Rate-distortion based reference viewpoints selection for multi-view video plus depth coding

For multi-view video plus depth (MVD) coding in 3D video (3DV) applications, texture videos and depth maps of a few reference viewpoints should be compressed and transmitted. The other intermediate virtual viewpoints are synthesized by depth-image-based rendering algorithm. The videos displayed for terminal users include the decoded reference viewpoints and the synthesized virtual viewpoints. Under a given bit rate constraint, how to choose the optimal reference viewpoints setting to obtain the best video quality of all display viewpoints is an important research issue. This paper proposes a rate distortion model based algorithm to obtain the optimal reference viewpoints selection. First, the impacts of the reference viewpoints setting on the entire quality of all display viewpoints is investigated, and then a quadratic distortion model for all display viewpoints is derived. Based on this distortion model, the optimal viewpoints selection problem is solved by computing a few model parameters. Experimental results demonstrate that the proposed distortion model estimates the actual distortion of all display viewpoints with high accuracy, and the proposed reference viewpoints selection method achieves almost the same rate distortion performance as compared to the full search method with a very low computational cost.