Rate-distortion optimized scan for point cloud color compression

We propose an adaptive scanning scheme to improve color attribute compression performance of static point cloud. To better exploit the intrinsic correlations of point cloud color data, multiple scanning modes are dedicated to projecting the color attributes into a series of texture blocks before compression. The best mode is subsequently selected in the sense of rate-distortion optimization, such that the compression flexibility and performance can be greatly improved. To achieve rate-distortion optimized scan, the Lagrange multiplier that balances the rate and distortion is off-line derived based on the statistics of color attribute coding. The proposed algorithm is implemented in reference software for point cloud compression (PCC-MP3DG), which is introduced by 3D Graphics (3DG) group of Motion Picture Experts Group (MPEG). Experimental results show that proposed method performs significantly better than the PCC-MP3DG reference software, and on average 6.51% and 9.36% bit-rate savings can be achieved for high and low bit rate codings, respectively.