To load predefined rig setups based on default guide values, see Loading Biped Rigs.
Creating a Biped or Biped Dog Leg Rig
After you load and adjust the biped guide to match your character, you can create a rig based on these new proportions. The rig is a skeleton that includes control objects that you can position and orient to animate the various parts of the character body.
The rig provides a foundation of rigging components, allowing you to define as much detail as you need. You can get very specific results by setting roll divisions, volume controls, shadow rigs, and more.
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.
|
|
To load predefined rig setups based on default guide values, see Loading Biped Rigs. |
To create a biped or biped dog leg rig
1. Modify the proportioning guide to match your character’s proportions (see Setting Up the Biped or Biped Dog Leg Guides).
2. Choose Create> Character > Rig from Biped Guide or Create> Character > Rig from Biped Dog Leg Guide from the Animate toolbar.
3. In the Make Biped or Make Biped Dog Leg dialog box that appears, set up the rig elements as you need. The sections following this procedure provide a summary of the options on each property page in the dialog box.
4. Click OK and a new skeleton rig based on the guide’s proportions and the options you selected is created.
|
|
• The biped dog leg foot controls are the same as for the quadruped rig—see Creating the Rig. • The Toe (tip) control allows the foot to point in a particular direction or rotate without the toes going below this control object. Select the Toe control and rotate it or translate it to control the foot placement. Unlike manipulating the Foot control, the third bone won’t go under the Toe control object. • You can also create a separate tail element that you can then use with any rig that you create, such as to create some fantastical creature using a biped dog leg rig. See Creating a Tail for more information. • 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 Biped or Biped Dog Leg Controls appear. These let you scale the spine and upper body volume, as well as set the foot roll angle (and leg extension for the biped dog leg rig).
See Using the Biped or Biped Dog Leg 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. 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.
See Tips for Using the Rigs for more information on using the rigs.
|
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. |
The options on the Chest page in the Make Biped/Biped Dog Leg dialog box let you select the way you want the spine to be set up in the torso area.
• The Torso spine type can be either quaternion or regular skeleton. Both the spine types are compatible in all combinations of rigs and with the shadow rigs.
- The Quaternion spine bi-directionally distributes the roll from the chest down and the hip up. This is the same spine that is created when you choose Create > Skeleton > Spine see Creating a Spine for details).
or
- The Skeleton spine is a simple chain that doesn’t allow for independent hip movement as does the quaternion.
• If you selected Quaternion for the spine, you can select the Spine type:
- Fixed Length creates a spine that can be extended only using the Scale slider in the Biped or Biped Dog Leg Controls (see Using the Biped or Biped Dog Leg Controls).
or
- Stretches creates a spine that extends to join with the chest icon.
• The Divisions let you specify the number of vertebrae that make up the spine. More vertebrae allow for a more flexible spine.
• The Control Icon for the chest can be a Square or the control icon for the Upper Body can be a Cube.
The options on the Belly page in the Make Biped/Biped Dog Leg dialog box let you create a belly control and set the weighting for it. This control may be useful for animating a character that has a large belly or paunch.
1. Select the Make belly option to create a box belly control that extends in front of the hips.
The curves that connect the box to the hips have a layer of secondary animation that dynamically reacts to the movement of the rig. You can also key the rotation of the box to directly animate the belly.
|
|
To open a control slider set for modifying the belly’s spring, see Spring-Driven Rig Controls. |
2. If you want the distribute the weighting of the belly around the hips (sliding), select Sides of belly slide to even the belly movement’s falloff.
This option creates a null on either side of the belly control at the hips. You can use these nulls to help distribute the weight of the belly (envelope) around the hips so that it’s not just like a big lump in the front.
3. Then set the Percentage of the slide falloff to control how much of the weight is distributed to these nulls. The higher the percentage, the more weight is spread to these nulls.
Setting Up the Head, Neck, and Ears
The options on the Head page in the Make Biped/Biped Dog Leg dialog box let you select the way you want the head and neck to be set up, including ears.
• The Head can be either a Skeleton or a Quaternion spine:
- The Quaternion spine head bi-directionally distributes the roll from the head down and the shoulders up. This is the same spine that is created when you choose Create > Skeleton > Spine (see Creating a Spine for details).
or
- The Skeleton head is a simple chain that doesn’t allow for independent movement as does the quaternion. The chain divisions in the neck are determined by the placement and duplication of the guide’s control cubes.
• If you selected Quaternion spine head for the neck, you can select the Head Spine (neck) type:
- Fixed Length creates a neck that can be extended only using the Scale slider in the Biped Controls (see Using the Biped or Biped Dog Leg Controls).
or
- Stretches creates a neck that extends to join with the head icon.
• The Divisions let you specify the number of vertebrae that make up the neck. More vertebrae allow for more flexibility.
• You can also create Ear controls, useful if you are making a humanoid creature.
The curves of the ear controls have a layer of secondary animation that dynamically reacts to the movement of the rig. You can also key the rotation of the cubes on the curves to directly animate the ears.
|
|
To open a control slider set for modifying the ears’ springs, see Spring-Driven Rig Controls. |
Setting Up the Arms and Fingers
The options on the Limbs page in the Make Biped/Biped Dog Leg dialog box let you select the way the arms and fingers are created and animated.
• The Arm Rotation options let you choose between two different rotation orders:
- YZX creates the arms with the rotation order of YZX, which often helps reduce the occurrence of gimbal lock. This means that the Y rotation becomes the primary up-and-down motion of the arm and is evaluated first, then Z, then X (roll). See Changing the Bones’ Order of Rotation for more information.
- XYZ, which is the default rotation order in XSI.
• The Symmetrical Manipulation of Arms options determine if the arm rotation values will mirror exactly:
- Symmetrical: the arms are manipulated symmetrically. For example, if you select both forearms and rotate them 30 degrees forward, both arms will rotate down. This also makes it easier to copy animation from the right arm to the left and have it mirror properly. The right arm is scaled to a value of -1.
- Non symmetrical: both arms have positive scaling, but if you rotate them, the motion is not symmetrical. For example, if you select both forearms and rotate them 30 degrees forward, the left arm will rotate down but the right arm will rotate up. This option is useful when you need to transfer the animation data to a platform that doesn’t support negatively-scaled bones.
• The Arm Attachment options lets you choose between:
- Making the arms children of the shoulders to animate them in FK (rotating the arm bones).
or
- Making the arms children of the hips if you want to have shoulder movements that are more independent of the hands and arms. For example, this style is useful for characters who do a lot of up-and-down shrugging movements with their shoulders.
• The Finger options let you choose between making fingers with 2D chains or 3D chains.
2D chains are constrained to a single plane and work more predictably in IK for typical character fingers. 3D chains allow for a full range of movement on all axes (not restricted to a plane) and can make good abstract tree branch, monster, or robotic tentacle fingers. See 2D and 3D Chains for more information.
|
|
To manipulate the fingers, see Animating the Fingers and Hands. |
The options on the Roll Division page in the in the Make Biped/Biped Dog Leg 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).
The roll division reduces the pinching that occurs when appendages with simple bone structure roll. These quaternion-based options create a set of nulls, based on the number of subdivisions that you specify, to distribute the weighting along the bone.
• The Biceps and Thigh Roll Subdivision options break up the biceps and thigh rotation along the length of those bones so that the nulls allow more rotation at the start of the bone than the end. For example, the start of the biceps is joined at the shoulder (and armpit), which require more rotation than the elbow. This allows for more refined envelope weighting for these difficult areas.
• The ForeArm Roll Subdivision option divides the rotation in the opposite way as the biceps and thigh because more rotation is required at the wrist instead of the elbow.
In this case, the rotation starts at the end of the forearm bone where it joins the wrist. This setup is compatible with animation on the last bone of the arm, hand effector, hand root, or hand bone. It also works with IK and FK, and IK/FK blending.
|
|
Although it’s unlikely that you will rotate hands 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 hand bone (LHand or Rhand) 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. |
Selecting Volume Controls for the Skin (Envelope)
When you’re animating a rig, you need to take the final body envelope into consideration. This helps you animate appropriately, especially when the body is very large or unusually shaped.
To help you visualize and estimate the body’s volume with the rig, you can select the options on the Skin page in the Make Biped/Biped Dog Leg dialog box. Based on the yellow splines you set up with the proportional guide (see Setting Up the Biped or Biped Dog Leg Guides), these options create a series of controls and nulls that approximate the body sliding and compressing over the skeleton.
Using these controls, you can allow a character to reach extreme poses more easily than by weighting alone.
• The Simple Sliding options (Hips and Armpits) option use 2-point constraints to approximate sliding.
• The Sliding and Volume Preservation options (Thighs) do the same thing but outside a bounding volume, forcing the body to keep its shape as it deforms.
• The Joint Compression options simulate the elbow pushing the mass of a biceps muscle or the knee pushing the thigh muscle. The volume is placed as an approximation from the guide’s yellow spline volume controls (see Setting Up the Biped or Biped Dog Leg Guides) and needs to be fine-tuned in the pose of the compressed joint.
After you adjust the volume controls’ position, rotation, and scale to get them into the poses that work optimally for your character, you should key these values. If you need to return to the original position where the control splines were generated (such as to modify or reapply the envelope), you can apply an action source to the rig called DefaultPose (see Action Sources).
Shadow rigs, sometimes referred to as export skeletons, are simpler rigs that are constrained to the more complex main rig that is used for animating the character. When you generate the main rig, you can create a shadow rig at the same time.
Shadow rigs are usually used for exporting animation, such as to a game or crowd engine or other 3D software programs. To transfer the animation from the complex rig to the shadow rig, plot the animation while the shadow rig is still constrained in place to the complex rig. Then you can export the shadow rig or just its animation.
To create a shadow rig
1. On the Shadow Rigs page in the Make Biped/Biped Dog Leg dialog box, select the Type of shadow rig to create:
- SI|3D Skeleton creates a SOFTIMAGE|3D style skeleton hierarchy with the effectors as children of the last bone.
- XSI Skeleton creates a skeleton hierarchy with the effectors as children of the chain’s root.
- Null Hierarchy creates a skeleton made of nulls. A null is created at the root of each chain.
- Box Hierarchy creates a body of boxes that surround the regular rig.
- Box with IK Arms and/or Legs creates a body of boxes but with the arms and/or legs as IK bone chains.
2. Select whether the shadow rig Hands have Fingers or not.
For example, select the No Fingers option to create “mitten” hands when finger animation is not needed.
|
|
The shadow rig is constrained to the main rig in various ways. To manage these constraints easily, use the Constraints Outside Model Boundaries commands as described in Controlling the Constraints between Rigs (Models). |
When you animate the rig, the shadow rig follows along. You can then plot the animation on to the shadow rig, remove the constraints between the rigs, and the shadow rig is ready to be exported.
For information on plotting, see Plotting (Baking) Animation in the Animation guide.
Using the Biped or Biped Dog Leg Controls
After the rig is created, the Biped or Biped Dog Leg Controls are displayed. You can use these to adjust the scale of the spine, neck, and upper body volume, as well as set the foot roll angle. For the Biped Dog Leg, there are some additional controls that set the leg extension.
|
|
If you close these Controls, you can find them (a custom parameter set) in the explorer under the Biped or Biped_DogLeg model’s node. 
|
• 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 its length.
• 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 (arms, 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 arms 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 Left/Right Foot Roll 1 and 2 sliders set the angle at which the break points of the foot roll propagate rotation. For example, you can set it so that it appears as if the character is wearing high heels or is stepping over something.
Another example is if a character is putting out a cigarette with its foot: set both angles to 0 and the roll will pivot from the front of the foot.
Biped Dog Leg Controls
With the biped dog leg rig, there are extra sliders that control the locking of the leg extension control (the middle box in the three foot controls):
• The Left/Right Lock Percentage sliders determine the length percentage that will lock the two lower bones of the dog 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.
Features to Help You Use the Rig
There are a number of features in the rig that can help you use it.
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, reset it, and have detailed control over the hands.
When you scale the rig, the synoptic’s control systems adapt to the new proportions, so you can still select items.
Each rig control element has several character key sets to define which parts of the character are keyed, plotted, and posed by the synoptic view. These character key sets can help you quickly key the different controls in a rig.
For more information, see Keying with Character Key Sets in the Animation guide.
The biped rigs contain various action sources to help pose the hands or return to the default pose. For example, if you need to return to the rig’s original position (such as to modify or reapply the envelope), you can apply the action source called DefaultPose to the rig.
To apply an action, select it from the rig’s Mixer > Sources > Actions folder and choose Actions > Apply > Action (see Applying or Restoring the Animation from Action Sources to an Object in the Nonlinear Animation guide for more information).
Animating the Fingers and Hands
Under each hand’s root node, you can find a custom parameter set that contains sliders for rotating each finger bone in the hand. This set is also available by clicking the Sliders button on the Hands page in the synoptic view (select an element and press F3).
You can also use the buttons on the Hands page to easily select and pose the hands. As well, you can apply action sources that can relax, make a fist, or spread the fingers on each hand.
The following tips provide information about how to set up and use the rig.
Default Position, Rotation, and Scaling Values
The rig’s default position has translation and rotation values of zero so that you’re always working from a known base line. This makes it easier to transfer and keep track of the animation. You can get back this position easily by choosing Transform > Reset All Transforms (press Ctrl+Shift+r), as with any other skeleton.
As well, the default scale of all the components is 1, again making it easy to return to this base. You can scale the rig proportions without adding scale by using the bone length sliders and the spine Scale slider (in the Control set).
|
|
You can also create your own neutral pose for the rig with position and rotation values of 0 and scaling values of 1. See Creating Neutral Poses for Skeletons for more information. |
Animating and Enveloping the Rig
• To animate the rig, you translate and rotate the appropriate rig controls and key them to animate the parts of the skeleton.
However, 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.
• To envelope this character, weight it to the envelope_group group found in the rig’s model. 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.
The control objects are all curve-based wireframes and have no geometry. This makes it easy to keep the rig and body geometry (envelope) on the same layer because you can turn off the 3D Geometry option in a viewport’s visibility menu (click the eye icon) to have only the rig displayed.
To scale the control objects
If you need to resize the control icons (such as the foot and hip controls), follow these steps:
1. Tag all the points of the control object that you want resize.
2. Scale the object in point mode.
3. Freeze the object’s geometry.
This way you don’t introduce scaling into your rig, which could create problems transferring animation later in a project.
You can use the same process to reposition and change the shape of the controls without affecting their centers.
Scaling or Changing the Shape of the Hip Control
If you need to change the shape of the hip control object, you can find a parameter set with sliders that control many facets of its size and shape, such as the hip sockets’ depth or width.
To open the hip control’s custom parameter set
1. Select the hip control.
2. In an explorer, press f to find the Hip control, then expand its node.
3. Click the S icon to open the control slider set.
Offsetting the Resolution Plane for the Leg’s Up Vectors
If you want to animate the resolution plane for the biped legs as you animate them in IK, here’s a good trick!
1. In an explorer, select the hidden group and press h to unhide the controls. Many nulls appear—do not be alarmed.
2. Select middle green null behind the knee called lastboneUpV/UpV1.
3. In the explorer, press f to find the null’s node and expand its Kinematics > Constraints folder.
4. Click the Two Point Cns icon to open the constraint’s property editor.
5. Set the Distance Percentage value (50% default) to change the position of the control null between the up vector control (100%) and the null below it (0%). Key this value at animate the plane.
|
|
If you’re animating the legs in the biped dog leg rig, be careful not to move the leg’s IK up vector controls too low or else some flipping may occur. |
SOFTIMAGE|XSI v.6.01