What does the rotation matrix truly represent, with only 1 image or camera?

The concept of extrinsic parameters of a camera seem fuzzy to me when there is only one viewing plane. What is the rotation matrix and translation vecto开发者_StackOverflow中文版r relative to when we only have one image? Why wouldn't this always be the origin?

It appears you are recovering extrinsic parameters (R+T, 6 DOF) from one image of a known object (calibration target). If this is true, then the recovered parameters correspond to the camera pose relative to the intrinsic coordinate system of the calibration target.

For instance, if you are viewing a Zhang's planar target, and if you denote the target point coordinates as (0,0), (0,1), (0,2), ..., (1,0), (1,1), etc, then the recovered camera pose is relative to the coordinate system with origin at (0,0), and whose axes are defined by the vectors e1((0,0),(0,1)), e2((0,0),(1,0)) and e3 = e1 x e2.