Your First Rig
As you remember from the last lecture, there are three steps in creating a character rig, 1) create a model, 2) set up deformations and 3) create controllers. In this lesson we are going to create a very simple character rig to introduce some of the concepts of character setup.
Step 1: Create a (Simple) Model
The first thing we need to do is model the character.
For now keep it VERY simple.
If you have a character of your own you would like to use, I recommend creating a simple version of that character using the method described below, keeping in mind the skeletal structure of your own design so you can then use the same skeleton for your character.
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Using polygonal cylinders, create a torso, arms
and legs; Put these all together as if your character
were standing in an average relaxed pose: - |
It is important to model a slight bend in the arms and legs for creating the bones.
When designing a character for animating, there are a few things you
may want to keep in mind:
- Long legs are easier to animate in 3D space
than short stubby ones.
- Floppy things like pony tails, big ears, or
antennae are great to use for overlapping action to fill out the animation
with interesting detail
Step 2: Adding Deformers (Just a skeleton this time)
Adding Bones
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The Legs In the Side View Panel, frame the legs of your
character, and using the Joint tool, Skeleton > Joint Tool,
Make sure to put a bend at the knee and ankle because (only if you are going to use IK, which we will be on the legs) a chain needs to know which way you intend it to bend. When you have reached the toe, accept the chain by hitting enter, and then rename the joints accordingly. It is important to name the joints so you can easily refer to them later; for example: rleg is easier to identify in a list than joint36, (rLeg, rKnee, rAnkle, rToe).
When you have finished with the legs, draw one single little ball joint in the middle of the hips. Name that joint Pelvis. Parent the leg to the hip joint, and a bone will automatically be conntected to each leg. Directly above the hip joint, make another single joint. Name this one Root. This joint will be the top of the entire joint hierarchy, and will be used to translate your model through space. If you accidentally draw your joints in an incorrect order, you may select this root joint and use 'Re-Root' and all connected joints will then be reordered below the Root in the hierarchy. Parent the hip joint to the Root joint. You now have hips and legs that may move independently of the rest of the body. The Arms Now create the arm joints similar to the method we used to create the legs. Be careful when placing joints on top of existing joints, sometimes you will accidentally select the existing joint instead of placing a new one. You may need to move the existing ones out of the way for the time being, but be sure to move them back when you're done. Name the arm joints accordingly as well: rArm, rElbow, rWrist, rHand, rFingers, rThumb. Duplicate and place in the Left arm, and then rename those joints.
Again in the Side View Panel, draw the back chain starting right above the Root joint. (This is a situation where you may need to move the arms out of the way to place the back joints.) It is up to you how many bones you would like to put in the back, however, using two to four joints is sufficient unless you need some very fine deformation in the torso area. For the simplified character we created earlier, let’s just place them as the image shows, and use only back1 to animate the torso. Be sure to place a joint right between where the shoulders will meet, then another between that and the head so you can rotate the head without rotating the shoulders too. Name them back1, back2, etc..., neck, head and skull. After you have finished the back and head chain, parent them to the Root joint. Then, parent the arms to the shoulder joint With both the arm and leg parented to the back, we can now mirror the arm and leg. Skeleton > Mirror Joint
Make sure that you choose the correct axis to mirror across (in our case we will mirror the joints across the YZ plane. After mirroring rename each arm with a Right and Left prefix. A quick way to do this is to use the prefix hierarchy names Modify > Prefix Hierarchy Names ...
Use this for the left and right arms and legs. It is a good habit to learn early on in rigging as later when we make more and more complex structures, your good naming conventions will save you a lot of grief. Inverse Kinematics One of the 'short cut' tools we will be using to ease in animating is the IK tool. This is basically like the strings of a marionette. Inverse Kinematics (rotating the joints by way of translating an effector or handle) is the opposite of Forward Kinematics (rotating the joints by hand). It is a quick and easy way to control the movement and bending of a joint based on the position of a handle below it, ie: moving a foot up and down, and seeing the knee bend automatically. We will add them to the legs only, because it helps in placing the feet in a fixed spot, giving a natural look that legs and feet usually follow. It is a personal preference that I don't use IK on the arms of a character, I think that leads to a very puppet-like, computer-generated look. To apply IK to the legs using the IK tool, Skeleton>IK Handle Tool make sure that the tool is set to ikRPSolver Click the leg ball joint first, then click the ankle joint second. A green line will appear between the two joints as well as one running through the leg. The leg turns purple, telling you it is driven by the IK chain. At the bottom of the ankle there are two lines sticking back from the foot, this is the handle for the IK chain. Select this handle and move it around to see how it works. Your knee should bend, and the leg should move with the handle if applied correctly. Repeat this process for the other leg. One other feature with IK RPSolver is the Rotate Plane manipulator. If you have the IK handle selected, click the Show Manipulator Tool button on your shelf (or use the 'T' hotkey). A large blue circle appears around the IK chain. This is called the rotation plane. You can use this to rotate the hip as you would to rotate your own leg, changing the direction your knee is pointing. The other visible manipulator is the pole vector which we will explain later. Create IK handles for both feet and arms. Step 3: Controller Setup The final step in our simple rig is to create some controllers. The job of a controller is to give an indirect control of our skeleton and IK handles in a way that can be reset. Create a NURBS circle and point snap it to the ankle of one of the feet. Scale it such that its size roughly matches that of the foot. IMPORTANT: Freeze all transformations on the controller. This is a critical step in controller setup as we must be able to return our rig to its initial position after playing around with it or posing it. After the controller's transformations are frozen, parent the corresponding IK handle to it and then HIDE the IK handle. We cannot freeze transformations on IK handles nor can we restore their initial positions, so more often than not the best thing for IK handles after they have been created and set up it to make them inaccessible. Repeat this process for the other feet and hands. Move them around, pose them, go crazy... but always check to make sure that when your reset the transformations and rotations of your controllers that they return to your original pose. So there you go. That is your first simple rig, from beginning to end. Admittedly the controllers are not very complex and we have not yet deformed our mesh yet, but hopefully by this stage you have learned some of the important habits of highly effective riggers; - Draw skeletons as you please, but edit them
using rotate and scale In our next tutorial we will look at a more
involved foot setup. |
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