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ANTsX / ANTs

Advanced Normalization Tools (ANTs)
Apache License 2.0
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The rigid transform change the voxel size #1261

Closed xyimaging closed 3 years ago

xyimaging commented 3 years ago

I hope to register the T1 image to the MNI space, but when using ants.registration(fixed, moving, type_of_transform = "RIgid") for rigid registration, the output size has changed, that is, from the moving itself (X,Y, Z) becomes the same as fixed size (X',Y',Z').

I'm curious about this process, and my assumption is during the registration process, ants. registration does not only do Rigid transformation, it may also add interpolation and downsample steps to adjust the size of moving_img. However, in this way, the resampled image is not only very different in appearance from the original image but some features and details have also changed. I don't know whether this result is correct, or does the result still has medical meaning? Hope to get your answer!

cookpa commented 3 years ago

Any registration will involve resampling the moving image. You can control the method of interpolation at run time.

If you are registering to a 2mm MNI template, you can use the 1mm template instead.

If you want to change the output resolution further, you can do so by upsampling the fixed image, then calling antsApplyTransforms using the upsampled image as the reference image.

xyimaging commented 3 years ago

I think I have solved my problem. Thanks for your quick reply!