involves retroreflective balls glued to the actor.
they are automatically tracked. retroreflection is easy to locate, hence easy to track.
the assignment of track to joint in the model may require manual intervention (once per track).
get started with image processing and computer vision.
or buy such a system. motion capture is commercially available.
oh and forget accuracy. you can get that from a sufficiently developed commercial system but don’t expect it from DIY proofs of concept.
- the marker isn’t at the center of the joint. you have to apply model knowledge to get skeleton and joints.
- those markers move relative to the actor’s skeleton because humans consist of meat too.
- camera calibration and all that