A hotfix for SteamVR claims a prediction improvement that reduces positional latency for Oculus Quest in Oculus Link mode.
Oculus Link is the feature which lets the Oculus Quest act as a PC VR headset via any high quality USB 3.0 cable. This gives Quest owners who own a gaming PC access to the Oculus Rift library and SteamVR.
SteamVR supports Rift and Link by acting as a middleman between the Oculus runtime software and the running SteamVR app. Some features such as the safety boundary are left to the Oculus software, but other features, like tracking prediction, are handled by SteamVR.
Modern VR systems do not use the raw positional tracking value when deciding how to move the virtual cameras that represent the user’s eye. Even after the absolute tracking (from the cameras or lasers) is fused with the internal accelerometer values, the position cannot be used because it’s out of date. That’s because it has to be sampled before the frame begins rendering, and thus will be out of date.
Instead, algorithmic-based prediction is used. The positional data from the previous few seconds (or sometimes even more) is analyzed and from this the system can extrapolate to where the headset is likely to be when the photons from the next frame will actually hit the user’s eyes. Some platforms use machine learning for this, while others use hand crafted algorithms.
Valve didn’t go into details on exactly what was improved. The exact changelog entry reads:
Fixed prediction when using Quest+Link (improves positional latency).
Reductions in latency will be appreciated by Oculus Link users more than with other PC VR hardware. That’s because Link doesn’t send a raw video signal, it instead compresses the image. It takes time to encode (compress) and decode (decompress) each frame, and this adds latency.
How has your experience with Oculus Link on SteamVR been? Let us know in the comments below.