You only need a webcam and Opentrack free software to use Neural Net Tracker Headtracking. This video shows you how to set it up. I have only used it for IL-2 Sturmovik Great Battles but it may also be useable in other flight sims and games that support headtracking.
Link to Opentrack: https://github.com/opentrack/opentrack/releases
Notes:
1. Ensure your face is adequately illuminated when using the tracker
2. When calibrating, if you cannot achieve 12 pitch samples, you can perform circular movements of your head in order to complete the process and achieve 12+ pitch samples - note that the tracker will still work even without achieving full calibration
3. If the Pitch axis drifts upwards despite your head not moving, try using a different head pose file (in the Tracker Options, Tracker tab
https://youtu.be/6cvWn2Oy0CA?feature=shared&t=115, at the bottom left you have a button that reads "Select Pose Net ONNX") - try an alternative file from the handful that are available and see if it helps. I found that using "head-pose-0.2-small.onnx" worked well for me
4. I am using a 1440p 27" monitor, with the webcam mounted on the top, about 0.5 - 1.0m away from my face. If your setup is different then just copying my settings may not perform as intended
5. If the position of your chair and PC/webcam setup remains the same from one gaming session to the next, you may be able to use the tracker without re-calibrating each time. However, if you notice the tracking is not performing well, consider re-calibrating.
Music:
Artist - 8.864 | Track - Spring, thaw, gentle glow, hope, nature: 10 minute (1610707)
Time Codes
00:00 - Intro
00:51 - NeuralNet Tracker Options
03:00 - Headtrack Mappings
05:16 - Calibrating
06:58 - Example Testing