[ITK-users] Registration: Fix transform parameter?

[Bradley Lowekamp]

Hello Tobias,

You are correct that it is generally recommended to explicitly set the optimizer scale to an extremely high value to disable the optimization in that space.

However, please keep in mind that the VersorRigid3DTransform parameters are not X,Y,Z rotations they are the components of a versor. You can look into the Euler3DTransform which is paramerterized with the angles.

The alternative to this would be to write your own transform class.

Brad

On Feb 23, 2015, at 1:00 PM, Nöbauer,Tobias <tobias.noebauer at imp.ac.at> wrote:

> Hi all,
> 
> is there a simple/generic way to exclude a transform parameter from getting optimized during a registration process, i.e. just hold it at its initial value? I would for example like to allow for rotations around x, but not y, in a VersorRigid3DTransform, because I know the latter can't happen. Would it make sense to set the corresponding optimizer scale value to an extremely high value? -- This would not really disable this DOF, but just make larg values unlikely, correct?
> 
> I'm using the current alpha version of SimpleITK 0.9 (Python wrapped), so it would be even greater if a solution existed within SimpleITK...
> 
> Thanks a lot (also, for the great software),
> Tobias
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