[Insight-users] Centered Transform

[Luis Ibanez]

Hi Robert,

I'm not sure I understand what you mean by "measure the rotation"
and "measure the translation".

Do you mean to solve the rotational (translational) component
of the registration ?


Solving the registration by intermediate steps is always
convenient, in particular is there are any hints that help
to reduce the degrees of freedom of the transforms involved.

The loop that you mention is what the RegistrationMethod
does implicitly in the optimizer iterative loop. At each iteration
the parameters of the transform are updated and the metric
use the transform in order to sample the values of the moving
image. This is equivalent to resample the moving image with
the current transform and the evaluate the image-metric between
the fixed image and the resampled moving image.

Please expand a bit the context of your question (an example
will be of great help).


Thanks,


   Luis


------------------------------
Robert-Paul Buitendijk wrote:
> Hi Luis
> 
> I have a question about the centered transform.
> In the softwareguide you mention that the rotation in images is well
> measered but there is a greater error in the translation of the pictures.
> Could you not first measure the rotation with a centered transform and then
> by using a ResampleImageFilter transform your MovingImagePicture so that the
> rotational difference between the 2 pictures is now reduced to a very small
> one.
> When you then measure the translation (and rotation) of the to pictures
> again with a centered transform, wouldn't the translation be less
> inacurate??
> 
> Is there for instance a loop which Measures -> Resamples -> Measures so that
> both the rotational and translational differences are accuratly measured??
> 
> tnx Robert
> 
> 
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