Is it possible to use deformationFieldTransform to transform an image?

[Orlando Trejo]

Hi all,

I have been attempting to apply a transformation that corresponds to a particular deformationField.mhd file, to a 3D-CT image.

The reason I am doing this is because I have developed a motion model in MATLAB that predicts the deformation field (inversedeformationFieldapprox.mhd) . Hence, I would like to find and apply the transformation that corresponds to this approximated dvf to a reference image (reference.mhd).

 Current method: The 'deformationFieldapprox.mhd' file that I have created in MATLAB takes points from reference.mhd, and outputs points that approximate the image, 00.mhd. Then I invert the approx dvf so that 'inversedeformationFieldapprox.mhd' takes points in the moving image, 00.mhd and outputs the reference image. So now I think that it is correct to say that this inversedvf corresponds to a transformation, in which my reference image, reference.mhd, is set as the moving image. So I use the following command to try and transform my reference image according to the approximated dvf:

elastix -f _____.mhd -m reference.mhd -t0 ___.txt -p ___.txt -out ___

where -t0 is using a parameter file with (Transform "DeformationFieldTransform") and with 'inversedeformationFieldapprox.mhd' as the dvf, and -p is a dummy parameter file.

Problem: I expected that it should not matter what fixed image I use or what dummy parameter file i use, since the initial parameters (TransformParameters.0.R0.txt) would only depend on the t0 file with my deformationFieldapprox.mhd information. Through testing I have noticed that the image (result.0.R0.mhd) does depend on what fixed image I use.

Why is this? Any ideas as to how I can transform my reference image with the approx dvf that I have created in MATLAB?

Thanks for any help with this.

Regards,

-Orlando

[M.St...@lumc.nl]

Dear Orlando,

For applying a known transformation you should use transformix instead of elastix.

Best regards, Marius

---

From: elastix-imag...@googlegroups.com <elastix-imag...@googlegroups.com> on behalf of Orlando Trejo <otre...@gmail.com>
Sent: 08 March 2021 9:21 PM
To: elastix-imageregistration
Subject: [elastix-imageregistration] Is it possible to use deformationFieldTransform to transform an image?

 

--
You received this message because you are subscribed to the Google Groups "elastix-imageregistration" group.
To unsubscribe from this group and stop receiving emails from it, send an email to elastix-imageregis...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/elastix-imageregistration/c3cdaf72-1040-4c00-9467-63e2e0d1e2c6n%40googlegroups.com.

[Orlando Trejo]

Hi Marius,

Thanls for the swift reply. My issue is that i do not know the transformation that corresponds to the deformation field i have created. Can i still get this from transformix?

To view this discussion on the web visit https://groups.google.com/d/msgid/elastix-imageregistration/7ddfdd0e8e5c4c9985c80d7576ea229e%40lumc.nl.