I'm working on a model that is going to incorporate those little amber or red bicycle reflectors. You know... The kind that are plastic and kinda clear with little diamond pattern directional reflective surfaces inside. I'm attempting to create it using SAMPLER INFO and CONDITION nodes attached both to the camera and some sort of RAMP or Checker pattern that triggers the CONDITION node and returns the SAMPLER INFO back to the camera.
I'm wondering if there's anyone out there who has created one of these little reflectors (for a Mental Ray render), that is camera sensitive, and photorealistic who can give me some suggestions, or ideas on how best to pull this off.
I agree with Alvaro--it sounds like you're on the right track.
The only other thing I'll mention is that I think the way these reflectors work is by being very good at sending light back towards the source--think about how bright a STOP sign is in headlights. So maybe a trick you could use to give them that extra bit of oomph would be to have a light somewhere behind (and parented to) the camera that just illuminates those reflector objects? That way they'd appear a little brighter than everything else in the scene.
You'd want it to be a spot light with a high Dropoff value, I think, so that the effect dimmed as the camera rotated away... off the top of my head I'm not sure if this would actually have any advantage over your method, or even if it will look substantially different from a slightly incandescent version of the material, but it might be worth a try.