By JMC Game Development Alumni David Keodara
In the beginning, rigging can be overwhelming and sometimes just plain impossible.
Newcomers are suddenly thrown into a new world filled with new words and meanings. Forget everything you knew about 3D because rigging is an entirely different beast.
Rigging is kind of like cooking. You can get by following a recipe but if something goes wrong, those who know their herbs and spices have a better chance of salvaging their dishes. Even people with prior animating experience tend to face some trouble. While animating experience definitely helps, kicking a ball and knowing how the ball was made are two different things.
Below are tips and some techniques I used in my own work which I hope comes in handy.
1. Joint Orients
Please orient your joints when you’re done constructing the joints (Skeleton > Orient Joint). Most cases of odd and incorrect rotations are because people considered this step as not important or forgot to do it. The idea behind this is to set a consistent rotational axis through your character.
Afterwards, check areas like hands and feet and make sure all the fingers are rotating correctly. If they still give an odd rotation and Maya’s orient joint function is definitely not giving you correct rotation, you can fix it manually (If you’re in class, consult your tutors first).
The image above shows where you can switch from Object Mode to Component Mode. After clicking Component Mode (1) select Miscellaneous Components which is the question mark (2). This will allow you to change the axis on joints manually during selection. After you’re done, deselect the question mark and go back to Object Mode. Not even I know what will happen if you continue working in component mode.
2. IK & FK Explained
While the majority of animators should already know this or have a strong idea about this, some students have trouble wrapping their head around this and that’s okay. I will attempt to explain this with really simple analogies and when I would use either one.
FK stands for Forward Kinematics; this is pure driving force coming from the person themselves without any influence from any other forces. Most standard movements of the body besides the legs rely on FK unless there’s another force.
IK stands for Inverse Kinematics. This is influence from another force that is enough to disturb the current movement. The legs for example, are mostly IK because it’s motion is always being influenced by the ground. IK would keep being used until the character starts flying or doing high kicks, basically anything away from the ground. Character arms would be mostly doing FK until the character has to lean on something or carry something heavy.
3. Freezing Transformations
You should always freeze transforms on everything except for one thing which I’ll explain soon. Forgetting this step is a common mistake newcomers and students tend to make. Rotations and unwanted values are left on joints and controllers, then something explodes because this one small step was missed. Freezing transforms on your object will make it’s current position and rotation the new default. If you don’t freeze transforms on your joints and controllers, you won’t know the default positions of them. You’ll eventually go too far and rig everything up all nicely, only to attempt to return a limb to a default position that you didn’t set.
4. Null Groups
This is one of those things you should not freeze transforms on. Null groups are empty groups. Some people like to use locators, I like to use groups. Null groups are amazing. They save your life. I’m sure there’s more uses for them, but currently I use them for 2 things. Holding values and isolated substitution. When creating FK arms, finding the exact rotation of the joints is necessary so I parent constraint the desired joint to a null group, which transfers rotational information to the null, then delete the constraint. Since my null now holds the exact rotational information as the joint, if I parent a controller under the null and freeze transforms (of the controller), it will correct itself to follow the same rotational information as the null. Information which originally came from the joint. This is why you don’t freeze transforms on nulls, because they’re holding important values.
5. Isolated Head
This is the “isolated substitution” I mentioned earlier. The isolated head is something that I find gets overlooked at times. It’s not a necessity but I find it incredibly difficult not having this during animation. The idea behind this is that humans will try to keep their head upright during most of their movements. By isolating the head control away from the rig, but not completely isolating it, it’s very easy to simulate this concept. With this method, you will always have a clean head to animate on, free of rotation influence but still follows the body on it’s own without you having to do anything. Without isolating the head, there will always be rotational influence coming from the body so every time you animate, you’re actually always counter-animating and you can get some unwanted movements.
Isolated head left, non-isolated head right.
To do this is actually very simple. This is assuming your head controller is already orient constrained to it’s appropriate joint.
Group your head controller to itself. Make sure the pivot point of the group matches the head controller’s pivot point. So that would be the neck unless your head rotates from somewhere else.
Make a new null group. Make sure the pivot point of this new null matches the pivot point of your head controller so again, neck.
Point constrain your new null group to the head controller’s group. Then place your null group in where your head was supposed to go. For me it’s usually under my neck control or my last spine control if I don’t have a neck. This null group has the actual head attached to it via point constraint and is substituting in for your real head. So when the body moves, it has this null group parented to it, but this null group has your head point constrained to it. You can actually do a lot with this technique in other areas of the body if you’re confident.
If rigging is your assignment for class you should never do this last minute. Leave a lot of time for rigging. This is not an exaggeration as you may need to restart certain areas several times until you realise what you missed or until it works. Not just in relation to deadlines, but rigging needs a lot of time as a whole. Time is needed for memorising, understanding and even forgiving. There’s a lot of things to memorise and a lot of small things that are easily missed. The worse thing about something breaking is not knowing why something broke. If you have the understanding, you know what to do and what not to do on your second or fifth attempt. Forgiving is important as the faster you forgive, the faster you can retry. Learn from your mistakes and move on.
7. Push On
I hope at least one thing on here is helpful with newcomers and students in some way. I’m no where near what I consider a good rigger but I abide by these rules in my own work. Rigging is delicate and making a small mistake can lead to your character possibly even exploding. A lot of problems can appear as if Maya just doesn’t want to listen to you or acting of it’s own accord. What I have accepted is that I was mostly the problem, not Maya. I just didn’t have the understanding to realise what my mistakes were. When all the pieces come together correctly, rigging actually never fails you. It can just take a very long time to get to a decent stage. You can only really do one thing and that is to push on. The more you rig the easier things get.
Things definitely become easier.
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