Homework:

Performance of DCE compared to subsampling

Does the DCE really perform better than simple subsampling in the sense of the Hausdorff distance ?

Please program the following experiment:
For all shapes in a given testset:
Create simplified versions having 103,98,93,88,..,3 vertices using
  1. DCE
  2. Subsampling with equal runlength distance
Measure the distance to the original object using the polygonal Hausdorff distance HP, which is defined in the following way:
Let S be the original shape, A the simplified (abstracted) version. Then
HP=max(min(d(S,ai)) for all vertices ai of A, d(S,ai) being the set of euclidean distance between ai and all segments of S (distance point-segment = shortest euclidean distance).

Draw 3 diagrams showing on the x axis the number of vertices in A, on the y axis the distance value. Draw curves for

  1. the average,
  2. min and
  3. max distance over all shapes
for both distance measures.

You will be given matlab programs for: DCE, subsampling, distance point-segment, tools (loading/saving/plotting), and a set of shapes. The set of shapes is the 1400 shapes used for the MPEG-7 test. It is more or less the industrial standard set for tests regarding shape.

You get it all HERE (about 4MB)