Perceptual Quality Assessment of Compressed Volumetric Human Holographic Sequences at Varying Viewing Distances in VR

Volumetric video compression is essential for addressing processing and bandwidth challenges, while minimizing perceptual quality loss, in emerging holographic tele-transportation (i.e. holo-portation) services. Research in this field has primarily focused on compression efficiency and/or on real-time performance, but less attention has been given to the perceptual impact of volumetric video compression when viewing dynamic sequences of human holograms at varying distances in Virtual Reality (VR) scenarios. This paper first provides objective evidence on the promising performance of a novel Video-based Point Cloud Compression Codec (V*-PCC) compared to a state-of-the-art Geometry / anchor octree-based (G-PCC) codec. Then, the V*-PCC codec is adopted to run a user study in which observers view sequences of volumetric holographic user representations at different compression levels, shown at varying distances. The results reveal two key insights: (i) perceptual quality improves at equivalent compression settings as the viewing distance increases; and (ii) compression artifacts become less noticeable and more tolerable at greater distances. These findings not only support the need for further Quality of Experience (QoE) studies but interestingly reinforce the potential of devising dynamic viewport- and position-aware encoding strategies to overcome current scalability and interoperability limitations in this field.