Lossless compression of point-based data for 3D graphics rendering

A lossless compression algorithm of 3D point data is proposed in this work. QSplat is one of the efficient rendering methods for 3D point data. In QSplat, each point is assigned a sphere, and the geometry and normal data are stored in the hierarchical structure of bounding spheres. To compress QSplat data, child spheres are sorted based on their limit radii to constrain the indices for the geometry data. Then, the radii and the positions of spheres are encoded separately using the reduced index sets. Also, each normal is encoded using the parent normal context, and the normal indices are reduced by the normal cone information. Simulation results show that the proposed algorithm achieves a high compression ratio by combining the reduced index sets with the context-based entropy coding.