[Insight-users] Re: scale factor in registration methods

[Luis Ibanez]

Hi Silvester,

Setting the optimization-scale factors for Scaling
is even harder than for rotations.  The reason is
that scales should in principle be treated in a
logarithmic framework.

The following example uses the Similarity Transform,
which does Rotation, Translation and Scaling:

Insight/Examples/Registration/ImageRegistration7.cxx


You may want to keep smaller step sizes when Scale
Factors are present in the transform, because the
non-linearity of the scale makes the optimization
quite unstable.

This involves a laborious work of parameter
tunning... so... don't expect it to work at the
first try.


Please let us know if you find any problem.

    Thanks

      Luis

-----------------------------
Silvester Czanner wrote:
> Hi Luis,
> 
> I am trying to use the registrations methods from ITK. The assumption 
> is, that there will be some small rotation, shifting and also scaling. I 
> received quite good results, when the registration images have the same 
> size, but there is a problem with scaling factor. When I look to the 
> examples there are use only images with shifting and rotation. Where can 
> I find how to setup or use the scaling factor in registration?
> 
> Thank you,
> 
> Silvester
>