HN user
R.I.P He is really a wonderful person. His blog CoolShell helped countless people starting the career in programming. It's been a long journey for me through my undergrad and now PhD student in CS, but I still remember the time that learnt quite a lot from his blog. It's still stared on my homepage all the time. I'll carry on his passion about explaining many complicate concepts in software engineering.
I've been working with motion capture system for several years as a phd student in robotics. The first thing came into my mind is the motion capture system which is already mentioned by someone ahead. I worked in one of the largest indoor motion capture in academy, the ASU drone studio which possibly can be a reference if you searched it. But the cost of such a field is pretty high since you basically have to cover every corner with camera each of which costs 4k-6k dollars. It can track 10s of objects easily with sub-mm accuracy and 360 frame per second.