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tomasmiguel

Vellum Guide Simulate - Creating Stiff Fur

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Posted (edited)

Hi everyone, my name is Tomás and I'm new to the forum.

I'm creating a fur sim for a chimpanzee using the Guide Simulate node with the Vellum solver. The chimpanzee will later be animated. The sim works fine but I can't find a way to make it keep its wild messy look. The guides do keep their shape (bend, guideinit, etc) because I increased the constraint iterations and the bend stiffness. But I can't find a way to make the hairs keep their direction. In other words, once the gravity affects the guides they all go too down. So I want a way to keep the original shape of the hair a bit more.

I could tone down gravity or the mass of the guides but that would make it look as if it's underwater or something once I animate the chimpanzee. Increasing the constraint iterations to a ridiculous value would maybe fix this but at a high cost to sim time, same for stubsteps. Increasing Bend Stiffness to billions and billions doesn't seem to help either. Obviously, I don't want the hair to be hard as rock. I want it to behave this way because it's light, strong and covered in dust and sweat, if that makes sense.

It's also important to note I committed the noobie mistake of not resizing my mesh after exporting from Maya which works with different centimeters instead of meters. Meaning my monkey was more than 100 meters tall. I believe I already fixed this by going to preferences>Hip file options but I did this after creating the simulation so I'm not entirely sure if everything was resized correctly.

Attached are 5 images: the guides at frame 1, the guides at frame 73 (3 seconds into the sim), a render of the fur at frame 1 (the way I like it), a render of the fur at frame 73 (the way I dislike it) and a reference image for the sort of hair I'm aiming for.

I also added the project folder.

ApeODForce.zip

Thanks in advance!

1.thumb.PNG.c5d6761b7c9cd74c872bfee86fa78d23.PNG2.thumb.PNG.d4a5b21d9d7af2944a7d57a9097e7c1f.PNG3.thumb.jpg.8aeced69291d5a997e3038632b49ddeb.jpg4.thumb.jpg.cfcc7caf96bbd6e0ede6963e0bb7508c.jpg5.jpg.d3b8c9ab8ae792408929969fae809e60.jpg

Edited by tomasmiguel

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for stiff hair I'd suggest simulating as few segments per hair as possible

so either remove your resample1 sop from groom or adjust it in such a way that your longest hair keeps the current 8 segments for example, otherwise you are just making it more difficult for Vellum without adding any more detail anyway

also your bend damping is pretty high

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On 20/03/2019 at 6:25 AM, anim said:

for stiff hair I'd suggest simulating as few segments per hair as possible

so either remove your resample1 sop from groom or adjust it in such a way that your longest hair keeps the current 8 segments for example, otherwise you are just making it more difficult for Vellum without adding any more detail anyway

also your bend damping is pretty high

Thanks Tomas! That tweak did it and it really makes sense.

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On Vellum solver go to solver tab and you will see Constraint Iteration. keep that very high number like 15000, 25000 as long as you keep it high you will have stiffer. And also you can play with Bend stiffness and damping Ratio from Vellum Constraint sop too

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