Unit of Vectors in a Deformation/displacement Vector Field

I have a basic question that I cannot wrap my head around because I might have thought about a problem to solve for too long.

When I non-rigidly register two images and look at the deformation field array, are the vectors image(index) or physical(cm/mm) magnitudes/directions?

Thank you for your help!

Hello @RT_newbie,

All transformations in ITK/SimpleITK are in physical space, so cm/mm/nm…

Thanks a lot!