Would like to additionally calculate Inverse, when giving Displacement Field and its Inverse as Input.

[MSco]

I have the following situation:

I have caluclated a Displacement Field Transform and have its Inverse. Now, I would like to use both as initial fixed transform and calculate another Displacement Field Transform, but I also need the Inverse of that transformation.

How can I achieve this using ANTs? I did not find a option to give antsRegistration an initial transform + its inverse as input.

[ntustison]

That functionality is not available but I don't see why it would be needed when one can concatenate transforms post-registration optimization. Please provide an example to clarify what is needed.

[MSco]

@ntustison
We do registration of 2D sections of a volume. However, some analysis will be done on the reconstructed 3D volume (like tracking in 3D, 3D segmentation algorithms, etc).

However, we do not want to store the analysis in the reconstructed space, we want to store it in the original space, so we have to be able to invert the transformation.

[ntustison]

It's still not clear. Perhaps a diagram would help. The way I see it, you have two spaces A & B which you first align using SyN. Then, for your scenario, you want to align A to a third space, C, through B. So you use the forward (or inverse) displacement field, depending on how you've set it up, as the initial transform for calculating AC. I don't see why you need both. I can see wanting to have both the forward and inverse transforms for AC but you could simply compose the displacement fields, where appropriate, afterwards.