[Paraview] DatasetTriangleFilter "creating" non-tet cells during volume visualization

[Will Schroeder]

The way the filter is right now it assumes that people will not use 
vtkDataSetTriangleFilter if they already have tetrahedra. There is an 
easy test for this: if you invoke vtkDataSet:GetCellTypes() it 
returns a list of all the types of cells found in a dataset. Using 
this test you can short circuit (i.e., skip using) the filter.

Having said this, I believe VTK should make life easier, not harder; 
and pipelines that change based on datatypes are hard to program in 
ParaView So IMHO the filter should be modified so that it simply 
passes data through in cases where the input is already simplices. 
This could be done pretty easily, and I'd be willing to do it before 
VTK 5.0 is cut.

Further, I am concerned that non-tetra cells are being created. While 
this is hard to believe, it is after all software and nothing 
surprises me anymore :-)  I'd like to see a simple dataset where this 
happens so we can find the problem and fix it.

Will

At 05:10 PM 8/16/2005, Lisa Avila wrote:
>Hi Ken,
>
>I am calling in some expert help on this since I am not the author 
>of vtkDataSetTriangleFilter.
>
>Will: when given an input that consists solely of tetrahedra, what 
>does vtkDataSetTriangleFilter do? Does it actually copy its output? 
>Can it possibly produce non-tetra cells?
>
>Lisa
>
>
>At 10:34 AM 8/16/2005, Gage, Kenneth wrote:
>>Dear ParaView list -
>>
>>I am exporting Ensight Gold format files from a FLUENT CFD 
>>simulation for reading into ParaView.  The simulation consists of 
>>all tetrahedrons (and triangle surfaces) - I checked the output 
>>file manually to confirm this fact.  ParaView reports the presence 
>>of non-tet cells when attempting volume visualization, which I 
>>assume are created during the use of DatasetTriangleFilter prior to 
>>visualization.  Has anyone else seen this problem, and is there 
>>some sort of workaround?
>>
>>Best regards -
>>Ken
>>
>>Kenneth Gage
>>MD-PhD Student
>>McGowan Institute for Regenerative Medicine
>>University of Pittsburgh
>>228 MCGOWN
>>3025 East Carson Street
>>Pittsburgh, PA 15203-2155
>>
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>
>