I have 2 webcams with removed IR blocking filters and applied visible light blocking filters. Thus, both cameras can only see IR light. So I can not calibrate the stereo cameras by oberserving points on a chessboard (because I don't see the chessboard). Instead of this I had the idea to use some amount of IR-LEDs as a tracking pattern. I could attach the LEDs on some chessboard, for instance. AFAIK, the OpenCV stereoCalibrate function awaits the objectPoints, as well as the imagePoints1 and imagePoints2 and will return both camera matrices, distortion coeffs as well as the fundamental matrix.
How many points in my images do I need to detect in order to get the function running appropriate? For the fundamental matrix I know the eight-point algorithm. So, are 8 points enough? The problem is, I don't want to use a huge amount of IR-LEDs as a tracking pattern. Are there some better ways to do so?