Method for obtaining the optical projection mechanism of a camera

A method for obtaining a camera's optical projection mechanism, the camera including a lens and being configured to project an image of a physical object in a field-of-view space onto an image plane, the image formed by the camera having axisymmetric and nonlinear distortion properties, the method comprising:

• (a) confirming an optical axis of the camera and a projection center of the camera;
• (b) providing a stereoscopic target including a front view surface and at least one side view surface, wherein both the front view surface and the at least one side view surface have a first pattern;
• (c) forming an image of the first pattern on the front view surface and the side view surface onto the image plane to create a second pattern;
• (d) aligning the projection center of the camera with a center point of the front view surface of the stereoscopic target, and making the optical axis perpendicular to the front view surface;
• and
• (e) comparing the first pattern with the second pattern to find a corresponding relationship between the first pattern and the second pattern, thereby obtaining the optical projection mechanism of the camera.