Hi,

I am simming tissue for a human character. While the muscle sim was pretty fast ( under 45 sec per frame), tissue sim is taking about 2 min per frame. Even if i generate a low res remesh / tissue solidify mesh, still i dont see any difference in the simulation time.

Are there any tips on how can i speed up the tissue simulation time?

thanks!

Hi Rohit,

Something that I have experienced that greatly speeds up tissue sims, but depends on your workflow, is if you are doing anything to your muscles after simming, such as delta mushing them, is to cache them out again.

The tissue sim only uses the polygonal surfaces of the muscles and bones as colliders, and the more points there are to lookup in collisions, the slower the sim time. If you have any bones outside the tissue such as hand or foot bones, blast those away. You could do a polyreduce of the muscles and bones (with the tpose as the second input to keep the point count stable), cache those out, and then use that as a collider for the tissue sim instead.

Also have you cached out your tissue solidify node, that also speeds things up.

Let me know if that helps, as always, you can submit a question with an example file through the SideFX bug/RFE support page, and I can dig into it further to look into the sim settings.

Kind regards,
Liesbeth

Also, check out this post for further tips https://www.sidefx.com/forum/topic/95770/#post-421064 [www.sidefx.com]

Thanks @Liesbeth for the tips, I will try to use polyreduce and see if that helps. Yeah tissue solidify is been cached.

Btw, I feel one of the major contributing factor in slowing down the sim must be the "Convert" node I have applied on cached muscle sim. Its increasing the primitives count to 4 times. As i mentioned in the other thread, if we dont use "convert to polygons" on muscles, the tissue does not collide with the muscles. It seems like a bug.
https://www.sidefx.com/forum/topic/94109/ [www.sidefx.com]

I have noticed the same behavior in the example file provided by Side FX as well. I will try to post the screenshots to explain the issue in detail.

thank you!

Hi Rohit,

Try to use a "Convert Tets" SOP instead of a "Convert" SOP, that should give lower prim counts. Please submit a bug report with an example file attached as it's hard to reproduce bugs from screenshots

Also, another tip, in your "Tissue Solidify" node, in the "Visualization Guides" tab, set the "Guide Display" to "Outliers". If you then see any orange points in your viewport it means that some of your muscles/bones are too close to the surface of the skin. You can follow the example file from John in the post I linked to above for how to shrink in your rest muscles in your preroll to fix that issue.

Let me know how it goes!

thank you!

Convert tet worked great and reduced the primitive counts by half, my sim is much faster now. thanks!