[vtkusers] vtkLoopSubdivisionFilter problem the 2nd

[Marcel Weiss]

I just realized, that the error can be avoided by using a different isocontour extractors ... 

using vtkMarchingContourFilter or vtkImageMarchingCubes (similar results, probably calling identical functions) the error does not occur.
	
using vtkContourFilter or vtkMarchingCubes (different results) the error occurs.

but this still is no explanation for the results from vtkLoopSubdivisionFilter

any more ideas?

some more info to the input data: it´s a 3D scalar image (float), representing a level set function. the topology of the represented object is spherical. vtkImageDate is used.

thanks
Marcel


----- Original Message -----
From: "Marcel Weiss" <mweiss at cbs.mpg.de>
To: "vtk users" <vtkusers at vtk.org>
Sent: Wednesday, March 4, 2009 3:37:22 PM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
Subject: [vtkusers] vtkLoopSubdivisionFilter problem

Hi,

I´m trying to create a subdivision of a polygon mesh created by vtkMarchingCubes from vtkImageData. I´m using vtkLoopSubdivisionFilter as shown at the end of the mail.

the vtkLoopSubdivisionFilter works fine for many datasets but sometimes he screws up the whole mesh (creating hunderd or more triangles all sharing one vertex somewhere in nowhere) while prompting the following message several times:

Warning: In /SCR/VTK/Graphics/vtkLoopSubdivisionFilter.cxx, line 143
vtkLoopSubdivisionFilter (0x8167db8): numCellsInLoop < 1: 0

I tried vtkTriangleFilter previous to the subdivision, but with no effect.

any ideas? which other filter or configurations might help?

Marcel Weiss
PhD student
Department of Neurophysics
Max Planck Institute for Human Cognitive and Brain Sciences 
------------------------------
CODE:

vtkLoopSubdivisionFilter* divider = vtkLoopSubdivisionFilter ::New();
ivider -> SetInput ( filter -> GetOutput() );
divider -> UpdateInformation();
divider -> Update();


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