[Insight-users] Registration and Spacing : Bug

[David Holmes]

Luis-

I am not sure that it is simply an issue with non-unit
spacing.  I have had this problem for some time (refer
to
http://www . itk . org/pipermail/insight-users/2003-February/002637 . html).
 To confirm the problem again, I used the
ImageRegistration8.cxx example with a very simple
dataset and show the same results (i.e. the cost value
 increases).  In my case, the spacing is [1,1,1] for
both fixed and moving.  I've fooled with parameters. 
That is not the problem.  I've run both simple and
multi-resolution registration.  That is not the
problem.

thanks

david


--- Luis Ibanez <luis . ibanez at kitware . com> wrote:
> 
> Hi Michael, Carolyn
> 
> We were finally able to duplicate the problem you
> both
> reported concerning the registration of image data
> with
> non-unit spacing.
> 
>
http://www . itk . org/pipermail/insight-users/2003-July/004215 . html
>
http://www . itk . org/pipermail/insight-users/2003-July/004314 . html
> 
> Using a simple registration case with translation
> transform,
> we found that a very small spacing causes the
> optimizer to
> become erratic.
> 
> We are tracking this problem in order to find a fix.
> 
> Our guess is that the spacing is not correctly
> considered
> when computing the metric derivatives in the
> registration
> method. A bug report has been filed in GNATS.
> 
> 
>   Thanks for pointing this out.
> 
> 
>      Luis
> 
> 
> 
> 
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