The process of rigging a 3D character can often
be long and complex depending on what you expect that character to
be able to do. In our comprehensive “Creating a Character Rig”
tutorial, we showed you how to create a character with
full FK/IK skeletons, squash and stretch appendages, space
switching, custom controls, and more. While this level of customization is ideally suited
for high fidelity movie or cutscene characters, what if we just wanted to make a simple rig for a
game or background character that wouldn’t be looked at quite so closely? For that we can use the Quick Rig tool,
introduced in Maya 2016 extension 2. Set your current project to the provided scene
folder, then open the file “01-Quick_rig_start.ma.” This file contains a basic character model for us
to rig. The Quick Rig tool is located in the Rigging menu
set, under Skeleton > Quick Rig. To use it, simply select the character mesh and
click the Auto-Rig button. After a few seconds, Maya generates an entire
HIK control system for the mesh. As you can see, you can move and rotate the
various IK and FK controls to pose the character. However, the auto-rig isn’t perfect. In particular, notice how the wrist control is quite
far from the actual wrist, causing an incorrect bend at the hand. The same goes for a few other effectors, which
could be better positioned too. We can fix all these issues with just a bit more
effort. Open the Quick Rig tool again. If you look at the Character field, you’ll notice that
it now says QuickRigCharacter. This is the character definition created by the
Auto-Rig operations we just did. Let’s delete it since it’s not quite what we want. Now create a new Character Definition. This time rather than using One-Click, let’s use
Step-By-Step. Start by selecting the mesh and adding it to the
Geometry section. Next in the Guide section, set the Embed Method
to Imperfect Mesh. We need this because our mesh is not perfectly
watertight (there’s holes for the eyes and inside the mouth). A resolution of 256 will be sufficient for a starting
point. We could modify other options here, such as the
number of guides used in the various areas, but in this case we’ll stick with the defaults, so
click Create. Maya generates a series of guides inside the
mesh. These are just the start points for creating a
skeleton, not the skeleton itself. However, they do show us where the original
auto-rig went wrong. Switch to the 4-View. Using the Move Tool, translate the left wrist joint
to a more appropriate position in all views. Once satisfied, you can use the Mirror button in
the User Adjustment of Guides section to automatically line up the corresponding right
wrist joint. Adjust other joints as necessary. Don’t forget to
mirror them as well. In the Skeleton and Rig Generation section, note
that T-Stance Correction is enabled. This allows Maya to automatically orient our joints
relative to a perfect T-Stance, even though the model itself is in A-Stance. This will ensure it’s still compatible when
transferring animation to and from other characters built in T-Stance. Make sure Skeleton and Control Rig is selected,
then click Create. Like the Auto-Rig, Maya automatically generates
an HIK rig for your character. However, this time the controls line up perfectly
with the geometry. All you need to do is skin it by clicking the Create
button in the Skinning section. Now the appendages bend at the proper spots. We’re already three-quarters of the way to being
finished now, all we need to do is a clean up the skinning. First, note that the head features don’t yet move
along with the head itself. We’ll fix this by parent constraining them to the
appropriate joint. Select the head_features_GRP, and press Insert
to change to pivot mode. Hold V to activate point snapping and middle drag
to the head joint to center the pivot on it. Press Insert again to return to normal mode. Now expand the character skeleton and select
the head joint. Ctrl + Select the head_features_GRP and select
Constraint > Parent to create a parent constraint. Now the head features will follow the head joint. However, notice that they don’t move in unison
with the rest of the head. This is due to the skin weighting, which we’ll fix
via painting. Select the body geometry, then go to Skin > Paint
Skin Weights > [] This changes the shading on the model to reflect
how the geometry deforms when the selected joint rotates. White represents areas that are fully influenced
by the current joint, while black represents areas that are not
affected at all. In the Tool Settings, under Influences, scroll down
and select the Head joint. Notice that it colors the head light grey. This indicates that the skin here is only partially
influenced by the head joint. We’d prefer it be fully influenced. So set the
Value and Opacity to 1 and paint over the entire head. You can temporarily hide the head features to
make this easier. Also make sure to get areas inside the throat and
eyes as well. Once you’re done, unhide the head features and
try rotating the head again. Now you can see that the head and head
features rotate at the same rate. When satisfied, you can lock the weights for this
joint to prevent any more accidental edits. After that, select the head control and click the
Stance Pose button in the Character Controls to return it to the bind position. Now, although the head is the most obvious
problem area, it’s far from the only one. For example, if you raise the arm, notice how that
pulls the torso out and the neck down. There’s a couple of reasons this is happening. If we return to the Paint Weights Tool, we can see that the spine’s influence isn’t strong
enough around the chest. Paint a value of 1 all around it. Likewise, the neck isn’t having the amount of
influence we want either. You can use the Smooth brush at any time to
create smooth transitions from white to black. Now continue this process across the rest of the
joints by bending them in various directions and
checking that the skin reacts appropriately. In general, try to keep vertices spread out evenly
as much possible in the various positions and avoid too much volume loss, particularly
around the underarms, elbows, and knees. Once you’re done with one side, you can use the
Skin > Mirror Skin Weights command to apply weights from left side appendages to the
right. Once you’re done, your character is ready for
animation.
