[Insight-developers] CurvatureAnisotropicDiffusionTest failing

[Joshua Cates]

Hi Bill and Luis,

Additionally, I made some adjustments yesterday to the CurvatureAD filter
which clamp the maximum timestep to guarantee stability.  I would suggest
generating a baseline image for the CurvatureAD filter using a time step
of 0.125 on the 2D image (0.0625 on 3D image).  Double those for the 
GradientAD filter.  In retrospect, exposing the time step to users was a 
dangerous idea.

I'll add more documentation to these filters to better explain the time 
step parameter.

Thanks,

Josh.

______________________________
 Josh Cates			
 School of Computer Science	
 University of Utah
 Email: cates@sci.utah.edu
 Phone: (801) 587-7697
 URL:   http://www.sci.utah.edu/~cates


On Thu, 20 Mar 2003, Luis Ibanez wrote:

> Hi Bill,
> 
> It's great to have the regression testing working !
> 
> ---
> 
> Looking at the images,
> http://www.itk.org/Testing/Sites/starsend.kitware.com/WinXP-VC7/20030320-1144-Experimental/Results/__Examples_Filtering_CurvatureAnisotropicDiffusionImageFilterTest.html
> 
> Here is what seems to happen,
> 
> Some day ago a glitch was found in the anisotropic diffusion
> filters that was preventing the TimeStep from being used.
> 
> That is, the User settings were not being honored. Instead,
> a default time step was always being used.  Josh rapidly
> fixed this bug, and as a consequence all the code that was
> using anisotropic filters suddenly started to actually use
> the TimeStep parameters. It happened that most of these settings
> were incorrectly tuned, often leading to numerical instabilities.
> 
> The Baselineimage for this filter seems to have been generated
> just after the bug was fixed but before the new parameters were
> tunned. The 'chekers'-like  appearance of the image is due to
> the numerical instabilities originated from too large values
> of the time step.
> 
> So, to summarize:
> 
>    Please update the Baseline image with the current one.
>    The smooth image appearing as "Testimage" is the right one.
> 
> 
> BTW, this may be happening with other tests...
> 
> 
>      Luis
> 
> 
> -----------------
> Lorensen, William E (Research) wrote:
> > Luis and Josh,
> > The subject regression test from Examples/Filtering is failing. I think the
> > changes Josh made yesterday to the filter have had an effect. Do you want me
> > check in a new baseline image or is there a problem?
> > 
> > http://public.kitware.com/Insight/Testing/HTML/TestingResults/Sites/coffee.k
> > itware/Linux-gcc296/20030320-0500-Nightly/Results/__Examples_Filtering_Curva
> > tureAnisotropicDiffusionImageFilterTest.html
> > 
> > Bill
> > 
> > _______________________________________________
> > Insight-developers mailing list
> > Insight-developers@public.kitware.com
> > http://public.kitware.com/mailman/listinfo/insight-developers
> > 
> 
> 
>