Side Project

Motion Capture systems cost a gazillion dollars. They have fancy infrared cameras, and lots of 'em. They have proprietary software. They are a big production, often with a kickin' soundtrack.

Screw that, says I.

Just because my lab doesn't have an expensive supersystem doesn't mean I'm not interested in a bit of motion capture. It just means that I have to put in a little bit of extra work to make it happen. And so I did, spending way too much time on the software, and then half-assing the hardware for the following demonstration.

Here is a simple video of me looking like a shmuck. Observe my incredibly slick dance moves and electric tape body markers. I am dancing. To "YMCA". By the Village People. Yes.



This video is two dimensional. So is the video that I recorded using another camera. Each point can only be located by left-right and up-down position, but we have no idea how far away it is from the camera. Using some trigonometry and some algebra, and a lot of programming, I reconstruct each point in a three dimensional space.

Each point. Every single one of them. In this video, that's 8 points at 320 frames for a grand total of 2560 points. And then I had to do it again, for the second camera. Oy.

And so here's the reconstruction, doing something that a real camera couldn't do...



If the angles look a little funky, it's because my choice of marker locations was bad, and also because I wasn't extremely precise in my marker identification. It's just a demo.

Here's another video, showing how the two cameras are used in making a 3-d stick figure. I think it looks like a dance class, like motion capture from a Richard Simmons exercise tape.


So there you have it. We've gone from two simple videos of movement to a completely digitized representation. It's nothing earth-shattering, more of a demonstration than a discovery. I'm reinventing the wheel here, but I'm doing it on the cheap, and the possibilities it allows are endless.

That was my Monday. And yes, YMCA looks RIDICULOUS, and by association, so do I.

UPDATE: Oh dear. I can create my own motion capture system, but I can't do the YMCA dance properly. Yes, I the C is backwards. Forgive me.