Hi, I just got the whiteboard up and running. I've noticed one problem though. First, why do we need to select 4 points? A plane can be defined using 3 points. I noticed though, that if one of the three points is way off, it throws the calibration way off. Also, I noticed that if I was not very exact when selecting the calibration points, the calibration was not very good. Why not allow user (say 3-15) setting the number of points to calibrate with and throwing out the really strange results and averaging in the good results? That way users can increase the accuracy of the calibration.

Doing the calibration has nothing to do with defining a plane, it's about perspective transformation.

It takes exactly 4 points to get the perspective transformation from one quadrilateral (4 points Wiimote sees) to the other quadrilateral (4 points of screen). Accuracy wouldn't improve just by taking more points. An improvement could be to do the calibration with the 4 "outmost" points of the screen, since you get a better "description" of the quadrilateral.

That's my understanding on the subject, I could be wrong about that since I'm not expert.
http://en.wikipedia.org/wiki/Quadrilateral

Uwe