How to rig legs of a digitigrade character using Eggington's 2001 rig?

[teal]

Hi folks. I'm working on a digitigrade character - a bird-person who stands on their toes as birds do, rather than flat on their feet as humans do. In effect, the knee is further up the leg, and the ankle acts as a reverse-bending knee. Look at the leg of a bird or hind leg of a dog to get the idea, if this description is unclear. If you want to see the model in action, a short 3Mb anim of it dancing can be found here: http://www.chromatic-dragonfly.com/newljst...imbusdanceB.avi

 

Anyway, the model's been rigged using Eggington's 2001 rig, very similar to the one on the Hash 2002 (v9) CD. With some adjustments, the legs work ok, but the problem is that the nulls that one uses to plant feet firmly are now further up the leg, and operate the "second knee". I've tried adding another pair of targets at foot level and simply constraining the lower leg bones (formerly the foot bones) to aim at them, but that screws up other aspects of the leg rigging right royally. I also went through Mr Eggington's documentation for the rig on his site (www.eggington.net) in an effort to work out what constraint-diddling might generate the effect I'm after, but I haven't found anything that seems to do the trick.

 

At present I'm animating the model using the foot target nulls for the upper legs, and doing the lower legs and feet manually, but as you can imagine it's a total PITA trying to keep the feet solidly planted on the ground without functional foot targets to work with.

 

Is there anyone out there who has gotten a 2001 rig to work successfully with a digitigrade model? I'd appreciate any input or suggestions!

[3DArtZ]

I wouldn't think of this as 2 knees, but rather 2 thighs.

Try add another orient like thigh bone that controls the lifting of the 2nd thigh, the one pointing towards the back, that connects the 2nd knee....

 

Mike Fitz

www.3dartz.com

[mtpeak2]

I would need to see how you positioned the bones, but you could remove the kinematic constraint from the calf. Add a bone between the calf and foot and attach to calf and reparent the foot to that bone, name it calf 2 or something, remove the kinematic constraint on the calf and add it to calf 2. You may need to add an orient like constraint on calf 2 to orient like the thigh orient bone, just like the thigh has.

[mtpeak2]

You would have to add euler limits to the calf also.

[mtpeak2]

Here's a project with the 2001 rig setup.

[teal]

Here's a project with the 2001 rig setup.

 

Thanks for that!

 

Unfortunately it crashes my copy of AM every time I load it. I'm running v9.5/2002 - should it run okay on an older version like this? Any idea what might be going on?

 

I would need to see how you positioned the bones, but you could remove the kinematic constraint from the calf. Add a bone between the calf and foot and attach to calf and reparent the foot to that bone, name it calf 2 or something, remove the kinematic constraint on the calf and add it to calf 2. You may need to add an orient like constraint on calf 2 to orient like the thigh orient bone, just like the thigh has.

 

Thanks for the advice. I'll give it a go and see what happens.

 

Unfortunately I don't really understand how the 2001 rig works - I apply it in a monkey-see-monkey-do sort of way to my models using the instructions on eggington.net. This makes it a bit tricky to modify it in any ways other than the most trivial without buggering it up completely! Hopefully working through the suggestions offered by folk in this thread will en-clue me sufficiently on the inner workings of the 2001 rig to fix future problems myself!

[3DArtZ]

teal, go to my site "www.3dartz.com" and under "free stuff" you'll see some documentation explaning the ik setup in the 2001 rig style.

 

Mike Fitz

www.3dartz.com

[mtpeak2]

Sorry the project was don't in v12, but I do have v9.5 and I'll post something tomorrow.

[teal]

I would need to see how you positioned the bones, but you could remove the kinematic constraint from the calf. Add a bone between the calf and foot and attach to calf and reparent the foot to that bone, name it calf 2 or something, remove the kinematic constraint on the calf and add it to calf 2. You may need to add an orient like constraint on calf 2 to orient like the thigh orient bone, just like the thigh has.

 

Okeydoke, I did that, and with a little bit of tweaking it's working... sort of! It's certainly better than the original rig, and the foot targets work just fine. The only problem now is that when I move the foot targets, the leg bends at the hip and the calf1-calf2 joint, but not at the thigh-calf1 joint. It's usable as it is, but it'd be nice to get both the whole leg moving in a nice kinematic chain, rather than frozen at the knee. I'm guessing there's some constraint-diddling I'm missing here. I shall continue fiddling and see what I can come up with, but if the answer is obvious to anyone more experienced than I in rigging, I'd certainly welcome input. :-7

 

(I tried to upload a copy of the model but the msg board wouldn't let me as it said it was too big.)

[mtpeak2]

Zip the file, it needs to be under 1 meg, I think. Did you put the euler constraints on the calves, they may need to be adjusted?

[zandoriastudios]

There is an Eggington model called "Musana Warrior" that is a kindof sci-fi dino thing that has legs like you want. Since It is Wegg's rig, it may have an easy solution. You could break it apart and look at it.

Musana_Warriror.zip

[3DArtZ]

Perfecto!!! Gotta back that Wegg guy!

 

good find Will.

 

Mike Fitz

www.3dartz.com