Doubly Curved surface?

I have a Sweep2 surface that I’m trying to do UnrollSrf on. It says that it is not developable because it is doubly curved. What is a doubly curved surface, and why is it not developable? My surface is a type of “sleeve” that bends along the length - 2 curved rails, with closed curve cross sections. The width of the sleeve increases along the length as well.


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Hi David- doubly curved means, by way of example, like a piece of a sphere - curved in two directions. This cannot be unrolled because the ‘material’ would need to stretch or compress. A convenient way to think of developability is to ask whether the shape could be made from paper (i.e. non stretchy) without folding or tearing. Of course many real materials may be able to ‘give’ more than paper.


Thanks Pascal. I’m doing fabric patterns out of nylon, so hopefully I’ll get a little “give” out of the fabric. Increasing to tolerance of UnrollSrf might help me as well for this.


Hi David - Squish may be better for what you are doing.


What does Squish do?

While I’m at it, what does Smash do? :smile:

Hi David- see Help for details but Squish can accommodate doubly curved surfaces, though not very doubly curved ones with much accuracy.

Smash unrolls some surfaces that are not strictly developable, albeit with some error reported.


Cool thanks!