ON PREDICTIVE RAHT FOR DYNAMIC POINT CLOUD CODING

We studied predictive coding applied to the region-adaptive hierarchical transform (RAHT) which is used for point cloud compression (PCC). RAHT is part of MPEG's geometry-based PCC test model and an intra-frame prediction scheme for RAHT (URAHT), wherein the prediction residual is encoded rather than the voxel attributes themselves, has been shown to deliver large gains. We extend the scheme to inter-frame prediction and show that a combination of simple zero-motion-vector (ZMV) inter-frame and intra-frame predictions can provide sizeable gains over pure RAHT or over intra-frame-only prediction when compressing dynamic point clouds. An adaptive method is used such that sections where ZMV does not yield good prediction switch to intra-frame prediction, assuring the performance to be at least that of the intra-frame case. Be the gains large (in steady parts) or very small (where there is rapid motion) results show consistent positive gains coming from a simple inter- and intra-frame prediction combination.