Planar pattern for automatic camera calibration

We present a method for automatic camera calibration that requires only that a planar pattern be visible by the camera from a few (at least three) different views. A major issue is how to obtain the projection of an absolute point using the planar pattern. In the calibration, we can move either the camera or the planar pattern and no knowledge about the motion is required. We consider and resolve both linear and nonlinear parameters. In testing the proposed methods, satisfactory results are achieved in the simulation and in real data experiments.