Camera calibration

So far, we have worked with whatever image came straight out of our webcam, without questioning the way in which it was taken. However, every camera lens has unique parameters, such as focal length, principal point, and lens distortion. What happens behind the covers when a camera takes a picture, is that; light falls through a lens, followed by an aperture, before falling on the surface of a light sensor. This process can be approximated with the pinhole camera model. The process of estimating the parameters of a real-world lens such that it would fit the pinhole camera model is called camera calibration (or camera resectioning, and it should not be confused with photometric camera calibration).

The pinhole camera model

The pinhole camera model is a simplification of a real camera in which there is no lens and the camera aperture is approximated by a single point (the pinhole). When viewing a real-world 3D scene (such as a tree), light rays pass through the point-sized...