Direct linear calibration
Advantage:
•Very simple to formulate and
solve
Disadvantages:
•Doesn’t
tell you the camera parameters
•Doesn’t
model radial distortion
•Hard
to impose constraints (e.g., known focal length)
•Doesn’t
minimize the right error function
For these reasons, nonlinear methods are preferred
•Define error function E
between projected 3D points and image positions
–E is nonlinear function of
intrinsics, extrinsics, radial distortion
•Minimize E using nonlinear
optimization techniques
–e.g., variants of Newton’s
method (e.g., Levenberg Marquart)