Skeleton-based motion estimation for Point Cloud Compression

With the rapid development of point cloud acquisition technologies, high-quality human-shape point clouds are more and more used in VR/AR applications and in general in 3D Graphics. To achieve near-realistic quality, such content usually contains an extremely high number of points (over 0.5 million points per 3D object per frame) and associated attributes (such as color). For this reason, disposing of efficient, dedicated 3D Point Cloud Compression (3DPCC) methods becomes mandatory. This requirement is even stronger in the case of dynamic content, where the coordinates and attributes of the 3D points are evolving over time. In this paper, we propose a novel skeleton-based 3DPCC approach, dedicated to the specific case of dynamic point clouds representing humanoid avatars. The method relies on a multi-view 2D human pose estimation of 3D dynamic point clouds. By using the DensePose neural network, we first extract the body parts from projected 2D images. The obtained 2D segmentation information is back-projected and aggregated into the 3D space. This procedure makes it possible to partition the 3D point cloud into a set of 3D body parts. For each part, a 3D affine transform is estimated between every two consecutive frames and used for 3D motion compensation. The proposed approach has been integrated into the Video-based Point Cloud Compression (V-PCC) test model of MPEG. Experimental results show that the proposed method, in the particular case of body motion with small amplitudes, outperforms the V-PCC test mode in the lossy inter-coding condition by up to 69% in terms of bitrate reduction in low bit rate conditions. Meanwhile, the proposed framework holds the potential of supporting various features such as regions of interests and level of details.