Rigid/Affine mode of FFD model in Image Registration

ImFusion Suite General & How-to
1

Hello,

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?

Screenshot from 2021-11-17 11-53-43
Screenshot from 2021-11-17 11-53-43446×809 49.9 KB

Thanks in advance!

2

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.