atthews. IJCV 2004.
 The implementation is optimized and can easily run at 20-30 fps.
 
 type may take on the following values:
  'translation'  - translation only
  'rigid'        - translation and rotation
  'similarity'   - translation, rotation and scale
  'affine'       - 6 parameter affine transform
  'rotation'     - pure rotation (about x, y and z)
  'projective'   - full 8 parameter homography
 Alternatively, type may be a vector of ids between 1 and 8, specifying
 exactly the types of t