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Vellum Balloon questions

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Hi everybody!

I'm trying to make balloon letters as on the picture.


Unfortunately I have a couple of problems. First, it seems pressure constraint distorts balloons in a weird way and forces them to fly away. Second, I can't get such wrinkles, while the balloons look fully filled with air.

Here is the file: BalloonTest.hipnc

Thanks in advance!

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Are you planning to have the balloons deflate or squish against one another? If not, perhaps you don't have to use Vellum and can go with a simple rigids sim instead. If you are going to do a Vellum sim, it may be better to sim using simplified proxy geometry and then point deform the results to high-res geometry that contains additional detail (e.g. the fins around the balloons, wrinkles) that isn't going to be affected by the sim. Also, your current sim takes place in a vacuum with no external forces, so any tiny velocities that arise from resolving the constraints can move your geometry around unpredictably. You might want to attach your balloons to a string that is pinned at one end, and apply an upward force in the Vellum solver to push the balloons up, for example.

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Yes, I want to make initially deflated balloons that will be inflated and as a result collide with each other, that's why i decided to make a vellum sim. I added pin to target constraint be low stiffness, but balloons still try to fly away. Funny thing, it looks like it is no a whole balloon moves somewhere but a certain area of the balloon that is pushed from the inside and pulls the rest of the balloon...


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