The Experts below are selected from a list of 46710 Experts worldwide ranked by ideXlab platform
Judy M. Vance - One of the best experts on this subject based on the ideXlab platform.
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A MESH REDUCTION APPROACH TO Parametric Surface POLYGONIZATION
2016Co-Authors: Asif M. Khan, Judy M. Vance, I I &aposAbstract:Surface polygonization is the process by which a representative· polygonal mesh of a Surface is constructed for rendering or analysis purposes. This work presents a new Surface polygonization algo-rithm specifically tailored to be applied to a large class of models which are created with Parametric Surfaces. This method has partic-ular application in the area of building virtual environments from computer-aided-design (CAD) models. The algorithm is based on an edge reduction scheme that collapses two vertices of a given polygon edge onto one new vertex. A two step approach is imple-mented consisting of boundary edge reduction followed by interior edge reduction. A maximin optimization is used to determine the location of the new vertex. The concept of a visible region as the lo-cation space of the new vertex is introduced. The method presented here differs from existing methods in tha
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a mesh reduction approach to Parametric Surface polygonization
Design Automation Conference, 1995Co-Authors: Asif M. Khan, Judy M. VanceAbstract:Surface polygonization is the process by which a representative· polygonal mesh of a Surface is constructed for rendering or analysis purposes. This work presents a new Surface polygonization algo rithm specifically tailored to be applied to a large class of models which are created with Parametric Surfaces. This method has partic ular application in the area of building virtual environments from computer-aided-design (CAD) models. The algorithm is based on an edge reduction scheme that collapses two vertices of a given polygon edge onto one new vertex. A two step approach is imple mented consisting of boundary edge reduction followed by interior edge reduction. A maximin optimization is used to determine the location of the new vertex. The concept of a visible region as the lo cation space of the new vertex is introduced. The method presented here differs from existing methods in that it takes advantage of the fact that for many models, the exact sur face representation of the model is known -before the polygoniza tion is attempted. Because the precise Surface definition is known, a maximin optimization procedure, that uses the Surface informa tion, can be used to locate the new vertex. The algorithm attempts to overcome the deficiencies in existing techniques while minimiz ing the number of polygons required to represent a Surface and still maintaining Surface integrity in the rendered model. This paper pre sents the algorithm and testing results.
Asif M. Khan - One of the best experts on this subject based on the ideXlab platform.
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A MESH REDUCTION APPROACH TO Parametric Surface POLYGONIZATION
2016Co-Authors: Asif M. Khan, Judy M. Vance, I I &aposAbstract:Surface polygonization is the process by which a representative· polygonal mesh of a Surface is constructed for rendering or analysis purposes. This work presents a new Surface polygonization algo-rithm specifically tailored to be applied to a large class of models which are created with Parametric Surfaces. This method has partic-ular application in the area of building virtual environments from computer-aided-design (CAD) models. The algorithm is based on an edge reduction scheme that collapses two vertices of a given polygon edge onto one new vertex. A two step approach is imple-mented consisting of boundary edge reduction followed by interior edge reduction. A maximin optimization is used to determine the location of the new vertex. The concept of a visible region as the lo-cation space of the new vertex is introduced. The method presented here differs from existing methods in tha
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a mesh reduction approach to Parametric Surface polygonization
Design Automation Conference, 1995Co-Authors: Asif M. Khan, Judy M. VanceAbstract:Surface polygonization is the process by which a representative· polygonal mesh of a Surface is constructed for rendering or analysis purposes. This work presents a new Surface polygonization algo rithm specifically tailored to be applied to a large class of models which are created with Parametric Surfaces. This method has partic ular application in the area of building virtual environments from computer-aided-design (CAD) models. The algorithm is based on an edge reduction scheme that collapses two vertices of a given polygon edge onto one new vertex. A two step approach is imple mented consisting of boundary edge reduction followed by interior edge reduction. A maximin optimization is used to determine the location of the new vertex. The concept of a visible region as the lo cation space of the new vertex is introduced. The method presented here differs from existing methods in that it takes advantage of the fact that for many models, the exact sur face representation of the model is known -before the polygoniza tion is attempted. Because the precise Surface definition is known, a maximin optimization procedure, that uses the Surface informa tion, can be used to locate the new vertex. The algorithm attempts to overcome the deficiencies in existing techniques while minimiz ing the number of polygons required to represent a Surface and still maintaining Surface integrity in the rendered model. This paper pre sents the algorithm and testing results.
Gershon Elber - One of the best experts on this subject based on the ideXlab platform.
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arbitrary precise orientation specification for layout of text
Pacific Conference on Computer Graphics and Applications, 2000Co-Authors: Tatiana Surazhsky, Gershon ElberAbstract:A novel method for the layout of text strings over some given free-form Parametric base curves is considered. Each letter of the string is represented by a collection of cubic and linear Bezier curves. The layout of the string over the free-form Parametric curve is derived as a symbolic composition of the string geometry (i.e. a sequence of Bezier curves) and a free-form Parametric Surface S(u, v) with the parameters u, v between zero and one, and S(u, 0) given by the base curve. This method has proven to provide great flexibility and give high quality results in layout of text.
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Isometric Texture Mapping for Free‐form Surfaces
Computer Graphics Forum, 1997Co-Authors: Nur Arad, Gershon ElberAbstract:Texture mapping is a frequently exploited technique in computer graphics aimed at the emulation of high-resolution details in Surfaces. In this paper we present a distance-ratios preservation method for bivariate raster texture mapping to free-form Surfaces in an arbitrarily precise manner. The proposed method reduces the original general problem of computing the inverse of a three-dimensional Parametric Surface mapping into a problem of two-dimensional image warping. Several examples that demonstrate the proposed approach are also provided.
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Isometric Texture Mapping for Free-form Surfaces
Computer Graphics Forum, 1997Co-Authors: Nur Arad, Gershon ElberAbstract:Texture mapping is a frequently exploited technique in computer graphics aimed at the emulation of high-resolution details in Surfaces. In this paper we present a distance-ratios preservation method for bivariate raster texture mapping to free-form Surfaces in an arbitrarily precise manner. The proposed method reduces the original general problem of computing the inverse of a three-dimensional Parametric Surface mapping into a problem of two-dimensional image warping. Several examples that demonstrate the proposed approach are also provided.
Luc Biard - One of the best experts on this subject based on the ideXlab platform.
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Parametric Surfaces and Ray Tracing
Photorealism in Computer Graphics, 1992Co-Authors: Luc BiardAbstract:A new method for ray tracing polynomial and rational Parametric Surfaces is presented. The algorithm we describ is based on algebraic tools (implicitization and inversion) and does not proceed by a previous approximation of the Surface. Each Surface can be associated with numerical matrices in such a way that operations to be done on Surfaces can be translated into operations on the corresponding matrices and treated by numerical matrix techniques. These matrices are an implicit version of a given Parametric Surface and contain all algebraic and topological informations about it.
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Curves and Surfaces - Ray tracing rational Parametric Surfaces
Curves and Surfaces, 1991Co-Authors: Luc Biard, Patrick CheninAbstract:Abstract We present a new algorithm for ray tracing rational Parametric Surfaces based on implicitization and inversion. Each patch is associated with a pre-computed square matrix which represents an implicit version of the given Parametric Surface. This matrix then allows to solve the intersection problem in the ray parameter in an efficient way and permits to discuss qualitative aspects about inversion.
Andres G Marrugo - One of the best experts on this subject based on the ideXlab platform.
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robust automated reading of the skin prick test via 3d imaging and Parametric Surface fitting
PLOS ONE, 2019Co-Authors: Jesus Pineda, Raul Vargas, Lenny A Romero, Javier Marrugo, Jaime Meneses, Andres G MarrugoAbstract:The conventional reading of the skin prick test (SPT) for diagnosing allergies is prone to inter- and intra-observer variations. Drawing the contours of the skin wheals from the SPT and scanning them for computer processing is cumbersome. However, 3D scanning technology promises the best results in terms of accuracy, fast acquisition, and processing. In this work, we present a wide-field 3D imaging system for the 3D reconstruction of the SPT, and we propose an automated method for the measurement of the skin wheals. The automated measurement is based on pyramidal decomposition and Parametric 3D Surface fitting for estimating the sizes of the wheals directly. We proposed two Parametric models for the diameter estimation. Model 1 is based on an inverted Elliptical Paraboloid function, and model 2 on a super-Gaussian function. The accuracy of the 3D imaging system was evaluated with validation objects obtaining transversal and depth accuracies within ± 0.1 mm and ± 0.01 mm, respectively. We tested the method on 80 SPTs conducted in volunteer subjects, which resulted in 61 detected wheals. We analyzed the accuracy of the models against manual reference measurements from a physician and obtained that the Parametric model 2 on average yields diameters closer to the reference measurements (model 1: -0.398 mm vs. model 2: -0.339 mm) with narrower 95% limits of agreement (model 1: [-1.58, 0.78] mm vs. model 2: [-1.39, 0.71] mm) in a Bland-Altman analysis. In one subject, we tested the reproducibility of the method by registering the forearm under five different poses obtaining a maximum coefficient of variation of 5.24% in the estimated wheal diameters. The proposed method delivers accurate and reproducible measurements of the SPT.