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15th brazilian symposium on computer graphics and image processing

作者： Aranha, CC Carvalho, SR Gonçalvez, LMG Univ Estadual Campinas BR-13083970 Campinas SP Brazil

ISBN: (纸本)076951846X

We introduce concepts and algorithms for control of visual motor commands and realistic simulation of basic abilities as visual servoing and perception for robotics simulation. the introduced tools can also be used in a straightforward way to build computer animated devices as virtual agents, and avatars. We use the tools to build part of a humanoid (arms and head) robot, effectively named "C (a) over cap mbio". We will describe C (a) over cap mbio's design, providing an overview on the most used feature extraction techniques for perception, discussing implementation issues. We intend to show the usefulness of a simulated platform as an inexpensive alternative for testing and developing computer vision algorithms in real-time robotics applications and its possible extensions to computer animated agents and avatars.

关键词： Visual servoing

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On determining a signature for skeletal maturity 14

On determining a signature for skeletal maturity

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14th brazilian symposium on computer graphics and image processing

作者： da Silva, AMM Olabarriaga, SD Dietrich, CA Schmitz, CAA Univ Fed Santa Maria CCNE Dept Fis BR-97105900 Santa Maria RS Brazil

ISBN: (纸本)0769513301

In this paper we present a computational framework for semi-automated assessment of skeletal age based on a multi-scale image analysis approach. through 2D digital X-ray images of the left hand, maturity indicators are searched by means of a two-step process: the user interactively indicates a point inside the middle finger, and the computational method analyzes the image intensity profile, along this line, searching for physiological signatures related to different epiphyseal events (ossification, cartilage stage, early fusion and complete fusion). A scale-space approach is used to select the best scale to enhance the edges between the bones and soft tissues. Initial results indicate that this approach could be useful to facilitate the analysis of growth disorders in pediatrics.

关键词： image analysis

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A parallel engine for graphical interactive molecular dynamics simulations

A parallel engine for graphical interactive molecular dynami...

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16th symposium on computer Architecture and High Performance Computing

作者： Rodrigues, ER Preto, AJ Stephany, S INPE Brazilian Inst Space Res Postgrad Program Appl Comp Sao Jose Dos Campos Brazil

ISBN: (纸本)0769522408

the current work proposes a parallel implementation for interactive molecular dynamics simulations (MD). the interactive capability is modeled by finite automata that are executed in the processing nodes. Any interaction implies in a communication between the user interface and the finite automata. the ADKS, an interactive sequential MD code that provides graphical output was chosen as a case study. A parallel version of this code was developed using the MPI cummunication library to check its parallel performance without/with visualization. Performance results are discussed for both cases and the influence of visualization in the performance is also treated, including image update rate. In order to allow a modular approach, a new parallel version of the ADKS is being implemented employing the PyMPI Python extension.

关键词： Parallel processing systems

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three-dimensional reconstruction of urban scenes from a single image 15

Three-dimensional reconstruction of urban scenes from a sing...

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15th brazilian symposium on computer graphics and image processing

作者： Policarpo, F Azevedo, E Conci, A Paralelo Comp BR-24230191 Niteroi RJ Brazil

ISBN: (纸本)076951846X

this work presents a method to output the 3D structure of an urban area from only one aerial photo. the reconstruction is based on the inverse process done when a parallel projection is used to construct a two-dimensional image from a three-dimensional object. A new algorithm for reconstruction is developed and implemented. It recovers depth information by identification of object height on the image plane. While the 3D-objects are reconstructed, their original texture is used for rendering, using control points defined by the user. Results show that when seen from the same capture angle, the virtual 3D scene and the original picture are exactly the same. In the virtual environment of this implementation, the user can visualize, visit and interact with the structure of the 3D scenario. the spatial structure of the real world is recovered at real time;it is possible to see the 3D growing out of the 2D images.

关键词： Virtual reality

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Polygonization of volumetric reconstructions from silhouettes

Polygonization of volumetric reconstructions from silhouette...

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19th brazilian symposium on computer graphics and image processing (SIBGRAPI 2006)

作者： Montenegro, Anselmo Antunes Velho, Luiz Carvalho, Paulo C. P. Sossai, Jonas, Jr. Univ Estado Rio De Janeiro IME Dept Informat & Ciencia Comp Rio De Janeiro Brazil IMPA Inst Nac Matemat Pura Aplicada Rio De Janeiro Brazil

ISBN: (纸本)0769526861

In this work we propose a method for the polygonization of octree-based reconstructions by dual contouring. Dual contouring is an adaptive method for determining contiguous polygonal meshes from signed octrees. It determines the positioning of the vertices of the mesh by minimizing a quadratic error expressed in terms of hermitian data. In order to apply dual contouring on volumetric reconstruction from silhouettes we devised a method that is able to determine the discrete topology of the contour in relation to the octree cells, as well as the hermitian data corresponding to the intersections and normals of conic volumes whose intersection approximates a structure known as Visual Hull. Due to the discrete and extremely noisy nature of the data used in the reconstruction we had to devise a different criterion for mesh simplification that applies topological consistency tests only when the geometric error measure is beyond a given tolerance. We present results of the application of the proposed method in the extraction of a mesh corresponding to the surface of objects of a real scene.

关键词： image reconstruction

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Parallel DSP architecture for reconstruction of tomographic images using wavelets techniques. 14

Parallel DSP architecture for reconstruction of tomographic ...

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14th brazilian symposium on computer graphics and image processing

作者： Pereira, MFL Koenigkan, LV Cruvinel, PE UFSCar Dept Comp BR-13565905 Sao Carlos SP Brazil

ISBN: (纸本)0769513301

this poster describes a technique for reconstructing tomographic images generated by a minitomograph scanner for soil science developed by Embrapa Agricultural Instrumentation using a parallel DSP architecture with an HEPC2E board from Hunt Engineering with two TMS320C40 processors from Texas Instruments. the software designed for visualization of bi-and tri-dimensional images uses Code Composer tool combined with Parallel C from 3L and Borland Builder C++. Reconstruction and interpolation tasks were distributed throughout the platform processors, using parallel algorithms in order to improve speed and processing power. the work resulted in an increase of about 15% in the system speed when compared with that reached using a classical platform at 200 MHz.

关键词： image reconstruction

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Denoising and enhancing digital mammographic images for visual screening

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computerIZED MEDICAL IMAGING AND graphics 2006年第4期30卷 243-254页

作者： Scharcanski, Jacob Jung, Claudio Rosito Univ Fed Rio Grande do Sul BR-91501970 Porto Alegre RS Brazil Univ Vale Rio dos Sinos PIPCA Grad Sch Appl Comp UNISINOS BR-93022000 Sao Leopoldo RS Brazil

Dense regions in digital mammographic images are usually noisy and have low contrast, and their visual screening is difficult. this paper describes a new method for mammographic image noise suppression and enhancement, which can be effective particularly for screening image dense regions. Initially, the image is preprocessed to improve its local contrast and the discrimination of subtle details. Next, image noise suppression and edge enhancement are performed based on the wavelet transform. At each resolution, coefficients associated with noise are modelled by Gaussian random variables;coefficients associated with edges are modelled by Generalized Laplacian random variables, and a shrinkage function is assembled based on posterior probabilities. the shrinkage functions at consecutive scales are combined, and then applied to the wavelets coefficients. Given a resolution of analysis, the image denoising process is adaptive (i.e. does not require further parameter adjustments), and the selection of a gain factor provides the desired detail enhancement. the enhancement function was designed to avoid introducing artifacts in the enhancement process, which is essential in mammographic image analysis. Our preliminary results indicate that our method allows to enhance local contrast, and detect microcalcifications and other suspicious structures in situations where their detection would be difficult otherwise. Compared to other approaches, our method requires less parameter adjustments by the user. (c) 2006 Elsevier Ltd. All rights reserved.

关键词： mammography contrast equalization image denoising image enhancement multiresolution analysis wavelets

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An approach based on image processing techniques to segment lung region in chest X-ray images 34

An approach based on image processing techniques to segment ...

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34th SIBGRAPI Conference on graphics, Patterns and images (SIBGRAPI)

作者： de Menezes, Luiza C. de Araujo, Augusto R. V. F. Conci, Aura Univ Fed Fluminense Inst Comp BR-24210346 Niteroi RJ Brazil

ISBN: (纸本)9781665423540

Chest X-ray (CXR) images help specialists worldwide to diagnose lung diseases, such as tuberculosis and COVID-19. A primary step in an image-based diagnostic tool is to segment the region of interest. that facilitates the disease classification problem by reducing the amount of information to be processed. However, due to the noisy nature of CXRs, identifying the lung region can be a challenging task. this paper addresses the lung segmentation problem using a less costable computational process based on image analysis and mathematical morphology techniques. the proposed method achieved a specificity of 92.92%, a Jaccard index of 77.77%, and a Dice index of 87.37% on average.

关键词： graphics image segmentation image analysis Pulmonary diseases Lung Morphology Noise measurement

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Level lines continuation based digital inpainting

Level lines continuation based digital inpainting

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17th brazilian symposium on computer graphics and image processing/2nd Ibero-American symposium on computer graphics

作者： Barcelos, CAZ Batista, MA Martins, AM Nogueira, AC Universidade Federal de Goiás CAC Univ. Federal de Uberlândia Brazil Univ. Federal de Uberlândia 38.400-902 Uberlândia MG CX.P. 593 Brazil

ISBN: (纸本)0769522270

Inpainting digital models have been since the late 1990's a powerful image reconstruction tool for missing data. After the original work of Bertalmio, Sapiro, Caselles and Ballester [1] several different approaches have been used to tackle the problem. Some are based on Partial Differential Equations to model a transport process and a diffusion process, others are based on the Eider elastica functional. this paper presents a model using the level lines continuation to perform the filling-in of the inpainting domain D. the model is proposed in a way as to satisfy the "Connectivity Principle". the image u(x,y) is represented by a family of level lines and the missing part Of the image is filled-in by the propagation of the available surrounding information, from outside to inside of the inpainting domain D along the level lines of the image. After defining the domain D the restoration process becomes automatic and the final result u(x, y, t(n)) is carried out by the evolutionary process starting with the initial degraded image u(x, y, 0). Examples on real and textured images show the performance of this proposed model.

关键词： image reconstruction

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Interactive DTI-Based Constrained Tractography using OpenGL Pipeline 36

Interactive DTI-Based Constrained Tractography using OpenGL ...

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36th SIBGRAPI Conference on graphics, Patterns and images (SIBGRAPI)

作者： Wu Shin-Ting Voltoline, Raphael Benites, Rodrigo L. Univ Estadual Campinas Sch Elect & Comp Engn Campinas Brazil

ISBN: (纸本)9798350338737;9798350338720

this paper addresses the limitations of the DTI-based tracking algorithms commonly applied in routine clinical practice. Interactive tracking and rendering algorithms are presented using the OpenGL pipeline, allowing experts to explore, adjust, interpret, and validate the reconstructed pathways. the key features of our algorithms are fiber tracking preprocessing and separation of tracking and rendering stages.

关键词： Rendering (computer graphics)

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