[Elastix] Fwd: How to combine transformations within the registration?

M.Staring at lumc.nl M.Staring at lumc.nl
Thu Jul 25 14:12:26 CEST 2013


Hi Marvin,

Then you can add transform A as an initial transform to elastix using -t0.

Regards, Marius

From: Marvin Albert [mailto:marvin.albert at gmail.com]
Sent: donderdag 25 juli 2013 14:10
To: Staring, M. (LKEB)
Subject: Re: [Elastix] Fwd: How to combine transformations within the registration?

Hi Marius,
thanks for the tip!
However, I do not want two registrations to be performed. Instead I have a fixed initial transform A, which should then be combined with the transformation to be optimized (transform B). Are you suggesting then to somehow specify a "trivial registration" (for example the right initial parameters and then zero iterations) for the first of two parameter files as described in the manual section 3.3?
Thanks a lot.
Marvin

2013/7/25 <M.Staring at lumc.nl<mailto:M.Staring at lumc.nl>>
Hi Marvin,

Please check the manual, section 3.3.
You will need two parameter files each specifying a specific transform. No need to write new code.

Good luck!
Marius

From: elastix-bounces at bigr.nl<mailto:elastix-bounces at bigr.nl> [mailto:elastix-bounces at bigr.nl<mailto:elastix-bounces at bigr.nl>] On Behalf Of Marvin Albert
Sent: donderdag 25 juli 2013 11:57
To: elastix at bigr.nl<mailto:elastix at bigr.nl>
Subject: [Elastix] Fwd: How to combine transformations within the registration?

Hi,
thanks for the great tool.
I was wondering wether there is a simple way of combining two transformations as described in the documentation of itk:AdvancedCombinationTransform:

"If the transform is used in a registration framework, the initial transform is assumed constant, and the current transform is assumed to be the transform that is optimised. So, the transform parameters of the CombinationTransform are the parameters of the CurrentTransform."
I am pretty new to itk and elastix, so I tried to just specify AdvancedCombinationTransform as the transform type in elastix but I get the error that the component is not installed. I guess this means the class is not wrapped and exposed to elastix.
So in my case I want to apply an affine transform as an "initial transform" and proceed optimizing using an euler transform. Is there a simple way to do this without pretransforming the image (unwanted because of time reasons and double interpolation) or would I need to create a new component for elastix?
Thank you so much in advance.
Best,
Marvin


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