Broken Chains

[abvfx]

Hey guys,

Im moving into the rigging world with Houdini, and need a little advise, rather than a solution. (which can always be dangerous on forums , but this place is a little... sorry alot more mature than some places )

So my question, is i own the Magic of Houdini and have obviously seen the 3D BuZZ VTM's, and i can really see potential in character animation, but in VTM 2, buzz creates a leg rig, it looks like a setup i would like to use, ive created it a few times to get used to the workflow, but then create the back setup seperately and in the Magic of Houdini the Dragonfly tutorial you create the legs seperately and then parent all the bones under a null object titled "Body", still makes sense.

I have looked a prodded the Rabbit OTL, and even on that there are seperate bone chains fro the legs, body, head, yet there is an option to turn the connecting bones on which i still dont quite understand.

Anyways, is it a good workflow to create broken chains for different limbs, one chain for the arm, one for the back, one for the leg, one for the head etc? Or is it best to keep the setup with one chain that branches off, i only think this would be better for deformations in the shoulder, pelvis and neck.

And here is a quesiton that can be answered with a solution, if i do create these chains is there a way to connect them without messing them up.

Ie i create a back rig, and leg and want to connect them so they have a joint and a common root?

and one final quesiton, one that might require someone fromthe maya world, but ther is alot of playing with independant motion, ie pose and animate the character, but then if you want to tweak the hips they move independantly frmo the whole body. It can be done with expression as in VTM 2, but i wonder if there was a standard setup or approach i could take?

Thanks hoodniks, i await your response (esp arctor , what would a houdini forum dedicated to characters be without arctor)

cheers

-andy

[michael]

Anyways, is it a good workflow to create broken chains for different limbs, one chain for the arm, one for the back, one for the leg, one for the head etc? Or is it best to keep the setup with one chain that branches off, i only think this would be better for deformations in the shoulder, pelvis and neck.

in a word : yes

drop down an auto rig biped in the Houdini install and then crack it open to see how it's made...

there are not only seperate chains for the arms, spine etc - they are in fact seperate HDAs

one thing that many people get confused about is the difference between bones that animate and bones that control deformation - most bones do both, but many times you'll add bones just to help out the deformation (shoulders etc)...because people want good deformation they often try to build rigs that will do everything - I mean that the bones for animation are expected to handel the deformation as well....so things like bones connecting the leg and the hip are used when such a bone isn't needed at all...

And here is a quesiton that can be answered with a solution, if i do create these chains is there a way to connect them without messing them up.

Ie i create a back rig, and leg and want to connect them so they have a joint and a common root?

just use a null.

wire the leg root to something in the back rig...

and one final quesiton, one that might require someone fromthe maya world, but ther is alot of playing with independant motion, ie pose and animate the character, but then if you want to tweak the hips they move independantly frmo the whole body. It can be done with expression as in VTM 2, but i wonder if there was a standard setup or approach i could take?

Thanks hoodniks, i await your response (esp arctor , what would a houdini forum dedicated to characters be without arctor)

cheers

-andy

not really following you on this last one...not sure what you mean...

[abvfx]

in a word : yes

drop down an auto rig biped in the Houdini install and then crack it open to see how it's made...

there are not only seperate chains for the arms, spine etc - they are in fact seperate HDAs

one thing that many people get confused about is the difference between bones that animate and bones that control deformation - most bones do both, but many times you'll add bones just to help out the deformation (shoulders etc)...because people want good deformation they often try to build rigs that will do everything - I mean that the bones for animation are expected to handel the deformation as well....so things like bones connecting the leg and the hip are used when such a bone isn't needed at all...

I dont know if its the best method for me then, thinking about two rigs one for deformations and one for animating might be a bit to much to think about.

just use a null.

wire the leg root to something in the back rig...

dont know what you mean lol, do i wire the null into the leg or to the back etc lol.

But i must have understood you as i figured it out, keeping transformations on when parenting different bones chains helped.

To be honest, looking at the stucture of bones and cant seem to find whats the benfit of having a root node when creating bones, is it so create custom attributes? Ie a root node for the leg, so i can turn IK on or Off, root node for the back so i can have Spline Ik or FK control it etc.

anyways, i a few days i will whip up a rig, and was wondering if you or any other houdini guys could critque it?

[edward]

To be honest, looking at the stucture of bones and cant seem to find whats the benfit of having a root node when creating bones

The translations on the bones are locked by default because if you translate any of them except for the first one, then the chain gets broken up. So instead of unlocking the translates of the first bone (so that you can move the entire bone chain), a null is added for you to move it. Say you had created two bone chains separately, then you can parent them together by wiring the last bone of the first chain to the first bone of the second chain. ie. discarding the null object of the second chain. Otherwise, you would need to clear the translate values of the first bone in the second chain.

Use it if it helps you, delete it if not.

[michael]

I dont know if its the best method for me then, thinking about two rigs one for deformations and one for animating might be a bit to much to think about.

LOL...yeah this is exactly NOT what I meant

I meant a single rig.

BUT...some of the bones are just to help deformation...

I'd be happy to have a look at any rig you make...that will help the discussion...

[abvfx]

doh.

yeah ive seen it before, im sure i even have some, i know i have maya rigs that have bones in them just to help out on deformations.

Like some people put an extra bone in the should because its a ball and socket joint and that has like 320 degrees of motion, and i know one of the most common setups is to have two bones in the forearm because the hand doesnt twist at the wrist it twists the whole forearm pretty much. (try grabbing your forearm and twist your hand, pretty hard ).

i get ya now mate .

Let me cook up a quick rig, should have it up later tonight... its 7:30pm so wont be long.

again guys thanks for all you help.

-andy

[abvfx]

ok, well lost track of time, woo three days goes fast hehe.

Havent spent much time on this rig, but i have setup a bit of Ik and some controls, just for the legs so far. Ive played a bit with the capturing capsules, so the leg leg is bit bad.

but have a look at the skeletal workup?

with the way its setup will i run into a problems. Is is essential to have a root for every limb or can i get rid of them?

-cheers, had fun putting this together

Rig.v1.hipnc