Ground truth

Hi everyone, I am working on a simulator for a project and we need to do a ground truth of the camera's view at every moment.
Here is an exmaple of what we would like to developt:

http://www.google.es/imgres?q=groun...dsp=45&ved=1t:429,r:16,s:0,i:136&tx=147&ty=32

Any idea?, I was thinking of painting the mesh of the character in a colour but I would also like to turn black the rest of the elements...