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brazilian symposium on computer graphics and image processing (SIBGRAPI)

作者： Francisco Ganacim Luiz Henrique Figueiredo Diego Nehab IMPA-Instituto Nacional de Matemática Pura e Aplicada Rio de Janeiro Brazil

We present a GPU-based beam-casting method for rendering implicit surfaces in real time with antialiasing. We use interval arithmetic to model the beams and to detect their intersections with the surface. We show how beams can be used to quickly discard large empty regions in the image, thus leading to a fast adaptive subdivision method.

关键词： graphics processing unit Rendering (computer graphics) Surface treatment Casting Instruction sets Ray tracing image color analysis

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COLON FOLD CONTOUR ESTIMATION FOR 3D VISUALIZATION OF COLON STRUCTURE FROM 2D COLONOSCOPY imageS

COLON FOLD CONTOUR ESTIMATION FOR 3D VISUALIZATION OF COLON ...

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8th IEEE International symposium on Biomedical Imaging (ISBI) - From Nano to Macro

作者： Hong, DongHo Tavanapong, Wallapak Wong, Johnny Oh, JungHwan de Groen, Piet C. Iowa State Univ Dept Comp Sci Ames IA 50011 USA Univ North Texas Dept Comp Sci & Engn Denton TX 76203 USA Mayo Clin Coll Med Mayo Clin Rochester MN 55905 USA

ISBN: (纸本)9781424441280

This paper presents a novel colon fold contour estimation technique, a crucial step toward fully-automated reconstruction of a 3D colon segment from an image captured from colonoscopy for automated labeling of unseen mucosa areas (where polyps or abnormal lesions may reside) during colonoscopy. The endoscopist can then manipulate the endoscope to inspect these unseen areas. The proposed technique estimates colon fold contours taking advantage of both computer graphics and image processing. The algorithm detects edges of the colon folds, filters noise edges, pairs edges from the same colon fold, and finally completes the contours. The completed colon fold contours and pixel properties around the contours are used to reconstruct a 3D virtual colon segment. We evaluate recall and precision of the algorithm and similarity between algorithm estimated fold contours and manually drawn fold contours.

关键词： Colonocopy colon structure 3D reconstruction 3D Visualization image processing

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Multi-camera calibration based on an invariant pattern

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computerS & graphics-UK 2011年第2期35卷 198-207页

作者： Loaiza, Manuel E. Raposo, Alberto B. Gattass, Marcelo Pontifical Catholic Univ Rio de Janeiro Dept Informat Tecgraf Comp Graph Technol Grp Rio De Janeiro Brazil

In this paper we present a method for the calibration of multiple cameras based on the extraction and use of the physical characteristics of a one-dimensional invariant pattern which is defined by four collinear markers. The advantages of this kind of pattern stand out in two key steps of the calibration process. In the initial step of camera calibration methods, related to sample points capture, the proposed method takes advantage of using a new technique for the capture and recognition of a robust sample of projective invariant patterns, which allows to capture simultaneously more than one invariant pattern in the tracking area and recognize each pattern individually as well as each marker that composes them. This process is executed in real time while capturing our sample of calibration points in the cameras of our system. This new feature allows to capture a more numerous and robust set of sample points than other patterns used for multi-camera calibration methods. In the last step of the calibration process, related to camera parameters' optimization, we explore the collinearity feature of the invariant pattern and add this feature in the camera parameters optimization model. This approach obtains better results in the computation of camera parameters. We present the results obtained with the calibration of two multi-camera systems using the proposed method and compare them with other methods from the literature. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： processing image Structure from motion Camera calibration Projective invariant patterns computer vision

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High Level computer Vision Using OpenCV

High Level Computer Vision Using OpenCV

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Tutorials of the brazilian symposium on computer graphics and image processing (SIBGRAPI TUTORIALS)

作者： Mauricio Marengoni Denise Stringhini Faculdade de Computação e Informática Universidade Presbiteriana Mackenzie Sao Paulo Brazil

This paper presents some more advanced topics in image processing and computer vision, such as Principal Components Analysis, Matching Techniques, Machine Learning Techniques, Tracking and Optical Flow and Parallel computer Vision using CUDA. These concepts will be presented using the open CV library, which is a free computer vision library for C/C++ programmers available for Windows, Linux Mac OS and Android platforms. These topics will be covered considering not only theoretical aspects but practical examples will be presented in order to understand how and when to use each of them.

关键词： computer vision Correlation image segmentation Pattern recognition image edge detection Histograms Feature extraction

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Screen-space bias compensation for interactive high-quality global illumination with virtual point lights 11

Screen-space bias compensation for interactive high-quality ...

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symposium on Interactive 3D graphics and Games

作者： Novák, Jan Engelhardt, Thomas Dachsbacher, Carsten Computer Graphics Group Karlsruhe Institute of Technology Germany

ISBN: (纸本)9781450305655

In this paper we present a method that targets high-quality global illumination at interactive frame rates. As many techniques in this context, our method is based on instant radiosity, which represents the indirect illumination in a scene with a set of virtual point lights, and therefore enables efficient GPU rendering. Instant radiosity captures light transport over larger distances well, but it requires clamping of the point lights' contribution to avoid bright splotches on nearby surfaces. By bounding the short distance light transport, the algorithm removes some energy and thus introduces bias, that is visible as incorrect darkening near edges and corners. Our method improves the quality and correctness of the rendered images by removing bias using a hierarchical screen space approach. We show that the bias compensation can be formulated as a post-processing step and demonstrate renderings comparable to results from offline algorithms at interactive speed. Copyright © 2011 by the Association for Computing Machinery, Inc.

关键词： image enhancement

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A Survey of computer graphics and graphics image processing Technology

A Survey of Computer Graphics and Graphics Image Processing ...

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International symposium on Intelligence Information processing and Trusted Computing (IPTC)

作者： Haoyong Lv Zhihong Wu Network center Huanggang normal university Huanggang China College of Computer Science Huanggang normal university Huanggang China

Introduce the research contents of computer graphics research, development history, composition and function of the graphics system, applications and implementation of realistic graphics technology, generalize the gra... 详细信息

关键词： computer graphics computers Computational modeling Solid modeling image processing Surface treatment

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GPGPU acceleration algorithm for medical image reconstruction

GPGPU acceleration algorithm for medical image reconstructio...

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9th IEEE International symposium on Parallel and Distributed processing with Applications, ISPA 2011

作者： Archirapatkave, Virasin Sumilo, Hendra See, Simon Chong Wee Achalakul, Tiranee Department of Computer Engineering King Mongkut's University of Technology Thonburi Thailand Department of Mechanical and Aerospace Engineering Nanyang Technological University Singapore Singapore Nvidia Corporation Singapore Singapore

ISBN: (纸本)9780769544281

Medical imaging techniques such as X-ray, Ultrasound, CT and MRI scan are widely used for diagnosis. The 2D medical images from these scans are difficult to interpret because they can only show cross section views of a human body. Interpreting these images requires experts or trained professionals. Reconstructing 2D images into 3D models can help with the interpretation process. However, such model reconstruction is normally time-consuming and costly. It requires high performance computation, such as grid or parallel computing. This research, thus, proposes a high performance 3D reconstruction method using the General-Purpose computation on graphics processing Units (GPGPU). The GPGPU has a high computational performance. Parallel computing method on GPU can thus regenerate a model for real-time 3D visualization. In other words, the GPU computational speed sufficiently improves the visualization effectiveness of both images and models to the point where a real-time navigation of the data set is possible. In our work, the 3D reconstruction process reconstructs a set of 2D cross-section images and stacks them to generate a volume data, and then transform them into a 3D model. The generated models are then displayed on the user interface developed with OpenGL. Finally, the performance of the GPU acceleration is presented in this paper. © 2011 IEEE.

关键词： graphics processing unit

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Fast Inverse Halftoning Algorithm for Ordered Dithered images

Fast Inverse Halftoning Algorithm for Ordered Dithered Image...

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brazilian symposium on computer graphics and image processing (SIBGRAPI)

作者： Pedro Freitas Mylene Farias Aleteia Araujo Department of Computer Science University of Brasília (UnB) Brasília Brazil

In this paper, we present a simple and fast inverse half toning algorithm, targeted at reconstructing half toned images generated using dispersed-dot ordered dithering algorithms. The proposed algorithm uses a simple set of linear filters combined with a stochastic model in order to predict the best intensity values for the binary image pixels. The algorithm produces images with a better perceptual quality than the available algorithms in the literature, preserving most of the fine details of the original gray-level image. It has a high performance, which can be further improved with the use of parallelization techniques.

关键词： image reconstruction Prediction algorithms PSNR Measurement Clustering algorithms Hurricanes Signal processing algorithms

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FAST PARAMETRIZED VOLUMETRIC DTI TRACT PARCELLATION

FAST PARAMETRIZED VOLUMETRIC DTI TRACT PARCELLATION

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8th IEEE International symposium on Biomedical Imaging (ISBI) - From Nano to Macro

作者： Ho, Hon Pong Harwood, Catherine G. Staib, Lawrence H. Yale Univ Dept Biomed Engn New Haven CT 06520 USA

ISBN: (纸本)9781424441280

A fast method is proposed for DTI neural tract extraction and visualization. Existing efficient tract extraction approaches are based on localizing fibers from a pre-computed whole brain tractography. However, the tracking parameters of pre-computed fibers cannot be easily adjusted quickly. Moreover, high noise in the estimated orientation around crossing and neighboring tracts often diverts fibers away from desired pathways. Therefore, insufficient numbers of localized fibers decreases the quality of the tract visualization and also makes surface reconstruction difficult. Our method constructs a tract surface by considering tensor orientation along and around a single or double-seeded streamline and quickly expands it to a parametric surface. A noise reduction surface filter is applied to the parametric surface to provide a smooth surface rendering. Our method is particularly useful in areas of dense tracts such as the brainstem.

关键词： Biomedical imaging Diffusion tensor imaging Surface reconstruction Tensile stress Three dimensional displays Trajectory biodiffusion biomedical MRI brain brainstem double-seeded streamline fast parametrized volumetric DTI tract parcellation feature extraction image denoising image reconstruction medical image processing neural tract extraction noise reduction surface filter precomputed whole brain tractography rendering (computer graphics) single-seeded streamline smooth surface rendering surface reconstruction tensor orientation tract visualization

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Interactive Seismic Interpretation with Piecewise Global Energy Minimization

Interactive Seismic Interpretation with Piecewise Global Ene...

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4th IEEE Pacific Visualization symposium

作者： Hoellt, Thomas Beyer, Johanna Gschwantner, Fritz Muigg, Philipp Doleisch, Helmut Heinemann, Gabor Hadwiger, Markus King Abdullah Univ Sci & Technol Thuwal Saudi Arabia VRVis Res Ctr Vienna Austria SimVis GmbH Vienna Austria Heinemann OiL GmbH Leoben Austria

ISBN: (纸本)9781612849324

Increasing demands in world-wide energy consumption and oil depletion of large reservoirs have resulted in the need for exploring smaller and more complex oil reservoirs. Planning of the reservoir valorization usually starts with creating a model of the subsurface structures, including seismic faults and horizons. However, seismic interpretation and horizon tracing is a difficult and error-prone task, often resulting in hours of work needing to be manually repeated. In this paper, we propose a novel, interactive workflow for horizon interpretation based on well positions, which include additional geological and geophysical data captured by actual drillings. Instead of interpreting the volume slice-by-slice in 2D, we propose 3D seismic interpretation based on well positions. We introduce a combination of 2D and 3D minimal cost path and minimal cost surface tracing for extracting horizons with very little user input. By processing the volume based on well positions rather than slice-based, we are able to create a piecewise optimal horizon surface at interactive rates. We have integrated our system into a visual analysis platform which supports multiple linked views for fast verification, exploration and analysis of the extracted horizons. The system is currently being evaluated by our collaborating domain experts.

关键词： I.3.8 [Computing Methodologies]: computer graphics-Applications I.4.6 [image processing and computer Vision]: Segmentation-Edge and feature detection

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