Point Cloud Rendering after Coding: Impacts on Subjective and Objective Quality

TL;DR

This paper evaluates how different point cloud coding and rendering methods affect perceived visual quality and the accuracy of quality metrics, providing insights into artifact visibility and metric performance.

Contribution

It assesses the impact of coding and rendering on perceived quality and evaluates recent MPEG coding solutions across multiple rendering methods for the first time.

Findings

Coding artifacts vary with rendering approach

Objective metrics have strengths and weaknesses post-rendering

Rendering significantly influences perceived quality

Abstract

Recently, point clouds have shown to be a promising way to represent 3D visual data for a wide range of immersive applications, from augmented reality to autonomous cars. Emerging imaging sensors have made easier to perform richer and denser point cloud acquisition, notably with millions of points, thus raising the need for efficient point cloud coding solutions. In such a scenario, it is important to evaluate the impact and performance of several processing steps in a point cloud communication system, notably the quality degradations associated to point cloud coding solutions. Moreover, since point clouds are not directly visualized but rather processed with a rendering algorithm before shown on any display, the perceived quality of point cloud data highly depends on the rendering solution. In this context, the main objective of this paper is to study the impact of several coding and rendering solutions on the perceived user quality and in the performance of available objective quality assessment metrics. Another contribution regards the assessment of recent MPEG point cloud coding solutions for several popular rendering methods which were never presented before. The conclusions regard the visibility of three types of coding artifacts for the three considered rendering approaches as well as the strengths and weakness of objective quality metrics when point clouds are rendered after coding.