1 The mathematical meaning of the camera
The real world is three-dimensional, but the pictures taken are two-dimensional. Therefore, the camera can be regarded as a generalized function. The input of the function is a three-dimensional real-world scene, and the output is a two-dimensional picture. The mapping relationship of this function is irreversible, which means that we cannot directly restore the three-dimensional world from two-dimensional photos.
2 Significance of camera calibration
Camera calibration is the process of using a calibration board with a pattern to solve the camera parameters. A simplified mathematical model is used to represent the complex 3D to 2D imaging process. Camera parameters include: camera intrinsic parameters (focal length, principal point) and camera extrinsic parameters (rotation and translation matrix), lens distortion parameters, etc. The purpose of camera calibration: distortion correction, structured light, 3D reconstruction, slam, etc.