Authors:
Akshay Narayan
1
;
Jaya Sreevalsan-Nair
1
;
Kelly Gaither
2
and
Bernd Hamann
3
Affiliations:
1
International Institute of Information Technology - Bangalore, India
;
2
University of Texas at Austin, United States
;
3
University of California, United States
Keyword(s):
Volume Visualization, Isosurface Extraction, Hybrid Meshes, Marching Methods.
Related
Ontology
Subjects/Areas/Topics:
Computer Vision, Visualization and Computer Graphics
;
General Data Visualization
;
Large Data Visualization
;
Spatial Data Visualization
;
Volume Visualization
Abstract:
Grid-based computational simulations often use hybrid unstructured grids consisting of various types of elements. Most commonly used elements are tetrahedral, pentahedral (namely, square pyramids and right triangular prisms) and hexahedral elements. Extracting isosurfaces of scalar fields defined on such hybrid unstructured grids is often done using indirect methods, such as, (a) subdividing all non-tetrahedral cells into tetrahedra and computing the triangulated isosurfaces using the marching tetrahedra algorithm, or (b) triangulating intersection points of edges of cells and computing the isosurface using a standard triangulation algorithm. Using the basic ideas underlying the well-established marching cubes and marching tetrahedra algorithms, which are applied to hexahedral and tetrahedral elements, respectively, we generate look-up tables for extracting isosurfaces directly from pentahedral elements. By using appropriate look-up tables, it is possible to process nearly all types
of hybrid unstructured grids used in practical applications without the need for indirect methods. We construct look-up tables for square pyramidal and triangular prismatic cells with accurate topological considerations.
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