Improved tfan-based encoding of 3D mesh models composed of triangles

摘要

Method for encoding a 3D mesh model into a bitstream, comprising: traversing successively each vertex constituting the 3D model; for each vertex traversed: performing a triangle-based fan analysis centred on the current vertex to discover any new triangle(s) not yet discovered when traversing the previous vertices; determining connectivity data, comprising connectivity variables, between vertices based on the newly discovered triangle(s); classifying the values taken by the same connectivity variable into connectivity classes; wherein two independent entropy encoders code the values classified respectively in two separate connectivity classes. Identification data for vertices may include a bitmap. Bitmap and vertex indices may be represented using case predictors of the Scalable Complexity 3D Mesh Compression Triangle Fan standard. Coding cost criteria may be used to select vertex index predictors restricted to positive vertex indices. Predictor flags may be encoded. Sign bits representing sign of residue between current vertex index and numerical value two may be encoded. Degree of vertex may indicate number of times that vertex was identified as a vertex of previously found triangles. Lists of vertices connected to the current vertex may be generated. Number of triangle fan portions may be predicted by half the number of vertices in a list.