Visualisation question

[Will Schroeder]

To add to Paul's comments: vtkDelaunay3D does a pretty good job of constrained Delaunay triangulation...it's a relatively new feature added within the last year or so.
Will

At 08:04 AM 5/2/00 -0700, pahsieh at usgs.gov wrote:

> > There are various algorithms for contouring : you have data at
> > specified grid locations, and you generate (in 2-d) a line which
> > represents all points with a given value.
> >
> > Question : How would one go the other way? I have a contour line
> > representing the boundary between two regions. How can I generate
> > the data set on a set of regular points that would generate this
> > contour line? (Is there even a unique solution?)
>
>I have done this by constrained Delaunay triangulation. Assuming
>each contour is a polyline (defined by points connected by straight
>line segments), a constrained Delaunay triangulation will create
>triangles such that the contour line segments are triangle edges.
>Then, for each grid point, find the triangle that contains the
>point and estimate the value by interpolation.
>
>To perform constrained Delaunay triangulation, I use the
>Jonathan Shewchuk's program triangle.c, which can be downloaded
>from
>
>http://www.cs.cmu.edu/~quake/triangle.html
>
>I think vtkDelaunay2D performs only unconstrained triangulation.




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