dForce questions - Wrinkle Removal
chris the stranger
Posts: 132
(Edit: Part 1 - Sticky Collisions is resolved. See below for the questions pertaining to wrinkle reduction)
When running a simulation along timeline animation, the cloth seemed to flatten against whatever surface it collided with, then stayed that way for the rest of the simulation. So it just sticks to every wrinkle and crevice of the pants, as if A) they were covered in a really strong adhesive, or B) the coat material is a liquid. What parameters could help fix this? And if it's not a problem with the product's native settings, what else could be the cause?
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What outfit is this? (I may have it to play with.) And are the settings in your screenshot the ones that come with the product?
Also, I didn't see Self Collide parameter… Is it On or Off?
Oops, sorry for not including those details. That's the Adventurer Knight outfit, but with the sleeves, collar and cuffs hidden. Those are the settings that load with the product (though there may be an update waiting for me, that I won't see until next time I make a purchase). Self Collide is set to on.
I would have spent more time experimenting with this, but I'm facing another problem on the material shader front. Having two unrelated issues in one day that both have no obvious answer really does a mental number on you. I was able to make some monstrous-looking shapes when messing with different settings, but nothing I did from the time I started fiddling, to the point whereany attempt to run a simulation was interrupted by an error message, solved the problem of the melting cloth.
I'm afraid I don't have that outfit, so I can't test it for you.
I'd suggest you try setting Self Collide to Off and see if that helps.
I'm not overly familiar with each of the settings in use, but the Bend Stiffness seems too small to me. I've seen 0.15 recommended for a silky dress. The Dynamic Strength of 0.62 will offset that to some degree, you could try increasing it in 0.10 increments. (The default is 0.40, so I wouldn't go any higher than that.
I"m sorry I can't be more help than that, but without the product to test, I'm just guessing.
No worries, I appreciate the advice about the settings, and any increased exposure the thread may have as an added bonus.
I did a lot of reading up on the Surface Simulation parameters yesterday, so I have a bit better of an understanding now. I've managed to take care of the stickiness by upping the Dynamic Strength (contrary to what I expected) and the Bend Stiffness. The latest problem is trying to iron out the wrinkles. There are some settings I thought might help with this (Like lowering the Buckling Ratio, upping the Density, and cranking up Shear Stiffness) - but messing with these too much often resulted in the outfit exploding. I've gotten to a point where, at least, the coat no longer continues to twist around the leg after the character lands in the desired position, through the end of the simulation. The wrinkles are still pretty strong, though. I'm trying to go for something like in the promo images, where it looks like a smooth, ironed-out fabric (albeit somewhat thick). Results are attached. Thanks again, for the advice on Bend Stiffness.
(Side note: the description makes Dynamic Strength sound like, "surface's ability to change from its unsimulated state." Since it's at its smoothest when not simulated, I'd have expected it to try and maintain that smoothness with a lower Dynamic Strength, but that actually caused it to sink back into the crevices even with a higher bend stiffness).
Another important tip that just occurred to me. This may or may not apply to you since you're working through it though.
You say you're using timeline animation. You need to make sure that in the first frame of the timeline anything that is dynamic is not sticking through other objects. For instance, in frame 1 you wouldn't want the cloak to be sticking through the pants or boots.
When objects intersect at the beginning of a dForce simulation, dForce thinks that was intentional; so it won't pull the dynamic object out, this can result in things sticking together in unexpected ways and cause severe deformations of your clothing. Even a single face or vertex that is inside another object can cause some strange behaviors.
That could be happening with the invisible sleeves. I set the material's opacity to 0 for sleeves, cuffs and collar surfaces, because deleting them in the geometry editor caused problems with the buttons (that's another topic), and just hiding them wasn't permanent. I believe the parts that are shown are free from clipping, but I definitely notice that the armpit area of the outfit is where a lot of the exploding takes place.
Exploding armpits is one of the primary reasons that I will turn off the "self-collision". Especially when you're animating, the fabric can definitely have issues when you have poses where the arms are close to the body.
As an aside, "Exploding Armpits" sounds like a great alt-rock band name!
As I understand it, setting opacity to 0 does not make items invisible to dforce. The geometry has to be set to not visible, or deleted altogether. Try going at that item in the Scene tab, and switch off the visibility of the arm bones.
...well, switching visibility off in the Node Editor for the outfit's bones didn't seem to do anything. But if you were referring to hiding or deleting using the Geometry editor, you can read all about my efforts in my Misadventures with Adventurer Knight topic. I'm at peace with the idea of just deleting the geometry and not using the buttons, my only concern is how that might affet the dForce simulation in the future.
As for wrinkles, this might be a result of me doing dForce all wrong. I noticed that once the legs stopped changing on the timeline, the cloth position looked pretty acceptable, but this was about 2-3 frames before the character reached the final pose. In those last few frames, as the arms continued to raise while the feet remained stationary, the cloth of the skirt kept moving, as if still responding to the force applied by the legs twisting. This would make sense, it's dForce, not d-"Stop Once You Collide Against The Model Please". He starts from T-pose and goes into that open-stance position, so the cloth continues to wrinkle before starting to settle down. I can imagine a few possible solutions:
Could use a bit more advice on those two approaches, since cloth simulation is still pretty new to me - and currently, I'm still in the phase of messing around with parameters and then waiting 4 minutes to see how they affect the final outcome.
EDIT: What I was really searching for this whole time, it seems, was Air Resistance. I was so caught up in material settings, that it didn't even cross my mind that the cloth was behaving like it would in a vacuum.