[vtkusers] vtkDelaunay2D

[Will Schroeder]

Hi Allen-

>I have a question about vtkDelaunay2D.
>I read the site about vtkDelaunay2D and there are something about alpha and
>tolerence variables. I am not quite understand what are they and how to set
>those variables.

Alpha: from Edelsbrunner's work on alpha shapes. Think of alpha as a 
radius. Any mesh feature whose circumradius is <= alpha is sent to the 
output. This removes extra features from the mesh, and in some cases can be 
used to extract surfaces.

Tolerance: some points are duplicates or nearly duplicates. Duplicate 
points are discarded. The tolerance determines what are considered 
duplicates. If too small you can get very bad meshes, and even numerical 
failure in extreme cases.

Will



William J. Schroeder, Ph.D.
Kitware, Inc.
469 Clifton Corporate Parkway
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will.schroeder at kitware.com
1-518-371-3971 x102 (phone)
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