An Algorithm for Polygon Subdivision Based on Vertex Normals

In order to achieve the impression of a smooth surface while rendering a polygon mesh, normal vector vectors may be provided in the vertices of the mesh that are the average of the surface normals of the adjacent polygons. Interpolation of these normal vectors while rendering of the polygons in the mesh, and using the interpolated normal vectors in the shading computations, yields a smoothly varying intensitydistribution. There is an inherent mismatch, however, between the smoothnessof the shadingthusachieved andthe non-smoothness of the geometry which is particularly visible at silhouettes, showingas straight edges andnon-smooth edge junctions at the silhouette vertices. In this paper, a remedy for these artefacts is suggested. The remedy consists of subdividing each input polygon into a mesh of polygons prior to rendering. The shape of this resulting polygon mesh is controlled by the normal vectors that are provided in the vertices of the original polygon, unlike other subdivision s...

• Type: Conference
• Year: 1997
• Where: CGI
• Authors: Cornelius W. A. M. van Overveld, Brian Wyvill
• Keywords: CGI 1997, Computer Graphics, Normal Vectors, Polygon, Polygon Mesh