[vtkusers] contouring point data

Erik Anderson eranders at sci.utah.edu
Thu Jul 26 12:42:50 EDT 2007

Hi all,
     I have been trying to get iso-contours generated for 
point data for a while now with no luck.  Any help anyone 
can give would be much appreciated.  Below is a more 
complete description of the problem:

I have a vtkUnstructuredGrid that is storing point data. 
 In other words, every vertex in the dataset is a discrete 
point to be rendered.  Each point has several data arrays 
associated with it to be used for coloring, scaling, etc 
operations during glyph rendering.  I now want to generate 
isosurfaces for these data, but I cannot figure out how to 
do something like this from within VTK.

One method that I can loosely translate into VTK language 
(but which I've had no success getting a pipeline working 
with) would be as follows:

embed the point set in a structured grid
for each vertex in the grid:
    evaluate an implicit function (meta-ball like 

apply marching cubes or other isosurface extraction 
render surface

The problem with the above approach is that I have been 
unable to construct a pipeline that would evaluate a 
function taking input from each point in the dataset.

Any help would be greatly appreciated!

Thank you,
Erik Anderson

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