Arm Rigs

[Mcronin]

I'm spawning this because of a discussion in the main forum.

Attached is an arm I built. Please take a look at it, tell me what sucks, make changes, and post your own if you like.

I built this before Siggraph, and there have been major OTL improvements in Houdini since then, so I want to try to improve it and create an OTL control set. What I do like about it is the forearm. You can see how the forearm works by manipulating the "Wrist Z" slider in the Hand Contols OP. There are two radius bone objects in the forearm. One twists basicly like a real forearm; this is what the bone geometry is linked to. The other radius does not twist, and is used to capture muscles, skin, whatever.

From an animators point of view....

The red tiles are effectors and controllers that are driven through expressions and relationships, no need to touch them.

The cream tiles are bone geometry, no need to touch them.

The pink tiles are the bone objects, no need to touch them.

The green tiles are the actual controls. There is an IK handle for the arm, another for the thumb, a target for the elbow, and the Hand Controls OP which has a boatload of sliders for the wrist, hand, and fingers.

arm1.zip

[edward]

Rather than a practical example, I'd contribute some techniques with a slightly modified file. Basically, I added HUD sliders to all the things inside Hand_Controls so that you can animate with the viewport maximized. To use the modified setup, make sure you turn off "Select Entire Subnet" in the left viewer toolbar. After that, use the Pose tool to pick your controller objects for animating. When you pick the wrist goal object, all the hud sliders will show up that are in Hand_Controls. In practice, one would probably break these sliders up into more controller objects but this was sufficient to show the concept.

Here's what I changed:

- moved the Wrist_Goal object inside Hand Controls (also changed the IK chop to reflect this)

- made it _not_ pickable (ie. turn off the brown flag)

- note that the Hand_Controls object is still pickable. This makes it possible to pick the wrist control at the top level and bind to the Hand_Controls object when using the Pose tool. This means that now we can have all the handles specified in the Hand_Controls object show up.

- exported the translates on the Wrist_Goal object up into Hand_Controls

- brought up the handle for the wrist goal and used the "Export All Handles To Type Properties" item under the Operator pane menu to create a handle for it. Make sure the Type Properties dialog for the Hand_Controls object is up when you do this.

- so now, I added all the HUD sliders to the Hand_Controls object. This is not as arduous as it may seem. I simply dragged all the parameters into the viewer, re-arranged them, locked them and then use the "Export All Handles To Type Properties" item under the Operator pane menu.

- tweaked the handle settings a bit by adding "showoppath(0)" to all the Default settings of the handle and shortened up all the hud slider labels.

- as a futile exercise, also added the "Enable Sliders" parameter which is tied to all the hud slider's onoff parameter.

arm_sliders1.zip

[Mcronin]

Those are some subtle, great improvements over what I posted Edward. How about the controls themselves? Are there any glaring omissions, or areas that can be improved in this arm setup?

[edward]

I'm sure a real animator would be more qualified than I am to say. Perhaps some way to do the WristX/Y/Z parameters as actual rotators?

[calin_casian]

nice job

if you are interested in automatic clavical movement along with the arm take a look at my file. I'm very new to Houdini and curently I'm trying to translate the character setup that I'm using in Maya. It's not mine as a conceptual scheme, it's from AWGUA Maya seminar, Character setup at Weta.

Please feel free to make some changes (maybe too many OP's, or a simplier solution) because as I've said I'm new to Houdini.

see ya

calin

arm_setup.tar.gz

[michael]

lol...I just replied to your post at SESI...

thanks for the arm

[anakin78z]

Sweet dude!

There does seem to be quite a bit of popping going on, but over all it's pretty darn neat! I'll have to check out what exactly is going on

-Jens

[edward]

I haven't taken an in depth look at the file but here's my guesses at the flipping problems:

- the blend1 object is set to interpolate rotations in euler space. If you change the blend type to Sequence and then put 0.6 in the sequence parameter, then that seems to eliminate one set of flipping problems

- the other source i think is somehow a combination the fact that you're using an IK w/Constraints solver with no constraints actually set and/or improper rest positions of the bones.

[michael]

that's a pretty nice arm calin...edward's fixes help alot though...

I always wonder why people attach bone models to their rigs...not much point, unless you're animating skeletons....

I'll cook up some thing this week(end) and I'll see if alex will post his clavical OTL (unless it's already here somewhere....)

[TheUsualAlex]

Howdy.

Actually, the clavical rig is already in that test rig that I sent. If you open it up, it should be under proto-clavical or something like that. It's essentially my hack of Weta's clavical set up. I must admit, Houdini is quite capable.

Now we just need one-of-the-kind world-class dynamic simulation system from SideFX........................hmmmm...................I don't think I know what I am talking about....

[calin_casian]

many thx for your feedback

I was thinking since all of us were talking about that "Weta character setup"; we can try to do a serious character setup in Houdini for the community. Follow that case, Alex can you please tell me from where I can dnld your setup file to take a look, learn and inspire...

Again thx for the feedback and I'll keep you posted with changes and new files.

see ya

calin

[Jason]

Hi Calin,

look here, it's in this topic.

Of course, we'd all like to see this autorigger in all it's glory!

Hey master Alex, any chance?

[TheUsualAlex]

Hi Jason,

I am in absolutely no way a "master" and never will be. I am a perpetual student who doesn't know anything at all. So you're most likely going to have to teach me.

[bah! I'll see what I can do. ]

Let me know if anyone still want that autorig. I'll see what I can do.

Alex

[calin_casian]

Hi Jason,

can you please write the link down because I got an "MySQL error" when I click it.

I'll post my complete rig example when it's finished. I'm no TD and curently I wanna know how I'm gonna connect bone lenght to IK spline. I have to write an expression about arclen (Maya curve lenght) and bone lenght. Do you know how I get the curve lenght in Houdini?

see ya

calin

[TheUsualAlex]

Hey there. Actualy, there is an arclen function available in Houdini. Just type:

exhelp arclen

and I think you'll find the info on what you need.

Hope that helped.

Alex

PS: Say... what's your equation for finding arc-length?

[old school]

Measure SOP will do both perimeter (arc length) and area. It adds the data as a primitive attribute to the curves.

You can use resample as a lo-tech pinch solution as well. Count the dots.

[calin_casian]

I just save this webpage. Thx for your help. Curently I'm modeling a complete character and after I'm done, hopefuly at the end of next week, I'll begin the riging proces so if you don't mind more questions to come in the next weeks. Afterward I'll post the complete character (I want to make it OTL) here and waiting for some feedback.

Again Thx a'lot and see ya

calin

[MatrixNAN]

Hey All,

This is for the Arm Slider File.

I did not see anyone mention this so I am going to go ahead and do so now. The Meta Carpal bones can not spread in the fashion that the spread sliders envoke. The Meta Carpal bones stay stationary for the most part held in place by little tendions and muscles all intertwined. They do however move when a fist is made and then clenched. You will notice a drop along in this case the Z axis downward mostly for the Pink Meta Carpal and then the Ring Finger Meta Carpal next but not as much as the Pinky. About half or less as much. The upper knuckles for the Middle Finger and the Index Finger which are created by the Meta Carpal Bones stay in one place. Now this is important in martial arts for punches in particular Tae Kwon Do. Percision punching to say the Solar Plexes or some of the pressure points in the should etc etc etc. The attacker would strike with those two upper knuckles to those pressure points. In Wing Chung KungFu you would use the bottom three knuckles but you would still only clench right upon impact. So those bottom two knuckles are still going to be pulled back. It might be a good idea to have a slider for the Pinky and Ring Finger Meta Carpal to be rotated down along the Z axis. Which would be a rotation on the X axis if I am thinking correctly. I was just reviewing the file and I thought I would post my two cents to help out. Oh I noticed the Wiggle slider which does mainly what I was talking about the spread. My comments about the spread still stand in that they do not move like that unless there is serious injury. Like a knife being driven through someones hand seperating the bones. So I can defantly see leaving it in there for that reason alone. However I still think their needs to be a X rotation for the Meta Carpal Pinky and Ring Fingers for making a fist. Overall nice job. Oh and the Pinky Finger is missing a curl slider.

Cheers,

Nate Nesler