[Insight-users] itkMattesMI: LocalSupport Transforms

[brian avants]

hi R

yes, a local support transformation only needs a few of the parameters
to define a transformation of a given point.    for instance,  the
transformation of a point by a discrete displacement field is
determined by a small local neighborhood of information.   for
transformations of this type, the derivative of a specific parameter
only depends upon the support or the local neighborhood that affects
it.   one of the main changes in v4 is that you can use the same
metros for both local and global support transformations.   the Mattes
MI metric originated from this paper:

 "PET-CT Image Registration in the Chest Using Free-form Deformations"
D. Mattes, D. R. Haynor, H. Vesselle, T. Lewellen and W. Eubank IEEE
Transactions in Medical Imaging. Vol.22, No.1, January 2003.
pp.120-128

but much has changed in the implementation since then and there is
currently no technical paper that accurately describes what's being
done, in particular for the local support case.   however, the basic
idea is as described above:  just compute the local derivative if your
transform has local support.

hope this helps,

brian




On Fri, Aug 17, 2012 at 8:51 PM, Roshni <roshni.b at gmail.com> wrote:
> Hi,
>
> I am trying to modify "itkMattesMutualInformationMetricv4" but am having
> trouble following the logic behind the derivative computations when a "local
> support" transformation is used.
> Please could someone explain the basic ideas used?
>
> Also, do local support transforms imply dense transformations with local
> support basis functions, e.g. BSpline deformations?
> Please help!
>
> Thanks much,
> R
>
>
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