hi arnaud: in a future version, I'll give it a try;I was just wondering, at the time, whether or not there was a particular color tape I could find, if I could get some spectral sensitivity & perhaps temperature information about the camera's lens. I was thinking that perhaps I could find some particular green tape that would work a bit better.
also, up to this moment, since I was doing everything "by hand," and in a "naive" way, I didn't know about either ROS or ARToolkit, but, as I make this project more sophisticated, I'll look at these tools; definitely thanks for giving me a heads up on these projects.
in the version of this that I wrote, I was using opencv to chop the image into half and then look at the bottom part, since I was only examining things on the floor. Then I filtered the image using the HSV conversion to throw out anything except my H ranges, and then further filtered for S and V. The S & V were actually problems because, as I stated, light flares from reflections of sunlight on the floor, and noise produced in very low-light situations would appear blue. But those could be filtered out, because, in the end, the tape's S & V values were, generally speaking, different from the camera artifacts.