Alex’s method 3, and some tasty paper.

by Joe

Just thought I would share a little failure with regard to Alex’s method. I just tried to implement it using FFT to solve some convolutions, which is a LOT faster – even without me trying to streamline it. It does, however, result in every pixel having a negative colour. Which is bad. Very bad.

The worst part is that I’ve seen *I MY CHAIR JUST DISINTEGRATED UNDERNEATH ME!!* Alex’s method implemented in matlab code, but I such a matlab noob, I have a lot of trouble following it. In the near future I might just sit down and try extremely hard to make it work, using the matlab code and everything.

In other news, I have been trying to do a literature review on circle finding techniques (my first ever lit review!). It seems to me there are a few main techniques.

  1. Hough Transform. This is originally used for detecting straight lines, but has been modified to detect any number of shapes, including circles.
  2. Wavelets. Wavelets are the basis for how jpegs works, and are very powerful tools for looking at a picture in different resolutions. In particular, there have been modifications to “circlets” which can be used to track down circles.
  3. Other, misc. Lots of them similar to mine, in which some estimate is made of the centre of each pixel or group of pixels.

I also read n interesting paper about the relationship between head pose and eye gaze, and in particular, how to tell if someone is surprised by something they looked at, or whether they always intended to look at it. Essentially it showed that if a person looks with their eyes, and then turns their head, they are startled. But if they move their head a bit before their eyes, then they intended to look over there.

Fascinating stuff.

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