2.6. Self-Calibration

Self-calibration is also called autocalibration. Techniques in this category do not require any particular calibration object. They can be considered 0D approach because only image point correspondences are required. Just by moving a camera in a static scene, the rigidity of the scene provides in general two constraints [22, 21, 20] on the cameras' internal parameters from one camera displacement by using image information alone. Absolute conic, described in Section 2.2.2, is an essential concept in understanding these constraints. Therefore, if images are taken by the same camera with fixed internal parameters, correspondences between three images are sufficient to recover both the internal and external parameters, which allow us to reconstruct 3D structure up to a similarity [20, 17]. Although no calibration objects are necessary, a large number of parameters need to be estimated, resulting in a much harder mathematical problem.

Two recent books [15, 7] provide an excellent recount of those techniques.