[Insight-users] Fwd: Few questions about quad edge mesh filters

[Arnaud GELAS]

Hi Andriy,

I have recently change the threshold on the SVD decomposition for the 
computation of the optimal position for the new point. These threshold 
were too large...
It is possible that my changes may fix your problem.

If it does not work, can you open a ticket in the bug tracker with the 
mesh in question, assign it to me.

thanks,
Arnaud

On 03/17/2010 12:07 PM, Andriy Fedorov wrote:
> Previous message bounced, I put the attachments here:
> http://dl.dropbox.com/u/3770904/QuadEdgeScreenhots.tgz
>
>
> ---------- Forwarded message ----------
> From: Andriy Fedorov<fedorov at bwh.harvard.edu>
> Date: Wed, Mar 17, 2010 at 12:04
> Subject: Few questions about quad edge mesh filters
> To: ITK Users<insight-users at itk.org>
>
>
> Hi,
>
> I have a processing pipeline that starts from a binary image,
> generates quad-edge marching cubes surface, performs decimation, and
> computes the surface normals. I am trying to use quad edge filters for
> this task.
>
> I stumbled across two issues:
>
> 1) the normals produced by QuadEdgeMesh are always (nan,nan,nan). I
> saw the comment in the documentation, that the input and output mesh
> traits should be the same for this filter to work, but this does not
> seem to help.
>
> 2) whenever I am using QuadEdgeMeshQuadricDecimation, the decimated
> surface is obviously incorrect
> (QuadEdgeMeshSquaredEdgeLengthDecimation generates very nice surface).
> Attached are screenshots for the MC surface, quadrics-decimated
> surface, and squared edge decimation result
>
> Source code and test data: http://dl.dropbox.com/u/3770904/QuadEdgeTests.tgz
> Command line to reproduce the first problem (second issue can be
> reproduced trivially by swapping the decimator): "QuadEdgeMeshTests
> blob1.nrrd output_mesh.vtk 10"
>
> I see this problem both with the latest checkout of the 3.16 branch,
> and with the current trunk build.
>
> Am I doing something wrong, or is this a bug?
>
> Thanks
>
> Andriy Fedorov
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