Non-Photorealistic Computer Graphics Library

Drawing Skeletons

Author(s): Tom Brunet, Nina Amenta, Thore Karlsen.
Misc: 2002.
[BibTeX]

Abstract:
We often want to visualize the relationship between an internal structure, which we call a ‘skeleton’, inside of some threedimensional object, whose boundary we call a ‘shell’. One important example, illustrated above, is the relationship of a hypothetical molecular structure to an electron density iso-surface. Since, by nature, the skeleton is inside the shell, the shell needs to be at least partially transparent. In this paper, we explore several rendering techniques, including some non-photorealistic, to visualize the skeleton and shell. We are particularly interested in techniques which work well with stereo, because stereo is used almost universally in molecular visualization. Rather than using a realistic physical lighting model of a surface, we strive for clarity and good depth perception. The techniques we use include silhouette edges, texture mapped contour lines, cartoon shading, and selective opacity. The result is a new ‘stereo cartoon’ non-photorealistic rendering style. We examine the performance and quality tradeoffs involved with these techniques on typical graphics hardware.