We have developed an automatic calibration method for a global camera system. Firstly, we show how to define automatically the color maps we use for tracking the robots’ markers. The color maps store the parameters of each important color in a grid superimposed virtually on the field. Secondly, we show that the geometric distortion of the camera can be computed automatically by finding white lines on the field. The necessary geometric correction is adapted iteratively until the white lines in the image fit the white lines in the model. Our method simplifies and speeds up significantly the whole setup process at RoboCup competitions. We will use these techniques in RoboCup 2004.