  Point cloud compression plays a crucial role in reducing the huge cost of
data storage and transmission. However, distortions can be introduced into the
decompressed point clouds due to quantization. In this paper, we propose a
novel learning-based post-processing method to enhance the decompressed point
clouds. Specifically, a voxelized point cloud is first divided into small
cubes. Then, a 3D convolutional network is proposed to predict the occupancy
probability for each location of a cube. We leverage both local and global
contexts by generating multi-scale probabilities. These probabilities are
progressively summed to predict the results in a coarse-to-fine manner.
Finally, we obtain the geometry-refined point clouds based on the predicted
probabilities. Different from previous methods, we deal with decompressed point
clouds with huge variety of distortions using a single model. Experimental
results show that the proposed method can significantly improve the quality of
the decompressed point clouds, achieving 9.30dB BDPSNR gain on three
representative datasets on average.
