Enabling Low Bit-Rate MPEG V-PCC-encoded Volumetric Video Streaming with 3D Sub-sampling

MPEG's Video-based Point Cloud Compression (V-PCC) is a recent new standard for volumetric video compression. By mapping a 3D dynamic point cloud to a 2D image sequence, V-PCC can rely on state-of-the-art video codecs to achieve high compression rate while maintaining the visual fidelity of the point cloud sequence. The quality of a compressed point cloud degrades steeply, however, below the operational bit-rate range of the video codec. In this work, we show that redundant information inherent in a 3D point cloud can be exploited to further extend the bit-rate range of the V-PCC codec, enabling it to operate in a low bit-rate scenario that is important in the context of volumetric video streaming. By simplifying the 3D point clouds through down-sampling and down-scaling during the encoding phase, and reversing the process during the decoding phase, we show that V-PCC could achieve up to 2.1 dB improvement in peak signal-to-noise ratio (PSNR), 7.1% improvement in structural similarity index (SSIM) and 14.8 improvement in video multimethod assessment fusion (VMAF) of the rendered point clouds at the same bit-rate and correspondingly up to 48.5% lower bit-rate at the same image quality.