Scalar Tagged PN Triangles

Abstract

This paper presents a new technique to convert a coarse polygonal geometric model into a smooth surface interpolating the mesh vertices, by improving the principle proposed by Vlachos et al. in their "Curved PN-Triangles". The key idea is to assign to each mesh vertex, a set of three scalar tags that act as shape controllers. These scalar tags (called sharpness, bias, and tension) are used to compute a procedural displacement map that enriches the geometry, and a procedural normal map that enriches the shading. The resulting technique offers two majors features: First, it can be applied on meshes of arbitrary topology while always generating surfaces with consistent behaviors across edge and vertex boundaries, second, it only involves operations that are purely local to each polygon, which means that it is very well suited for hardware implementations.