[Greg McKaskle]

I think what is going on is that the tutorial you are following uses a very accurate, but very unforgiving method of locating colored objects. It assumes that you have very good control over the type and amount of light, distance to the object, etc.

I'm sure that you can write simple color threshold code to locate a frisbee, and you can do a few additional particle measurements to see if it is round. This approach will be more forgiving in varied lighting conditions. Even then, make sure to follow the recommendations in the white paper regarding camera white balance setting, compressions, focus, etc.

Greg McKaskle