[vtkusers] vtk bug, when clipping

[Dominik Szczerba]

For the sake of completeness, here is another way for degenerate elements 
after clipping. Clip the image data directly (with the scalar), and 
tetrahedralize after. There are many tets that reference a point more than 
once. Unfortunately, removing them breaks the mesh.

-- Dominik

On Saturday 12 January 2008 18.00:00 you wrote:
> Hi VTK users and developers,
> 
> 
> 
> I think I found the bug in vtkTetra related to clipping. After clipping 
> a 3D mesh I get degenerate wedges.
> I did following operations (first in paraview, then with my own code, 
> using VTK-5.0).
> 
> 
> 1.
> I load an image (signed distance function in a vti file)
> 
> 2.
> tetrehedralized it using the vtkDataSetTriangleFilter
> 
> 3.
> clipped using scalar (vtkClipDataSet)
> 
> 4.
> found that the mesh contains tets and wedges (VTK_CELL_TYPE=13)
> 
> 5.
> I removed the wedges, there where no degenerate tets.
> 
> 6.
> I checked the wedges:  some of the wedges are degenerated, i.e. contain 
> at least one point id twice (2762 out of 56123).
> 
> 
> Apparently this fixed over two years ago, but it seems there is still a bug.
> 
http://public.kitware.com/cgi-bin/viewcvs.cgi/Filtering/vtkTetra.cxx?rev=1.7&view=log
> 
> Can anybody please help to fix this? I would really appreciate some help.
> 
> 
> Thanks a lot
> 
> Bryn
> 
> 
> 
> 
> 



-- 
Dominik Szczerba, Ph.D.
Computer Vision Lab CH-8092 Zurich
http://www.vision.ee.ethz.ch/~domi