Maya 2018 - very junior rigger - quadruped rigging

zuka_banana

Hi there,

I'm new here and I am also a very junior rigger with a lot of question! I have to rig this buffalo for school, I already have rig a biped from scratch.
 I don't use any auto-rig, so I learned to make ik/fk switch etc but for this one I wanted to know what was the best spline to animate with, the most easy for animators? 
Also I saw a rig where you have a normal FK, like from the tail to the neck, and another Fk but from the neck to the tail, and I was asking myself how can you switch between both ? 
I first thought to make a switch between a FK spline and Ribbon, but is it really easy to animate ?

So here are some question I have, thank you for reading me !!

Have a nice day !

Mark Dygert

Hi Zuka,

IK and FK spines are very common. Every rig I create has both and most animators tend to leave it in IK because it allows you to work on each set of limbs independently. 



WIth FK the front legs and chest are driven by hips and spine so any change to do to the hips affects the chest and then you have to counter animate the chest and everyone hates that.

With most rigging questions it almost always comes down to which is the best way to animate and the rig needs to support that.

Richard williams has decent section in his book "The animators survival kit" that gets you thinking about a quadruped as two separate pieces and that's how most people tend to animate quadrupeds. 
 

Basically quadrupeds are just 2 people in a horse costume...


With the key differences being the person in the back is an ostrich and the front is actually walking around on their fingernails.

But I'm getting side tracked...

TLDR: Most people prefer IK spine. Give them the option for FK because its easy to do, but they'll probably ignore it.

zuka_banana

Hi Mark ! First, thank you very much for your answer ! 

IK and FK spines are very common. Every rig I create has both and most animators tend to leave it in IK because it allows you to work on each set of limbs independently. 

so for the spine you only need 3 or 4 joints going from the tail to the neck, is that it ?

What is the difference between an Ik spline and a Ribbon ? I though ribbon is an ik spline but you have nicer rotation and stretch and squash in bonus ?

Mark Dygert

Yea IK or Ribbon-IK ,they're pretty much the same. you say tomato i say tomato but really, same-same

The key difference is in process and how you build the control rig that drives the final skeleton. Each way will cause you to design and build your rig in specific ways, which will help and hurt you in slightly different ways but both methods have workflows for dealing with their particular eccentricities.

Ribbon tends to be used for things like rendering projects (feature films, shorts, kids shows). When things that aren't realtime it doesn't really matter if you go with ribbon or IK. Ribbon tends to take a little longer to set up and it can be harder to automate that setup through scripting because you spend time noodling a strip of polys and fiddling with weights and doing that through script is a pain. Setting up a Ribbon can be slow, manual work but it gives you decent results. The extra time would slow down iteration, so if you're trying out different joint counts or placement of things having to do all of that tedium can be a real drag. 

I mostly stick with IK-IK because it's kind of the standard, it does what I need it to do and I've heavily automated it's creation.

Squash and stretch can be a pretty big issue because... 
It affects scale and most engines don't play nicely when scale is animated. It can impact performance because it's another 3 channels of data being piped in and scaled joints can really screw with physics and dynamics. BUT, if it's REALLY important to the project, you compromise by drawing down resources in other ways and you spend time fixing the issues it creates.

So most realtime rigs tend to not include squash and stretch.

I should probably mention that rigs are typically two separate parts.
1) A skeleton/mesh, this hierarchy is straightforward, joints linked to joints and only the mesh is bound to it. If you're working on a realtime project, this the skeleton that you grab when you export animations.
2) A control rig, this is made up of several systems and subsystems that get cobbled together in a not so straightforward manner. This all puppeteers 1 and it never gets exported.

zuka_banana

I think I am trying to do something hard compare to my knowledge  It's my second rig but it is for my demoreel, principaly for animation and not game so I want to do something very good but don't want to skip a step

Mark Dygert

A quadruped is a bit harder rig up than a standard bipedal. If you're just getting into rigging then I would rig up a ball with legs similar to the Ultimate Walker rig. https://www.highend3d.com/maya/downloads/character-rigs/c/ultimate-walker-for-maya

Here is a good 3 part tutorial that goes through the entire process https://www.youtube.com/watch?v=cOokoFED7QE

zuka_banana

Thanks for the tips I will try this.

Yeah i watched this tutorial several times for my biped rigg haha, I also found a well explained tutorial by Antcgi https://www.youtube.com/user/antCGi/playlists?view=50&sort=dd&shelf_id=5 there are several playlist about rigging and I found this one very simple to understand the basics of rigging

zuka_banana

Hi here, I'm coming back because of some trouble i have setting up pole vector for my quadruped, I don't really understand how you can place it properly. I watched several tutorial explaining different method but if it's not a script whitout explaination, it's a tutorial that doesn't work in my case and I really want to understand why every time I apply the pole vector, my ik chain has an offset even a little one. 

the last one I tried was with a triangle to have the orientation of the knee and you apply a normal constrain etc but it doesnt work or I did it wrong ?

So if someone can explain me a proper way to set up pole vector without applying a script I don't even understand I will be very very thankful   

Have a nice day/night !

mattkushner

Hi @zuka_banana, not sure if this is too late a reply but the simple answer is that all of your joints contained by the IK (start, middle joints and end effector) all need to be on a single plane, and the pole vector control needs to be on that plane as well for it to not move. This is always the case for three joints since three points will always make a plane, but orienting them is very important. In the case of a quadruped hind leg where there are 4 joints it gets trickier because you have to be very careful to keep all the joints on the same plane.

It's not the easiest thing in the world to understand or setup, but I find it's best to build the joint chain initially in the side view so all the joints are by default on one plane. Then you can orient them all, pick the axis going down the bones, and use the top joint to rotate the whole chain into place without touching the children. That way, no matter the angle of the plane needed for your leg, all the joints don't leave the plane. For the pole vector there's a nice trick to setting it up as well as the above orienting of joints and placing the pole vector to ensure it's on the same plane by Corey Ross on YouTube here: https://www.youtube.com/watch?v=m3gwBKHtkbk