still not clear, what do you mean by transform as displacement field?

This is what elastix returns: (TransformParameters θ_x , θ_y , θ_z , t_x , t_y , t_z)
3 angles in radians and 3 translations in mm.
Aren’t these the 3D rigid transform 6 parameters?
Please correct me if I am wrong, in your extension, you saved the result of elastix registration transform as a big hdf5 transform file, which includes each point in the moving image and its displacement point_0, dis_x0, dis_y0, dis_z0, point_1, dis_x1, dis_y1, dis_z1, ..., point_n, dis_xn, dis_yn,dis_zn
How did you compute the displacement field from the above 6 parameters?

Again, We need this feature, any update on this? I cant use elastix the way it is now without this feature.
Actually is the input transformation what I am missing. I need that the Moving volume may have already associated a transformation, So I will just modify it.
Hmm, I realize this is a whole new request, I will make the new thread.