Accurate full-body tracking in Virtual Reality (VR) is heavily underconstrained when relying solely on consumer-grade sparse sensors, such as Head-Mounted Displays (HMDs) and handheld controllers. Indeed, the self-avatar full-body pose must be inferred based on the 3 available upper-body joints tracked by these devices.

This leads to significant tracking error, especially in lower-body pose. To overcome this issue, we propose to extend the tracking setup with external multiview RGB cameras.

We show that integrating RGB-based pose estimation this framework is able to significantly decrease lower-body tracking errors, even under common artifacts in RGB-based estimates. Additionally, we evaluate a only-once HMD-camera calibration procedure that does not require any physical markers.

We finally propose an implementation of the overall framework, achieving an end-to-end animation at 60 FPS on a Nvidia RTX3080 GPU. Codes are available at https://github.com/antmaio/MuCHMDPoser.