Using CAT in 3ds Max - Part 2 - New Rigs

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  • Film & VFX
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  • 2011
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Skill Level
  • Intermediate
13 min

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.


00:00:00 --> 00:00:06
In most cases, you start off a CAT project by using a preset rig
and editing it as seen in the previous movie.

00:00:07 --> 00:00:14
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.

00:00:14 --> 00:00:21
In this case, you have a quadruped creature that looks like a cross
between a dog, a wolf, and maybe a bit of hyena.

00:00:22 --> 00:00:26
The creature on the left is already rigged and animated
with a walk cycle.

00:00:26 --> 00:00:32
You will create a "manual" rig to the creature on the right
to learn about the process of creating new original rigs.

00:00:33 --> 00:00:35
Select the animated beast and hide it.

00:00:35 --> 00:00:40
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
the skeleton.

00:00:46 --> 00:00:50
To create a rig, go to the Helpers panel and select the CAT Objects list.

00:00:50 --> 00:00:57
Click the CATParent button. Make sure the CATRig preset reads "None"
and click and drag under the beast mesh.

00:00:58 --> 00:01:01
This creates a node for a rig but no bone elements yet.

00:01:01 --> 00:01:09
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.

00:01:15 --> 00:01:18
With the Node selected, go to the Modify panel.

00:01:18 --> 00:01:26
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.

00:01:26 --> 00:01:30
On some system, you may experience some refresh problems.

00:01:30 --> 00:01:38
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.

00:01:39 --> 00:01:45
Keep that in mind anytime you create a hub or a bone.
A simple refresh will ensure the object is visible in the viewport.

00:01:46 --> 00:01:49
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.

00:02:02 --> 00:02:09
Before you start editing its parameters, it is very important
to rotate the pelvis as the spine on this character is mostly horizontal.

00:02:09 --> 00:02:15
Failure to do that will result in the character snapping to an upright
position if you apply a motion file to it later.

00:02:16 --> 00:02:21
After that you can adjust the Length, Width and Height parameters.

00:02:24 --> 00:02:29
With the Pelvis selected, click the Add Leg button. A leg gets created.

00:02:29 --> 00:02:37
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.

00:02:37 --> 00:02:43
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
the anatomy.

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Do the same with the knee and the hock joint as well.

00:03:11 --> 00:03:14
Adjust the foot angle as it seems a little high.

00:03:14 --> 00:03:18
Keep on making transform adjustments until you are satisfied.

00:03:25 --> 00:03:34
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.

00:04:01 --> 00:04:06
Once you've adjusted the foot, set its number of digits to 3.

00:04:09 --> 00:04:12
Adjust the Toe Bones based on the geometry.

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This takes care of the first leg.

00:04:27 --> 00:04:30
Select the Pelvis again and choose Add Leg one more time.

00:04:31 --> 00:04:35
Notice that all the work you've done so far is preserved and transposed
to the other side.

00:04:36 --> 00:04:44
Still, always look for possible errors. The geometry was not modeled
perfectly symmetrical, so you may need a few adjustments on the right leg.

00:04:48 --> 00:04:53
Next you create a Spine. Select the pelvis and click the Add Spine button.

00:04:53 --> 00:04:57
Select the uppermost bone on the spine and rename it Torso.

00:05:00 --> 00:05:06
Move it closer to the shoulder area. Notice how the spine is
automatically stretched to accommodate that shift.

00:05:06 --> 00:05:11
Rotate the torso bone so that it follows the natural contours
of the character.

00:05:12 --> 00:05:16
Adjust its parameters to help with the skinning later.

00:05:16 --> 00:05:21
Similarly, select the individual spine bones and adjust their parameters.

00:05:27 --> 00:05:34
If you wish, double-click the base spine bone to select the whole chain,
and then change the wirecolor.

00:05:34 --> 00:05:42
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.

00:05:43 --> 00:05:49
In addition to specifying a 3-bone leg as you did earlier,
you may want to enable the Collarbone option.

00:05:51 --> 00:05:56
The collarbone will act like an inner bone in this case
and will also help with the skinning.

00:06:00 --> 00:06:07
Adjust the front leg using transforms and editing parametric values
like you did earlier with the back leg.

00:07:11 --> 00:07:16
Once done, select the torso hub again and add another leg on the other side.

00:07:17 --> 00:07:19
That still leaves you with a neck and a head to add.

00:07:20 --> 00:07:25
With the torso hub selected, add another spine. This is essentially
what a neck is.

00:07:26 --> 00:07:29
Select the top bone and rename it "Head".

00:07:29 --> 00:07:35
Select any neck bone and rename it "Neck" to differentiate this spine
from the back spine.

00:07:39 --> 00:07:43
Adjust the head position and the position of the neck bones based
on the existing geometry.

00:07:50 --> 00:07:55
Adjust the parameters of the head, and the parameters of the individual
neck bones.

00:07:56 --> 00:08:04
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.

00:08:04 --> 00:08:12
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.

00:08:13 --> 00:08:17
These include the character's jaw and snout, mane and tail.

00:08:18 --> 00:08:22
In order to accommodate those areas, you need to add
more individual bones.

00:08:23 --> 00:08:32
The tail is easy enough to create. This is done by selecting
the pelvis hub, switching to Wireframe mode (F3) and clicking Add Tail.

00:08:33 --> 00:08:35
Notice the tail inside the skeleton.

00:08:35 --> 00:08:39
Select the tail base and rotate it in the correct direction.

00:08:44 --> 00:08:48
Set the number of links. In this case, 3 should be enough.

00:08:48 --> 00:08:54
Adjust the position, orientation and parameters of the individual bones.

00:09:00 --> 00:09:06
The mouth and the mane are slightly more complex and require a more
manual insertion of bones.

00:09:06 --> 00:09:11
Start with the mouth area. Zoom in on that area and select the head.

00:09:11 --> 00:09:13
Make sure you are in wireframe mode.

00:09:14 --> 00:09:18
Click on Add Bone. A bone should appear at the center of the head.

00:09:18 --> 00:09:23
A word of warning: if a bone doesn't appear, you simply need to refresh
the screen by pressing tilde (~).

00:09:24 --> 00:09:27
Sometimes, the wire colors are difficult to read too.

00:09:28 --> 00:09:34
Do not keep pressing the Add Bone button indefinitely,
otherwise you'll be adding bones that you do not need.

00:09:34 --> 00:09:38
This is the same phenomenon that happens sometimes when you add a pelvis.

00:09:38 --> 00:09:44
Select the newly created bone and move it outside the head,
near the lower jaw.

00:09:44 --> 00:09:47
You can even rename it as such if you wish.

00:09:47 --> 00:09:52
Go back to shaded mode (F3) and adjust the bone to fit the character.

00:09:54 --> 00:09:57
Repeat this procedure to create an upper jaw.

00:10:32 --> 00:10:39
You can create Mane bones much the same way,
by selecting an appropriate bone and adding more bones to it.

00:10:45 --> 00:10:50
Even the underbelly area could use a few more bones to help
with the skinning process.

00:10:57 --> 00:11:01
Once you have all the bones in place and adjusted,
it is time for a skin test.

00:11:02 --> 00:11:08
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.

00:11:20 --> 00:11:26
You would then be able to recreate it with a simple click,
and adjust its size using the CATUnits Ratio.

00:11:27 --> 00:11:31
Delete any extra rigs to go back to the one you were working on.

00:11:33 --> 00:11:38
Unfreeze all objects and disable XRay mode (Alt+X) on the mesh.

00:11:39 --> 00:11:42
With the mesh selected, apply a Skin Modifier.

00:11:44 --> 00:11:50
Choose Add (Bones) and in the dialog that appears,
click once on the myBeast_Pelvis entry.

00:11:51 --> 00:11:56
Press CTRL+C to select all the children bones,
and then click the Select button.

00:11:56 --> 00:12:00
Select any bone on the skeleton and go to the Motion panel.

00:12:00 --> 00:12:07
In the Layer Manager rollout, click the Layer flyout and choose the last
option. This creates a CATMotion layer.

00:12:08 --> 00:12:11
Enable Animation Mode and test the animation.

00:12:14 --> 00:12:18
Chances are you will need some adjustments to the bone
and/or the Skin modifier.

00:12:18 --> 00:12:23
In that case, you simply toggle off the animation button to go back
to setup mode.

00:12:26 --> 00:12:30
If you haven't adjusted your animation yet, you can even delete
the layer altogether.

00:12:31 --> 00:12:34
It is easy enough to recreate after you have fixed the problem areas.

00:12:35 --> 00:12:39
In the next movie, you start looking more thoroughly
into animation layers.
Posted By
  • 3ds Max
  • Animation
  • Character
  • 2011
  • Character Animation
  • Character Effects
  • Workflow
1 Comment
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| 2 years ago
OMG cool site, beautiful lessos! Russian tutorials are so few, and they are so incomprehensible... And the courses are insanely expensive. How nice that there is this site and simultaneous translation =)