Delphi Encoding: Improving Edgebreaker 3D Compression by Geometry based Connectivity Prediction

Delphi is a new geometry-guided predictive compression scheme for squeezing the connectivity of a triangluar mesh. The mesh is traversed using the Edgebreaker state machine. Instead of creating the Edgebreaker clers sequence both compression and decompression perform the same geometric prediction of the location of the unknown vertex of the next triangle during the mesh traversal. Based on this geometric prediction the connectivity is predicted , by snapping thepredicted vertex to the nearest boundary vertex, if one lies sufficiently close. If the guess is correct, a single confirmation bit is sufficient. Otherwise, an entropy-based code is received and used to encode the rectification of that prediction. For a series of meshes that we have tested, up to 97% of Dephi's predictions are correct, and result in a compressed connectivity format requiring between 0.19 and 1.5 bits per triangle.