[vtkusers] triangulation

[Jonathan Bailleul]

Dear Mr, Dear All,

I suppose you already have a polydata mesh, probably obtained from marching
cubes or so, and I assume you want to decimate the mesh to reduce the number
of triangles. The problem is to decimate without modifying the relative size
of triangles, and to maintain equilateral geometry for triangles as far as
possible.
In that case, I'm having the same problem and I'd be happy to benefit from
anybody's experience!

To that day, some good ways I've found to approximate these goals could be:
-1 to use vtkQuadricDecimate with standard parameters. Filter with
vtkWSincWindow before and after can help a lot.
-2 to use cleanpolydatafilter with tolerance 1 (very big). I can't explain
why, but I never managed to get so neat equilateral triangles with any other
filter... the result is really impressive. Of course, the drawback is that
we lose some precision relatively to the distance to the original surface,
but it remains more than acceptable - for my needs.

The problem remaining with the second option is that many single vertices
and edges are created (though easily removed), but there also remains
overlapping triangles sharing same vertices, triangles causing reversed
normals, and worse than all, holes appear on the surface as missing
triangles. Please, if anybody has any hint to solve this, help me out!

Best regards,



----- Original Message -----
From: "Leo Santos" <leonardomrs at gmail.com>
To: <vtkusers at vtk.org>
Sent: Friday, September 16, 2005 1:22 PM
Subject: [vtkusers] triangulation


When trying to triangulate my data, I would like to have triangles
more or less in the same size, or better, exactly one triangle by
pixel (instead of huge triangles among tiny ones when the region is
homogeneous). Does anybody have any idea of which class and parameter
I should set?

Yours most fully entirely faithfully,
Leo
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