Some thoughts on a low cost IR markeless tracking system- Elements required- 2 cameras, one for color capture one for IR marker capture. Beam splitter rig. Here's a guy that built one with two Canon T2i cameras. Easily adapted for IR tracking rig.Here is a sie to get the 50% mirrors required. http://stereoscopicmirror.com/ The applications or VFX are HUGE!
tracking system based on invisible markers which are created/drawn with an IR fluorescent pen. The tracking system consists of one scene camera, one IR camera, and one half mirror. The two cameras are positioned in each side of half mirror so that their optical centers coincide with each other. Two simultaneous takes are recorded. One that will record the invisible markers using the IR modified camera and a second take, a normal color recording with a regular camera. In post, the IR markers are used to track the scene and produce 3d scene data. The footage is then swaped out with the color take.