Résumé: Multiresolution methods are often needed for the interactive visualization of large volumetric data sets. Here, we present a multiresolution algorithm which is designed to extract and render multiple transparent isosurfaces very quickly. To this end, the underlyingdata set is covered with a hierarchical tetrahedral grid. The multiresolution extraction is based on an adaptive traversal of the tetrahedral grid with the help of error indicators. The display of transparent isosurfaces usingalpha blendingrequires the back- to- front renderingof the isosurface triangles. This is achieved by a hierarchical sortingprocedure of the tetrahedra and the isosurface components inside each tetrahedron. The sorting of the isosurface components requires the data gradients, though. These gradients can in principle be precomputed but are quite expensive to store. We therefore show how these gradients can be very ef .ciently computed on- the- .y duringthe grid traversal. We will also comment on the automated selection of suitable isovalues for visualization applications.

Langue: Anglais