Is it possible to obtain sensitivity map without defining FFD?

[Mohsin-Bashir]

or is it compulsory to have FFD box?

[friedenhe]

Nope... You have to define a FFD.

[Mohsin-Bashir]

Could you please explain how FFD is used for the calculation of surface sensitivity (sensitivity map)?
From your paper

Originally posted by @Mohsin-Bashir in #544 (comment)
what I understood is, FFD is used by pyGeo to deform FFD and give deformed surface nodes. But since I have changed this functionality in my version of code, as I explained here #576 (comment), there should not be a requirement to define FFD anymore. Is there any other place where FFD is used? If yes where and for what?

[friedenhe]

You are right; we really don't need to have an FFD box for sensitivity maps. However, having an FFD is required by DAFoam. It will tell DAFoam that this is a shape variable. We do not actually use the FFD box in sensitivity map calculation.