The surface reconstructed for the Fandisk dataset with embedded sharp features approximation. The image on the right shows additional interior points corresponding to vertex sharp features depicted with red colors, while additional basic polygon edge points corresponding to edge sharp features are depicted with green color.

M. Kazakov, A. Pasko, V. Adzhiev,
Fast isosurface polygonization with embedded sharp features extraction, Technical Report HCIS-2003-04, Hosei University, Tokyo, Japan, April 7, 2003, 11 p.

This paper presents a novel isosurface polygonization algorithm capable of approximating isosurface sharp features. For the scalar field sampled at the nodes of a regular grid, it requires normal vectors to be provided in the intersection points of the isosurface with cell edges. Unlike most of other methods, the sharp features reconstruction is embedded into the polygonization algorithm and no further post-processing is necessary. The algorithm is designed assuming possible interactive modification of the source data and does not use information from the neighborhood of the grid cell. To reconstruct a sharp feature for the current cell, additional points are introduced on the intersection line of the isosurface tangent planes for each cell face and in the cell interior. We use some heuristics to avoid time-consuming singular value decomposition for the interior point calculations. The implementation of the proposed algorithm demonstrates high performance of the polygonization of the isosurface with sharp features and allows for interactive rates of isosurface visualization.