March 2, D Mesh Coding and Transmission Lihang Ying Department of Computing Science University of Alberta

L.Ying, 3D Mesh Coding and Transmission, Outline  3D Mesh Data  3D Mesh Coding –Valence-Driven Approach  Error-Resilient 3D Mesh Coding and Transmission –Multiple Description Coding  Proposed Research

L.Ying, 3D Mesh Coding and Transmission, D Mesh Data  Geometry: –3D positions (x-y-z coordinates) of vertices –Coding: 1)Quantization, 2)Differential Coding, 3) Entropy Coding  Connectivity: –How vertices are connected Raw data: vertex indices of each face Large redundancy –Main Focus of 3D Mesh Coding  Photometry –Colors,Normals,Texture

L.Ying, 3D Mesh Coding and Transmission, D Mesh Coding  Since early 1990s  Up-to-date Survey: [PKK05] VRML V.2 and MPEG-4 Standard State-of-the-art Method

L.Ying, 3D Mesh Coding and Transmission, Valence-Driven Approach  Encoding  Thick line: active lists  Dashed line: visited edge  Dark point: focus  Encoding Stream: add 6, add 7, add 4, add 4, add 8, add 5, add 5, add 4, add 5, split 5, add 4, add 4, add dummy 6, add 4 add 6, add 7, add 4add 4add 8 add 5 add 4 add 5 split 5add 4 add dummy 6 add 4

L.Ying, 3D Mesh Coding and Transmission, Valence-Driven Approach  Decoding  Encoding Stream: add 6, add 7, add 4, add 4, add 8, add 5, add 5, add 4, add 5, split 5, add 4, add 4, add dummy 6, add 4  Thick line: active lists  Dashed line: visited edge  Dark point: focus add 6, add 7, add 4add 4add 8add 5 add 4add 5 split 5 add 4 add dummy 6 add 4

L.Ying, 3D Mesh Coding and Transmission, Progressive Valence-Driven 3D Mesh Coding –

L.Ying, 3D Mesh Coding and Transmission, Connectivity Coding is Sensitive to Error –Previous codes impact all subsequent codes. –Example: one-code error in Edgebreaker method [Rossignac99] results (the right):

L.Ying, 3D Mesh Coding and Transmission, Error Resilience  Error-Resilient Transmission [AAR05] –Unequal Error Protection –Interleaved Packets  Piece-based Error-Resilient Coding [YKK01] –Divide mesh into pieces, encode piece by piece, then encode connectivity between pieces.

L.Ying, 3D Mesh Coding and Transmission,  Progressive Coding –Enhance layers depends on base layers  Piece-based Error-Resilient Coding –Not friendly to Perceptual Quality  Multiple Description Coding –Each description can be encoded independently –More descriptions received result higher quality. –Less efficient Multiple Description Coding(1)

L.Ying, 3D Mesh Coding and Transmission, Multiple Description Coding(2)  Existing Work [JWC04] –Idea: Only split the geometry (vertex position) data into descriptions Transmit the connectivity of the entire mesh via a high quality channel. –How to split vertices into descriptions Should be spaced evenly in the mesh for interpolating missed vertices Construct a vertex spanning tree and assign each vertex at level l into i -th description.

L.Ying, 3D Mesh Coding and Transmission, Multiple Description Coding(3)  Existing Work [JWC04]

L.Ying, 3D Mesh Coding and Transmission, Proposed Research  Objective –With packet loss: wireless network –No retransmission: real-time applications –No error protection –Perceptual quality friendly  Multiple Description Connectivity Coding

L.Ying, 3D Mesh Coding and Transmission, Will Improve on Valence- Driven Approach  With trivial size and be kept in all descriptions  Or, can be interpolated add 6, add 7, add 4add 4add 8add 5 add 4add 5 split 5 add 4 add dummy 6 add 4

L.Ying, 3D Mesh Coding and Transmission, The End Thank you!