Working with MotionBuilder in 3ds Max - Part 4 - CAT Rigs

Login to Follow
  • Film & VFX
  • Games
  • Character
  • 2011
  • Character Animation
  • Character Effects
  • Workflow
  • 3ds Max
Skill Level
  • Advanced
11 min

Working with MotionBuilder in 3ds Max - Part 4 - CAT Rigs

In this tutorial,learn how to export a CAT skeleton, for rigging and animation in MotionBuilder. You will also learn how to create a special MotionBuilder template, as a CAT rig skeleton does not follow a naming convention recognized by MotionBuilder.


  • Recorded in: Motionbuilder 2011, 3ds Max 2011
  • This tutorial is intended for use with 3ds Max version 2011 or higher.


00:00:00 --> 00:00:08
CAT is a very powerful character animation tool but its interoperability
with Motionbuilder requires a bit more work than what you have seen so far.

00:00:08 --> 00:00:13
First, the bones in a CAT rig are named differently between
one skeleton type and another.

00:00:13 --> 00:00:20
This is because CAT offers many more rig types than a Character Studio
Biped, where all the bones are always named the same way.

00:00:21 --> 00:00:29
You could rename your CAT bones on a project basis, or you could ultimately
edit the .rig files to change the bone names globally.

00:00:29 --> 00:00:43
These are text files that can be found in the user's Appdata folder under
\AppData\Local\Autodesk\3dsMax\2011 - 64bit\enu\plugcfg\CAT\CATRigs

00:00:44 --> 00:00:49
If you are using the 32-bit version of 3ds Max, substitute 64 for 32
in the path.

00:00:50 --> 00:00:58
An example is given here where the Ape2 rig is named similarly
to the Base Human rig, while the Ape rig is more generic.

00:00:59 --> 00:01:03
The problem with some CAT rigs like Ape, is that
some of the bone names are duplicated.

00:01:04 --> 00:01:06
The legs and the arms have the same names.

00:01:07 --> 00:01:13
This is not a problem for 3ds Max where name duplication is tolerated,
but it is a problem for Motionbuilder.

00:01:14 --> 00:01:19
Motionbuilder would have to rename bones with the same names,
breaking your workflow in the process.

00:01:19 --> 00:01:27
Secondly, the process of bringing back a Motionbuilder animation
onto a CAT rig in 3ds Max is slightly more complex.

00:01:27 --> 00:01:34
In this movie, you will concentrate on the export process,
and how to make a CAT skeleton compatible with Motionbuilder.

00:01:34 --> 00:01:38
The scene you will use shows a superhero character skinned
to a CAT skeleton.

00:01:39 --> 00:01:45
The CAT skeleton is based on the Base Human CAT Parent rig
and was edited to match the topology of the mesh.

00:01:45 --> 00:01:52
However, the individual bone names do not follow the naming convention
of Motionbuilder,

00:01:54 --> 00:02:00
nor do they follow the same names as a biped skeleton
which would let you use the Motionbuilder 3ds Max Biped template.

00:02:01 --> 00:02:05
It is actually very close to the biped template but not exactly the same.

00:02:05 --> 00:02:10
Therefore, you need to create your own template, one that fits
the CAT skeleton you have created.

00:02:11 --> 00:02:16
Select the CAT reference and verify its name. It reads "Base Human".

00:02:16 --> 00:02:20
This initial name repeats itself as a prefix for every bone in the skeleton.

00:02:21 --> 00:02:27
If you were to create a Motionbuilder template based on this skeleton,
it would be hard coded for a skeleton named "Base Human".

00:02:28 --> 00:02:34
This means that if you were to create an additional skeleton for this scene,
you would not be able to use the same template again.

00:02:34 --> 00:02:42
Make a copy of this skeleton by using Shift + Move.
Notice that the new skeleton's base name is "Base Human001".

00:02:42 --> 00:02:47
A template created for the first skeleton would not work for this new one.

00:02:47 --> 00:02:50
This is where the magic of the colon ( : ) comes into play.

00:02:50 --> 00:02:54
The colon is a special character that Motionbuilder reads as a separator.

00:02:54 --> 00:03:02
Internally, Motionbuilder considers only the bone names that come
after the colon, while the prefix prevents any name duplication.

00:03:02 --> 00:03:09
Select the character reference on the left and rename it: "ALICE:".
Don't forget the colon after the name.

00:03:16 --> 00:03:22
Rename the one on the right: "BOB:"
This is to differentiate characters A & B.

00:03:26 --> 00:03:30
Export the FBX file as you have learned before.

00:03:41 --> 00:03:44
Open the fbx file in Motionbuilder.

00:03:53 --> 00:03:58
If you tried characterizing one of the skeletons, say Alice,
you would get an error.

00:03:58 --> 00:04:04
Motionbuilder is looking for a set of required bones and cannot find them,
since the CAT bones are named differently.

00:04:07 --> 00:04:17
In the Navigator, expand Characters and rename the new entry:
"CAT Base Human".

00:04:22 --> 00:04:27
Double-click it to view its parameters
and then click the Character Definition tab.

00:04:27 --> 00:04:32
Expand the Base (required) option. This is mostly what needs to be defined.

00:04:32 --> 00:04:38
In the viewer, select the pelvis bone. It's a small bone named Alice:Pelvis.

00:04:38 --> 00:04:42
Press Alt and drag this bone into the Hips channel in the Navigator.

00:04:43 --> 00:04:45
Do the same with the other required bones.

00:04:45 --> 00:04:52
ALICE:LThigh becomes LeftUpLeg, ALICE:LCalf becomes LeftLeg, and so on…

00:04:52 --> 00:04:57
You may find it easier to use the Schematic View (Ctrl+W)
to do this kind of work.

00:04:57 --> 00:05:03
Remember to always hold Alt when you drag a bone into a channel.

00:05:20 --> 00:05:26
For the Spine, use ALICE:Spine1 as a requirement, you'll fill
the other spine bones in a moment.

00:05:26 --> 00:05:33
For the arms, do not worry about the collarbones at this time.
Again, you will deal with those in a second.

00:05:48 --> 00:05:52
The head is already in place as its name matches Motionbuilder's
naming convention.

00:05:53 --> 00:05:57
Once you have the 13 required bones, you can start filling in the rest.

00:05:57 --> 00:06:03
Expand the Spine list. You need to make some corrections there as Spine1
is duplicated.

00:06:04 --> 00:06:09
Remap the spine so that it starts with Spine1 and ends with Ribcage.

00:06:18 --> 00:06:23
Expand the Auxiliary list and use the collarbones in the shoulder channels.

00:06:29 --> 00:06:33
Use ALICE:Neck1 in the Neck channel.

00:06:36 --> 00:06:43
At the bottom of the Navigator, in the Neck List, correct the Neck entry
so that only the Neck and Neck1 channels are populated.

00:06:44 --> 00:06:48
You can cancel a channel by double-clicking and deleting its contents.

00:06:48 --> 00:06:56
Now that you have filled your channels, required and auxiliary alike,
you can go ahead with the characterization process.

00:06:56 --> 00:07:01
However, this would work only on Alice and you would have to redo
all this work on Bob.

00:07:01 --> 00:07:06
Instead, you will extract a template from Alice that would also work on Bob.

00:07:07 --> 00:07:13
Click the Extract Naming Template button and notice how the bone names
get translated into the template.

00:07:13 --> 00:07:21
Everything to the left and including the colon gets discarded, and the
template would work equally well on any CAT rig
based on the Base Human CAT Parent.

00:07:21 --> 00:07:29
To save this template to disk so you can reuse it, first click the
Clear Mapping List to get rid of any reference to Alice.

00:07:29 --> 00:07:34
Select the CAT Base Human entry in the Navigator and then choose
File > Save Selection.

00:07:35 --> 00:07:39
Give your Template a name, for example: "CAT_BaseHuman_Template".

00:07:40 --> 00:07:46
You can choose what to store in this file to reduce file size;
in this case, you only need the Character Element.

00:07:46 --> 00:07:49
For this example however, just accept the defaults.

00:07:49 --> 00:07:54
You can use this technique to create a template for any 2 or 4-legged
CAT Parent.

00:07:54 --> 00:08:00
From this point on, the process of rigging any CAT character
based on the Base Human skeleton becomes much easier.

00:08:01 --> 00:08:05
To prove this point, reopen the Alice/Bob file.

00:08:05 --> 00:08:08
Adjust your view and place it in X-Ray mode.

00:08:08 --> 00:08:14
To characterize either of your CAT skeletons, merge in the template file.

00:08:17 --> 00:08:21
Double-click its entry in the navigator to see
the Character Definition window.

00:08:21 --> 00:08:26
Only this time, you won't need any manual labor
as the template is already in place.

00:08:26 --> 00:08:30
Using region select, select all the bones that make up Alice.

00:08:31 --> 00:08:35
Alt-drag the bones from the viewer into any of the channels
in the navigator.

00:08:36 --> 00:08:39
All the Alice bones fall into place.

00:08:39 --> 00:08:45
If you wish, you can rename the character entry as ALICE,
to differentiate it from any other.

00:08:45 --> 00:08:51
This done, you can enable the Characterize option to get
into familiar territory.

00:09:02 --> 00:09:07
To rig Bob, merge the template once again into this scene.

00:09:11 --> 00:09:15
In the Navigator, rename the new entry BOB.

00:09:18 --> 00:09:24
Region select an area around Bob. Because you are in X-Ray mode,
only the skeleton is selected.

00:09:24 --> 00:09:29
Alt-drag into the navigator, all of Bob's bones fall into place.

00:09:29 --> 00:09:33
It is usually a good idea to add a topmost reference to the character.

00:09:33 --> 00:09:36
We didn't do it with Alice but let's do it properly with Bob.

00:09:37 --> 00:09:44
Using the Schematic view, Alt+drag the BOB: red node
into the Reference channel.

00:09:47 --> 00:10:03
Characterize the Biped. Use it in conjunction with a Control Rig,
or retarget it to follow an animation, like the Punch sequence
in the Tutorials folder.

00:10:20 --> 00:10:24
Plot the animation to the skeleton as you learned to do.

00:10:29 --> 00:10:32
Save the animated file to disk for use in 3ds Max.

00:10:33 --> 00:10:38
In the next movie, you will import the punch sequence into 3ds Max
to use on your existing CAT rig.
Posted By
  • 3ds Max
  • Character
  • 2011
  • Character Animation
  • Character Effects
  • Workflow
To post a comment please login or register
*Save $66 per month on Autodesk's Suggested Retail Price (SRP) when purchasing 1 year term 3ds Max or Maya subscription.