We describe a robust, exact, and efficient implementation of an algorithm that computes the width of a three-dimensional point set. The algorithm is based on efficient solutions to problems that are at the heart of co...
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Superscalar microprocessor efficiency is generally not as high as anticipated. In fact, sustained utilization below thirty percent of peak is not uncommon, even for fully optimized, cache-friendly codes. Where cycles ...
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作者：
MOHAMED CHERIETYEE-HONG YANGLaboratoire d'Imagerie
de Vision et d'Intelligence Artificielle École de Technologie Supérieure 1100 rue Notre-Dame Ouest Montréal (Québec) H3C 1K3 Canada SAM (Scene Analysis and Modelling Group)
Computer Vision and Graphics Lab Department of Computer Science University of Saskatchewan 57 Campus Drive Saskatoon (Saskatchewan) S7N 5A9 Canada
Customizable meta-objects are a powerful abstraction for extending language features and implementation mechanisms, but interpretive execution suffers from severe performance penalty. Some of this penalty can be reduc...
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Although direct volume rendering is a powerful tool for \isualizing complex structures within volume data, the size and complexity of the parameter space controlling the rendering process makes generating an informati...
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ISBN:
(纸本)1581131054
Although direct volume rendering is a powerful tool for \isualizing complex structures within volume data, the size and complexity of the parameter space controlling the rendering process makes generating an informative rendering challenging. In particular, the specification of the transfer function - the mapping from data values to renderable optical properties-is frequently a time-consuming and unintuitive task. Ideally, the data being visualized should itself suggest an appropriate transfer function that brings out the features of interest without obscuring them with elements of little importance. We demonstrate that this is possible for a large class of scalar volume data, namely that where the regions of interest are the boundaries between different materials. A transfer function which makes boundaries readily visible can be generated from the relationship between three quantities: the data value and its first and second directional derivatives along the gradient direction. A data structure we term the histogram volume captures the relationship between these quantities throughout the volume in a position independent, computationally efficient fashion. We describe the theoretical importance of the quantities measured by the histogram volume, the implementation issues in its calculation, and a method for semiautomatic transfer function generation through its analysis. We conclude with results of the method on both idealized synthetic data as well as real world dataseis. Copyright 1998 IEEE.
The diagnosis of intracranial aneurysms and the planning of related interventions is effectively assisted by spiral CT-angiography and interactive direct volume rendering. Based on 3D texture mapping, we suggest a har...
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The article deals with dependencies of a piecewise linear vector field and the triangulation of the domain. It shows that the topology of the field may depend on the triangulation and gives a suitable choice to obtain...
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ISBN:
(纸本)9780818684456
The article deals with dependencies of a piecewise linear vector field and the triangulation of the domain. It shows that the topology of the field may depend on the triangulation and gives a suitable choice to obtain a simple topology by changes of the triangulation. The main point is the appearance of pairs of critical points with positive and negative Poincare index. Many of these occurrences can be avoided by changing the grid. This is proved in the article. An algorithm is presented which uses these results to extract simpler topological skeletons than usual methods. Finally there are several examples comparing these algorithms to demonstrate the effects of the data dependent triangulation.
Iconic hand gestures are a natural and intuitive way to convey spatial information. Capturing and interpreting iconic hand gestures will augment users' abilities to convey spatial information with computers. This ...
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Iconic hand gestures are a natural and intuitive way to convey spatial information. Capturing and interpreting iconic hand gestures will augment users' abilities to convey spatial information with computers. This paper discusses the on-going research and the results of a study to employ iconic hand gestures as a human computer interaction (HCI) technique for the input and manipulation of objects and shapes within 3D computer generated graphical environments.
The paper describes some fundamental issues for robust implementations of progressively refined tetrahedralizations generated through sequences of edge collapses. We address the definition of appropriate cost function...
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The paper describes some fundamental issues for robust implementations of progressively refined tetrahedralizations generated through sequences of edge collapses. We address the definition of appropriate cost functions and explain on various tests which are necessary to preserve the consistency of the mesh when collapsing edges. Although considered a special case of progressive simplicial complexes (J. Popovic and H. Hoppe, 1997), the results of our method are of high practical importance and can be used in many different applications, such as finite element meshing, scattered data interpolation, or rendering of unstructured volume data.
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