Research Of Encoding And Compression Algorithm Of Three Dimensional Models

As the development of information technology,the scanning technology for the three dimensional shape has been mature,and some kinds of advanced geometry modeling tools have been innovated and improved,those make the structure of the three dimensional model become more complicated and the amount of data has be expanded continuously.At present,the details and resolution of the three dimensional model has been fully promoted,and the amount of data is great.The requirement of computing ability of the workstation is becoming higher and higher,and the required storage space is expanding.In addition,with the rapid development of Internet technology,also makes the three dimensional models are useful widely in a lot of areas such as film and television,animals and plants science,medicine,building,mechanical engineering and VR,which puts forward a serious challenge for huge amounts of online data transmission.Progressive Meshis a kind of classical topology-drivenalgorithm for three dimensional model compressions,which is usedwidely.But this algorithm and the subsequent improved algorithmsare not ideal on simplify efficiency and compression ratio.Based on those,this paper devotes to the research of promoting the Progressive Mesh method,and proposes a new improved algorithm which makes up for the shortageThe improved algorithm in this paper is mainly divided into two steps: mesh decimation and topological geometry data compression coding.In the mesh decimation step,this paper employs the half-edge collapse operation as the basic operation instead of using the well-known Quadric Error Metric,to choose to edge which should be folded.This can improve the speed of mesh decimation,and Ensure the quality of each level of detail in meshes.At the same time,the algorithmanalyzesthe possible result of each half-edge collapse.In order to avoid generating the face normal flips which will degrade the mesh quality,the algorithm verify for each face of the patch that the cosine of the angle between the normal before and after the collapse does not exceed threshold.This method can ensure that the irregular mesh will not be generated during the mesh decimation step.In the step of mesh reconstruction and encoding,the algorithm use 4 symbols to represent the vertex split operation in each level of detail and encode them as the connectivity information of the mesh,and use a residual vector to represent the position of the split vertex and use the local Frenet frame to encode residual vectors as the geometry information.At last,the algorithm employ a range coder with a quasi-static probability model to compress connectivity and geometry symbols.And the progressive mesh compression algorithm in this paper is a lossless compression scheme except for a tolerated geometry quantization.Finally,the paper implements the proposed improved progressive mesh compression scheme with C++ programming.And the program is used to process several mesh models and the experiment result verifying the effectiveness of the algorithm.