory, then He burners outnumber H burners in the approximate ratio 2:1.

Dopita, M. A.; Vassiliadis, E.; Meatheringham, S. J.; Bohlin, R. C.; Ford, H. C.; Harrington, J. P.; Wood, P. R.; Stecher, T. P.; Maran, S. P.

1996-03-01

331

Computer-aided diagnosis of splenic enlargement using wave pattern of spleen in abdominal CT images  

NASA Astrophysics Data System (ADS)

It is known that the spleen accompanied by liver cirrhosis is hypertrophied or enlarged. We have examined a wave pattern at the left boundary of spleen on the abdominal CT images having liver cirrhosis, and found that they are different from those on the images having a normal liver. It is noticed that the abdominal CT images of patient with liver cirrhosis shows strong bending in the wave pattern. In the case of normal liver, the images may also have a wave pattern, but its bends are not strong. Therefore, the total waving area of the spleen with liver cirrhosis is found to be greater than that of the spleen with a normal liver. Moreover, we found that the waves of the spleen from the image with liver cirrhosis have the higher degree of circularity compared to the normal liver case. Based on the two observations above, we propose an automatic method to diagnose splenic enlargement by using the wave pattern of the spleen in abdominal CT images. The proposed automatic method improves the diagnostic performance compared with the conventional process based on the size of spleen.

Seong, Won; Cho, June-Sik; Noh, Seung-Moo; Park, Jong Won

2006-03-01

332

[FeII] Narrow Band Imaging of Supernova Remnants in the Magellanic Clouds  

NASA Astrophysics Data System (ADS)

Optical, radio and X-ray emission from supernova remnants (SNRs) has been used extensively to study the properties of SNRs, and as such, much is known about their general characteristics in these wavebands. However, surprisingly little work has been done in the near infrared. The early work of Oliva et al. (1989, A&A, 214, 307) suggested that SNRs are generally bright in the emission of [FeII], although this conclusion was based upon observations of only a few very bright SNRs. In order to better define the general characteristics of the [FeII] emission of SNRs, we have undertaken a survey of 35 SNRs in the Magellanic Clouds. These represent a well defined sample with a large range of intrinsic properties, all at the same distance. We present [FeII] fluxes of 1.64mu m emission and discuss correlations of SNR properties observed at other wavelengths with the [FeII] flux. In addition, we discuss the feasibility of using [FeII] flux as an indicator of supernova rates in distant galaxies.

Tavarez, M.; Smith, R. C.; Elston, R.

1996-12-01

333

Uv Imaging of Intermediate-Age Magellanic Cloud Clusters: Hot Stellar Populations in Composite Stellar Systems  

NASA Astrophysics Data System (ADS)

Hot stars were first recognized to be an important component of galactic spheroids with early vacuum ultraviolet observations of ellipticals and spiral bulges that were made with OAO. Now, 20 years later, we still do not have a full understanding of the VUV evolution of intermediate and old age stellar populations. Using the WFPC2, we therefore propose to undertake an ultraviolet survey of a sample of star clusters spanning a range in age in the Large Magellanic Cloud. The objective of this investigation is to determine the nature of the hot stellar components in rich, intermediate-to-old age LMC clusters. Ground-based optical/IR studies suggest the presence of short-lived hot horizontal branch and post-asymptotic giant branch stars in these clusters but detailed characterizations of the stars require the ultraviolet capability of HST. In this effort we will be aided by the absence of red leaks in the WFPC2 Woods filter and very high angular resolution of the HST. Although old star clusters in the Galaxy and M31 are, and will be, the subjects of intense investigation by HST, OUR SURVEY WILL BE THE FIRST OF ITS KIND FOR POPULATIONS OF INTERMEDIATE AGE. Such systems are critical for interpreting the spectra and colors of high redshift galaxies, and will provide important support to these studies.

Freedman, Wendy

1994-07-01

334

Surface Reflectance Modeling for Martian Cloud Optical Depth Retrievals from CRISM Multispectral Image Cubes  

NASA Astrophysics Data System (ADS)

In order to retrieve the ice optical depth of martian clouds using a radiative transfer model, one needs to have an independent spectral model of the surface reflectance. Presented here is a comparison of three methods used to model the surface reflectance and the effects on the retrieved ice and dust optical depth. In order to reduce the complexity of the radiative transfer modeling, a fixed set of aerosol optical constants and single aerosol size parameters were used. The retrieval uses DISORT subroutines in an atmosphere modeling program tuned for martian atmospheres to create model reflectance spectra which are then compared to CRISM data. The parameters of total optical depth of ice and dust and surface reflectance are methodically adjusted until the chi-squared between model and data is minimized. This is done over all spatial points to create maps of dust and ice optical depth which are compared to MGS-TES and MO-THEMIS results to assess the effectiveness of the particular surface model. Three types of surface models were tested: a spectrally gray surface, a two-element linear combination of spectral endmembers chosen from the data cube itself, and a two-element linear combination of endmembers recovered from the data cube using principle components analysis and target transformation.

Klassen, David R.

2013-10-01

335

Flux lattice imaging of a patterned niobium thin film  

SciTech Connect

Using our cryogenic magnetic force microscope, we have investigated a superconducting Nb thin film, 100 nm in thickness with T{sub c}{similar_to}6.5K. The film is patterned with a square array (1{mu}m{times}1{mu}m) of antidots, which serve as artificial pinning centers for magnetic flux. We have observed flux lattice matching as a function of applied magnetic field and temperature, for field strengths up to the third matching field, with evidence of flux dragging by the tip around the antidots. Force gradient distance curves acquired at temperatures about T{sub c} clearly demonstrate an observable Meissner force between tip and sample, and allow for an estimation of the magnetic screening penetration depth. {copyright} 2001 American Institute of Physics.

Roseman, M.; Grutter, P.; Badia, A.; Metlushko, V.

2001-06-01

336

Imaging the debris cloud around the final flash star IRAS15154-5258  

NASA Astrophysics Data System (ADS)

A brief yet common evolutionary process is a post-AGB final episode of helium shell burning. This occurs after a low mass star has ejected a planetary nebula and has started on the white dwarf track. Seven stars are now classified with varying degrees of certainty as one of these ``final flash'' objects. Two of these have actually been observed to eject a shell of gas first as a pseudo-photosphere and then as a thick, expanding dust envelope. In 2010B we obtained Gemini NIRI/Altair time to take high spatial resolution images in the K band of the ejecta around five final flash objects. These AO images of the circumstellar shell will be used to measure changes from images recorded a decade or more ago. From these changes we will determine geometric parallaxes and hence luminosities. The luminosity will be compared to stellar evolution models. To complete this project we request time to take a first infrared image of the

Hinkle, Kenneth; Joyce, Richard; Lebzelter, Thomas

2011-02-01

337

Rain clouds tracking with radar image processing based on morphological skeleton matching  

Microsoft Academic Search

The aim of this study is to perform a short term forecasting of dynamic radar clutter evolution (shape and position). This dynamic clutter, like thunderstorms, can be tracked by means of adapted algorithms based on the matching of the morphological skeleton polygonal approximation by relaxation labeling processes. The efficiency of our methods is demonstrated on meteorological radar images. The objective

Fridiric BARBARESCO; Bernard MONNIER

2001-01-01

338

Use of Gas Imaging as a Means of Locating Leaks and Tracking Gas Clouds.  

National Technical Information Service (NTIS)

A new concept for the detection and tracking of toxic or flammable gases resulting from accidental spills or leaks is presented. The Backscatter/Absorption Gas Imaging (BAGI) technique is based on the optical radiation augmentation of the field of view of...

T. McRae J. Stahovec

1986-01-01

339

Extraction and comparison of gene expression patterns from 2D RNA in situ hybridization images  

PubMed Central

Motivation: Recent advancements in high-throughput imaging have created new large datasets with tens of thousands of gene expression images. Methods for capturing these spatial and/or temporal expression patterns include in situ hybridization or fluorescent reporter constructs or tags, and results are still frequently assessed by subjective qualitative comparisons. In order to deal with available large datasets, fully automated analysis methods must be developed to properly normalize and model spatial expression patterns. Results: We have developed image segmentation and registration methods to identify and extract spatial gene expression patterns from RNA in situ hybridization experiments of Drosophila embryos. These methods allow us to normalize and extract expression information for 78 621 images from 3724 genes across six time stages. The similarity between gene expression patterns is computed using four scoring metrics: mean squared error, Haar wavelet distance, mutual information and spatial mutual information (SMI). We additionally propose a strategy to calculate the significance of the similarity between two expression images, by generating surrogate datasets with similar spatial expression patterns using a Monte Carlo swap sampler. On data from an early development time stage, we show that SMI provides the most biologically relevant metric of comparison, and that our significance testing generalizes metrics to achieve similar performance. We exemplify the application of spatial metrics on the well-known Drosophila segmentation network. Availability: A Java webstart application to register and compare patterns, as well as all source code, are available from: http://tools.genome.duke.edu/generegulation/image_analysis/insitu Contact: uwe.ohler@duke.edu Supplementary information: Supplementary data are available at Bioinformatics online.

Mace, Daniel L.; Varnado, Nicole; Zhang, Weiping; Frise, Erwin; Ohler, Uwe

2010-01-01

340

Automated cloud tracking system for the Akatsuki Venus Climate Orbiter data  

NASA Astrophysics Data System (ADS)

Japanese Venus Climate Orbiter, Akatsuki, is cruising to approach to Venus again although its first Venus orbital insertion (VOI) has been failed. At present, we focus on the next opportunity of VOI and the following scientific observations.We have constructed an automated cloud tracking system for processing data obtained by Akatsuki in the present study. In this system, correction of the pointing of the satellite is essentially important for improving accuracy of the cloud motion vectors derived using the cloud tracking. Attitude errors of the satellite are reduced by fitting an ellipse to limb of an imaged Venus disk. Next, longitude-latitude distributions of brightness (cloud patterns) are calculated to make it easy to derive the cloud motion vectors. The grid points are distributed at regular intervals in the longitude-latitude coordinate. After applying the solar zenith correction and a highpass filter to the derived longitude-latitude distributions of brightness, the cloud features are tracked using pairs of images. As a result, we obtain cloud motion vectors on longitude-latitude grid points equally spaced. These entire processes are pipelined and automated, and are applied to all data obtained by combinations of cameras and filters onboard Akatsuki. It is shown by several tests that the cloud motion vectors are determined with a sufficient accuracy. We expect that longitude-latitude data sets created by the automated cloud tracking system will contribute to the Venus meteorology.

Ogohara, Kazunori; Kouyama, Toru; Yamamoto, Hiroki; Sato, Naoki; Takagi, Masahiro; Imamura, Takeshi

2012-02-01

341

Global tracking of the ocular fundus pattern imaged by scanning laser ophthalmoscopy.  

PubMed

This paper presents an algorithm for the automatic global tracking of ocular fundus landmarks in video image sequences generated by scanning laser ophthalmoscopy (SLO). The tracking algorithm is based on the computation of the discrete unnormalized cross-correlation of an interactively preselected small template and respective images in time sequences of fundus patterns. The correlation is executed with binary images derived from an automatical threshold limitation of the grey-value images. Due to the [+1/-1] representation of the binary images the unnormalized correlation functions directly relate to the Hamming distance of the template and the objects in the images. Experiments show that even templates with features distorted by noise are accurately recognized at any position. The accuracy of position detection is better than 0.4%. Possible hardware implementations of the algorithm which would reduce computation time are briefly mentioned. PMID:2004844

Bantel, T; Ott, D; Rueff, M

1991-01-01

342

Spatial pattern separation of chemicals and frequency-independent components by terahertz spectroscopic imaging  

NASA Astrophysics Data System (ADS)

We separated the component spatial patterns of frequency-dependent absorption in chemicals and frequency-independent components such as plastic, paper, and measurement noise in terahertz (THz) spectroscopic images, using known spectral curves. Our measurement system, which uses a widely tunable coherent THz-wave parametric oscillator source, can image at a specific frequency in the range 1-2 THz. The component patterns of chemicals can easily be extracted by use of the frequency-independent components. This method could be successfully used for nondestructive inspection for the detection of illegal drugs and devices of bioterrorism concealed, e.g., inside mail and packages.

Watanabe, Yuuki; Kawase, Kodo; Ikari, Tomofumi; Ito, Hiromasa; Ishikawa, Youichi; Minamide, Hiroaki

2003-10-01

343

Speckle pattern of the images of objects exposed to monochromatic coherent terahertz radiation  

SciTech Connect

By using a free electron laser and a microbolometer array, real-time images are recorded for the first time in the terahertz range at the rate of up to 90 frames per second. In the case of diffusive illumination of objects by coherent monochromatic radiation, the images consist of speckles. The study of the statistical properties of speckle patterns shows that they are quite accurately described by the theory developed for speckles in the visible range. By averaging a set of images with the help of a rotating scatterer during the exposure time of a frame (20 ms) and by summing statistically independent speckle patterns of many frames, images of the acceptable quality are obtained. The possibilities of terahertz speckle photography and speckle interferometry are discussed. (terahertz radiation)

Vinokurov, Nikolai A; Knyazev, Boris A; Kulipanov, Gennadii N [G.I. Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation); Dem'yanenko, M A; Esaev, D G [A.V.Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation); Chashchina, O I; Cherkasskii, Valerii S [Novosibirsk State University, Novosibirsk (Russian Federation)

2009-05-31

344

Accelerated computation of hologram patterns by use of interline redundancy of 3-D object images  

NASA Astrophysics Data System (ADS)

We present a new approach for accelerated computation of hologram patterns of a three-dimensional (3-D) image by taking into account of its interline redundant data. Interline redundant data of a 3-D image are extracted with the differential pulse code modulation (DPCM) algorithm, and then the CGH patterns for these compressed line images are generated with the novel lookup table (N-LUT) technique. To confirm the feasibility of the proposed method, experiments with four kinds of 3-D test objects are carried out, and the results are comparatively discussed with the conventional methods in terms of the number of object points and the computation time. Experimental results show that the number of calculated object points and the computation time for one object point have been reduced by 73.3 and 83.9%, on the average, for four test 3-D images in the proposed method employing a top-down scanning method, compared to the conventional method.

Kim, Seung-Cheol; Choe, Woo-Young; Kim, Eun-Soo

2011-09-01

345

Study of scattering patterns and subwavelength scale imaging based on finite-sized metamaterials  

NASA Astrophysics Data System (ADS)

A metamaterial slab, used as a superlens in a subwavelength imaging system, is frequently assumed homogeneous. It is the bulk properties of the metamaterial which are responsible for the resolution of the transferred information in the image domain, as a result of high transverse wave-vector coupling. However, how in a discretized metamaterial, individual meta-atoms (i.e., the meta-elements composing a negative index metamaterial slab) contribute to the imaging process is still actively studied. The main aim of this paper is to investigate the consequences of using only a few meta-atoms as a negative index slab-equivalent for subwavelength scale imaging. We make a specific choice for a meta-atom and investigate its resonant scattering patterns. We report on how knowledge of these 3D scattering patterns provides a means to understand the transfer of high spatial frequencies and assist with the design an improved negative index slab.

Zhang, Yuan; Chuang, Yi-Chen; Schenk, John O.; Fiddy, Michael A.

2012-04-01

346

Spatio-temporal patterns of neuronal activity: analysis of optical imaging data using geometric shape matching.  

PubMed

Optical imaging of neuronal network activity yields information of spatial dynamics which generally is analyzed visually. The transient appearance of spatial activity patterns is difficult to gauge in a quantifiable manner, or may even altogether escape detection. Here, we employ geometric shape matching using Fréchet distances or straight skeletons to search for pre-selected patterns in optical imaging data with adjustable degrees of tolerance. Data were sampled from fluorescence changes of a voltage-sensitive dye recorded with a 464-photodiode array. Fluorescence was monitored in a neuronal network in vitro. Neuronal activity prompting fluorescence fluctuations consisted of spontaneous epileptiform discharges in neocortical slices from patients undergoing epilepsy surgery. The experiments show that: (a) spatial activity patterns can be detected in optical imaging data; (b) shapes such as "mini-foci" appear in close correlation to bioelectric discharges monitored with field potential electrodes in a reproducible manner; (c) Fréchet distances yield more conservative matches regarding rectangular, and less conservative hits with respect to radially symmetric shapes than the straight skeleton approach; and (d) tolerances of 0.03-0.1 are suited to detect faithful images of pre-selected shapes, whereas values >0.8 will report matches with any polygonal pattern. In conclusion, the methods reported here are suited to detect and analyze spatial, geometric dynamics in optical imaging data. PMID:11850035

Köhling, R; Reinel, J; Vahrenhold, J; Hinrichs, K; Speckmann, E-J

2002-02-15

347

The use of thermal images of palm-dorsa vein-patterns for biometric verification  

Microsoft Academic Search

A novel personal verification method using the thermal images of palm-dorsa vein-patterns is presented in this paper. The characteristics of the proposed method are that no prior knowledge about the object is necessary and the parameters can be set automatically. In our work, an infrared (IR) camera is adopted as the input device to capture the thermal images of palm-dorsa.

Kuo-Chin Fan; Chih-Lung Lin

2004-01-01

348

Imaging open-path Fourier transform infrared spectrometer for 3D cloud profiling  

Microsoft Academic Search

OPTRA and University of North Carolina are developing an imaging open-path Fourier transform infrared (I-OP-FTIR) spectrometer for 3D profiling of chemical and biological agent simulant plumes released into test ranges and chambers. An array of I-OP-FTIR instruments positioned around the perimeter of the test site, in concert with advanced spectroscopic algorithms, enables real time tomographic reconstruction of the plume. The

Julia Rentz Dupuis; David J. Mansur; Robert Vaillancourt; Thomas Evans; Elizabeth Schundler; Lori Todd; Kathleen Mottus

2008-01-01

349

Remote sensing of cloud, aerosol and water vapor properties from the Moderate Resolution Imaging Spectrometer (MODIS)  

Microsoft Academic Search

The Moderate Resolution Imaging Spectrometer (MODIS) is an Earth-viewing sensor being developed as a facility instrument for the Earth Observing System (EOS) to be launched in the late 1990s. MODIS consists of two separate instruments that scan a swath width sufficient to provide nearly complete global coverage every two days from a polar-orbiting, Sun-synchronous, platform at an altitude of 705

M. D. King

1992-01-01

350

Images of star-forming regions. III. Sources in the NGC 7538 molecular cloud complex  

SciTech Connect

Deep optical CCD images of the embedded infrared sources associated with NGC 7538 are presented. A reflected image of IRS 1, the most luminous infrared source in the region, is shown to be positionally offset from the VLA radio source in a direction that is consistent with that of the blueshifted portion of the bipolar molecular outflow toward the north. Maps of the IRS 1 region at 1.65 and 2.2 microns, made with a prototype infrared camera, confirm the positional displacement. The H-K color of IRS 1 is extremely red (greater than 5 mag), which shows that the radio source is indeed totally obscured at wavelengths less than 1.5 micron. This is also consistent with other estimates of the extinction to IRS 1. New VLA radio images of IRS 2 and IRS 3 are also presented. The peculiar object IRS 9, a source that displays deep absorption due to CO molecules in the solid phase, is associated with a diffuse optical nebula that corresponds with the infrared reflection nebula found by Werner et al. (1979). The young stellar objects in NGC 7538 represent a broad evolutionary range in high-mass star formation, from a fully evolved blister-type H II region to much younger objects which have yet to break through their protostellar cocoons. 35 references.

Campbell, B; Persson, S.E.

1988-04-01

351

Detection of prodromal Alzheimer's disease via pattern classification of magnetic resonance imaging.  

PubMed

We report evidence that computer-based high-dimensional pattern classification of magnetic resonance imaging (MRI) detects patterns of brain structure characterizing mild cognitive impairment (MCI), often a prodromal phase of Alzheimer's disease (AD). Ninety percent diagnostic accuracy was achieved, using cross-validation, for 30 participants in the Baltimore Longitudinal Study of Aging. Retrospective evaluation of serial scans obtained during prior years revealed gradual increases in structural abnormality for the MCI group, often before clinical symptoms, but slower increase for individuals remaining cognitively normal. Detecting complex patterns of brain abnormality in very early stages of cognitive impairment has pivotal importance for the detection and management of AD. PMID:17174012

Davatzikos, Christos; Fan, Yong; Wu, Xiaoying; Shen, Dinggang; Resnick, Susan M

2006-12-14

352

Preliminary validation of a new variable pattern for daily quality assurance of medical image display devices  

SciTech Connect

This paper reports on a comparative study between the well-established test patterns for daily quality assurance (QA) of monitors of the American Association of Medical Physicists, Task Group 18 (AAPMtg18) and the Deutsches Institut fuer Normung e.V (DIN), and a newly proposed variable test pattern. A characteristic of the test patterns currently used for the QA of monitors is their static nature: The same test pattern is always used. This enables a learning effect that may bias the results over time. To address this problem we have developed a variable pattern for the quality assurance of monitors (MoniQA) that allows an evaluation of contrast visibility, geometric distortion, resolution, global image quality including uniformity, and artifacts. The test pattern includes randomly generated elements intended to prevent the observer from learning the test. Examples are random characters that have to be discriminated from the background to evaluate the threshold luminance difference and variable positions of different features in the test pattern. The newly proposed test patterns were generated and visualized on different viewing stations with a software tool developed in JAVA. In this study, we validated these patterns against the well-known AAPMtg18 and DIN test patterns on 22 monitors. The results showed that the MoniQA test can indicate the same monitor problems as the other well-known patterns and is significantly quicker to evaluate than the AAPMtg18 test patterns. The MoniQA pattern is a promising alternative for daily quality control of medical viewing stations.

Jacobs, Jurgen; Rogge, Frank; Kotre, John; Marchal, Guy; Bosmans, Hilde [University Hospitals of Leuven, Herestraat 49, Leuven, Brabant 3000 (Belgium); Regional Medical Physics Department, Newcastle General Hospital Newcastle-upon-Tyne, NE4 6BE (United Kingdom); University Hospitals of Leuven, Herestraat 49, Leuven, Brabant 3000 (Belgium)

2007-07-15

353

Cloud cover analysis with Arctic advanced very high resolution radiometer data. 2. Classification with spectral and textural measures  

SciTech Connect

The variation in cloud amount over polar ice sheets, sea ice, and ocean surfaces can have important effects on planetary albedo gradients and on surface energy exchanges, so that monitoring of polar cloud cover is crucial to studies of climate change. The spectral and textural characteristics of polar clouds and surfaces for a 7-day summer series of advanced very high resolution radiometer (AVHRR) data in two Arctic locations are examined, and the results used in the development of a cloud classification procedure for polar satellite data. Since spatial coherence and texture sensitivity tests indicate that a joint spectral-textural analysis based on the same cell size is inappropriate, cloud detection with AVHRR data and surface identification with passive microwave data are first done on the pixel level as detailed in part 1 (Key and Barry, 1989). Next, cloud patterns within (250 km){sup 2} regions are described, then the spectral and local textural characteristics of cloud patterns in the image are determined and each cloud pixel is classified by statistical methods. Results indicate that both spectral and textural features can be utilized in the classification of cloudy pixels, although spectral features are most useful for the discrimination between cloud classes. This methodology provides a basis for future objective automated mapping of cloud types and amount over snow and ice covered surfaces.

Key, J. (Univ. of Colorado, Boulder (United States))

1990-05-20

354

Efficient and effective extraction of vocal fold vibratory patterns from high-speed digital imaging  

PubMed Central

Objectives High-speed digital imaging can provide valuable information on disordered voice production in voice science. However, the large amounts of high-speed image data with limited image resolutions produce significant challenges for computer analysis, and thus effective and efficient image edge extraction methods allowing for the batch analysis of high-speed images of vocal folds is clinically important. In this paper, a novel algorithm for automatic image edge detection is proposed to effectively and efficiently process high-speed images of the vocal folds. Methods The method integrates Lagrange interpolation, differentiation, and Canny edge detection, which allow objective extraction of aperiodic vocal fold vibratory patterns from large numbers of high-speed digital images. This method and two other popular algorithms, histogram and active contour, are performed on 10 sets of high-speed video data from excised larynx experiments in order to compare their performances in analyzing high-speed images. The accuracy in computing glottal area and the computation time of these methods are investigated. Results and Discussion The results show that our proposed method provides the most accurate and efficient detection, and is applicable when processing low resolution images. In this study, we focus on developing a method to effectively and efficiently process high-speed image data from excised larynges. However in addition we show the clinical potential of this method by use of example high-speed image data obtained from a patient with vocal nodules. Conclusions The proposed automatic image-processing algorithm may provide a valuable biomedical application for the clinical assessment of vocal disorders by use of high-speed digital imaging.

Zhang, Yu; Bieging, Erik; Tsui, Henry; Jiang, Jack J.

2010-01-01

355

Geodesics-based image registration: applications to biological and medical images depicting concentric ring patterns.  

PubMed

In many biological or medical applications, images that contain sequences of shapes are common. The existence of high inter-individual variability makes their interpretation complex. In this paper, we address the computer-assisted interpretation of such images and we investigate how we can remove or reduce these image variabilities. The proposed approach relies on the development of an efficient image registration technique. We first show the inadequacy of state-of-the-art intensity-based and feature-based registration techniques for the considered image datasets. Then, we propose a robust variational method which benefits from the geometrical information present in this type of images. In the proposed non-rigid geodesics-based registration, the successive shapes are represented by a level-set representation, which we rely on to carry out the registration. The successive level sets are regarded as elements in a shape space and the corresponding matching is that of the optimal geodesic path. The proposed registration scheme is tested on synthetic and real images. The comparison against results of state-of-the-art methods proves the relevance of the proposed method for this type of images. PMID:23880058

Nasreddine, Kamal; Benzinou, Abdesslam; Fablet, Ronan

2013-07-18

356

Cloud Protocols  

NSDL National Science Digital Library

The purpose of this activity is to observe the type and cover of clouds including contrails. Students observe which of ten types of clouds and how many of three types of contrails are visible and how much of the sky is covered by clouds (other than contrails) and how much is covered by contrails. Intended outcomes are that students learn how to make estimates from observations and how to categorize specific clouds following general descriptions for the categories. They will learn the meteorological concepts of cloud heights, types, and cloud cover and learn the ten basic cloud types. Supporting background materials for both student and teacher are included.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

357

Turbulent mixing of clouds with the environment: Small scale two phase evaporating flow investigated in a laboratory by particle image velocimetry  

NASA Astrophysics Data System (ADS)

In this report, experiments mimicking some aspects of cloud-clear-air mixing in a laboratory chamber are discussed. A saturated plume containing small droplets of water (a surrogate of an atmospheric cloud) is mixed with unsaturated environmental air in order to study effect of evaporative cooling at the interfaces between cloudy and clear air filaments on small-scale turbulence. Two components of the turbulent velocity at a small scale are determined using particle imaging velocimetry of the cloud droplets. Enhanced velocity fluctuations between the Kolmogorov (??0.8mm) and Taylor (??8mm) microscales are observed.The characteristic feature of these microscales is anisotropy with a preferred vertical direction. A straightforward dependence of the observed effects on the relative humidity of the environment indicates the importance of buoyancy production by evaporative cooling. This conclusion is in agreement with previous numerical experiments described in the literature and suggests that, under certain conditions, effects similar to the above may influence the smallest scales of turbulence in natural clouds.

Korczyk, Piotr M.; Kowalewski, Tomasz A.; Malinowski, Szymon P.

2012-02-01

358

Narrow Band Imaging Applied to Pleuroscopy for the Assessment of Vascular Patterns of the Pleura  

Microsoft Academic Search

Background: Narrow band imaging (NBI), which enhances blood vessels, is a new endoscopic technology for diagnosing malignancies, but it has not been investigated for pleuroscopy. Objectives: To evaluate the efficacy of NBI applied to pleuroscopy for detecting malignant lesions by assessing vascular patterns of the pleura. Methods: From May 2006 to September 2008, 45 patients with undiagnosed pleural ef-fusion underwent

Atsuko Ishida; Fuzuki Ishikawa; Miho Nakamura; Yuka M. Miyazu; Masamichi Mineshita; Noriaki Kurimoto; Junki Koike; Takashi Nishisaka; Teruomi Miyazawa; Philippe Astoul

2009-01-01

359

Performance evaluation of pattern painting camouflage based on the texture characteristic of multi-spectral images  

Microsoft Academic Search

Multi-spectral images have a high degree of spectral resolution. Through distilling the spectrum features as well as texture features between target and background, and calculating the Mahalanobis Distance of spectrum features as well as texture features data vector, then we can accordingly analyze the blend performance of pattern painting camouflage quantitatively. Utilizing the generating pixel spectrum curve function by the

Xiaopeng Li; Xuliang Lv; Youjun Wang; Chuan'an Cui; Yv Huang

2007-01-01

360

Relationships between volcanic patterns and neotectonics in Eastern Anatolia from analysis of satellite images and DEM  

Microsoft Academic Search

The late Neogene to Quaternary volcanism in Eastern Anatolia is related to the Arabia–Eurasia convergence but a clear deformation pattern has not yet been established in this region. We have used the distribution and shape of volcanoes and fault geometry as indicators of the tectonic regime. Volcanic edifices and related faults were analyzed in vertical view using SAR–ERS, Spot images

Ö. Ad?yaman; J. Chorowicz; O. Kose

1998-01-01

361

Image-based display of activation patterns derived from scattered electrodes  

Microsoft Academic Search

Presentation of electrophysiologic data, such as activation patterns, can take many forms, the most common of which are hand or machine-drawn isochronal maps. The authors present an image-based method which provides accurate matching between electrophysiologic data and the anatomic sites from which the data were derived. This method is linear, simple, and straightforward to implement, and presents results in a

David S. Buckles; Matthew M. Wienecke; David A. Golod; Kenneth W. Hewett

1995-01-01

362

Multichannel 2-D pattern transfer model based on imaging optics for submarine laser uplink communication  

Microsoft Academic Search

An optical communication scheme of 2-D pattern transfer based on imaging optics for submarine laser uplink communication (SLUC) is suggested. Unlike the methods aiming at avoiding neighboring crosstalk used in traditional multi-channel optical beam transferring, we make full use of the overlapping of each spreading beam other than controlling divergence effect of each beam to avoid interference noise. The apparent

Wei Lu; Liren Liu; Jianfeng Sun; Weiqing Pan

2008-01-01

363

Imaging energy analyzer for RHEED: energy filtered diffraction patterns and in situ electron energy loss spectroscopy  

Microsoft Academic Search

An imaging energy analyzer for the filtering of diffraction diagrams and for the measurement of electron energy distribution has been developed. It allows the separation of the inelastic and elastic contribution of the scattered electrons in the diffraction pattern, which are energy filtered and monitored at with video speed using a CCD camera. The inelastic diffuse background can be eliminated

P. Staib; W. Tappe; J. P. Contour

1999-01-01

364

Exploiting adaptive total variation model for image reconstruction from speckle patterns  

NASA Astrophysics Data System (ADS)

Due to the multiple scattering of light in turbid media such as biological tissues, the image of target becomes highly deteriorated even disappears entirely. The adaptive total variation (ATV) image reconstruction algorithm, which is based on majorization-minimization approach together with Bayesian framework, is utilized to recover the object from its speckle pattern. Numerical simulation results indicates that, compared with Tikhonov regularization method, the ATV approach can effectively suppress the noise of the restored image and preserve more image details as well, consequently greatly boosts the SNR and the sharpness of the result image. Furthermore, the recovered results by ATV algorithm have overcome the diffraction-limit of the conventional optical system. Consequently, the combination of ATV algorithm with multiple scattering of turbid media will be beneficial to the observation of cells and protein molecules in biological tissues and other structures in micro/nano scale.

Gong, Changmei; Shao, Xiaopeng; Wu, Tengfei

2013-08-01

365

Reduced-reference image quality assessment based on statistics of edge patterns  

NASA Astrophysics Data System (ADS)

Recently, research of Objective Image Quality Assessment (IQA) has gained much attention due to its wide application prospect. Among them, the Reduced-Reference (RR) methods estimate perceptual quality of distorted images with partial information from the reference images. This paper proposes a novel universal RR-IQA metric based on the statistics of edge patterns. Firstly, the binary edge maps of the reference and distorted images are created by the LOG operator and zero-crossing detection. Based on them, 15 groups of typical edge patterns are extracted and then their statistical distributions are calculated respectively for the reference and distortion images. The proposed RR-IQA metric is achieved by computing the L-1 Minkowski distance between those two distributions. We have evaluated this metric on six publicly accessible subjective IQA databases. Experiments shows that the proposed metric featured with typical edge patterns outperform other methods in terms of data volume, accuracy and consistency with human perception. In a way, our work provides a new view to the IQA metric design.

Chen, Yuting; Xue, Wufeng; Mou, Xuanqin

2012-01-01

366

Binary pattern codification strategies in an active stereoscopic system based on flexible image guides  

NASA Astrophysics Data System (ADS)

A wide variety of three dimensional (3D) measurement systems that can extract shape information's with sub millimetric accuracy is available in the industry. However, they generally are of macroscopic size and measuring on confined areas is not feasible. To miniaturize such systems, the step proposed is the integration of flexible image guides combined with compact optical probes. This miniaturization process is tested on an active stereoscopic measurement system. In the projection channel of the system, a digital micro-mirror device (DMD) generates structured binary patterns from an incoherent white light source and injects them into a first image guide. Then, a compact optical system projects the pattern on the measurement area. The same configuration principle is applied to the acquisition channel and allows the capture of the measurement area through a second image guide and finally to a digital camera. In this miniaturized system, image guides have lower resolution than in standard imaging devices. Indeed they are equivalent of 70k pixels devices to compare to the almost 800k pixels of the DMD and camera. That implies lower axial and lateral resolutions and consequently the shape reconstruction method must be carefully chosen. In this paper, several reconstruction strategies such as tuning the projected patterns frequency and also phase-shfit versus gray code based methods were compared considering the best axial resolution criteria.

Dupont, Erwan; Hou, Yingfan; Lamarque, Frederic; Redarce, Tanneguy

2013-03-01

367

Probabilistic Neural Network Approach to Cloud Classification.  

National Technical Information Service (NTIS)

Automated satellite image interpretation would be useful in many forecasting operations. One aspects of that interpretation, cloud classification, is examined. Ten classes, composed of low, middle, high, and precipitation cloud types plus clear, are used ...

P. Rabindra R. L. Bankert S. K. Sengupta

1991-01-01

368

Content-based high-resolution remote sensing image retrieval with local binary patterns  

NASA Astrophysics Data System (ADS)

Texture is a very important feature in image analysis including content-based image retrieval (CBIR). A common way of retrieving images is to calculate the similarity of features between a sample images and the other images in a database. This paper applies a novel texture analysis approach, local binary patterns (LBP) operator, to 1m Ikonos images retrieval and presents an improved LBP histogram spatially enhanced LBP (SEL) histogram with spatial information by dividing the LBP labeled images into k*k regions. First different neighborhood P and scale factor R were chosen to scan over the whole images, so that their labeled LBP and local variance (VAR) images were calculated, from which we got the LBP, LBP/VAR, and VAR histograms and SEL histograms. The histograms were used as the features for CBIR and a non-parametric statistical test G-statistic was used for similarity measure. The result showed that LBP/VAR based features got a very high retrieval rate with certain values of P and R, and SEL features that are more robust to illumination changes than LBP/VAR also obtained higher retrieval rate than LBP histograms. The comparison to Gabor filter confirmed the effectiveness of the presented approach in CBIR.

Wang, A. P.; Wang, S. G.

2006-10-01

369

An approach to improve the quality of infrared images of vein-patterns.  

PubMed

This study develops an approach to improve the quality of infrared (IR) images of vein-patterns, which usually have noise, low contrast, low brightness and small objects of interest, thus requiring preprocessing to improve their quality. The main characteristics of the proposed approach are that no prior knowledge about the IR image is necessary and no parameters must be preset. Two main goals are sought: impulse noise reduction and adaptive contrast enhancement technologies. In our study, a fast median-based filter (FMBF) is developed as a noise reduction method. It is based on an IR imaging mechanism to detect the noisy pixels and on a modified median-based filter to remove the noisy pixels in IR images. FMBF has the advantage of a low computation load. In addition, FMBF can retain reasonably good edges and texture information when the size of the filter window increases. The most important advantage is that the peak signal-to-noise ratio (PSNR) caused by FMBF is higher than the PSNR caused by the median filter. A hybrid cumulative histogram equalization (HCHE) is proposed for adaptive contrast enhancement. HCHE can automatically generate a hybrid cumulative histogram (HCH) based on two different pieces of information about the image histogram. HCHE can improve the enhancement effect on hot objects rather than background. The experimental results are addressed and demonstrate that the proposed approach is feasible for use as an effective and adaptive process for enhancing the quality of IR vein-pattern images. PMID:22247674

Lin, Chih-Lung

2011-12-01

370

A local-sky star recognition algorithm based on rapid triangle pattern index for ICCD images  

NASA Astrophysics Data System (ADS)

Local-sky star recognition algorithm is a process of recognizing the extracted stars in image by making use of the prior rough attitude of star sensor in celestial sphere. In order to improve the detection and response performance of star sensor working in dynamic condition, ICCD is applied to imaging stars. However, image taken by ICCD has more non-Gaussian noise and the energy of imaging star is unstable. So a local-sky star recognition algorithm using spatial triangular relationship as matching features is supposed to deal with the difficulties. In the first place, an index array is designed according to Guide Triangles, which is applied to construct Guide Triangle Index List. In the second place, a general directing range of star sensor boresight is calculated according to FOV of star sensor and the output of inertial guidance system, and then, the candidate Guide Triangles set in above region is obtained rapidly. In the third place, construct image triangle patterns by applying position and energy of the extracted stars in the image, and then match the image triangle patterns with the above candidate Guide Triangles set for two stages, until N(N>=2) groups of successfully matched triangles pairs with smallest matching deviations sum are obtained. At the last, the recognized Guide Stars have to be matched posterior referring to the principle of simulated sky image, and the recognition results of image stars are all obtained. The proposed algorithm has compact Guide Database structure, rapid local-sky guide triangles obtaining, and good recognition correction percentage, even it has worse star location precision and more false stars. The simulation tests are performed to validate the relative efficiency and adaptation of the algorithm.

Zhang, Wei; Qi, Sheng-xiang; Zhang, Rui; Yang, Lili; Sun, Ji-fu; Song, Li-quan; Tian, Jin-wen

2013-09-01

371

Simulations of a Demonstration of Cloud Albedo Change  

NASA Astrophysics Data System (ADS)

The Twomey effect describes how the reflectivity of marine stratocumulus clouds can be increased by a change of the concentration of cloud condensation nuclei. The increase can be sufficient to reverse global warming Latham et (2008). This paper combines real MODIS cloud images supplied by Rob Wood as part of the recent VOCALS experiment off the Pacific coast of South America with computer-simulated reflectivity change in pixels down wind of the release point. Initial cloud conditions, spray rate, wake divergence angle and drop half-life are varied over a range of reasonable values. The resulting images show that it may be very difficult to detect reflectivity changes necessary to reverse catastrophic global warming with the human eye to a level which would convince a non-technical decision maker that the procedure has had any effect. The paper goes on to show that by taking a large number of different digitized cloud images, shifting them in the computer to align release points, rotating them to align wind directions and then adding them the background of uncorrelated cloud patterns will converge towards an even middle grey from which the correlated cloud images will emerge. The figure below shows the result for one hundred super-positions except that it had to be removed because of EGU rules. The spray rate was 0.03 m3 sec, drop half life 59 hours, plume dispersion half-angles 1, 2, 5 and 10 degrees, initial drop concentration 65/cm3, wind-speed 6 m/sec, liquid water content 0.3 gm/m3 , boundary layer depth 1000 metres.

Salter, Stephen

2010-05-01

372

Aircraft measurements of wave cloud  

NASA Astrophysics Data System (ADS)

In this paper, aircraft measurements are presented of liquid phase (ice-free) wave clouds made at temperatures greater than -5 °C that formed over Scotland, UK. The horizontal variations of the vertical velocity across wave clouds display a distinct pattern. The maximum updraughts occur at the upshear flanks of the clouds and the strong downdraughts at the downshear flanks. The cloud droplet concentrations were a couple of hundreds per cubic centimetres, and the drops generally had a mean diameter between 15-45 ?m. A small proportion of the drops were drizzle. A new definition of a mountain-wave cloud is given, based on the measurements presented here and previous studies. The results in this paper provide a case for future numerical simulation of wave cloud and the interaction between wave and clouds.

Cui, Z.; Blyth, A. M.; Bower, K. N.; Crosier, J.; Choularton, T.

2012-05-01

373

Aircraft measurements of wave clouds  

NASA Astrophysics Data System (ADS)

In this paper, aircraft measurements are presented of liquid phase (ice-free) wave clouds made at temperatures greater than -5°C that formed over Scotland, UK. The horizontal variations of the vertical velocity across wave clouds display a distinct pattern. The maximum updraughts occur at the upshear flanks of the clouds and the strong downdraughts at the downshear flanks. The cloud droplet concentrations were a couple of hundreds per cubic centimetres, and the drops generally had a mean diameter between 15-45 ?m. A small proportion of the drops were drizzle. The measurements presented here and in previous recent studies suggest a different interaction of dynamics and microphysics in wave clouds from the accepted model. The results in this paper provide a case for future numerical simulation of wave cloud and the interaction between wave and cloud.

Cui, Z.; Blyth, A. M.; Bower, K. N.; Crosier, J.; Choularton, T.

2012-10-01

374

Magnetic resonance imaging of muscle disease: a pattern-based approach.  

PubMed

Magnetic resonance imaging (MRI) is a powerful tool to assess the severity, distribution, and progression of muscle injury and disease. However, a muscle's response to a pathological insult is limited to only a few patterns on MRI, and findings can be nonspecific. A pattern-based approach is therefore essential to correctly interpret MR studies of abnormal muscle. In this article we review the anatomy, function, and normal MRI appearance of skeletal muscle. We present a classification scheme that categorizes abnormal MR appearances of muscle into 4 main pattern descriptors: (1) distribution; (2) change in size and shape; (3) T1 signal; and (4) T2 signal. Each category is further subdivided into the various patterns seen on MRI. Such an approach allows one to systematically assess abnormal findings on muscle MRI studies and ascertain clues to the diagnosis or differential diagnosis, particularly when findings are correlated with the clinical context. PMID:22987686

Costa, Andreu F; Di Primio, Gina A; Schweitzer, Mark E

2012-10-01

375

Reliable, Intense, Ultrafast and Compact Guided-Wave Laser for Cloud Penetration, Remote Sensing, and Active Imaging.  

National Technical Information Service (NTIS)

The goal of this program is to develop reliable, ultrafast, high peak-power lasers. These lasers will be used in the military for cloud penetration, reconnaissance, remote sensing, and active illumination; in the microelectronic industry for repair of pho...

P. Bado

2000-01-01

376

An Improved Cloud Classification Algorithm for China's FY-2C Multi-Channel Images Using Artificial Neural Network.  

PubMed

The crowning objective of this research was to identify a better cloud classification method to upgrade the current window-based clustering algorithm used operationally for China's first operational geostationary meteorological satellite FengYun-2C (FY-2C) data. First, the capabilities of six widely-used Artificial Neural Network (ANN) methods are analyzed, together with the comparison of two other methods: Principal Component Analysis (PCA) and a Support Vector Machine (SVM), using 2864 cloud samples manually collected by meteorologists in June, July, and August in 2007 from three FY-2C channel (IR1, 10.3-11.3 ?m; IR2, 11.5-12.5 ?m and WV 6.3-7.6 ?m) imagery. The result shows that: (1) ANN approaches, in general, outperformed the PCA and the SVM given sufficient training samples and (2) among the six ANN networks, higher cloud classification accuracy was obtained with the Self-Organizing Map (SOM) and Probabilistic Neural Network (PNN). Second, to compare the ANN methods to the present FY-2C operational algorithm, this study implemented SOM, one of the best ANN network identified from this study, as an automated cloud classification system for the FY-2C multi-channel data. It shows that SOM method has improved the results greatly not only in pixel-level accuracy but also in cloud patch-level classification by more accurately identifying cloud types such as cumulonimbus, cirrus and clouds in high latitude. Findings of this study suggest that the ANN-based classifiers, in particular the SOM, can be potentially used as an improved Automated Cloud Classification Algorithm to upgrade the current window-based clustering method for the FY-2C operational products. PMID:22346714

Liu, Yu; Xia, Jun; Shi, Chun-Xiang; Hong, Yang

2009-07-14

377

3-D Range Map Acquisition System Based on CMOS Image Sensor Using Time-Multiplexing Structured Pattern  

NASA Astrophysics Data System (ADS)

We present a 3-D range map acquisition system using a gray-encoded time-multiplexing structured pattern. In this method the only information needed to reconstruct 3-D range map is whether the pixel is bright or not for the exposed structured patterns. A dedicated image sensor to capture the pattern consists of pixel parallel 1-bit A/D converter, in-pixel pattern address memory and column parallel digital pattern address readout circuit. This in-pixel memory and digital bit-parallel pattern address readout eliminate unnecessary readout of pattern data to enhance 3-D acquisition speed. We fabricated the image sensor in 0.18µm CMOS and demonstrated up to 122 range map per second 3-D range map acquisition performance for 7 patterns with the average error of 3.2mm under the condition of 10% pattern recognition error.

Yabe, Hiroki; Ikeda, Makoto

378

Multi-Probe SPM using Interference Patterns for a Parallel Nano Imaging  

NASA Astrophysics Data System (ADS)

This paper proposes a new composition of the multi-probe using optical interference patterns for a parallel nano imaging in a large area scanning. We achieved large-scale integration with 50,000 probes fabricated with MEMS technology, and measured the optical interference patterns with CCD, which was difficult in a conventional single scanning probe. In this research, the multi-probes are made of Si3N4 by MEMS process, and, the multi-probes are joined with a Pyrex glass by an anodic bonding. We designed, fabricated, and evaluated the characteristics of the probe. In addition, we changed the probe shape to decrease the warpage of the Si3N4 probe. We used the supercritical drying to avoid stiction of the Si3N4 probe with the glass surface and fabricated 4 types of the probe shapes without stiction. We took some interference patterns by CCD and measured the position of them. We calculate the probe height using the interference displacement and compared the result with the theoretical deflection curve. As a result, these interference patterns matched the theoretical deflection curve. We found that this multi-probe chip using interference patterns is effective in measurement for a parallel nano imaging.

Koyama, Hirotaka; Oohira, Fumikazu; Hosogi, Maho; Hashiguchi, Gen

379

Color treatment in endoscopic image classification using multi-scale local color vector patterns.  

PubMed

In this work we propose a novel method to describe local texture properties within color images with the aim of automated classification of endoscopic images. In contrast to comparable Local Binary Patterns operator approaches, where the respective texture operator is almost always applied to each color channel separately, we construct a color vector field from an image. Based on this field the proposed operator computes the similarity between neighboring pixels. The resulting image descriptor is a compact 1D-histogram which we use for a classification using the k-nearest neighbors classifier. To show the usability of this operator we use it to classify magnification-endoscopic images according to the pit pattern classification scheme. Apart from that, we also show that compared to previously proposed operators we are not only able to get competitive classification results in our application scenario, but that the proposed operator is also able to outperform the other methods either in terms of speed, feature compactness, or both. PMID:21624846

Häfner, M; Liedlgruber, M; Uhl, A; Vécsei, A; Wrba, F

2011-05-17

380

Color treatment in endoscopic image classification using multi-scale local color vector patterns  

PubMed Central

In this work we propose a novel method to describe local texture properties within color images with the aim of automated classification of endoscopic images. In contrast to comparable Local Binary Patterns operator approaches, where the respective texture operator is almost always applied to each color channel separately, we construct a color vector field from an image. Based on this field the proposed operator computes the similarity between neighboring pixels. The resulting image descriptor is a compact 1D-histogram which we use for a classification using the k-nearest neighbors classifier. To show the usability of this operator we use it to classify magnification-endoscopic images according to the pit pattern classification scheme. Apart from that, we also show that compared to previously proposed operators we are not only able to get competitive classification results in our application scenario, but that the proposed operator is also able to outperform the other methods either in terms of speed, feature compactness, or both.

Hafner, M.; Liedlgruber, M.; Uhl, A.; Vecsei, A.; Wrba, F.

2012-01-01

381

Partial tear of the anterior cruciate ligament of the knee: injury patterns on MR imaging  

Microsoft Academic Search

Purpose  To describe rupture patterns of partial anterior cruciate ligament (ACL) tears on magnetic resonance (MR) imaging.\\u000a \\u000a \\u000a \\u000a Methods  MR images of 51 patients with a surgically confirmed partial ACL tear were retrospectively and independently interpreted by\\u000a 2 experienced, blinded radiologists. Using previously described MR criteria, ACLs were categorized as follows: complete tear,\\u000a partial tear, isolated anteromedial or posterolateral bundle tear, mucoid degeneration

Pieter Van Dyck; Eline De Smet; Jan Veryser; Valérie Lambrecht; Jan L. Gielen; Filip M. Vanhoenacker; Lieven Dossche; Paul M. Parizel

382

WW2010: Clouds and Precipitation  

NSDL National Science Digital Library

This site covers many of the components of cloud formation and cloud types. Although written for the high school level, the middle school student could grasp most of the concepts with the assistance from the teacher. Specific concepts covered include the importance of and mechanisms that produce rising air, cloud types, and ptyes of precipitation. There are nice graphics and images to support the text.

Bramer, Daniel

1997-01-01

383

Cloud Watch  

NSDL National Science Digital Library

The purpose of this activity is to explore the connections between cloud type, cloud cover, and weather and stimulate student interest in taking cloud type observations. Students observe cloud type and coverage and weather conditions over a five-day period and correlate these observations. Students make and test predictions using these observations. The intended outcome is that students learn to draw inferences from observations and use them to make and test predictions.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

384

Modeling, calibration, and correction of nonlinear illumination-dependent fixed pattern noise in logarithmic CMOS image sensors  

Microsoft Academic Search

At present, most CMOS image sensors use an array of pixels with a linear response. However, pixels with a logarithmic response are also possible and are capable of imaging high dynamic range scenes without saturating. Unfortunately, logarithmic image sensors suffer from fixed pattern noise (FPN). Work reported in the literature generally assumes the FPN is independent of illumination. This paper

Dileepan Joseph; Steve Collins

2002-01-01

385

Scattered Brain Infarct Pattern on Diffusion-Weighted Magnetic Resonance Imaging in Patients with Acute Ischemic Stroke  

Microsoft Academic Search

Background and Purpose: Infarct patterns on brain imaging contribute to the etiologic classification of ischemic stroke. However, the association of specific subtypes of infarcts and etiologic mechanisms is often weak, and acute lesions are frequently missed on initial computed tomography (CT). Diffusion-weighted imaging (DWI) is superior in visualizing acute ischemic lesions as compared to CT and conventional magnetic resonance imaging

Hans-Christian Koennecke; Johannes Bernarding; Jürgen Braun; Andreas Faulstich; Chris Hofmeister; Roland Nohr; Stefanie Leistner; Peter Marx

2001-01-01

386

Comparison of thallium-201 SPECT redistribution patterns and rubidium-82 PET rest-stress myocardial blood flow imaging  

Microsoft Academic Search

To compare regional thallium-201 SPECT redistribution patterns with rubidium-82 PET, we studied 81 patients with both imaging modalities. Sixty patients had significant coronary artery disease. All patients underwent PET imaging after dipyridamole infusion, while SPECT imaging was performed after exercise stress (38 patients) and dipyridamole (43 patients). Sixty-eight percent of patients with prior infarct had fixed defects on SPECT, compared

Richard E. Stewart; Jeffrey Popma; Gerald M. Gacioch; Morton Kalus; Sheila Squicciarini; Ziad Al-Aouar; M. Anthony Schork; Markus Schwaiger

1994-01-01

387

Magneto-optical imaging of magnetic domain pattern produced by intense femtosecond laser pulse irradiation  

NASA Astrophysics Data System (ADS)

An important and intriguing area of research is laser plasma generated giant magnetic field pulses. Interaction of ultrashort high intensity laser pulses with matter involves several mechanisms for generating ultrastrong magnetic fields. By irradiating a magnetic recordable tape constituting of ?-Fe2O3 particles with an intense p-polarized femtosecond laser pulses (˜ 10^16 W cm-2, 100fs), we have found complex magnetic field patterns stored in the tape. We image the local magnetic field distribution around the irradiated region [1] using the high sensitivity magneto-optical imaging technique. We understand the complex magnetic domains patterns recoded on the tape in terms of interesting instabilities [1] generated in the plasma produced during the irradiation of the tape with intense laser pulses. [0pt] [1] Jaivardhan Sinha, Shyam Mohan, S. S Banerjee, S. Kahaly, G. Ravindra Kumar, Phys. Rev. E 77, 046118(2008). *satyajit@iitk.ac.in

Sinha, Jaivarhan; Mohan, Shyam; Banerjee, S. S.; Kahaly, S.; Kumar, G. Ravindra

2009-03-01

388

Atomic Force Microscopy for Analyzing Metaphase Chromosomes: Comparison of AFM Images with Fluorescence Labeling Images of Banding Patterns.  

PubMed

The combined use of fluorescence microscopy with atomic force microscopy (AFM) has been introduced to analyze the replication-banding patterns of human chromosomes. Human lymphocytes synchronized with excess thymidine are treated with 5-ethynyl-2'-deoxyuridine (EdU) during the late S phase. EdU-labeled DNA is detected in metaphase chromosomes using Alexa Fluor 488(®) azide, through the 1,3-dipolar cycloaddition reaction of organic azides with the terminal acetylene group of EdU. Chromosomes with EdU incorporated during the late S phase show a banding pattern similar to the G-banding pattern of normal human chromosomes. The comparison between the fluorescence and AFM image of the same chromosome indicates the presence of ridges and grooves in the chromatid arms, which correspond to G-positive and G-negative bands, respectively. This technique of EdU-labeled replication bands combined with AFM is useful to analyze the structure of chromosomes in relation to the banding pattern. PMID:24162986

Hoshi, Osamu; Ushiki, Tatsuo

2014-01-01

389

Cloud Types  

NSDL National Science Digital Library

This tutorial explains common cloud classifications and the Latin root words that have been adapted to create the various names of clouds. The classification is subdivided into high-, low-, and mid-level types, clouds with vertical development, and other, less common types. Each description is accompanied by an example photograph.

2005-03-10

390

Fixed-Pattern Noise Induced by Transmission Gate in Pinned 4T CMOS Image Sensor Pixels  

Microsoft Academic Search

In this paper, we present the characterization and analysis of fixed-pattern noise (FPN) in CMOS image sensor (CIS) pixels fabricated in CMOS 0.18-mum process. The experimental results demonstrate that the dark signal degradation of pinned 4T CIS is mainly due to the dark current generated from the transmission gate (TG) instead of the photodiode (PD). From our investigations of gate

Xinyang Wang; Padmakumar R. Rao; A. J. P. Theuwissen

2006-01-01

391

Gender and Age Patterns in Emotional Expression, Body Image, and Self-Esteem: A Qualitative Analysis  

Microsoft Academic Search

This qualitative study used written narrativesto examine gender and age patterns in body image,emotional expression, and self-esteem for a total of 209boys and girls in the fifth, eighth, and twelfth grades. Seventy-six percent of the sample wasCaucasian, 18% African-American, 5% Asian-American, and.5% Hispanic. A major finding indicates that boysrestrict emotional expression from early adolescence through late adolescence, while girls increaseemotional

Mary Polce-Lynch; Barbara J. Myers; Christopher T. Kilmartin; Renate Forssmann-Falck; Wendy Kliewer

1998-01-01

392

Meso-scale imaging of patterned surfaces by decoration with liquid crystals  

Microsoft Academic Search

We report techniques for the imaging of patterned surfaces that are based on the use of random arrays of microdroplets of the nematic liquid crystal 4-cyano-4?-pentylbiphenyl (5CB). Microdroplets of 5CB were delivered to surfaces by spray atomization of a nematic phase or by condensation of a vapor of mesogens. By comparing the optical textures of microdroplets of 5CB in their

Rahul R Shah; Dawn M Heinrichs; Nicholas L Abbott

2000-01-01

393

Drainage patterns of the cholecystic vein evaluated by power doppler imaging  

Microsoft Academic Search

Power Doppler imaging (PDI) is a new technique that enhances detection of low-velocity blood flow. We used this modality to\\u000a assess gallbladder vasculature, especially drainage pattern and flow analysis of the cholecystic vein. The power Doppler equipment\\u000a used in this study was the Acuson Sequoia 512 system (Mountain View, California). Subjects were 27 patients with acute cholecystitis,\\u000a 9 with gallbladder

Keisuke Osakabe; Yuji Horiguchi; Hideo Imai; Hiroshi Sakamoto; Tomohiro Suzuki; Hiroshi Kubo; Masanao Uematsu; Fumiyasu Takeuchi; Yuko Nakamura; Takao Hayashi; Masahiro Asano; Toru Nishikawa; Yuko Kushi; Horoshi Nakano

2001-01-01

394

Near-field imaging of neurotransmitter release and uptake in patterned neuron networks  

NASA Astrophysics Data System (ADS)

A SNOAM system is capable of obtaining simultaneous topographic and optical images with a resolution beyond than the diffraction limit of far field optical imaging. Fluorescence tagging combined with optical resolutions of better than 100nm allow us to detect structures not possible with conventional microscopes. Also in contrast with electron microscopy SNOAM has the ability to look at biological structures in the liquid medium. Presently there is much interest in understanding the processes that lead to LTP in neuron synapses. LTP is widely associated with memory function in neurons. Hence, better understanding will lead to advances in medicine, as well as neuron-based memory and processing devices. Better understanding is also crucial to the development of neuron-electronic interfaces. In this research, neuron networks are grown on a patterned polylysine substrate. Polylysine is patterned using micro lithographic techniques. Neurons are extracted from the hippocampus of chick embryos, and are then grown on this pattern under standard sterile incubating conditions. The neurons are stimulated to release the neurotransmitter glutamate. The glutamate is then fluorescently imaged with Amplex-red SNOAM.

Degenaar, Patrick; Murakami, Yuji; Yokoyama, Kenji; Tamiya, Eiichi; Le Pioufle, Bruno; Fujita, Yiroyuki

2000-04-01

395

Deep Imaging Surveys of Star-forming Clouds. V. New Herbig-Haro Shocks and Giant Outflows in Taurus  

NASA Astrophysics Data System (ADS)

We report the discovery of new Herbig-Haro shocks in the southeastern portion of the Taurus molecular cloud complex. The embedded protostar IRAS04325+2402, located in the eastern end of the B18 dark cloud in the cloud region known as L1535, drives a parsec-scale outflow with a length of at least 134' (5.5 pc) toward P.A. = 17°/197° making this the largest protostellar outflow found thus far in Taurus. The southern terminus of this flow located about 65' (~2.7 pc) from the IRAS source consists of a large previously discovered shock, HH 434-436. The northern lobe contains three faint shocks with the most distant being HH 696 located 2.8 pc north of the source. Two smaller shocks, HH 699 and HH 703, are found midway between the IRAS source and HH 434-436. HH 703 has a proper motion of 170 ± 30 km s-1 toward P.A. = 195° ± 10°. Additionally, we report the discovery of a dozen new Herbig-Haro objects tracing outflows and protostellar jets in B18 and near IC 2087, at least two of which have also attained parsec-scale dimensions. These observations demonstrate that some low-mass stars forming from the Taurus clouds drive giant flows which can excite shocks in the inter-cloud medium degrees from their sources, providing further evidence for the generation of large-scale mass motions and turbulence by protostellar outflows.

Bally, John; Walawender, Josh; Reipurth, Bo

2012-11-01

396

Surface plasmon resonance phase imaging measurements of patterned monolayers and DNA adsorption onto microarrays  

PubMed Central

The optical technique of surface plasmon resonance phase imaging (SPR-PI) is implemented in a linear microarray format for real-time measurements of surface bioaffinity adsorption processes. SPR-PI measures the phase shift of p-polarized light incident at the SPR angle reflected from a gold thin film in an ATR Kretschmann geometry by creating an interference fringe image on the interface with a polarizer-quartz wedge depolarizer combination. The position of the fringe pattern in this image changes upon the adsorption of biomolecules to the gold thin film. By using a linear array of 500 ?m biosensor element lines that are perpendicular to the interference fringe image, multiple bioaffinity adsorption measurements can be performed in real time. Two experiments were performed to characterize the sensitivity of the SPR-PI measurement technique; first, a ten line pattern of a self-assembled monolayer of 11-mercaptoundecamine (MUAM) was created via photopatterning to verify that multiple phase shifts could be measured simultaneously. A phase shift difference (??) of ?? = 182.08 ± 0.03° was observed for the 1.8-nm MUAM monolayer; this value agrees with the phase shift difference calculated from a combination of Fresnel equations and Jones matrices for the depolarizer. In a second demonstration experiment, the feasibility of SPR-PI for in situ bioaffinity adsorption measurements was confirmed by detecting the hybridization and adsorption of single stranded DNA (ssDNA) onto a six component DNA line microarray patterned monolayer. Adsorption of a full DNA monolayer produced a phase shift difference of ?? = 28.80 ± 0.03° at the SPR angle of incidence and the adsorption of the ssDNA was monitored in real time with the SPR-PI. These initial results suggest that SPR-PI should have a detection limit roughly 100 times lower than traditional intensity-based SPR imaging measurements.

Halpern, Aaron R.; Chen, Yulin; Corn, Robert M.; Kim, Donghyun

2011-01-01

397

Patterns of Nonmasslike Enhancement at Screening Breast MR Imaging of High-Risk Premenopausal Women.  

PubMed

Current U.S. recommendations for breast cancer screening of women with at least a 20%-25% lifetime risk of developing breast cancer include contrast material-enhanced magnetic resonance (MR) imaging of the breasts. The cancer detection rate in high-risk women undergoing screening MR imaging is approximately 10 times higher than that in normal-risk women undergoing screening mammography. Many of these high-risk women commence MR imaging screening while they are premenopausal, when the breasts are most influenced by cyclical hormonal changes. Healthy premenopausal breast tissue enhances in a cyclical and variable manner. This enhancement is described as background enhancement. Typically, enhancement of normal breast tissue occurs in a symmetric and diffuse pattern, and there is little diagnostic difficulty in classifying it as normal background parenchymal enhancement. However, sometimes the pattern is more focal, asymmetric, or regional. It may then be described as nonmasslike enhancement, an observation associated with both benign and malignant breast pathologic conditions. A review of the morphologic features and internal enhancement patterns in normal but nondiffuse background enhancement and abnormal nonmasslike enhancement in high-risk premenopausal women can help improve interpretive specificity and decrease false-positive interpretations. MR imaging pitfalls and interpretation strategies for localized background enhancement and pathologic nonmasslike enhancement in this high-risk population are highlighted. In evaluating nonmasslike enhancement, the use of the Breast Imaging Reporting and Data System (BI-RADS) lexicon to perform careful analysis of morphologic features, along with an understanding of the role and limitations of kinetic information, will help balance early breast cancer detection against false-positive interpretation. © RSNA, 2013. PMID:24025928

Giess, Catherine S; Raza, Sughra; Birdwell, Robyn L

2013-09-01

398

Customers' Preferences for Infrastructure Cloud Services  

Microsoft Academic Search

The pay-as-you-go pricing policies currently applied in Cloud Computing domain benefit customers with volatile demand but can lead to unmanageable utilization patterns for Cloud providers. Revenue management models that account for customer behavior enable to classify Cloud service users into customer segments and to increase the revenue for providers by offering different services. These theoretic models, however, make strong assumptions

Arun Anandasivam; Philipp Best; Simon See

2010-01-01

399

Soft Tissue Attenuation Patterns Associated with Upright Acquisition SPECT Myocardial Perfusion Imaging: A Descriptive Study  

PubMed Central

Background: Little is known about soft tissue attenuation artifacts when an upright patient-position SPECTmyocardial perfusion imaging (MPI) system is used. In this investigation we sought to describe the patterns and frequency of attenuation artifacts associated with this type of instruments and we explored the impact of gender and body habitus on these artifacts. Methods: In a cross-sectional study, we described the prevalence of various soft-tissue attenuation patterns in 212 normal SPECT-MPI studies acquired with an upright patient-position imaging system. Results: In these 212 normal, clinically-indicated, upright-acquisition SPECT-MPIs the attenuation patterns observed were: anterior (6.1%), inferior (63.7%) and lateral (24.1%). Though uncommon, anterior attenuation trended to being more prevalent among women [9.5% vs. 3.4%, P=0.07] and was independently associated with chest circumference. Lateral attenuation was more common among women [34.7% vs. 15.4%, p=0.001] and was strongly associated with obesity (p<0.001). Inferior attenuation was more prevalent among men than women (75.2% vs. 49.5% respectively, P<0.001). Conclusions: Soft-tissue attenuation artifacts are common in upright-acquisition SPECT-MPI. Recognizing the frequency of these attenuation patterns and their interaction with gender and body habitus is critical for the accurate interpretation of SPECT-MPI.

Doukky, Rami; Rahaby, Mouyyad; Chawla, Dave; Vashistha, Raj; Alyousef, Tareq; Amin, Amit P

2012-01-01

400

Nonintrusive measurements of mixture concentration fields by analyzing diffraction image patterns (point spread function) of nanoparticles  

NASA Astrophysics Data System (ADS)

The diffraction image patterns of small particles are referred to as their point spread function (PSF); these patterns vary distinctively with the refractive index (RI) of a transparent test medium when the particles are imaged through the medium. The RI correlates directly with the mixture concentration, so proper inversion of measured PSFs can provide full-field information on the mixture concentration field. In this study, fluorescent nanoparticles of 500 nm diameter are fixed on a glass surface by means of evaporative self-assembly, and the time-varying test mixture is placed in front of the glass surface. The time-varying and full-field PSF distributions are imaged and digitally analyzed to determine the local RI values as well as the local mixture concentrations. Both immiscible water/oil mixture and miscible water/glycerol mixture are imaged. The present method shows an RI measurement to have an uncertainty of ±5 × 10-3 RIU and the mixture concentration measurements to have uncertainty of approximately 4%.

Park, Jae-Sung; Kihm, Kenneth D.; Lee, Joon Sik

2010-07-01

401

Feasibility study on Compton imaging for visualization of flow patterns using radiotracers  

NASA Astrophysics Data System (ADS)

The radiotracer technique could be used in studies on multiphase flow systems by three-dimensional visualization of flow patterns, and, relatedly, there have been attempts to develop an industrial-purpose single photon emission computed tomography (SPECT) system. Compton cameras also have a great potential for industrial applications, due specifically to their inherent three-dimensional imaging capability, multi-tracing capability, and higher imaging sensitivity than imaging devices based on mechanical collimation. In the present study, the feasibility of Compton imaging for visualization of detailed flow patterns was determined using a Geant4 Monte Carlo simulation toolkit. The Compton camera considered is a double-scattering type consisting of three gamma-ray detectors: two double-sided silicon strip detectors (DSSDs) as scatterer detectors and one NaI(Tl) scintillation detector as an absorber detector. The results showed that the three-dimensional source distributions can be determined with the Compton camera under various source conditions, including a point source at the center, and two cylinderial volume sources of different dimensions or energies.

Seo, H.; Park, J. H.; Park, J. G.; Ushakov, A.; Kim, C. H.; Lee, J. H.; Lee, C. S.; Lee, J. S.

2011-01-01

402

Obtaining breathing patterns from any sequential thoracic x-ray image set.  

PubMed

A technique is presented to allow a breathing pattern to be obtained from any multi-slice CT, cone-beam or other series of sequential chest x-ray image sets. The technique requires no extra signals to be recorded and does not need specific external or internal oscillating structures to be visible in the field of view. The breathing pattern is instead acquired from analysing the variation in pixel values between projection images. For cone-beam image sets, slowly varying changes, due to an angular attenuation dependence, must be corrected before the breathing trace analysis can begin. All the results of the new technique were checked visually and were in good agreement. If the studied image set could be analysed using the existing 'Amsterdam shroud' technique, then the results it provided were also used for comparison. In cases that allowed comparison by both techniques, the results were in agreement. The new technique was also shown to provide a usable signal when applied to cardiac motion. PMID:19636080

Kavanagh, Anthony; Evans, Philip M; Hansen, Vibeke N; Webb, Steve

2009-07-27

403

Discrete techniques for 3D digital images and patterns under transformations  

NASA Astrophysics Data System (ADS)

Three dimensional (3-D) digital images and patterns under transformations are facilitated by the splitting-shooting method (SSM) and the splitting-integrating method (SIM). The combination (CSIM) of SSM and SIM and the combination (CIIM) of SIM and SIM are proposed for a cycle conversion T-1T, where T is a nonlinear transformation, and T-1 is its inverse transformation. This paper focuses on exploitation of accuracy of the obtained image greyness. In our discrete algorithms, let a 3-D pixel be split into N3 subpixels. The convergence rates of sequential errors can be denoted by O(1/Nk), k >= 1. High convergence rates indicate less CPU time needed. Both error bounds and computation of pixel greyness have shown the following important conclusions: (1) O(1/N) for CSIM; (2) O(1/N) or O(1/N2) for CIIM; (3) O(1/N3) for CIIM using quadratic B-spline functions in antialiasing images.

Li, Zi C.

1993-01-01

404

DEEP NEAR-INFRARED IMAGING OF THE {rho} Oph CLOUD CORE: CLUES TO THE ORIGIN OF THE LOWEST-MASS BROWN DWARFS  

SciTech Connect

A search for young substellar objects in the {rho} Oph cloud core region has been made with the aid of multiband profile-fitting point-source photometry of the deep-integration Combined Calibration Scan images of the 2MASS extended mission in the J, H, and K{sub s} bands, and Spitzer IRAC images at 3.6, 4.5, 5.8, and 8.0 {mu}m. The field of view of the combined observations was 1{sup 0} x 9.'3, and the 5{sigma} limiting magnitude at J was 20.5. Comparison of the observed spectral energy distributions with the predictions of the COND and DUSTY models, for an assumed age of 1 Myr, supports the identification of many of the sources with brown dwarfs and enables the estimation of effective temperature, T {sub eff}. The cluster members are then readily distinguishable from background stars by their locations on a plot of flux density versus T {sub eff}. The range of estimated T {sub eff} values extends down to {approx}750 K which, based on the COND model, would suggest the presence of objects of sub-Jupiter mass. The results also suggest that the mass function for the {rho} Oph cloud resembles that of the {sigma} Orionis cluster based on a recent study, with both rising steadily toward lower masses. The other main result from our study is the apparent presence of a progressive blueward skew in the distribution of J - H and H - K{sub s} colors, such that the blue end of the range becomes increasingly bluer with increasing magnitude. We suggest that this behavior might be understood in terms of the 'ejected stellar embryo' hypothesis, whereby some of the lowest-mass brown dwarfs could escape to locations close to the front edge of the cloud, and thereby be seen with less extinction.

Marsh, Kenneth A.; Plavchan, Peter; Kirkpatrick, J. Davy; Lowrance, Patrick J.; Cutri, Roc M. [Infrared Processing and Analysis Center, California Institute of Technology 100-22, Pasadena, CA 91125 (United States); Velusamy, Thangasamy, E-mail: kam@ipac.caltech.ed, E-mail: plavchan@ipac.caltech.ed, E-mail: davy@ipac.caltech.ed, E-mail: lowrance@ipac.caltech.ed, E-mail: roc@ipac.caltech.ed, E-mail: Thangasamy.Velusamy@jpl.nasa.go [Jet Propulsion Laboratory, MS 169-506, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

2010-08-10

405

All sky imaging observations in visible and infrared waveband for validation of satellite cloud and aerosol products  

Microsoft Academic Search

A series of satellite sensors in visible and infrared wavelengths have been successfully operated on board a number of research satellites, e.g. NOAA\\/AVHRR, the MODIS onboard Terra and Aqua, etc. A number of cloud and aerosol products are produced and released in recent years. However, the validation of the product quality and accuracy are still a challenge to the atmospheric

Daren Lu; Juan Huo; W. Zhang; J. Liu

2004-01-01

406

Spatiotemporal relations of primary sensorimotor and secondary motor activation patterns mapped by NIR imaging  

PubMed Central

Functional near infrared (fNIR) imaging was used to identify spatiotemporal relations between spatially distinct cortical regions activated during various hand and arm motion protocols. Imaging was performed over a field of view (FOV, 12 x 8.4 cm) including the secondary motor, primary sensorimotor, and the posterior parietal cortices over a single brain hemisphere. This is a more extended FOV than typically used in current fNIR studies. Three subjects performed four motor tasks that induced activation over this extended FOV. The tasks included card flipping (pronation and supination) that, to our knowledge, has not been performed in previous functional magnetic resonance imaging (fMRI) or fNIR studies. An earlier rise and a longer duration of the hemodynamic activation response were found in tasks requiring increased physical or mental effort. Additionally, analysis of activation images by cluster component analysis (CCA) demonstrated that cortical regions can be grouped into clusters, which can be adjacent or distant from each other, that have similar temporal activation patterns depending on whether the performed motor task is guided by visual or tactile feedback. These analyses highlight the future potential of fNIR imaging to tackle clinically relevant questions regarding the spatiotemporal relations between different sensorimotor cortex regions, e.g. ones involved in the rehabilitation response to motor impairments.

Khan, Bilal; Chand, Pankaj; Alexandrakis, George

2011-01-01

407

Quantitative planar imaging with technetium-99m methoxyisobutyl isonitrile: Comparison of uptake patterns with thallium-201  

SciTech Connect

To compare the myocardial uptake pattern of 99mTc-labeled methoxyisobutyl isonitrile (( 99mTc) MIBI) and 201TI, planar scintigraphy were performed in both patients with documented coronary artery disease and subjects with a low likelihood of disease. Quantitative analysis was employed using a standard interpolative background subtraction algorithm and a new algorithm modified to better accommodate for the differences in extracardiac activity seen with (99mTc)MIBI rest images. Among patients with coronary artery disease, the standard algorithm yielded no significant difference in relative defect magnitude between (99mTc)MIBI and 201TI on stress scintigrams (p = 0.48), although the magnitude of (99mTc)MIBI defects was greater on resting images (p = 0.02). When the modified algorithm was employed, defect magnitude was similar for both stress (p = 0.91) and rest (p = 0.20) images. Normal segmental uptake ratios derived from a comparison of contralateral segments (e.g., septal:posterolateral) in the low likelihood patients were similar for both (99mTc)MIBI and 201TI. Thus, modification of the standard interpolative background subtraction algorithm is necessary for quantitative planar (99mTc)MIBI perfusion imaging. When appropriate background subtraction is employed, myocardial uptake and quantitative defect magnitude of (99mTc)MIBI and 201TI planar images are similar.

Sinusas, A.J.; Beller, G.A.; Smith, W.H.; Vinson, E.L.; Brookeman, V.; Watson, D.D. (Univ. of Virginia Health Sciences Center, Charlottesville (USA))

1989-09-01

408

Tomographic Studies of Noctilucent Clouds  

NASA Astrophysics Data System (ADS)

Limb-scanning satellites can provide global information about the vertical structure of polar mesospheric clouds. However, information about horizontal structures usually remains limited. This is due to both a long line of sight and a long scan duration. on six days during the northern hemisphere summer 2010, the Swedish-led Odin satellite was operated in a special mesospheric mode with short limb scans limited to altitude range of polar mesospheric clouds. For Odin's Optical Spectrograph and InfraRed Imager System (OSIRIS) this provides multiple views through a given cloud volume and, thus, a basis for tomographic analysis of the vertical/horizontal cloud structure. Here we present algorithms for tomographic analysis of mesospheric clouds based on maximum probability techniques. We present retrieved cloud structures and discuss underlying dynamical conditions. We also discuss perspectives towards the use of common volume measurements by Odin/OSIRIS and AIM/CIPS for combined tomographic retrievals.

Hultgren, K.; Gumbel, J.; Degenstein, D. A.; Bourassa, A. E.; Lloyd, N. D.

2010-12-01

409

Investigating cirrus cloud behavior using A-Train and geostationary satellite data  

NASA Astrophysics Data System (ADS)

Knowledge of how the large-scale dynamics are coupled with microphysical properties is necessary for parameterizing cirrus in climate models. In this study, the synergy of the CloudSat and CALIPSO instruments is exploited for identifying cirrus. Mesoscale-size cirrus events are defined using a combined CloudSat-CALIPSO cloud mask and temperature data for one year in the Atlantic basin. In order to characterize the tendencies of cirrus, the instantaneous view of A-Train satellites is augmented with the temporal view from a geostationary satellite. Cirrus events are tracked using an algorithm, which follows patterns of 6.2?m brightness temperature in consecutive water vapor images. NCEP/NCAR reanalysis data is used to determine the environments in which the cirrus events exist. The cirrus events are sorted based on pressure- radar reflectivity patterns using a k-means cluster algorithm. The six clusters that are identified include Single-Layer Cirrus, Thick Cirrus and Low Cloud, High Cirrus, Deep Cirrus, Mixed Cloud and Thin Cirrus, and Low Cloud. A cluster algorithm is also applied to the large-scale dynamics to determine the basic synoptic states for cirrus. This analysis results in six dynamic clusters including Deep Wave Cirrus, Developing Tropical Cirrus, Subtropical Jet Cirrus, Zonal Jet/Stationary Front Cirrus, Dissipating Tropical Cirrus, and Ridge Crest Cirrus. We find that large-scale dynamic types do not necessarily predetermine the cirrus cloud properties.

Berry, Elizabeth

410

High-dimensional pattern regression using machine learning: from medical images to continuous clinical variables.  

PubMed

This paper presents a general methodology for high-dimensional pattern regression on medical images via machine learning techniques. Compared with pattern classification studies, pattern regression considers the problem of estimating continuous rather than categorical variables, and can be more challenging. It is also clinically important, since it can be used to estimate disease stage and predict clinical progression from images. In this work, adaptive regional feature extraction approach is used along with other common feature extraction methods, and feature selection technique is adopted to produce a small number of discriminative features for optimal regression performance. Then the Relevance Vector Machine (RVM) is used to build regression models based on selected features. To get stable regression models from limited training samples, a bagging framework is adopted to build ensemble basis regressors derived from multiple bootstrap training samples, and thus to alleviate the effects of outliers as well as facilitate the optimal model parameter selection. Finally, this regression scheme is tested on simulated data and real data via cross-validation. Experimental results demonstrate that this regression scheme achieves higher estimation accuracy and better generalizing ability than Support Vector Regression (SVR). PMID:20056158

Wang, Ying; Fan, Yong; Bhatt, Priyanka; Davatzikos, Christos

2010-01-04

411

Exploring the formation of focal adhesions on patterned surfaces using super-resolution imaging.  

PubMed

The formation of focal adhesions on various sizes of fibronectin patterns, ranging from 200 ?m to 250 nm, was systematically investigated by total internal reflection fluorescence microscopy and super-resolution imaging. It was found that cells adhered to and spread on these micro/nanopatterns, forming focal adhesions. On a micrometer scale the shape of the focal adhesions was elongated. However, on the nanometer scale, the shape of focal adhesions became dotlike. To further explore the distribution of focal adhesion proteins formed on surfaces, a localization-based super-resolution imaging technique was employed in order to determine the position and density of vinculin proteins. A characteristic distance of 50 nm was found between vinculin molecules in the focal adhesions, which did not depend on the size of the fibronectin nanopatterns. This distance was found to be crucial for the formation of focal adhesions. In addition, the density of vinculin at the focal adhesions formed on the nanopatterns increased as the pattern size decreased. The density of the protein was found to be 425 ± 247, 584 ± 302, and 703 ± 305 proteins ?m(-2) on the 600, 400, and 250 nm fibronectin patterns respectively. Whereas 226 ± 77 proteins ?m(-2) was measured for the matured focal adhesions on homogeneous fibronectin coated substrates. The increase in vinculin density implies that an increase in mechanical load was applied to the focal adhesions formed on the smaller nanopatterns. PMID:21861294

Chien, Fan-Ching; Kuo, Chiung Wen; Yang, Zong-Han; Chueh, Di-Yen; Chen, Peilin

2011-08-22

412

Evaluation of imaging plates as recording medium for images of negatively stained single particles and electron diffraction patterns of two-dimensional crystals  

PubMed Central

We evaluated imaging plates (IPs) and the DITABIS Micron scanner for their use in recording images of negatively stained single-particle specimens and electron diffraction patterns of two-dimensional crystals. We first established the optimal imaging and read-out conditions for images of negatively stained single-particle specimens using the signal-to-noise ratio of the images as the evaluation criterion. We found that images were best recorded on IPs at a magnification of 67?000×, read out with a gain setting of 20?000 and a laser power setting of 30% with subsequent binning over 2 × 2 pixels. Our results show that for images of negatively stained specimens, for which the resolution is limited to ?20 Å, IPs are a good alternative to EM film. We also compared IPs with a 2K × 2K Gatan charge-coupled device (CCD) camera for their use in recording electron diffraction patterns of sugar-embedded two-dimensional crystals. Diffraction patterns of aquaporin-0 recorded on IPs and with the CCD camera showed reflections beyond 3 Å and had similar RFriedel as well as Rmerge values. IPs can thus be used to collect diffraction patterns, but CCD cameras are more convenient and remain the best option for recording electron diffraction patterns.

Li, Zongli; Hite, Richard K.; Cheng, Yifan; Walz, Thomas

2010-01-01

413

Evaluation of imaging plates as recording medium for images of negatively stained single particles and electron diffraction patterns of two-dimensional crystals.  

PubMed

We evaluated imaging plates (IPs) and the DITABIS Micron scanner for their use in recording images of negatively stained single-particle specimens and electron diffraction patterns of two-dimensional crystals. We first established the optimal imaging and read-out conditions for images of negatively stained single-particle specimens using the signal-to-noise ratio of the images as the evaluation criterion. We found that images were best recorded on IPs at a magnification of 67,000x, read out with a gain setting of 20,000 and a laser power setting of 30% with subsequent binning over 2 x 2 pixels. Our results show that for images of negatively stained specimens, for which the resolution is limited to approximately 20 A, IPs are a good alternative to EM film. We also compared IPs with a 2K x 2K Gatan charge-coupled device (CCD) camera for their use in recording electron diffraction patterns of sugar-embedded two-dimensional crystals. Diffraction patterns of aquaporin-0 recorded on IPs and with the CCD camera showed reflections beyond 3 A and had similar R(Friedel) as well as R(merge) values. IPs can thus be used to collect diffraction patterns, but CCD cameras are more convenient and remain the best option for recording electron diffraction patterns. PMID:19643814

Li, Zongli; Hite, Richard K; Cheng, Yifan; Walz, Thomas

2009-07-30

414

Automated parasites detection in clams by transillumination imaging and pattern classification  

NASA Astrophysics Data System (ADS)

Quality control of clams considers the detection of foreign objects like shell pieces, sand and even parasites. Particularly, Mulinia edulis clams are susceptible to have a parasite infection caused by the isopoda Edotea magellanica, which represents a serious commercial problem commonly addressed by manual inspection. In this work a machine vision system capable of automatically detect the parasite using a clam image is presented. The parasite visualization inside the clam is achieved by an optoelectronic imaging system based on an transillumination technique. Furthermore, automatic parasite detection in the clam's image is accomplished by a pattern recognition system designed to quantitatively describe parasite candidate zones. The extracted features are used to predict the parasite presence by means of a binary decision tree classifier. A real sample dataset of more than 155000 patterns of parasite candidate zones was generated using 190 shell-off cooked clams from the Chilean south pacific coasts. This data collection was used to train a test the classifier using cross-validation. Primary results have shown a mean parasite detection rate of 85% and a mean total correct classification of 87%, which represent a substantive improvement to the existing solutions.

Soto, Miguel; Coelho, Pablo; Soto, Jose; Torres, Sergio; Sbarbaro, Daniel

2012-02-01

415

A Reverse Perfusion Pattern During Technetium99m Stress Myocardial Perfusion Imaging Does Not Predict Flow Limiting Coronary Artery Disease  

Microsoft Academic Search

Background:A reverse redistribution pattern during myocardial perfusion imaging is most widely described using thallium (Tl-201), when stress images exhibit greater perfusion than rest. Technetium (Tc-99 m) radiopharmaceuticals may also yield a reverse perfusion (RP) pattern, but its significance is uncertain. This study tested the hypothesis that RP correlates with the presence and location of flow limiting coronary stenosis(es). Method:We reviewed

E. J. Smith; A. Hussain; M. Manoharan; H. J. Testa; N. P. Curzen

2004-01-01

416

The Remarkable High Pressure of the Local Leo Cold Cloud  

NASA Astrophysics Data System (ADS)

Using the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope, we have obtained high-resolution ultraviolet spectra of the C I absorption toward two stars behind the Local Leo Cold Cloud (LLCC). At a distance (?20 pc) that places it well inside the Local Bubble, the LLCC is the nearest example of the coldest known (T ? 20 K) diffuse interstellar clouds. The STIS measurements of the C I fine-structure excitation toward HD 85259 and HD 83023 indicate that the thermal gas pressure of the LLCC is much greater than that of the warm clouds in the Local Bubble. The mean LLCC pressure measured toward these two stars (60,000 cm-3 K) implies an H I density of ?3000 cm-3 and a cloud thickness of ?200 AU at the 20 K cloud temperature. Such a thin, cold, dense structure could arise at the collision interface between converging flows of warm gas. However, the measured LLCC pressure is appreciably higher than that expected in the colliding-cloud interpretation given the velocity and column density constraints on warm clouds in the HD 85259 and HD 83023 sightlines. Additional STIS measurements of the Zn II, Ni II, and Cr II column densities toward HD 85259 indicate that the LLCC has a modest "warm cloud" dust depletion pattern consistent with its low dust-to-gas ratio determined from H I 21 cm and 100 ?m observations. In support of the inferred sheet-like geometry for the LLCC, a multi-epoch comparison of the Na I absorption toward a high-proper-motion background star reveals a 40% column density variation indicative of LLCC Na I structure on a scale of ?50 AU.

Meyer, David M.; Lauroesch, J. T.; Peek, J. E. G.; Heiles, Carl

2012-06-01

417

Cloud Types  

NSDL National Science Digital Library

This table provides a quick reference to cloud types. Clouds are divided into groups mainly based on the height of the cloud's base above the Earth's surface. The table further divides the types according to group, atmospheric layer, and base height. Links to additional information are embedded in the text, and users can select beginner, intermediate, or advanced levels of difficulty. A Spanish translation is available.

418

Visualization of nasal airflow patterns in a patient affected with atrophic rhinitis using particle image velocimetry  

NASA Astrophysics Data System (ADS)

The relationship between airflow patterns in the nasal cavity and nasal function is poorly understood. This paper reports an experimental study of the interplay between symptoms and airflow patterns in a patient affected with atrophic rhinitis. This pathology is characterized by mucosal dryness, fetor, progressive atrophy of anatomical structures, a spacious nasal cavity, and a paradoxical sensation of nasal congestion. A physical replica of the patient's nasal geometry was made and particle image velocimetry (PIV) was used to visualize and measure the flow field. The nasal replica was based on computed tomography (CT) scans of the patient and was built in three steps: three-dimensional reconstruction of the CT scans; rapid prototyping of a cast; and sacrificial use of the cast to form a model of the nasal passage in clear silicone. Flow patterns were measured by running a water-glycerol mixture through the replica and evaluating the displacement of particles dispersed in the liquid using PIV. The water-glycerol flow rate used corresponded to an air flow rate representative of a human breathing at rest. The trajectory of the flow observed in the left passage of the nose (more affected by atrophic rhinitis) differed markedly from what is considered normal, and was consistent with patterns of epithelial damage observed in cases of the condition. The data are also useful for validation of computational fluid dynamics predictions.

Garcia, G. J. M.; Mitchell, G.; Bailie, N.; Thornhill, D.; Watterson, J.; Kimbell, J. S.

2007-10-01

419

Quantitative imaging of the Dorsal nuclear gradient reveals limitations to threshold-dependent patterning in Drosophila  

PubMed Central

The NF-?B-related transcription factor, Dorsal, forms a nuclear concentration gradient in the early Drosophila embryo, patterning the dorsal-ventral (DV) axis to specify mesoderm, neurogenic ectoderm, and dorsal ectoderm cell fates. The concentration of nuclear Dorsal is thought to determine these patterning events; however, the levels of nuclear Dorsal have not been quantified previously. Furthermore, existing models of Dorsal-dependent germ layer specification and patterning consider steady-state levels of Dorsal relative to target gene expression patterns, yet both Dorsal gradient formation and gene expression are dynamic. We devised a quantitative imaging method to measure the Dorsal nuclear gradient while simultaneously examining Dorsal target gene expression along the DV axis. Unlike observations from other insects such as Tribolium, we find the Dorsal gradient maintains a constant bell-shaped distribution during embryogenesis. We also find that some classical Dorsal target genes are located outside the region of graded Dorsal nuclear localization, raising the question of whether these genes are direct Dorsal targets. Additionally, we show that Dorsal levels change in time during embryogenesis such that a steady state is not reached. These results suggest that the multiple gene expression outputs observed along the DV axis do not simply reflect a steady-state Dorsal nuclear gradient. Instead, we propose that the Dorsal gradient supplies positional information throughout nuclear cycles 10-14, providing additional evidence for the idea that compensatory combinatorial interactions between Dorsal and other factors effect differential gene expression along the DV axis.

Liberman, Louisa M.; Reeves, Gregory T.; Stathopoulos, Angelike

2009-01-01

420

A Sparse Representation-Based Algorithm for Pattern Localization in Brain Imaging Data Analysis  

PubMed Central

Considering the two-class classification problem in brain imaging data analysis, we propose a sparse representation-based multi-variate pattern analysis (MVPA) algorithm to localize brain activation patterns corresponding to different stimulus classes/brain states respectively. Feature selection can be modeled as a sparse representation (or sparse regression) problem. Such technique has been successfully applied to voxel selection in fMRI data analysis. However, single selection based on sparse representation or other methods is prone to obtain a subset of the most informative features rather than all. Herein, our proposed algorithm recursively eliminates informative features selected by a sparse regression method until the decoding accuracy based on the remaining features drops to a threshold close to chance level. In this way, the resultant feature set including all the identified features is expected to involve all the informative features for discrimination. According to the signs of the sparse regression weights, these selected features are separated into two sets corresponding to two stimulus classes/brain states. Next, in order to remove irrelevant/noisy features in the two selected feature sets, we perform a nonparametric permutation test at the individual subject level or the group level. In data analysis, we verified our algorithm with a toy data set and an intrinsic signal optical imaging data set. The results show that our algorithm has accurately localized two class-related patterns. As an application example, we used our algorithm on a functional magnetic resonance imaging (fMRI) data set. Two sets of informative voxels, corresponding to two semantic categories (i.e., “old people” and “young people”), respectively, are obtained in the human brain.

He, Lin; Lu, Haidong; Gu, Zhenghui; Sun, Pei

2012-01-01

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