An efficient coding algorithm for color and normal data of three-dimensional mesh models

Three-dimensional (3-D) mesh models have attribute data, such as colors, normal vectors, and texture coordinates to render or shade the surface of the mesh. Although several coding schemes have been developed to represent the topology and geometry information of the 3-D mesh, coding of the attribute data has received less attention. In this paper, we propose a new predictive coding scheme for colors and normal vectors of the 3-D mesh model, where we predict colors and normals based on several ancestors along the vertex ordering. In order to encode the color information, we define a mapping table that specifies how colors are mapped into other vertices. The mapping table can represent frequently occurring color patterns efficiently. For normal vectors, we also propose an average predictor and the 6-4 subdivision quantizer in the spherical coordinate system. The proposed scheme has demonstrated good coding efficiency for various VRML test data.