Rigid/Affine mode of FFD model in Image Registration


I am using FFD Transformation in Image Registration, I have noticed that in the DOF setting, the choices could be “rigid, affine and None”.

From my understanding, FFD stands for Free Form Deformation, so it should be a deformable model.

So how does the “rigid/affine” mode work, or say is it different from “linear” transformation?

Thanks in advance!

Hi Bailiang,
sorry for the late reply. You are correct, FFD stands for Free Form Deformation. If you set the DOF setting to rigid or affine, it will also optimize the rigid/affine matrix of the image together with the FFD parameters. So the moving image will be also translated or rotated as a whole while being deformed. I’m not sure how well this works for FFDs though.