the paper presents LGS, a geometric solver by LEDAS for systems requiring solving of geometric problems with constraints. LGS is presently a stable marketable product, and so the paper focuses on the future of LGS, su...
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the paper presents LGS, a geometric solver by LEDAS for systems requiring solving of geometric problems with constraints. LGS is presently a stable marketable product, and so the paper focuses on the future of LGS, such as possible development paths and applications to real tasks. Apart from the traditional use in large parametric CAD systems, possibilities for integrating the solver in small CADs and three-dimensional modeling systems are examined. Special attention is paid to applications of engineering constraints for geometrical models.
the algorithms which allow effective manage methods of very large terrains are considered in this paper. the developed algorithms of building and visualization of very large terrains are based on special data structur...
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the algorithms which allow effective manage methods of very large terrains are considered in this paper. the developed algorithms of building and visualization of very large terrains are based on special data structure, called a Multi-Triangulation (MT), which allows manipulating a surface at variable resolution. We suggest modifying the original MT structure in a way that makes possible to manipulate very large terrains (i.e. data models, which are larger than available computer's RAM).
Point feature tracking is the key step in solving such problems as camera calibration and 3d reconstruction. In this paper, we propose a new feature-tracking framework that is based on combination of guided tracking a...
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Point feature tracking is the key step in solving such problems as camera calibration and 3d reconstruction. In this paper, we propose a new feature-tracking framework that is based on combination of guided tracking and matching approaches. the proposed framework raises the quality of tracking in terms of mean track lengths and fraction of successfully tracked features. We also propose an adaptive track initialization scheme based on spatial partitioning of detected features into bins that reduces the influence of dominant planes on outlier segmentation. Results are given for a number of real image sequences. the algorithm is demonstrated to outperform previous approaches.
Ray tracing algorithm on octrees is described. the algorithm is based on decomposition of 3D search child sub-voxel to 2D task in coordinate planes. Optimization of algorithm at the path coherency in octree is suggest...
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Ray tracing algorithm on octrees is described. the algorithm is based on decomposition of 3D search child sub-voxel to 2D task in coordinate planes. Optimization of algorithm at the path coherency in octree is suggested. the notion of supporting rays with storing and common path of close rays is introduced. the algorithm of optimized traversal for intermediate rays, based on common paths, is presented. Two version of path coherency in octree realization is considered. Experimental efficiency values of considered optimization are received for different scenes. Comparative efficiency values of optimized discrete ray tracing algorithm and forward rendering algorithm are received also.
A generic approach to describing shape and topography of arbitrary objects is presented, using linguistic variables to combine different features in one fuzzy descriptor. Although the origin of the method lies in mole...
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A generic approach to describing shape and topography of arbitrary objects is presented, using linguistic variables to combine different features in one fuzzy descriptor. Although the origin of the method lies in molecular visualization and drug design, it can be applied in principle to any surface represented by a polygon mesh. Two approaches to shape description are presented that both lead to linguistic variables that can be used for surface segmentation by means of shape: One approach is based on the calculation of canonical curvatures, the other describes the "embeddedness" of a surface area related to the overall geometry of a 3D object.
Paper describes the design of open architecture for CAD systems and implementation of particular application based on this design. the purpose of described project is to provide CAD developers with open, scaleable set...
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Paper describes the design of open architecture for CAD systems and implementation of particular application based on this design. the purpose of described project is to provide CAD developers with open, scaleable set of software components, based on common architecture allowing to implement geometry modeling and drafting applications. In this paper is given description of projects logical hierarchy, external references implementation, wire-frame, surface and solid entities representation, applicationspecific data incapsulation into the projects. At the end of the paper is given short description of bCAD 4 software, developed using present design.
Robust parameter estimation methods are the general tool in computervision, widely used for such tasks as multiple view relation estimation and camera calibration. In this paper, we propose a new general robust maxim...
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Robust parameter estimation methods are the general tool in computervision, widely used for such tasks as multiple view relation estimation and camera calibration. In this paper, we propose a new general robust maximum-likelihood estimator called AMLESAC, which is a noise adaptive variant of renowned MLESAC estimator. It adopts the same sampling strategy and seeks the solution to maximize the likelihood rather then some heuristic measure, but unlike MLESAC, it simultaneously estimates the outlier share γ and inlier noise level σ. Effective optimization for computation speed-up is also introduced. Results are given for both synthetic and real test data for different types of models. the algorithm is demonstrated to outperform previous approaches for the task of pose estimation and provide results equal or superior to other robust estimators in other tests.
In this paper we present intelligent visibility-based techniques allowing efficient processing of 3D scenes in order to be used in real time in computer games. the presented techniques allow real time use of 3D scenes...
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In this paper we present intelligent visibility-based techniques allowing efficient processing of 3D scenes in order to be used in real time in computer games. the presented techniques allow real time use of 3D scenes either by simplifying the scene models (by suppressing useless details or by using improved image-based modelling) or by off-line automatic camera path pre-computation allowing fast exploration of the game environment.
We present a simple, automatic method for extracting feature curves, called crest lines, from point clouds. Crest lines are surface shape features having a mathematical background. Given an unstructured point cloud as...
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We present a simple, automatic method for extracting feature curves, called crest lines, from point clouds. Crest lines are surface shape features having a mathematical background. Given an unstructured point cloud as input, we pre-process the data to generate some topological information by creating an undirectional surface graph. the method starts withthe approximation of normal curvature on every point. Utilizing the crest point definition, the crest points are identified. Region growth follows to implicitly connect the crest points and create crest graphs. Finally, the computation of minimum spanning trees for every crest graph and the pruning of short branches create crest lines.
the issues of geometric modeling in the 3D numerical simulation problems are considered, including description of complicated computational domains and mathematical statements, automatical construction of algorithms, ...
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the issues of geometric modeling in the 3D numerical simulation problems are considered, including description of complicated computational domains and mathematical statements, automatical construction of algorithms, postprocessing and optimal control procedures for computer-aided design technologies. the main stages of computational processes are analysed in terms of accordance and transformation of flexible data structures: geometric and functional data, grid and algebraic ones.
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