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View Full Version : First attempt to rig a quadruped



Thomas M.
04-22-2009, 08:00 AM
I need a rig which is well suited for posing a character for a still, so some things will be strange for those who are familiar with rigging. I am not familiar with the tips and tricks of rigging, so it would be great if someone could point out the major mistakes and could give some advice on how to enhance it. I recently saw a rig with PLG ik and regular bones, but as it is for a still I need the ability to stretch the limbs to reach a certain spots. Also I want to try out the capability of joints, planning to make the step to Max, Maya or XSI.

On the hands there are a few extra bones I tried to bring into the game to maintain the volume on the hands and keep them from collapsing in extreme positions. But that's unfinished business.

So, I hope that we'll have a nice little thread about rigging in which everybody can learn something. Would be great to end up with a cool rig everybody can alter for their own quadruped.

Cheers
Thomas

P.S.: Mirror hierarchy hardly works with joints.

P.P.S.: Feel free to alter the rig and re-post it.

Otterman
04-22-2009, 08:06 AM
Thomas there is a new section on this forum where this thread is better suited.....

http://www.newtek.com/forums/forumdisplay.php?f=276.

There might b some useful info there for you to get your noggin around also.

Thanxs for the rig anyways!

RebelHill
04-22-2009, 08:56 AM
Ill take a look later... but in the meantime...

Mirror hierarchy works PERFECTLY with joints, see my vid here, www.newtek.com/forums/showthread.php?t=97899 to see it all in action.

SplineGod
04-22-2009, 08:58 AM
What doesnt work for you when mirroring joints?

RebelHill
04-22-2009, 10:00 AM
Ok, well... took a look, and here we go.

Hate to sound harsh, but the whole things a mess... what are the major mistakes?? everything basically.

U got knees follwing opposing knees, ur roots in the wrong location, ur spine runs the wrong way, ur using multiple goals per chain without having a way to properly terminate them, none of your chains are properly terminated, ur rest rotation angles are all over the place, nothing lines up, and the whole thing pops and snaps like a biatch... Basically you've overcomplicated the controls without keeping them in line with one another in any way, so everything fights everything else... sorry.

Also, joints are pretty a pretty poor choice for control rigging, better to stick with regular bones, and retarget in joints where you need them for deform purposes.

PLGcurve will give you far better control on your spine, and other long chain sections... otherwise for the limbs, plg or LW IK for something like this wont make a huge difference... so take or leave. But any which way, theres no difference between rigging for a still or animation, if something works for animation, then it works for a still (though not always the other way round)...

again, appologies if any of that seems harsh, just imo.

Thomas M.
04-22-2009, 11:56 AM
As I have no experience in rigging I won't mind taking even a harsh critic. No ego here, yet.

Would you be so kind and just add a "how it would be correct" to your summary in the third paragraph of your post? This way I would have a chance to change it for the better.

Thanks in advance!

Cheers
Thomas

RebelHill
04-22-2009, 01:05 PM
To answer how it would be correct would take hours and hours... you need to understand the co-ord sytem, how changes up the chains propgate down, how the different goal options work, and when to use them, etc, etc...

Quickest thing i can tell u stright off are...

The hip is ALWAYS the root... for every character... biped, quardruped, octopus... the root is always between the main driving limbs... You need to set your bones up with zero'd out angles in rest opse as much as possible, which requires a lot of record pivot (as well as knowing how record pivot works from parent to child without sending things lower in the chain nuts), and using offsets... u need additional offsets to manage gimbals on tough joints... and just dont bother using LWik for spines or spine like strctures, its not really up to it in the vast majority of cases. Ur goal hierarchies need to match, and work in tandem with you bones hierarchies, both in terms of parent-child order, and axially...

If u got no experience... its a LOT of explaining..

wait a week or few, ill have some tuts out (i hope).

Thomas M.
04-22-2009, 01:55 PM
Cool, looking forward to it. Unfortunately I need to get this beast up the tree tonight. Probably I change the spine as proposed by you before. Point with animals legs and arms is that they are the same as human arms and legs in their bone structure/hierarchy, but work in a different way and need another approach to be animated.

Cheers
Thomas

SplineGod
04-22-2009, 03:38 PM
Heres a couple of things that might be useful:
http://www.vfxcast.com/media/1259/Qiuadruped_Rig_Demo/
And a DVD on rigging a quadruped:
http://www.kurvstudios.com/lightwave/rigging_quadruped.php

Thomas M.
04-22-2009, 04:57 PM
Thanks Larry!

I just updated the rig. The spine now doesn't have an upper and lower part, but just one starting at the hip and going all the way to the head. The root now is at the hip and I corrected some rotation values, though I doubt in the way Rebel did have in mind. At least not all of them.

One big issue it that the rib cage goes up the roof penetrating the back in many situations.

The rig is far from being complex at the moment, so hopefully there is a lot of input from many LWers who can take a quick look. I guess Carm3d is now pretty good at rigging too. Although I doubt that Pooby is still hanging around in these quarters. Shame.

Good night and thanks so far.
Thomas

SplineGod
04-22-2009, 06:26 PM
One thing to remember is that the spine past the rib cage isnt quite as flexible as the part below the rib cage or we would all have issues with ribs colliding with each other etc.

RebelHill
04-23-2009, 01:56 AM
Dude thats a LOT better.... just changing the direction of the spine has made a huge difference...

Few things... Your knee goals (poles) are both parented into the bone chain of the right hind leg... so first the left follows the right, wrong, also, its better to have your pole free floating, or, if u want them in the chain, parent them into the foot ull hierarchy.
Also... cos of the way u have ur multi goal spine/neck setup ur still getting popping... take the joint that goals to the neck null, and turn off the neck goal for it, then take the joint before it in the chain, set that to have the neck as goal, but change the behaviour to point at goal, not go to goal, will make it much more stable for you.

Keep going.

Thomas M.
04-24-2009, 03:12 AM
I tried to stabilize the rib cage. Right now have a center rib, but split this up in a left and right part next. Unfortunately the whole thing collapses pretty easily. Any idea to keep the volume. The costal cartilage is parented to the rib ends, as are the rib ends parent to the costal cartilage. Probably that's not correct, but I haven't found a better idea yet.

RebelHill
04-24-2009, 08:08 AM
well... u should always avoid having two items be dependent on each other (a to b, and b to a)... as it causes issues (except in the case of targeting one another)...

as for your ribcage part... i personally wouldnt use the breatbone chain at all, id just rely on a few bones coming off the spine as ribs (and just songle bones at that, not chains), adn use either follower, or same as item (possibly with some referencing lookup nulls if need be) to counter rotate them against what the spine parts above are doing.