To help you make the skeleton’s rig proportional to your setup, you can load a rig-building guide. After you set up the quadruped guide as you like it, you can generate a quadruped rig based on this guide.
The guide can also be used as a starting point for different rigging styles, and technical directors can write their own proportioning script to attach their rig to the guide.
Setting Up the Quadruped Guide
To load the quadruped proportioning guide
1. Do one of the following:
- Choose Create > Character > Quadruped Guide from the Animate toolbar.
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- Choose Get > Primitive > Model > Quadruped - Guide from any toolbar.
2. Translate the red manipulator cubes on the guide to proportion the limbs so that it fits within the final envelope to be used.
When you manipulate any cube, the corresponding cube on the opposite side of the body is manipulated in the same way. This makes it quick and easy to set up matching proportions for both sides of the body at once.
3. After you’ve set up the proportions of the guide to match your character, you can create a rig from it, as described in the following section.
The rig is a skeleton that includes control objects that you can position and orient to animate the various parts of the character body (see the illustration on the next page).
The rig provides a foundation of rigging components, allowing you to define as much detail as you need. Although there are a great deal of styles available from generating a rig this way, it is simple to do further modifications. The rig is composed of standard XSI components that you can delete, constrain, or connect to new objects.
Unlike the biped rig, the preference angles are aligned for a proper quadruped with the legs pointing inward. You should always make sure that the rig is aligned correctly with the corresponding anatomical locations of the animal character’s bones. It’s worth the time to do research on the animal’s skeletal structures and motion when starting a project. This is good practice for successful animal creation and animation.
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To load a predefined rig based on
default guide values, choose |
To create a quadruped rig
1. Modify the proportioning guide to match your character’s proportions (see Setting Up the Quadruped Guide).
2. Choose Create > Character > Rig from Quadruped Guide from the Animate toolbar.
3. In the Make Quadruped dialog box that appears, set up the elements of the rig as you need.
The sections following this procedure provide a summary of the options on each property page, starting on Setting Up the Chest, Belly, and Head.
4. Click OK and a new skeleton rig based on the guide’s proportions and the options you selected is created.
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• You can hide the proportional guide after you’ve created the rig so that it’s easier to see the rig. • It’s a good idea to save a copy of the character’s proportional guide in case you want to change the rigging options later. |
5. After the rig is created, the Quadruped Controls appear. These let you scale the spine and tail, as well as set the foot roll angle.
See Using the Quadruped Controls for more information.
6. Envelope the body geometry to the rig.
To envelope this character, weight it to the envelope_group group found in the rig’s model, as shown on the left. The contents change based on the rigging options. If you have multiple envelope objects, weight all of them to the full envelope group. This makes it easier to paint weights across the multiple surfaces.
7. Translate and rotate the appropriate rig controls and key them to animate the parts of the skeleton.
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When you animate the rig, make sure to turn off both constraint and child transform compensations! You can deactivate the CnsComp and ChldComp buttons on the Constrain panel. Otherwise, you end up repositioning the constraints on the rig. |
There is a synoptic view available to control the rig, which you can open by selecting any part of the rig and pressing F3. This lets you easily select and key the rig and reset it. When you scale the rig, the synoptic’s control systems adapt to the new proportions so you can still select items.
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For information on various tips for using the rig, such as scaling or animating the control objects, see Tips for Using the Rigs. |
Setting Up the Chest, Belly, and Head
The options on the Chest, Belly, and Head pages in the Make Quadruped dialog box let you select the way you want the spine, shoulders, belly, and head (neck) to be set up. These options are the same as available for the biped rigs:
• For options on the Chest page, see Setting Up the Torso Spine.
• For options on the Belly page, see Creating a Belly Control.
• For options on the Head page, see Setting Up the Head, Neck, and Ears.
On the Tail page in the Make Quadruped dialog box, you can choose whether or not to create a tail for the rig. A tail is basically a chain where each bone is controlled by a spring that reacts to the rig’s animation (secondary animation). You can also animate the cube controls on the curve in FK to give precise control and posing when required.
If you select Make Tail, you can then specify the number of vertebrae Divisions. The more divisions, the more chain elements that will trace the inner curve of the tail. The outer cage driven by the spring stays the same. If you need greater control over the tail where it is in a specific pose, like a curl, you can set the FK/IK Blend on this chain and control it in FK, ignoring the outer cage.
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• To modify the tail’s spring, see Spring-Driven Rig Controls. • You can also create a separate tail element. You can then use this tail with any other rig that you create. See Creating a Tail for more information. |
Creating Shadow Rigs
The options on the Shadow Rigs page in the Make Quadruped dialog box let you create a secondary rig at the same time you’re creating the main rig. The types of shadow rigs you can create are the same as available for the biped rigs.
For options on the Shadow Rigs page, see Creating Shadow Rigs.
The options on the Roll Division page in the Make Quadruped dialog box allow you to choose how you want the skeleton’s envelope to be weighted at a more refined level when the bone is rotated (rolled). These options create a set of nulls based on the number of subdivisions that you specify, to distribute the weighting along the bone. These options are quaternion-based.
These options are similar to the ones for the biped rigs: see Setting the Roll Division for more information.
• The Humerus (upper front leg bone) Roll Subdivision option break up the rotation along the length of the humerus so that the nulls allow more rotation at the top of the bone than at the end.
For example, the top of the humerus is joined at the shoulder (and “armpit”), which requires more rotation than the leg joint (equivalent to an elbow). This allows for more refined envelope weighting for these difficult areas.
• The Femur (upper hind leg bone Roll Subdivision option divides the rotation in the opposite way as the humerus because more rotation is required at the “wrist” instead of the elbow. This is done with built-in IK/FK blending.
In this case, the rotation starts at the end of the second bone where it joins the paw. This helps solve the problem when there’s animation on the last bone of the leg, paw effector, paw root, or paw bone.
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Although it’s unlikely that you will rotate paws beyond the -180 to 180 degree range that the roll provides, you can extend this range. For example, certain setups may require that you adjust exactly where the center of the seam line is. To do so: 1. Select a paw bone and open it in the explorer. 2. Double-click the Roll_Compensation parameter and tweak the roll_offset slider to get the range you need. |
After the rig is created, the Quadruped Controls are displayed. You can use these to adjust the rig’s spine and foot roll.
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If you close these controls, you can open an explorer and click the Controls custom parameter set icon under the Quadruped model. |
• The Scale slider dynamically reproportions the quaternion spine’s length.
If you selected the Fixed Length type for the rig’s spine (see Setting Up the Torso Spine), this is the only way in which you can scale the spine.
If you created a quaternion head spine (neck), there is a separate Scale slider that lets you control it.
• The Volume Factor slider scales the quaternion spine vertebrae as the length of the spine changes. This may also result in the scale being inherited by the upper body controls (front legs, spine, neck, and head). Use positive values to shrink the upper body and negative values to expand it.
If you don’t want the head and front legs to be scaled down the vertebrae by the volume factor, select them, press Ctrl+k to open the Local Transform property editor, and deselect the Constrain > Scaling option on the Options page.
• The Front/Back Left/Right Foot Roll 1 and 2 sliders set the angle at which the break points of the foot roll propagate rotation.
For example, an elephant walks with a very shallow foot roll angle, which is basically the width of the foot’s bottom. Bears, on the other hand, have a back foot more like humans so there is a more exaggerated stepping angle, closer to 20 degrees.
• The Back Left/Right Lock Percentage sliders determine the length percentage that will lock the two lower bones of the hind leg. For example, if this value is set to 1, the two lower bones cannot rotate forward beyond a straight line as you rotate the leg’s extension control. If you set the lock percentage value to 0.95, the bottom leg bone cannot rotate beyond 95% of the length of a horizontally-locked leg.
For creatures like an ostrich that can rotate the two lower leg bones very straight while running, a value like 0.97 would make sense. For creatures like a cat, this maximum reach is not as straight, so a value like 0.95 would work better.
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