Homework 2 solutions

Prob 1

Intrinsic parameters "without" distortion correction:
focals=[735 663]
center=[341 232]

Intrinsic parameters "with" distortion correction:
focals=[733  657]
center=[386  212] 

Your solution has to be within 5% of the either solution.

Prob 2

  - [-1 0 1]' * [1 2 1]
  - [1 2 1]' * [-1 0 1]

Prob 3

(a) Harris corner detector is NOT a linear filter,
mainly because the elements of C: [Ix^2 Ix*Iy; Iy*Ix Iy*Iy]
are not linear functions of the pixel values.

(b) 

- Scaling:  not really (the image itself might be somewhat
    invariant, like a checkerboard, but that doesn't count)
- rotation: yes
- illumination: yes, but with some limitations
- perspective: yes, but only a little

If your have time, see this paper for more details:
"Evaluation of Interest Point Detectors"
By C. Schmid, R. Mohr, and C. Bauckhage.
http://citeseer.ist.psu.edu/schmid00evaluation.html

(c) The Harris Corner detector may trigger false
corners on unsmoothed raw images;
for instance images with salt and pepper noise.