There are a couple of technical issues we ran into. For example, rubber is hard to track. While nobody should be wearing a rubber suit, often belts and things make an empty section through your waist, which causes some tracing problems. Dark jeans, fresh denim jeans often completely bug the tracking out. Skirts are hard to track because you just have a single leg instead of two and without higher resolution it's hard to disambiguate. Baggy jeans. Shorts cause issues if you don't have higher res. Certain materials, like polyester.

Basically it's an infrared camera. Infrared light is not some sort of special light. It's just like visible light, but it's not visible. It's a different wavelength. I'm wearing a black shirt and if you look at it with a regular camera, that's black to the camera. The reason is because there's no light coming in from that colour. So there are certain objects that are infrared black. To an infrared light in an infrared camera they appear black. Those are the objects that are hard to track.

There are also some objects that are infrared reflective, just like a mirror is visible light reflective. Those tend to show up bright white on the camera, and then they come up as infinite depth. Those are the funky materials that sometimes just make the tracking bad. I don't know if that can be solved, but some cameras have fewer issues with them and some have more.