Re: On the nature of irregular sets

Hi,

I couldn't put the accompanying image on our server yesterday; I'm attaching it (and hoping this is allowed in this list!).

One sees on the left the "curtains" I mentioned. These are planes which are very close together and on the edge of the dataset. Intersting is really one one rotates the image, the planes sort of flicker.

On the right it's the same effect. This is not really a bug, I know (or think); but it's created when the algorithm joins exterior points (points on the boundary of the dataset), and which are concave. Is there a way to avoid that?

Cheers,

Ugo

Ugo Taddei wrote:

Hello everyone!

We're trying to use the visad Delaunay classes to triangulate some elevation data on-the-fly. I'm quite happy about the performance (at least on my machine ;-) but I've run into a few of problems and would like to clear the matter before carying on with development.

First, only DelaunayClarkson seems to work OK with my data. DelaunayWatson and DelaunayFast throw "java.lang.ArrayIndexOutOfBoundsException: 23320; at visad.DelaunayWatson.<init>(DelaunayWatson.java:190)
and "visad.SetException: Delaunay.finish_triang: error in triangulation!
   at visad.Delaunay.finish_triang(Delaunay.java:592)
   at visad.DelaunayFast.<init>(DelaunayFast.java:581)", respectively

Any ideas?

For this dataset we've 11560 points.

I've already tried the common hack for the irregular 2d sets (multiplying values by 1000 to spread them apart)...

The second problem concerns triangles on the edgdes of the dataset. Points very close together and on the edge are creating curtain-like artefacts. Is there a way to avoid that?

Thanks for the help!

Cheers,

Ugo


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