vtkContourFilter

[Bill Lorensen]

Folk,
	If you use vtk to extract isosurfaces AND build with the patented kit, read 
on.... otherwise you can ignore this message.

As you know, since the beginning of time (that is vtk time), 
vtkContourFilter used vtkMarchingCubes (or Squares) if  1) you built your 
vtk with patents and 2) your data was structured points. This has caused all 
of us difficulties in the build process and, for some, has caused confusion 
about what algorithm is being used.

To remedy the above, we have removed the patent dependencies from 
vtkContourFilter. The filter will now always use the "cell at a time" 
approach, regardless of the data set topology.

A new filter, vtkMarchingContourFilter, in the patented kit, acts like 
the old vtkContourFilter. It uses the Marching classes if the data is 
structured and vtkContourFilter (a cell at a time) if it's not.

vtkContourFilter is about 1/2 the speed of vtkMarchingContourFilter for  
structured data. So if you see a performance degradation in your app, change 
vtkContourFilter to vtkMarchingContourFilter.

Bill




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