Neglecting image noise, does the IPAN algorithm return the same dominant points as we zoom in on an object? As we rotate the object?

a. Give the reasons for your answer.

b. Try it! Use PowerPoint or a similar program to draw an interesting white shape on a black background. Turn it into an image and save. Resize the object Figure 8-14. Pairwise geometric histogram: every two edge segments of the enclosing polygon have an angle and a minimum and maximum distance (panel a); these numbers are encoded into a two-dimensional histogram (panel b), which is rotation-invariant and can be matched against other objects 08-R4886-AT1.indd 262 9/15/08 4:22:32 PM Exercises | 263 several times, saving each time, and reposition it via several diff erent rotations. Read it in to OpenCV, turn it into grayscale, threshold, and fi nd the contour. Th en use cvFindDominantPoints() to fi nd the dominant points of the rotated and scaled versions of the object. Are the same points found or not?

dmax dmax dmin dmin