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IEEE Radar conference - from Sensing to Information

作者： Kemkemian, Stephane Nouvel-Fiani, Myriam Thales Airborne Syst Sensors Syst Tech Directorate Elancourt France

ISBN: (纸本)9781479920358

Compressive Sensing (CS) was originally developed to directly acquire a compressed description of a sparse scene. This can be possible provided that the sampling scheme meet certain criteria. In Radar applications, the main advantage highlighted in the literature is the reduction of the data-flow between the R.F. front-end and processing that would be intractable in number of cases. However thanks to the technological progresses in fast Analog to Digital Conversion (ADC) and subsequent digital processing, the real problem is not at this level except in some special cases. The real issue is that it is not always possible to sample the radar signal ideally for practical and uncontrollable reasons. So far, most of the work in the literature has focused on the mathematical aspect of the underlying L1 inverse problem. This paper shows some examples where the use of sparse or incomplete sampling is really justified. We also show that the inverse problem resolution based on the minimization of the L1 norm, even if it is elegant way to solve the problem, is not the only means to address the problem.

关键词： image reconstruction Noise Radar imaging Sensors Synthetic aperture radar vectors Inverse method Synthetic aperture radar Cloning vectors radar image reconstruction front-ends Sensors Noise Analog-digital conversion Radar applications Compressed sensing Radar imaging

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A topological sampling theorem for Robust boundary reconstruction and image segmentation

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DISCRETE APPLIED MATHEMATICS 2009年第3期157卷 524-541页

作者： Meine, Hans Koethe, Ullrich Stelldinger, Peer Univ Hamburg Cognit Syst Lab D-22527 Hamburg Germany Heidelberg Univ D-69120 Heidelberg Germany

Existing theories on shape digitization impose strong constraints on admissible shapes, and require error-free data. Consequently, these theories are not applicable to most real-world situations. In this paper, we propose a new approach that overcomes many of these limitations. It assumes that segmentation algorithms represent the detected boundary by a set of points whose deviation from the true contours is bounded. Given these error bounds, we reconstruct boundary connectivity by means of Delaunay triangulation and alpha-shapes. We prove that this procedure is guaranteed to result in topologically correct image segmentations under certain realistic conditions. Experiments on real and synthetic images demonstrate the good performance of the new method and confirm the predictions of our theory. (c) 2008 Elsevier B.v. All rights reserved.

关键词： Alpha-shapes Geometric sampling theorem Delaunay triangulation Edgel linking Topology preservation

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Towards reconstructing HDR light fields by combining 2D and 3D CNN architectures 4

Towards reconstructing HDR light fields by combining 2D and ...

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conference on Big data Iv - Learning, Analytics, and Applications

作者： Guindy, Mary Kiran, Adhikarla, v Kara, Peter A. Balogh, Tibor Simon, Aniko Holografika Budapest Hungary Pazmany Peter Catholic Univ Budapest Hungary Budapest Univ Technol & Econ Budapest Hungary Kingston Univ London England Sigma Technol Budapest Hungary

ISBN: (纸本)9781510650718;9781510650701

High dynamic range imaging has become a technological trend in the past couple of decades, particularly through its integration into many applications. Numerous attempts were made to reconstruct HDR images from low-dynamic-range data. Such reconstruction techniques can be classified into single-camera and multi-camera approaches. Single-camera setups are less expensive, yet multi-camera setups are more efficient. At the time of this paper, there is already a great number of algorithms for single-camera HDR image reconstruction, but there are only a few for HDR video reconstruction. The latter takes into account the temporal coherence between consecutive video frames, leading to better results. For light field images, this remains a challenging open issue, as the HDR video reconstruction methods do not work as efficiently for light field images as HDR image reconstruction algorithms do. However, analogously to 2D videos, where consecutive frames have temporal coherence, many similarities can be found between the adjacent views of light field contents. In this paper, we investigate the theoretical possibilities of combining CNN architectures utilized for HDR images and videos, in order to enhance the outputs of HDR light field image reconstruction. The concept of our work is to exploit the similarities between light field images since they all visualize the same scene from different angular perspectives.

关键词： CNN architecture light field imaging light field reconstruction HDR

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Advances in 3-D frequency domain fluorescence tomography

Advances in 3-D frequency domain fluorescence tomography

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conference on Optical Tomography and Spectrosopy of Tissue v

作者： Eppstein, MJ Zhang, CY Godavarty, A Sevick-Muraca, EM Univ Vermont Dept Comp Sci Burlington VT 05405 USA

ISBN: (纸本)0819447552

We present results of ongoing research in 3-D fluorescence tomography on large clinically-relevant tissue-mimicking domains. Finite element predictions of excitation and emission phase shift and amplitude attenuation are compared to experimental data from both column-shaped and breast-shaped tissue mimicking phantoms containing embedded fluorophore;system noise and measurement noise are characterized and utilized in image reconstruction using the Bayesian APPRIZE algorithm.

关键词： fluorescence imaging optical tomography Bayesian image reconstruction

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Automatic reconstruction of 3D urban landscape by computing connected regions and assigning them an average altitude from LiDAR point cloud image 5

Automatic reconstruction of 3D urban landscape by computing ...

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conference on Earth Resources and Environmental Remote Sensing/GIS Applications v

作者： Kawata, Yoshiyuki Koizumi, Kouhei Kanazawa Inst Technol Res Lab Affect Design Engn Hakusan City Ishikawa 9240838 Japan

ISBN: (纸本)9781628413083

The demand of 3D city modeling has been increasing in many applications such as urban planing, computer gaming with realistic city environment, car navigation system with showing 3D city map, virtual city tourism inviting future visitors to a virtual city walkthrough and others. We proposed a simple method for reconstructing a 3D urban landscape from airborne LiDAR point cloud data. The automatic reconstruction method of a 3D urban landscape was implemented by the integration of all connected regions, which were extracted and extruded from the altitude mask images. These mask images were generated from the gray scale LiDAR image by the altitude threshold ranges. In this study we demonstrated successfully in the case of Kanazawa city center scene by applying the proposed method to the airborne LiDAR point cloud data.

关键词： automatic 3D modeling urban landscape modeling LiDAR point cloud

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Simultaneous reconstruction of Absorbed Optical Energy Density and Speed of Sound Distributions in Photoacoustic Computed Tomography

Simultaneous Reconstruction of Absorbed Optical Energy Densi...

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conference on Photons Plus Ultrasound: Imaging and Sensing

作者： Huang, Chao Wang, Kun Schoonover, Robert W. Wang, Lihong v. Anastasio, Mark A. Washington Univ Dept Biomed Engn St Louis MO 63130 USA

ISBN: (纸本)9780819498564

An important and interesting question in photoacoustic computed tomography (PACT) is whether the absorbed optical energy density distribution, A(r), and the speed of sound distribution, c(r), can both be accurately determined from the measured photoacoustic data alone. However, in many cases c(r) is unknown or cannot be accurately estimated. Therefore, it would be practically beneficial if A(r) and c(r) can be jointly reconstructed from the measurements. In this work, we propose a reconstruction approach to the joint reconstruction of both properties in PACT.

关键词： Photoacoustic tomography optoacoustic tomography thermoacoustic tomography iterative image reconstruction

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3D mosaicing for environment reconstruction

3D mosaicing for environment reconstruction

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15th International conference on Pattern Recognition (ICPR-2000)

作者： Murino, v Fusiello, A Iuretigh, N Puppo, E Univ Verona Dip Sci & Tecnol I-37100 Verona Italy

ISBN: (纸本)0769507514

This paper proposes a technique for the three-dimensional reconstruction of an underwater environment from multiple range views. The final target of the work lies in improving the understanding of a human operator guiding an underwater remotely operated vehicle (ROv) equipped with an acoustic camera, which provides a sequence of 3D images in real time. Since the field of view is narrow, we devise a technique for the reconstruction of relevant information of the image sequence up to build a mosaic of the surrounding scene. Due to the very noisy nature of the data and the low range resolution, smoothing, segmentation, registration, and fusion problems have been tackled. Examples on real images have been presented to show the promising performances of the algorithm.

关键词： image enhancement

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Improving PET sensitivity with a Compton algorithm

Improving PET sensitivity with a Compton algorithm

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International conference on Bio-Medical Instrumentation and related Engineering and Physical Sciences (BIOMEP)

作者： Ilisie, v. Gimenez-Alventosa, v. Moliner, L. Aguilar, A. Lamprou, E. Gonzalez, A. Sanchez, F. Benlloch, J. M. Univ Politecn Valencia Ctr Mixto CSIC Inst Instrumentac Imagen Mol I3M Camino Vera S-N Valencia Spain

Current PET detectors have a very low sensitivity, of the order of a few percent. One of the reasons is that Compton events are being rejected. In this work we aim to prove that Compton events are a very rich source of additional information that can play a crucial role in the image reconstruction process. With this additional data, the detector sensitivity will be substantially improved and thus, the applied dose on the patient can also be reduced. This could be a really breaking point for PET detector technology as one should be able to obtain better image quality with less patient radiation. By means of Compton cone matching (the Compton cones coming from the same event should be compatible) one should be able to better recognize matching events and discard randoms and even events that have previously suffered scattering within the patient's body.

关键词： image reconstruction

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The Quantitative Accuracy and Efficiency of the Dual reconstruction Scheme Including a Practical Scatter/Random Approximation in Dynamic PET Imaging

The Quantitative Accuracy and Efficiency of the Dual Reconst...

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15th International Workshop on Room-Temperature Semiconductor X- and Gamma-Ray Detectors/ 2006 IEEE Nuclear Science Symposium

作者： Cheng, Ju-Chieh (Kevin) Rahmim, Arman Blinder, Stephan Dinelle, Katherine Sossi, vesna Univ British Columbia Dept Phys & Astron Vancouver BC V6T 1Z1 Canada Johns Hopkins Univ Sch Med Dept Radiol Baltimore MD 21205 USA Pacific Parkinsons Res Ctr Vancouver BC V6T 1Z1 Canada

ISBN: (纸本)9781424405619

We describe a time-efficient reconstruction scheme with a practical approximate scatter and random correction for dynamic PET imaging on scanners with large data sets such as the High Resolution Research Tomograph (HRRT). This dual (histogram/list-mode) reconstruction scheme makes use of the efficiency advantage of both histogram and list-mode reconstructions (i.e. histogram-mode reconstruction is applied to the dynamic frames with a large number of counts, and list-mode reconstruction is applied to the frames with a low number of counts). The practical scatter and random approximation technique is based on a time averaged scatter and random estimate followed by scaling according to the global numbers of true and random events for each temporal frame. The quantitative accuracy of this dual reconstruction scheme including the scatter and random approximation was examined by comparing the time activity curves (TAC) obtained from the images reconstructed using the conventional histogram-mode algorithm and those obtained from applying the dual reconstruction scheme with the practical approximation. A representative dynamic C-11 non-human primate study with 14 temporal frames is presented here, and an excellent agreement between the conventional and the proposed scheme was found, while an overall gain of about 35% in time (which depends on the number of dynamic frames;the more frames with a similar spatial activity distribution there are, the more time we gain) and an over 4 times less storage cost for the scatter and random data sets (sinograms) was achieved in this case.

关键词： image reconstruction

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Experimental investigation of target and transducer effects on quantitative image reconstruction in photoacoustic tomography

Experimental investigation of target and transducer effects ...

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8th conference on Biomedical Thermoacoustics, Optoacoustics and Acousto-optics

作者： Gamelin, John Aguirre, Andres Huang, Fei Maurudis, Anastasios Castillo, Diego Wang, Lihong v. Zhu, Quing Univ Connecticut Dept Elect Engn Storrs CT 06269 USA Washington Univ Dept Biomed Engn St Louis MO 63130 USA

ISBN: (纸本)9780819465504

In principle, absorbed energy profiles can be exactly reconstructed from photoacoustic measurements on a closed surface. Clinical applications, however, involve compromises due to transducer focus, frequency characteristics, and incomplete measurement apertures. These tradeoffs introduce artifacts and errors in reconstructed absorption distributions that affect quantitative interpretations as well as qualitative contrast between features. The quantitative effects of target geometry, limited measurement surfaces, and bandpass transducer frequency response have been investigated using a ring transducer system designed for small animal imaging. The directionality of photoacoustic radiation is shown to increase with target aspect ratio, producing proportionate overestimates of absorption values for two-dimension apertures less than approximately 150 degrees. For all target geometries and orientations, mean absorption values approach the full view values for hemicircular measurement surfaces although the true spatial uniformity is recovered only with the complete surface. The bandpass transducer frequency spectrum produces a peaked amplitude response biased toward spatial features ranging from 1 to 8 times the system resolution. We discuss the implications of these results for design of clinical systems.

关键词： photoacoustic tomography limited view tomography clinical image reconstruction quantitative imaging array transducers

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