Point Cloud Geometry Prediction Across Spatial Scale using Deep Learning

A point cloud is a 3D data representation that is becoming increasingly popular. Due to the large size of a point cloud, the transmission of point cloud is not feasible without compression. However, the current point cloud lossy compression and processing techniques suffer from quantization loss which results in a coarser sub-sampled representation of point cloud. In this paper, we solve the problem of points lost during voxelization by performing geometry prediction across spatial scale using deep learning architecture. We perform an octree-type upsampling of point cloud geometry where each voxel point is divided into 8 sub-voxel points and their occupancy is predicted by our network. This way we obtain a denser representation of the point cloud while minimizing the losses with respect to the ground truth. We utilize sparse tensors with sparse convolutions by using Minkowski Engine with a UNet like network equipped with inception-residual network blocks. Our results show that our geometry prediction scheme can significantly improve the PSNR of a point cloud, therefore, making it an essential post-processing scheme for the compression-transmission pipeline. This solution can serve as a crucial prediction tool across scale for point cloud compression, as well as display adaptation.