From the introduction of this chapter, we learned that the essential parameters of a camera under the pin-hole model are its focal length and the size of the image plane (which defines the field of view of the camera). Also, since we are dealing with digital images, the number of pixels on the image plane (its resolution) is another important characteristic of a camera. Finally, in order to be able to compute the position of an image's scene point in pixel coordinates, we need one additional piece of information. Considering the line coming from the focal point that is orthogonal to the image plane, we need to know at which pixel position this line pierces the image plane. This point is called the principal point. It might be logical to assume that this principal point is at the center of the image plane, but in practice, this point might be off by a few pixels depending on the precision at which the camera has been manufactured.

Camera calibration is the process by...