CODEWITHSUNDEEP
computer-visionsift
shujj
shujj

Reputation: 355

Sift Implementation :: Keypoints from different octaves

I am trying to implement SIFT in MATLAB.

I have obtained keypoints for (say) 4 different octaves by locating local maxima and minima in DOG (difference of gaussian) space. However I am at loss at what to do with the keypoints from the last 3 octaves.

Do I include them in keypoints for the original image, if yes then how do I do the translation from the reduced image to the original e.g pixel (i,j) in 256 x 256 image(2nd octave) to pixel(i',j') in 512x512 image (1st octave). I tried many sift tutorials but didn't find anything conclusive.

Upvotes: 8

Views: 1127

Answers (1)

old-ufo
old-ufo

Reputation: 2850

It is not clear, what do you mean by "last 3 octaves"? About translation - you multiply obtained scale (from blurring kerkel) and (x,y) by factor of two for 2nd octave, by 4 for 3rd octave, etc...

Upvotes: 1

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