| HN Mirror

I was previously under the impression that the photodiodes figured out their own angular position and you received a library to convert those values into a single rectilinear position and orientation on the device. This is not the case. The photodiode ASICs basically just convert photons to voltage and clean up the signal. The official kit includes an FPGA to pack up all the sensor data and an MCU to give you an SPI interface to that data. The system is pretty much end-to-end, you mostly just get a chance to inject your own data about button clicks or what have you into the data stream from the device. SteamVR on the PC does the work of making sense of the data.

There is a huge amount of design that has to go into the sensor layout. Bad sensor layout will cause significant problems in tracking. It's extremely constraining in what you can do.

The system is designed to work with one base station. The second is only for redundancy, covering areas of the play area that are occluded for the master base station by your own body.

In contrast, Oculus uses cameras to detect IR LEDs on the device. It's kind of inside out from SteamVR. They have to them do image processing on the PC to get the angular position with regards to the camera of each LED. SteamVR just has to convert timing values into laser emitter motor positions. Once you get to that point, they are pretty much the same, having to compute position and orientation from that data. It's just a lot cheaper for SteamVR to acquire that data.

It also means that adding more cameras to Oculus adds to the workload, whereas adding base stations to SteamVR does nothing to the PC. Both will increase workload to add more devices, but it's negligible compared to the image processing Oculus has to do. Oculus' system is fundamentally unscalable. SteamVR is fundamentally scalable.