I got a problem when calibrating a camera with zhang's method! This method consist of two steps,that is,I must refine the internal and external parameters with nolinear estimate method after having calculate the intial estimate with linear method. That problem is about the rotation matrix R that has 3 degrees of freedom,so it is not appropriate to optimize every element of its. I have found some information in vxl documentation about the representation of rotation matrix(contrib/gel/mrc/vpgl/vgl_rotation_3d.h). Maybe Rodriques or quaternion is a good choice. But i don't find source file of the class. I don't know if it's a bug!
I hope someone can tell me if there is another solution in vxl for the problem,if not,maybe you can tell me how you resolve this problem!
Any hint and comment will be appreciated!