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arXiv 2018年

作者： Alsolami, Ibrahim Heidrich, Wolfgang Visual Computing Center KAUST

This paper addresses the problem of imaging in the presence of diffraction-photons. Diffraction-photons arise from the low contrast-ratio of DMDs (1000 : 1), and very much degrade the quality of images captured by SPAD-based systems. Herein, a joint illumination/deconvolution scheme is designed to overcome diffraction-photons, enabling the acquisition of intensity and depth images. Additionally, a proof-of-concept experiment is conducted to demonstrate the viability of the designed scheme. It is shown that by co-designing the illumination and deconvolution phases of imaging, one can substantially overcome diffraction-photons. Copyright © 2018, The Authors. All rights reserved.

关键词： Computational Imaging

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Creating optimal code for GPU-accelerated CT reconstruction using ant colony optimization

Creating optimal code for GPU-accelerated CT reconstruction ...

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作者： Papenhausen, Eric Zheng, Ziyi Mueller, Klaus Computer Science Department Center of Visual Computing Stony Brook University Stony Brook NY 11794-4400 United States

Purpose: CT reconstruction algorithms implemented on the GPU are highly sensitive to their implementation details and the hardware they run on. Fine-tuning an implementation for optimal performance can be a time consuming task and require many updates when the hardware changes. There are some techniques that do automatic fine-tuning of GPU code. These techniques, however, are relatively narrow in their fine-tuning and are often based on heuristics which can be inaccurate. The goal of this paper is to present a framework that will automate the process of code optimization with maximum flexibility and produce a final result that is efficient and readable to the user. Methods: The authors propose a method that is able to tune high level implementation details by using the ant colony optimization algorithm to find the optimal implementation in a relatively short amount of time. Our framework does this by taking as input, a file that describes a graph, such that a path through this graph represents a potential implementation. They then use the ant colony optimization algorithm to find the optimal path through this graph based on the execution time and the quality of the image. Results: Two experimental studies are carried out. Using the presented framework, they optimize the performance of a GPU accelerated FDK backprojection implementation and a GPU accelerated separable footprint backprojection implementation. The authors demonstrate that the resulting optimal implementation can be different depending on the hardware specifications. They then compare the results of the framework produced with the results produced by manual optimization. Conclusions: The framework they present is a useful tool for increasing programmer productivity and reducing the overhead of leveraging hardware specific resources. By performing an intelligent search, our framework produces a more efficient image reconstruction implementation in a shorter amount of time. © 2013 American Association of

关键词： Ant colony optimization

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Statistical finite element model for bone shape and biomechanical properties

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9th International Conference on Medical Image computing and Computer-Assisted Intervention, MICCAI 2006

作者： Querol, Laura Belenguer Büchler, Philippe Rueckert, Daniel Nolte, Lutz P. Gonzaález Ballester, Miguel Aá. MEM Research Center University of Bern Switzerland Visual Information Processing Department of Computing Imperial College London United Kingdom

ISBN: (纸本)3540447075

We present a framework for statistical finite element analysis combining shape and material properties, and allowing performing statistical statements of biomechanical performance across a given population. In this paper, we focus on the design of orthopaedic implants that fit a maximum percentage of the target population, both in terms of geometry and biomechanical stability. CT scans of the bone under consideration are registered non-rigidly to obtain correspondences in position and intensity between them. A statistical model of shape and intensity (bone density) is computed by means of principal component analysis. Afterwards, finite element analysis (FEA) is performed to analyse the biomechanical performance of the bones. Realistic forces are applied on the bones and the resulting displacement and bone stress distribution are calculated. The mechanical behaviour of different PCA bone instances is compared. © Springer-Verlag Berlin Heidelberg 2006.

关键词： Bone

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Fitting boxes to Manhattan scenes using linear integer programming

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International Journal of Digital Earth 2016年第8期9卷 806-817页

作者： Minglei Li Liangliang Nan Shaochuang Liu Integrated Spatial Information Lab Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijingPeople’s Republic of China Visual Computing Center King Abdullah University of Science and TechnologyThuwalSaudi Arabia

We propose an approach for automatic generation of building models by assembling a set of boxes using a Manhattan-world *** method first aligns the point cloud with a per-building local coordinate system,and then fits axis-aligned planes to the point cloud through an iterative regularization *** refined planes partition the space of the data into a series of compact cubic cells(candidate boxes)spanning the entire 3D space of the input *** then choose to approximate the target building by the assembly of a subset of these candidate boxes using a binary linear programming *** objective function is designed to maximize the point cloud coverage and the compactness of the final ***,all selected boxes are merged into a lightweight polygonal mesh model,which is suitable for interactive visualization of large scale urban *** results and a comparison with state-of-the-art methods demonstrate the effectiveness of the proposed framework.

关键词： Urban building models aerial point cloud Manhattan scenes linear integer programming

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GPU cluster for high performance computing 04

GPU cluster for high performance computing

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2004 ACM/IEEE Conference on Supercomputing, SC 2004

作者： Fan, Zhe Qiu, Feng Kaufman, Arie Yoakum-Stover, Suzanne Center for Visual Computing Department of Computer Science Stony Brook University Stony BrookNY11794-4400 United States

ISBN: (纸本)0769521533

Inspired by the attractive Flops/dollar ratio and the incredible growth in the speed of modern graphics processing units (GPUs), we propose to use a cluster of GPUs for high performance scientific computing. As an example application, we have developed a parallel flow simulation using the lattice Boltzmann model (LBM) on a GPU cluster and have simulated the dispersion of airborne contaminants in the Times Square area of New York City. Using 30 GPU nodes, our simulation can compute a 480x400x80 LBM in 0.31 second/step, a speed which is 4.6 times faster than that of our CPU cluster implementation. Besides the LBM, we also discuss other potential applications of the GPU cluster, such as cellular automata, PDE solvers, and FEM. © 2004 IEEE.

关键词： Computational fluid dynamics

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Database-assisted low-dose CT image restoration

Database-assisted low-dose CT image restoration

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作者： Xu, Wei Ha, Sungsoo Mueller, Klaus Center of Visual Computing Computer Science Department Stony Brook University Stony Brook NY 11794-4400 United States

Purpose: Acquiring data for CT at low radiation doses has become a pressing goal. Unfortunately, the reduced data quality adversely affects the quality of the reconstructions, impeding their readability. In previous work, the authors showed how a prior regular-dose scan of the same patient can efficiently be used to mitigate low-dose artifacts. However, since a prior is not always available, the authors now extend the authors' method to use a database of images of other patients. Methods: The authors' framework first matches the low-dose (target) scan with the images in the database and then selects a set of images that contain anatomical content similar to the target. These "priors" are then registered to the target and form the set of regular-dose priors for restoration via an extended nonlocal means (NLM) filtering framework. To accommodate the larger spatial variability of the patient scans, the authors subdivide the image area into blocks and perform the filtering locally. The database itself is first preprocessed to map each image from its 2D image space to a corresponding high-D image feature space. From this encoding a visual vocabulary is learned that assists in the query of the database. Results: The authors demonstrate the authors' framework via a lung scan example, for both streak artifacts (resulting from smaller projection sets) as well as noise artifacts (resulting from lower mA settings). The authors find that in the authors' particular example case three priors were sufficient to restore all features faithfully. The authors also observe that the authors' method is quite robust in that it generates good results even when the noise conditions significantly worsen (here by 20%). Finally, the authors find that the restoration quality is significantly better than with conventional NLM filtering. Conclusions: The authors image restoration algorithm successfully restores images to high quality when the registration is well performed and also when the prior

关键词： Image reconstruction

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Aging prediction of cultural heritage samples based on surface microgeometry

Aging prediction of cultural heritage samples based on surfa...

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2018 Eurographics Workshop on Graphics and Cultural Heritage, GCH 2018

作者： Ciortan, I.M. Marchioro, G. Daffara, C. Pintus, R. Gobbetti, E. Giachetti, A. Computer Science Department University of Verona Italy Visual Computing Group Center for Advanced Studies Research and Development in Sardinia Italy

ISBN: (纸本)9783038680574

A critical and challenging aspect for the study of Cultural Heritage (CH) assets is related to the characterization of the materials that compose them and to the variation of these materials with time. In this paper, we exploit a realistic dataset of artificially aged metallic samples treated with different coatings commonly used for artworks' protection in order to evaluate different approaches to extract material features from high-resolution depth maps. In particular, we estimated, on microprofilometric surface acquisitions of the samples, performed at different aging steps, standard roughness descriptors used in materials science as well as classical and recent image texture descriptors. We analyzed the ability of the features to discriminate different aging steps and performed supervised classification tests showing the feasibility of a texture-based aging analysis and the effectiveness of coatings in reducing the surfaces' change with time. © 2018 GCH 2018 - Eurographics Workshop on Graphics and Cultural Heritage. All rights reserved.

关键词： Coatings

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Surface reconstruction using oriented charges

Surface reconstruction using oriented charges

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Computer Graphics International 2005, CGI 2005

作者： Wang, Jianning Oliveira, Manuel M. Xie, Hui Kaufman, Arie E. Center of Visual Computing Computer Science Stony Brook University United States Instituto de Informática UFRGS Brazil

ISBN: (纸本)0780393309

We introduce the notion of oriented charges to compute distance fields from unorganized point clouds. Unlike traditional implicit function methods that usually require normal information, our approach only uses information about the position of the samples. Our approach is adaptive, using an octree to reorganize the input points, thus avoiding difficulties often associated with the use of local distance fields. The resulting representation is simple, efficient and general in the sense that it handles complex models of arbitrary topology, is robust in the presence of noise and fills holes automatically. © 2005 IEEE.

关键词： Image reconstruction

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Color design for illustrative visualization

Color design for illustrative visualization

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作者： Wang, Lujin Giesen, Joachim McDonnell, Kevin T. Zolliker, Peter Mueller, Klaus Center of Visual Computing Stony Brook University Dowling College Friedrich-Schilller-Universität Jena EMPA Dübendorf

Professional designers and artists are quite cognizant of the rules that guide the design of effective color palettes, from both aesthetic and attention-guiding points of view. In the field of visualization, however, the use of systematic rules embracing these aspects has received less attention. The situation is further complicated by the fact that visualization often uses semi-transparencies to reveal occluded objects, in which case the resulting color mixing effects add additional constraints to the choice of the color palette. Color design forms a crucial part in visual aesthetics. Thus, the consideration of these issues can be of great value in the emerging field of illustrative visualization. We describe a knowledge-based system that captures established color design rules into a comprehensive interactive framework, aimed to aid users in the selection of colors for scene objects and incorporating individual preferences, importance functions, and overall scene composition. Our framework also offers new knowledge and solutions for the mixing, ordering and choice of colors in the rendering of semi-transparent layers and surfaces. All design rules are evaluated via user studies, for which we extend the method of conjoint analysis to task-based testing scenarios. Our framework's use of principles rooted in color design with application for the illustration of features in pre-classifled data distinguishes it from existing systems which target the exploration of continuous-range density data via perceptual color maps. © 2008 IEEE.

关键词： Color

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Spike pattern recognition by supervised classification in low dimensional embedding space

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Brain Informatics 2016年第2期3卷 73-83页

作者： Zacharaki, Evangelia I. Mporas, Iosif Garganis, Kyriakos Megalooikonomou, Vasileios Department of Computer Engineering and Informatics University of Patras Patras Greece Center for Visual Computing CentraleSupélec/Galen Team INRIA Paris France St. Luke’s Hospital Thessaloniki Greece

Epileptiform discharges in interictal electroencephalography (EEG) form the mainstay of epilepsy diagnosis and localization of seizure onset. visual analysis is rater-dependent and time consuming, especially for long-term recordings, while computerized methods can provide efficiency in reviewing long EEG recordings. This paper presents a machine learning approach for automated detection of epileptiform discharges (spikes). The proposed method first detects spike patterns by calculating similarity to a coarse shape model of a spike waveform and then refines the results by identifying subtle differences between actual spikes and false detections. Pattern classification is performed using support vector machines in a low dimensional space on which the original waveforms are embedded by locality preserving projections. The automatic detection results are compared to experts’ manual annotations (101 spikes) on a whole-night sleep EEG recording. The high sensitivity (97 %) and the low false positive rate (0.1 min−1), calculated by intra-patient cross-validation, highlight the potential of the method for automated interictal EEG assessment. © 2016, The Author(s).

关键词： Electroencephalography

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