检索结果-内蒙古大学图书馆

brazilian symposium on computer graphics and image processing (SIBGRAPI)

作者： Bruno Cedraz Brandao Jacques Wainer Siome Klein Goldenstein Universidade Estadual de Campinas Instituto de Computacao Campinas SP Brazil

Particle filtering has become a standard tool for non-parametric estimation in computer vision tracking applications. It is an instance of stochastic search. Each particle represents a possible state of the system. Higher concentration of particles at any given region of the search space implies higher probabilities. One of its major drawbacks is the exponential growth in the number of particles for increasing dimensions in the search space. We present a graph based filtering framework for hierarchical model tracking that is capable of substantially alleviate this issue. the method relies on dividing the search space in subspaces that can be estimated separately. Low correlated subspaces may be estimated with parallel, or serial, filters and have their probability distributions combined by a special aggregator filter. We describe a new algorithm to extract parameter groups, which define the subspaces, from the system model. We validate our method with different graph structures within a simple hand tracking experiment with both synthetic and real data

关键词： Particle filters computer vision Particle tracking Probability distribution Data mining Filtering Application software Stochastic processes Convergence Sampling methods

来源：评论

学校读者我要写书评

暂无评论

Polygonization of volumetric reconstructions from silhouettes

Polygonization of volumetric reconstructions from silhouette...

引用

brazilian symposium on computer graphics and image processing (SIBGRAPI)

作者： Anselmo Antunes Montenegro Luiz Velho Paulo C. P. Carvalho Jonas Jr. Sossai Departamento de Informatica Ciencia da Computacao-IME-UERJ Brazil IMPA-Instituto Nacional de Matemática Pura e Aplicada Brazil

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 Layout Surface reconstruction Data mining Shape Photography Cameras Topology Testing Application software

来源：评论

学校读者我要写书评

暂无评论

Video Segmentation by Supervised Learning

Video Segmentation by Supervised Learning

引用

brazilian symposium on computer graphics and image processing (SIBGRAPI)

作者： G. Camara Chavez M. Cord F. Precioso S. Philipp-Foliguet Arnaldo De A. Araujo Federal University of Minas Gerais Computer Science Department Av. Antônio Carlos MG Brazil Equipe Traitment des Images et du Signal-ENSEA Cergy-Pontoise France Equipe Traitment des Images et du Signal-ENSEA France Federal University of Minas Gerais

In most of video shot boundary detection algorithms, proposed in the literature, several parameters and thresholds have to be set in order to achieve good results. In this paper, to get rid of parameters and thresholds, we explore a supervised classification method for video shot segmentation. We transform the temporal segmentation into a class categorization issue. Our approach defines a uniform framework for combining different kinds of features extracted from the video. Our method does not require any pre-processing step to compensate motion or post-processing filtering to eliminate false detected transitions. the experiments, following strictly the TRECVID 2002 competition protocol, provide very good results dealing with a large amount of features thanks to our kernel-based SVM classification method

关键词： Supervised learning Support vector machines Support vector machine classification Histograms Feature extraction Gunshot detection systems Statistical learning Machine learning Detection algorithms Motion detection

来源：评论

学校读者我要写书评

暂无评论

Two-Level Interaction Transfer Function Design Combining Boundary Emphasis, Manual Specification and Evolutive Generation

Two-Level Interaction Transfer Function Design Combining Bou...

引用

brazilian symposium on computer graphics and image processing (SIBGRAPI)

作者： Francisco De Moura Pinto Carla M.D.S. Freitas Instituto de Informatica Universidade Federal do Rio Grande do Sul Instituto de Informática Universidade Federal do Rio Grande do Sul Brazil

Direct volume rendering plays an important role in the investigation of volumetric data. In order to display these data, their values must be associated to optical properties. this task is accomplished by transfer functions (TFs), which assign properties like color and opacity to voxel values in the volume. TFs are very important to produce informative images that reveal volume features, but their specification is a non-trivial and unintuitive problem. Without any help in the TF design process, the user goes through a frustrating and time-consuming trial-and-error process. this work proposes a two-level interactive framework combining a few useful semi-automatic design techniques for one-dimensional opacity and color transfer functions. We use the histogram approach proposed by Kindlmann and Durkin, manual design aided by dual domain interaction (space domain and TF domain), stochastic evolutive design and qualitative analysis of multiple TF possibilities using a design galleries-inspired method (thumbnails in the first level of interaction and refinement of zoomed-in images in the second level). the combination of these strategies offers precise control over the transfer function specification, plus some interactive guidance, as well as semi-automatic and evolutive search in the TF space

关键词： Transfer functions Rendering (computer graphics) Stochastic processes image analysis Displays Design methodology Data visualization computer graphics Isosurfaces Data mining

来源：评论

学校读者我要写书评

暂无评论

Optimization of multiple continuous queries over streaming satellite data

Optimization of multiple continuous queries over streaming s...

引用

14th Annual ACM International symposium on Advances in Geographic Information Systems, ACM-GIS'06

作者： Hart, Quinn Gertz, Michael CalSpace University of California Davis Dept. of Computer Science University of California Davis

ISBN: (纸本)1595935290

Remotely sensed data, in particular satellite imagery, play many important roles in environmental applications. In particular applications that study rapid changes in the environment require frequent access to these data. For continuous data products, users are often interested in formulating continuous queries that deliver results for each incoming image. In the presence of multiple continuous queries, there is clearly an opportunity to share common intermediate data and thus, increase the overall processing speed of the *** on the widely used GRASS, this paper describes a system that realizes multiple query processing using two major components. A query optimizer maintains the current set of active continuous queries. Queries are organized into a single processing plan designed to share intermediate results. For each new image from the stream, the optimizer generates an execution plan specific to the active queries. the query executor then rewrites this plan into a set of geospatial processing steps and executes the *** detail experiments using data from NOAA's GOES. Continuous queries are defined in a way similar to the OGC WMS query specification. Using predicted query patterns over the visible hemisphere of GOES, experimental results indicate that multiple-query optimized plans can improve performance significantly when compared to queries that are executed separately. Copyright 2006 ACM.

关键词： Query languages

来源：评论

学校读者我要写书评

暂无评论

AFRIGRAPH: computer graphics in Africa

引用

computer graphics FORUM 2006年第4期25卷 697-698页

作者： Gain, J. E. Strasser, W. Univ Cape Town Collaborat Visual Comp Lab ZA-7925 Cape Town South Africa Univ Tubingen Wilhelm Schickard Inst Informat Graph Interakt Sy D-7400 Tubingen Germany

来源：评论

学校读者我要写书评

暂无评论

Extracting Discriminative Information from Medical images: A Multivariate Linear Approach

Extracting Discriminative Information from Medical Images: A...

引用

brazilian symposium on computer graphics and image processing (SIBGRAPI)

作者： Carlos E. thomaz Nelson A.O. Aguiar Sergio H.A. Oliveira Fabio L.S. Duran Geraldo F. Busatto Duncan F. Gillies Daniel Rueckert Department of Electrical Engineering Centro Universitario da FEI Sao Paulo Brazil Departments of Psychiatry and Radiology Faculty of Medicine University of São Paulo Brazil Department of Computing Imperial College London London UK

Statistical discrimination methods are suitable not only for classification but also for characterization of differences between a reference group of patterns and the population under investigation. In the last years, statistical methods have been proposed to classify and analyze morphological and anatomical structures of medical images. Most of these techniques work in high-dimensional spaces of particular features such as shapes or statistical parametric maps and have overcome the difficulty of dealing with the inherent high dimensionality of medical images by analyzing segmented structures individually or performing hypothesis tests on each feature separately. In this paper, we present a general multivariate linear framework to identify and analyze the most discriminating hyper-plane separating two populations. the goal is to analyze all the intensity features simultaneously rather than segmented versions of the data separately or feature-by-feature. the conceptual and mathematical simplicity of the approach, which pivotal step is spatial normalization, involves the same operations irrespective of the complexity of the experiment or nature of the data, giving multivariate results that are easy to interpret. To demonstrate its performance we present experimental results on artificially generated data set and real medical data

关键词： Data mining Biomedical imaging image analysis image segmentation Statistical analysis Anatomical structure Shape Performance analysis Performance evaluation Medical tests

来源：评论

学校读者我要写书评

暂无评论

Determining the branchings of 3D structures from respective 2D projections

Determining the branchings of 3D structures from respective ...

引用

brazilian symposium on computer graphics and image processing (SIBGRAPI)

作者： Jorge J. G. Leandro Roberto M. Jr. Cesar Luciano Da Fontoura Costa Institute of Mathematics and Statistics Department of Computer Science USP Sao Paulo Brazil Instituto de Física de São Carlos Department of Physics and Informatics USP Sao Paulo Brazil

this work describes a new framework for automatic extraction of 2D branching structures images obtained from 3D shapes, such as neurons and retinopathy images. the majority of methods for neuronal cell shape analysis that are based on the 2D contours of cells fall short of properly characterizing such cells because crossings among neuronal processes constrain the access of contour following algorithms to the innermost regions of the cell. the framework presented in this article addresses, possibly for the first time, the problem of determining the continuity along crossings, therefore granting to the contour following algorithm full access to all processes of the neuronal cell under analysis. First, the raw image is preprocessed so as to obtain an 8-connected, one-pixel wide skeleton as well as a set of seed pixels for each subtree and all the branching/crossing regions. then, for each seed pixel, the algorithm labels all valid neighbors, until a branching/crossing region is reached, when a decision about the proper continuation is taken based on the tangent continuity. the algorithm has shown robustness for images with parallel segments and low densities of branching/crossing densities. the problem of too high densities of branching/crossing regions can be addressed by using a suitable data structure. Successful experimental results using real data (neural cell images) are presented

关键词： Genetics Shape measurement Neurons Algorithm design and analysis Animals Nervous system Mathematics Statistics computer science Retinopathy

来源：评论

学校读者我要写书评

暂无评论

Non-Extensive Entropy for CAD Systems of Breast Cancer images

Non-Extensive Entropy for CAD Systems of Breast Cancer Image...

引用

brazilian symposium on computer graphics and image processing (SIBGRAPI)

作者： J.S. Suri Ruey-Feng Chang G.A. Giraldi P.S. Rodrigues National Lab. for Sci. Comput. Rio de Janeiro

Recent statistics show that breast cancer is a major cause of death among women in all of the world. Hence, early diagnostic with computer aided diagnosis (CAD) systems is a very important tool. this task is not easy due to poor ultrasound resolution and large amount of patient data size. then, initial image segmentation is one of the most important and challenging task. Among several methods for medical image segmentation, the use of entropy for maximization the information between the foreground and background is a well known and applied technique. But, the traditional Shannon entropy fails to describe some physical systems with characteristics such as long-range and longtime interactions. then, a new kind of entropy, called non-extensive entropy, has been proposed in the literature for generalizing the Shannon entropy. In this paper, we propose the use of non-extensive entropy, also called q-entropy, applied in a CAD system for breast cancer classification in ultrasound of mammographic exams. Our proposal combines the non-extensive entropy, a level set formulation and a support vector machine framework to achieve better performance than the current literature offers. In order to validate our proposal, we have tested our automatic protocol in a data base of 250 breast ultrasound images (100 benign and 150 malignant). With a cross-validation protocol, we demonstrate system's accuracy, sensitivity, specificity, positive predictive value and negative predictive value as: 95%, 97%, 94%, 92% and 98%, respectively, in terms of ROC (receiver operating characteristic) curves and A z areas

关键词： Entropy Breast cancer Ultrasonic imaging image segmentation Proposals Protocols Statistics Biomedical imaging Medical diagnostic imaging Level set

来源：评论

学校读者我要写书评

暂无评论

Differential representations for mesh processing

引用

computer graphics FORUM 2006年第4期25卷 789-807页

作者： Sorkine, Olga Tel Aviv Univ Sch Comp Sci IL-69978 Tel Aviv Israel

Surface representation and processing is one of the key topics in computer graphics and geometric modeling, since it greatly affects the range of possible applications. In this paper we will present recent advances in geometry processing that are related to the Laplacian processing framework and differential representations. this framework is based on linear operators defined oil polygonal meshes, and furnishes a variety of processing applications, such as shape approximation and compact representation, mesh editing, watermarking and morphing. the core of the framework is the definition of differential coordinates and new bases for efficient mesh geometry representation, based on the mesh Laplacian operator.

关键词： discrete Laplacian surface representation detail preservation geometry compression mesh editing

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：