I shall thus have a chunking UpWrite process which will take some subset of the image and declare it to be a single chunk.
We have now got something which is analogous to the kgram predictor, but which works in a wholly geometric setting. We use it to perform entropic chunking of the pixel set. More precisely, we `colour' a
http://ciips.ee.uwa.edu.au/~mike/PatRec/node206.html (2 of 7) [12/12/2000 4:33:07 AM]
The final stage of the chunking UpWrite is to assign a symbol to each chunk from a new alphabet. Since we want geometric representations, we want a single vector which describes the set of points along an edge. Since we want it to work for other sets in other images, it must not be specific to line segments but must work for any shaped set of points . We choose, from many possible representations, to compute low order moments. For straight line segments, zeroth, first and second order suffice. So we simply compute
three sets of moments, one for each side of the triangle, and since the original points are in , and there is one number for the zeroth order moment, two first order moments and three second order