Rate-Distortion Optimal Transform Coefficient Selection for Unoccupied Regions in Video-Based Point Cloud Compression

TL;DR

This paper introduces a rate-distortion optimized method for selecting transform coefficients in video-based point cloud compression, significantly improving compression efficiency for unoccupied regions in HEVC encoding.

Contribution

It proposes a novel generalized frequency selective extrapolation approach for optimizing transform coefficients specifically for unoccupied regions in point cloud videos.

Findings

Bitrate savings of over 4% for geometry and 6% for texture in all-intra coding.

More than twice the savings compared to existing methods.

Outperforms competing V-PCC methods by over 0.5% in random-access scenarios.

Abstract

This paper presents a novel method to determine rate-distortion optimized transform coefficients for efficient compression of videos generated from point clouds. The method exploits a generalized frequency selective extrapolation approach that iteratively determines rate-distortion-optimized coefficients for all basis functions of two-dimensional discrete cosine and sine transforms. The method is applied to blocks containing both occupied and unoccupied pixels in video based point cloud compression for HEVC encoding. In the proposed algorithm, only the values of the transform coefficients are changed such that resulting bit streams are compliant to the V-PCC standard. For all-intra coded point clouds, bitrate savings of more than 4% for geometry and more than 6% for texture error metrics with respect to standard encoding can be observed. These savings are more than twice as high as savings obtained using competing methods from literature. In the randomaccess case, our proposed method outperforms competing V-PCC methods by more than 0.5%.