Using CAT in 3ds Max - Part 2 - New Rigs
In this 3ds Max tutorial, learn how to build a skeleton from scratch with the CAT tool.
- Recorded in: 3ds Max 2011
- This tutorial is intended for use with 3ds Max version 2011 or higher.
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In most cases, you start off a CAT project by using a preset rig
and editing it as seen in the previous movie.
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In some cases however, you may find it easier to build a CAT rig from
scratch, when your character or creature is somewhat out of the ordinary.
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In this case, you have a quadruped creature that looks like a cross
between a dog, a wolf, and maybe a bit of hyena.
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The creature on the left is already rigged and animated
with a walk cycle.
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You will create a "manual" rig to the creature on the right
to learn about the process of creating new original rigs.
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Select the animated beast and hide it.
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Select the creature you will work on and press Alt+X to enable XRay mode
on the mesh.
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Next, freeze the mesh so it doesn't impede your work as you build
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To create a rig, go to the Helpers panel and select the CAT Objects list.
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Click the CATParent button. Make sure the CATRig preset reads "None"
and click and drag under the beast mesh.
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This creates a node for a rig but no bone elements yet.
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Rename the CATRig "myBeast_". This will be the prefix for all the limb
names you are about to create.
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Center the node to 0,0,0. This is where the mesh is positioned.
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With the Node selected, go to the Modify panel.
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The first thing you need to create is a Pelvis. This acts like a center
of mass for any creature. Click the Create Pelvis button.
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On some system, you may experience some refresh problems.
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If the pelvis does not automatically appear in the viewport, you may
need to refresh it by panning, or simply by pressing the Tilde (~) key.
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Keep that in mind anytime you create a hub or a bone.
A simple refresh will ensure the object is visible in the viewport.
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Now you can select the pelvis and move it into place.
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Rename the object "Pelvis" which is better than the generic "Hub001".
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To view the Main name update (with the "myBeast_" prefix),
simply deselect and re-select the object.
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Before you start editing its parameters, it is very important
to rotate the pelvis as the spine on this character is mostly horizontal.
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Failure to do that will result in the character snapping to an upright
position if you apply a motion file to it later.
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After that you can adjust the Length, Width and Height parameters.
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With the Pelvis selected, click the Add Leg button. A leg gets created.
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At this time, it is a human leg, with a thigh, a calf and a foot,
but the creature you are working on has an extra joint.
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Select the thigh and in the Modify panel, specify that this leg
has actually 3 bones instead of 2.
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Next move and rotate the foot platform into position.
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Select the thigh again and move it and rotate it so that it follows
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Do the same with the knee and the hock joint as well.
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Adjust the foot angle as it seems a little high.
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Keep on making transform adjustments until you are satisfied.
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Select the bones one at a time, from top to bottom, and adjust
parameters such as Width & Depth. This will help with the skinning later.
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Once you've adjusted the foot, set its number of digits to 3.
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Adjust the Toe Bones based on the geometry.
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This takes care of the first leg.
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Select the Pelvis again and choose Add Leg one more time.
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Notice that all the work you've done so far is preserved and transposed
to the other side.
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Still, always look for possible errors. The geometry was not modeled
perfectly symmetrical, so you may need a few adjustments on the right leg.
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Next you create a Spine. Select the pelvis and click the Add Spine button.
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Select the uppermost bone on the spine and rename it Torso.
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Move it closer to the shoulder area. Notice how the spine is
automatically stretched to accommodate that shift.
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Rotate the torso bone so that it follows the natural contours
of the character.
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Adjust its parameters to help with the skinning later.
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Similarly, select the individual spine bones and adjust their parameters.
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If you wish, double-click the base spine bone to select the whole chain,
and then change the wirecolor.
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At this time, you create the front legs much the same way you did
the rear legs, by selecting the torso hub and choosing Add Leg.
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In addition to specifying a 3-bone leg as you did earlier,
you may want to enable the Collarbone option.
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The collarbone will act like an inner bone in this case
and will also help with the skinning.
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Adjust the front leg using transforms and editing parametric values
like you did earlier with the back leg.
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Once done, select the torso hub again and add another leg on the other side.
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That still leaves you with a neck and a head to add.
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With the torso hub selected, add another spine. This is essentially
what a neck is.
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Select the top bone and rename it "Head".
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Select any neck bone and rename it "Neck" to differentiate this spine
from the back spine.
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Adjust the head position and the position of the neck bones based
on the existing geometry.
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Adjust the parameters of the head, and the parameters of the individual
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At this time, most of the skeleton is in place, but there are some areas
that are out of the skeleton's range if you apply a Skin modifier.
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Those out-of-range areas can still be controlled by the nearest bone but
will prove difficult to animate separately, should you decide to do so.
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These include the character's jaw and snout, mane and tail.
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In order to accommodate those areas, you need to add
more individual bones.
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The tail is easy enough to create. This is done by selecting
the pelvis hub, switching to Wireframe mode (F3) and clicking Add Tail.
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Notice the tail inside the skeleton.
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Select the tail base and rotate it in the correct direction.
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Set the number of links. In this case, 3 should be enough.
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Adjust the position, orientation and parameters of the individual bones.
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The mouth and the mane are slightly more complex and require a more
manual insertion of bones.
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Start with the mouth area. Zoom in on that area and select the head.
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Make sure you are in wireframe mode.
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Click on Add Bone. A bone should appear at the center of the head.
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A word of warning: if a bone doesn't appear, you simply need to refresh
the screen by pressing tilde (~).
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Sometimes, the wire colors are difficult to read too.
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Do not keep pressing the Add Bone button indefinitely,
otherwise you'll be adding bones that you do not need.
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This is the same phenomenon that happens sometimes when you add a pelvis.
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Select the newly created bone and move it outside the head,
near the lower jaw.
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You can even rename it as such if you wish.
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Go back to shaded mode (F3) and adjust the bone to fit the character.
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Repeat this procedure to create an upper jaw.
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You can create Mane bones much the same way,
by selecting an appropriate bone and adding more bones to it.
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Even the underbelly area could use a few more bones to help
with the skinning process.
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Once you have all the bones in place and adjusted,
it is time for a skin test.
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Notice in passing that you can save a CAT Rig to disk,
if you wish to use it as a preset at a later time.
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You would then be able to recreate it with a simple click,
and adjust its size using the CATUnits Ratio.
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Delete any extra rigs to go back to the one you were working on.
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Unfreeze all objects and disable XRay mode (Alt+X) on the mesh.
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With the mesh selected, apply a Skin Modifier.
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Choose Add (Bones) and in the dialog that appears,
click once on the myBeast_Pelvis entry.
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Press CTRL+C to select all the children bones,
and then click the Select button.
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Select any bone on the skeleton and go to the Motion panel.
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In the Layer Manager rollout, click the Layer flyout and choose the last
option. This creates a CATMotion layer.
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Enable Animation Mode and test the animation.
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Chances are you will need some adjustments to the bone
and/or the Skin modifier.
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In that case, you simply toggle off the animation button to go back
to setup mode.
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If you haven't adjusted your animation yet, you can even delete
the layer altogether.
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It is easy enough to recreate after you have fixed the problem areas.
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In the next movie, you start looking more thoroughly
into animation layers.