A motion-compensated inter-frame attribute coding scheme for dynamic dense point clouds

This paper addresses the problem of compressing the colour attributes of dynamic dense point clouds. Inter-frame prediction and motion compensation are key to removing temporal redundancies and thereby reaching major compression gains. For that purpose, an attribute compression scheme combining intra-frame and motion-compensated inter-frame predictions is presented. It is built upon the Test Model developed by MPEG within the Geometry-based Point Cloud Compression (G-PCC) activity to encode dense dynamic point clouds. More precisely, a motion-compensated inter-frame prediction is introduced into the RAHT encoding scheme, leveraging the local motion field already present in the geometry encoder. The best prediction mode according to rate-distortion optimization is decided at each node of the octree, encoded by means of arithmetic coding using a binary prediction tree and signalled to the decoder. Experimental results are provided using the MPEG test sequences and common test conditions. They demonstrate very significant compression gains, with average BD-Rates of -15.2%, -18.3% and -18.1% on Y, Cb and Cr colour components respectively, when compared with the current scheme with intra-frame only attribute compression.