Spring Errors when simulating DForce object

middle_watch

I am trying to add DForce to a simple dress made in Marvellous Designer, but when I run a simulation literally 100,000s of messages are generated along the line of:

Spring (xxxxxxx, xxxxxxx) of node "Kimono Dress" extended: rest length < collision offset (0.xxxxxxx < 0.20001) there are so many I give up after a while and kill the program.

Setting collision to "0" greatly reduced the number of warnings, but then I am getting poke through.

Is there some flaw in my transfer. I am exporting the dress as an OBJ from MD and importing as OBJ into Daz.

Cheers.

middle_watch

Ah, I seem to have fixed it. For info I noticed that when importing the OBJ file it was a little bit high on the body, not much, but there. Aligining it correctly, exporting back to OBJ and importing again I no longer see the spring errors. Though intriguingly the dress unbuttons itself and falls to the ground. If I could figure out how to get a dress to do that in real life I would be a millionaire!

Saxa -- SD

@middle_watch

Thank you so much for posting not just your question but your actual solution.  Have been searching for an answer to a dForce question I couldn't find anywhere in all the usual dForce places, until a web search turned up this thread.  Even picked up Arki's dForce tut today and scanned the areas in the videos that the question could/should have been answered.  Instead your post gave me the needed clue.  Thank you!

SickleYield

Hey, sorry to necromance the thread, does anyone else have any clues on this? Right now I think the issue I'm having might be caused by the base dynamic clipping into the body or itself or both, but it's impossible to be absolutely sure because of the high poly count and detail level of the mesh (can't be more specific because it's a product wip). I'm testing it piece by piece to try and figure it out.

Mada

Yes - if the base setting geo for the clothing is poking into the base setting geo for the figure it will give you the spring error. Also when clothing is poking into itself. The lower the polygon density the easier it is to dforce, DS will have less spring errors to calculate and it will settle quickly.

SickleYield

Mada said:

Yes - if the base setting geo for the clothing is poking into the base setting geo for the figure it will give you the spring error. Also when clothing is poking into itself. The lower the polygon density the easier it is to dforce, DS will have less spring errors to calculate and it will settle quickly.

Thanks, very helpful to hear from an expert. :)

barbult

This will help you locate the collision vertices (spring errors) in the object that you are trying to simulate.

SickleYield

Oh sweet, thanks!

SickleYield

barbult said:

This will help you locate the collision vertices (spring errors) in the object that you are trying to simulate.

 

Sadly, it didn't work. The process ran, declared "no collisions found," and then threw the spring error on sim anyway. It will simulate, technically, but it takes too long for any reasonable customer owing to the spring calculations on a high-poly item like this. At this point I have one more mesh trick to try before I give up trying to make this peculiar conformer dynamic. Even Blender's 3d Print addon diagnostics can't find intersecting verts on this thing and Daz Studio STILL doesn't like it, lol.

barbult

SickleYield said:

barbult said:

This will help you locate the collision vertices (spring errors) in the object that you are trying to simulate.

 

Sadly, it didn't work. The process ran, declared "no collisions found," and then threw the spring error on sim anyway. It will simulate, technically, but it takes too long for any reasonable customer owing to the spring calculations on a high-poly item like this. At this point I have one more mesh trick to try before I give up trying to make this peculiar conformer dynamic. Even Blender's 3d Print addon diagnostics can't find intersecting verts on this thing and Daz Studio STILL doesn't like it, lol.

Well, that's strange. When you ran the command, did you have your garment selected in the Scene pane? For me, it runs through the same spring error steps that happen during simulation, then displays a helpful message telling you how to view the results. I attached examples of what I see when I run the command. I am using DS 4.20.0.4 Public Build.

I do quite a bit of PA product beta testing and can be relied on to keep your project private, if you want me to try it.

barbult

Maybe there isn't a perfect correlation between collision vertices and spring errors. Maybe some dForce configuration parameters affect these results. We need someone like Richard Haseltine to offer some more detailed advice.

barbult

Another thought - have you tried lowering the Collision Offset in the Surfaces pane to see if that eliminates enough of the spring errors and and your item still simulates OK?

SickleYield

Morning!

Yes, the garment was selected. I tried redoing it with the garment selected and the geometry tool up, too, and I've been routinely having self collision off and a value of 0.10 for collision distance. Sadly I get the same result of no collisions found, followed by the same spring error on actual sim.

I've thought of something else to try this morning. If that doesn't work I may take you up on your generous offer to beta.

SickleYield

Okay, I can confirm on another type of test that this function of DS does work, but only for collisions of the item with the figure to which it is conformed, NOT with itself.

Collision of the object with itself can still trigger the spring error whether or not the object is a conformer or is colliding with a figure in the scene. But the initial collision finder function doesn't work unless it's a conformer. At the moment I'm experimenting with lower poly counts to see if that helps.

SickleYield

I think I've fixed it. The problem was Blender's tendency to create particles directly atop other particles when the particle mesh in use is a certain shape. I changed the particle shape and it seems to work without sim issues now. 

barbult

You've done some good troubleshooting and analysis there! Those details about what the initial collision will and won't detect are helpful. It sounds like you have a much more complex mesh (particles!) than the simple garment mesh I was using. Congrats on figuring out and fixing the source of the problem back in Blender. I'm impressed! And thanks for sharing your investigation results. This is probably the closest thing to documentation that we have about this. At least I couldn't find any.

SickleYield

barbult said:

You've done some good troubleshooting and analysis there! Those details about what the initial collision will and won't detect are helpful. It sounds like you have a much more complex mesh (particles!) than the simple garment mesh I was using. Congrats on figuring out and fixing the source of the problem back in Blender. I'm impressed! And thanks for sharing your investigation results. This is probably the closest thing to documentation that we have about this. At least I couldn't find any.

 

Thanks! Like so many of my projects, it's a weird edge case. :D But I hope it does help someone googling it in future. That's how I found the thread to begin with.