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PolyCAD

Reverse in U, Reverse in V

Reverses the direction of the U or V parameter, i.e the first line of the control polygon U=0 is now U=Max and vice versa. Simularly for V. Point locations remain the same it is only the order of the point columns/rows within the control polygon that are changed.

Flip in U-V

Swaps the U and V directions of the surface. Point locations remain the same it is only the order of the point columns/rows within the control polygon that are changed.