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

[Will Schroeder]

Ken-

Please go to https://www.kitware.com/KWWiki/index.php/Main_Page and 
read the instructions for "Upload File To Kitware". Let me know when 
it's there please.

Will

At 12:56 PM 8/18/2005, Gage, Kenneth wrote:
>Will, Lisa -
>
>Thanks for looking into this; I didn't find this in an application 
>that I myself built but in ParaView stable and development; Does 
>ParaView perform the cell type check you mentioned prior to calling 
>vtkDataSetTriangleFilter before volume visualization?
>
>The grid I have is quite fine in some areas due to the need to 
>resolve flow accurately; could there be some merging of 
>near-coincident nodes during the import-triangularization process 
>that could cause "non-tet" cells to be created? Unfortunately, I 
>don't have a simple dataset that could be an example.  The dataset I 
>have is about 1.4 - 1.5 million tets but I could ftp it if you would 
>like to test it on your installation. I can also try to put a small 
>program together to see what dumps out of vtkDataSetTriangleFilter 
>and let you know what I find.
>
>Thanks and 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
>
>
>
>-----Original Message-----
>From: Will Schroeder [mailto:will.schroeder at kitware.com]
>Sent: Tue 8/16/2005 7:44 PM
>To: Lisa Avila; Gage, Kenneth; paraview at paraview.org
>Subject: Re: [Paraview] DatasetTriangleFilter "creating" non-tet 
>cells  during volume visualization
>
>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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> >
> >