When getting started with the new muscles system in Houdini 19; how does one create the muscles, can I import sculpted geometry muscles and turn them into vellum muscles ? I read the documentation but it's not that clear to me.

Yes, you can model them in any way you want as long as resulting individual muscles are manifold non-intersecting polygonal surfaces

Feed them to Muscle Solidify to turn into tetrahedral geometry for muscle sim

Yes, the workflow is built around the notion that your muscle surfaces will already exist.

While manifold, non-intersecting surfaces are strongly encouraged, they aren't a strict requirement. There is a certain amount of forgiveness built into the vellum MuscleSolver. ie, intersecting points will have collisions automatically disabled at startup to prevent explosions.

Does the forgiveness have a radius or scale or attribute that can be modded? I have some finger tendons that are not intersecting the finger bones. On frame 1 they look like this:


And on the next frame they sproing away from the bones by some radius.
Q: Is there a way to visualize the collision radius?
Q: is there a procedural way to detangle penetrating geom before solidifying it? Or deactivate those points like with a nocollide attribute or something like in the vellum cloth solver?

crashes Houdini if you try to lower the collision radius below 0.25

HI does anyone know a good way to fix minor intersections of the muscles? Also I cant get the skin pass to work at all. It just falls straight down and doesn't collide with the tissue pass?

geordiemartinez
Does the forgiveness have a radius or scale or attribute that can be modded? I have some finger tendons that are not intersecting the finger bones. On frame 1 they look like this:

Collision Radius can be visualized on the Guides tab of the Muscle Solver. Points in a state of intersection at the t-pose will be disabled. But this looks like something else is going on. Please submit a bug or hip file so we can take a closer look.

tarincamarena
HI does anyone know a good way to fix minor intersections of the muscles? Also I cant get the skin pass to work at all. It just falls straight down and doesn't collide with the tissue pass?

At the present time you need to rely on a Boolean SOP to detect intersections and address fixes that way. You can also try moving muscles and bones into a non-intersecting state, and then simulating them back into position with collisions.

And please provide us with a hip file for the skin pass issue.

Thanks John! I accidentally blasted away the tissue geometry instead of the tetrahedral component. It now works. I also was able to fix the intersecting muscles. I attached the node tree image if it helps anyone. On a side note it would be great to have the muscle tension lines automatically created like in Ziva for a future release. It would save alot of time forsure.

tarincamarena
I accidentally blasted away the tissue geometry instead of the tetrahedral component. It now works.

can you elaborate? I am having the same issue of muscle collapsing in specific places. I do have intersective muscles but idk how to solve them apart or boolean them. care to share a hip file or explain the node tree?