[vtkusers] non-manifold edges in output of vtkDecimatePro

[Dominik Szczerba]

If it's a bug or not depends on the required output: for visual 
purposes, for which VTK is actually designed, nobody cares. Using VTK 
for computation appears to not be the beaten track, and yes, from that 
perspective it is definitely a bug, that I would love to have fixed.

PS. Unfortunately, broken meshes are generated by decimation virtually 
by everybody, including leading commercial applications.

- Dominik

Bryn Lloyd wrote:
> Hi,
> 
> 
> I am using following code to decimate a surface mesh:
> 
>  vtkNew(vtkDecimatePro,decimate);
>   decimate->SetInput(reader->GetOutput());
>   decimate->SetTargetReduction(target);
>   decimate->SetFeatureAngle(angle);
>   decimate->PreserveTopologyOn();
>   decimate->SplittingOff();
>   decimate->PreSplitMeshOff();
>   decimate->BoundaryVertexDeletionOff();
> 
> 
> The output can be a broken surface mesh: There are non-manifold edges in 
> the output of vtkDecimatePro. Additionally there are duplicate
> triangles.
> 
> The input comes from running marching cubes on a vtkStructuredPoints. 
> According to my test routines it is a good triangle mesh (i.e. NO 
> non-manifold edges etc.)
> 
> 
> Must I set a parameter of vtkDecimatePro differently, or is this a bug? 
> Is there actually a guarantee that vtkDecimatePro will not break my mesh?
> 
> 
> Thanks for any help
> 
> Bryn
> 
> 
> 
> 
> 
> 
> 
> 

-- 
Dominik Szczerba, PhD
Computational Physics Group
IT'IS Foundation
http://www.itis.ethz.ch