Hiding furniture from an infrared depth camera

Question

I have a setup where an infrared depth camera is being used to do some (very basic) motion tracking in realtime. This is now generally working very well, but if a performer sits down on a sofa for example, they end up at both a similar depth to the sofa as they are sitting on it and the sofa's fabric deforms enough that the motion capture software starts to consider it an animate object, usually part of the performer who sat down, throwing the whole capture off.

I've noticed that certain objects (shiny, black plastic usually) don't appear to reflect much infrared light at all and come through as being at an infinite depth which got me thinking - is it possible that I could get a throw or something which either absorbs or scatters the vast majority of incoming infrared light to hide the object(s) beneath from the depth camera?

The hard thing with this is, if I'm looking at fabrics online, they unsurprisingly rarely if ever include any details regarding their properties in the infrared spectrum.

Is a material like this a thing? And if anyone is aware of a more appropriate stack exchange for this question I will gladly move it.

Answer 1

Take a camera with infrared filter of same wavelength you're using for tracking to a fabric store, and look through the viewfinder at the fabrics. The darker the fabric appears, the more IR absorbent it is.

Preferably, the camera should be without internal IR-blocking filter, though enough IR can come through, even with a blocking filter... set ISO high and test with the IR-pass filter on.

Of course, this assumes you are using Near-IR, rather than thermal imagiung for tracking.