[sanddrag]

For film productions, there is some special stuff they use to do a green screen effect. The backdrop cloth is actually this very special strange type of grey cloth. (sorry I don't know what it is called). Then on the camera is a ring of maybe 50 super bright green LEDs around the lense. The subject (actor) must be placed between the LEDs and the screen, otherwise it doesn't work.

So, due to their color/whatever the LEDs have very little effect on the color of the subject at all but on camera, the grey backdrop cloth comes up a smooth, solid, uniform greeen with no texture. The cloth is made specially to reflect the green light evenly back to the camera. It cannot be seen just by a person, but it is very bright, uniform green on the camera.

So, I was thinking if the robots could have lots of green LEDs and then there could be field elements with this cloth on them. It should make homing in on it very easy with a camera since the color reflected back to the camera doesn't really depend on lighting conditions.

However, I'm not really sure how well this works over distance. I've only tried this operation from maybe 10 feet away.