Hierarchical Bit-Wise Differential Coding (HBDC) of Point Cloud Attributes

Targeting both computing and coding efficiencies, we propose in this work a novel hierarchical bit-wise differential coding scheme to compress point cloud attributes. The encoder firstly quantizes and organizes the points into an octree structure and, for each internal node, picks its attribute(s) from a child named source child. Next, the encoder conducts a top-down scanning of the hierarchy. For each node with more than one child, it computes the bit-wise attribute difference between the current node and each non-source child by exclusive-OR and encodes the difference with an arithmetic coder. Further, a table look-up approach is proposed to accelerate the online source child identification. The proposed scheme produces superior computing and coding efficiencies for lossless point cloud attribute compression, outperforming the MPEG benchmark coders by large margins in our experiments.