Weird FFD behavior / deformation

[aleszvolanek]

Hey guys, 

anybody knows why FFD modifier distorts geometry that is at the edge in such a weird way?
I dunno what happened but recently MAX started to do this weird sh......

I only wanted to deform the plane in y direction to create sort of a wave, but on the left it pushes way beyond the original shape in a completely different direction.

[MartinBeh]

I was able to repro this on a 50-segment plane by increasing the FFD Continuity parameter to 50.

FWIW the generic NxNxN FFD(box) modifier is known to have more "overshooting" than the normal (fixed) FFDs, due to the math involved. This is even true if you use the same number of FFD subdivisions.

I guess you will have to adjust the FFD cage before moving the control points, such that you are not using the second-leftmost row but the third or fourth.

Or maybe a different deformation tool is suitable, e.g. Skin Wrap, Patch Deform, Skin?

[Casey_H_]

Likely caused by your FFD having no thickness so the calculation is getting borked. Adjust the "lattice" of the FFD so that it extends around the object boundary by 3mm. Basically like a very thin box.

Simplify it. If all you are doing is moving the control points "up", then you only need 1 "row" of points, not 8, especially since the plane is horizontally subdivided with no vertical subdivisions.

[lauri_barnhart]

Welcome to the community, @aleszvolanek.

Hope you are well. Checking in to see if you saw the information provided by MartinBeh and Casey_H_. Did either reply provide the information you needed to resolve your question? If so, please consider clicking on the 'Accept Solution' button on the post(s) that provided the help.

Thanks,

[aleszvolanek]

I tried that (extended the cage), even tried to push the ffd control points more otwards that the 2nd was the one controling the edge and not the first - it still didn't work. The same for adjusting continuity... it seems it is overall bugged.

[MartinBeh]

I think what you are seeing is the result of the maths behind FFD. You might have to use some other deformation tool.