Hello. I am very interested in rigging in houdini. I've done some rigging before in maya, it was a while ago and it wasn't anything special, just personal projects.

I'm very confused how how the whole rigging process goes, I'm hoping someone can clear this up for me.

Right now I am painting weights on a character to each joint(bones, but not the modeled kind)

At the end of the day I want to have a skin that deforms by muscles for realism. Right now I made a auto rig in houdini, and painted weights on for each bone(joint). What is my next step for the muscles? and how do I get them to collide with the skin and deform it? Also in this video this person has bones modeled to collide with the the muscles. Do I do that too?

https://www.youtube.com/watch?v=kIsttuOO3NU [youtube.com]

Also, for the ribcage, I guess that I can model the ribcage and have that collide with the skin?(How to set this up in houdini?) So if my character bends back the ribs will deform my skin to show the ribcage.

Some examples of what I'm talking about….

http://www.tierrescue.org/horsepix/5-21-10%20Lft%20Hip%20Rib%20Cage.jpg [tierrescue.org]

http://farm9.static.flickr.com/8392/8510424027_0a0aecf2ff_m.jpg [farm9.static.flickr.com]

Thank you.

Unfortunately this is a deep topic. To give an overview, there's multiple deformation systems in Houdini:
- Bones: Uses Deform SOP to do weighted blending from bones
- Muscles: Uses DeformMuscle SOP to do weighted blending from muscles, or more generally, groups of metaballs

There's also the Inflate SOP for more generic shapes. A lot of this comes down to some rigging ingenuity.

For an old discussion on this, see:
http://forums.odforce.net/index.php?/topic/7646-houdini-muscles-workflow/ [forums.odforce.net]
(found by googling “houdini muscles”)

Also search for “houdini muscles” on youtube for some inspiration.

Thanks. I'm surprised the “autorig” doesn't come with the muscles built in, an option for that at least.

I thought it did? Change the “Deform Type” from Bones to Muscles.

That is just meta balls, but I cant figure it out… I tried looking through the houdini help, I can't figure that out, I'm pretty sure its not like actual hand placed muscles, its more of a general metaball of you're whole mesh, but I really don't know. Anyone know how to use this?

That's what Houdini “muscles” are, they're formed by groups of metaballs.

CMIVFX has some very new lessons about using the Autorig in Houdini:

http://www.sidefx.com/index.php?option=com_content&task=view&id=2416&Itemid=132 [sidefx.com]

They teach how to use the metaball muscles to deform the surface but I don't think they get into a full realistic muscle system. That would be something that you would need to build yourself since the autorig uses a simplified muscle system to accommodate a simple surface capture. You could either add to the muscles in the deform rig or build a custom rig. There are no lessons covering that topic right now.

Robert

PS - this lesson also covers similar rigging topics but for a quadruped. It is from an older version of Houdini but the concepts would be the same:
http://www.sidefx.com/index.php?option=com_content&task=view&id=991&Itemid=258 [sidefx.com]

Thanks a lot Robert, I hope they sidefx adds to there character rigging system and more tutorials.

I'll check out the tutorials

The most in-depth tutorials I've seen on rigging in Houdini is by 3dbuzz.