Impact of Texture Resolution, Polygon Count, Quality Level, and Viewing Distance on Volumetric Avatar Visual Quality

Volumetric videos, here referred to as volumetric avatars when depicting human subjects, are an extension of traditional videos for 3D objects in immersive Virtual Reality (VR) / eXtended Reality (XR) environments. Various compression methods have been developed, all of which offer a wide range of possible encoding parameters. Despite their potential for advanced teleconferencing and XR experiences, determining the optimal encoding parameters to maximize perceived visual quality remains a challenge. In this paper, we aim to evaluate how various encoding parameters affect the perceived visual quality of volumetric avatars. Our test method is novel for volumetric video quality evaluation and is another contribution of the paper, besides the volumetric video quality results. We adopted a test design used in classical 2D video quality evaluation into VR, with the viewers placed at distinct viewing distances on a swivel chair where they can explore the volumetric avatars from the given positions. This test method is an integrative solution between predefined exploration trajectories with subsequent fixed 2D video presentation as performed, e.g., in ISO-MPEG and a completely free exploration. We conducted three subsequent tests, to assess the impact of texture resolution, mesh polygon count, and quality level (linear mapping of CRF-factor). Our findings indicate that texture resolution and quality level influenced the perceived visual quality the most. These results provide valuable insights for developing more lifelike and immersive representations of human avatars, paving the way for improved XR experiences.