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

[Arnaud GELAS]

On 03/17/2010 02:27 PM, Arnaud GELAS wrote:
> ooops, I pressed reply not reply all...
>
> -------- Original Message --------
> Subject: 	Re: [Insight-users] Few questions about quad edge mesh filters
> Date: 	Wed, 17 Mar 2010 14:26:21 -0400
> From: 	Arnaud GELAS <arnaud_gelas at hms.harvard.edu>
> To: 	Andriy Fedorov <fedorov at bwh.harvard.edu>
>
>
>
> On 03/17/2010 12:55 PM, Andriy Fedorov wrote:
> >  On Wed, Mar 17, 2010 at 12:07, Andriy Fedorov<fedorov at bwh.harvard.edu>   wrote:
> >
> >>  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.
> >>
> >>
> >  Update: this happens with the default (THURMER) weight type for
> >  normals calculation, because the weight is calculated to NaN. If I
> >  switch to GOURAUD or AREA weights, it seems to work.
> >
> I'll check that!
>
> >  By the way, the documentation does not mention what is the difference
> >  between the different normal calculation modes.
> You're right, I should update the doxygen documentation to explain
> differences between normal calculation modes.
> >  Is there an Insight
> >  Journal paper that lists the details?
> >
> Yes there is one insight journal paper where you will find references
> for each method
> http://www.insight-journal.org/browse/publication/303
> >
>    

I have just updated the doxygen documentation of the class with all 
formulas!

I have also fixed the bug for the normal computation in the THURMER case 
(normalizations were missing) leading to out-range values before calling 
vcl_acos.
I am now running an experimental build before submitting the changes. 
You'll be able to get it in few minutes

> >
> >>  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?
> >>
>
> ok, I'll have a look that one too!
>    
I am now looking at the decimation one!

> >>  Thanks
> >>
> >>  Andriy Fedorov
> >>
> >>
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