Using CAT in 3ds Max - Part 4 - Adjustment Layers

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  • Film & VFX
  • Games
  • Animation
  • Character
  • 2011
  • Character Animation
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  • 3ds Max
Skill Level
  • Intermediate
5 min

Using CAT in 3ds Max - Part 4 - Adjustment Layers

In this tutorial, you learn about Adjustment Layers and their benefits. Because Adjustment Layers are often used with Motion Capture files, you will also learn about importing MoCap files and adjusting your rig to match the imported file.


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


00:00:00 --> 00:00:03
In this movie, you learn about Adjustment Layers.

00:00:03 --> 00:00:11
As their name implies, and contrary to Absolute Layers, Adjustment Layers
are meant for simple changes or simple offsets of body parts.

00:00:12 --> 00:00:19
Adjustment Layers work in additive mode, in that they do not overwrite
previous layers but simply offset an existing animation.

00:00:20 --> 00:00:27
Because of this fact, they are often used to correct limb positioning,
after you have applied a motion capture file.

00:00:27 --> 00:00:31
There are two types of Adjustment Layers, Local & World.

00:00:31 --> 00:00:36
The difference between the two is subtle and has to do with how
the adjustment layer deals with a limb's pivot point.

00:00:36 --> 00:00:43
Most often, you will find yourself using the World Adjustment Layer
as it is more predictable and easier to use.

00:00:43 --> 00:00:51
In this scene, you have the familiar character you have worked
on previously, skinned to a rig that's been adjusted to its body shape.

00:00:51 --> 00:00:56
You will experiment with importing a motion capture file,
and adjusting the rig to fit the motion.

00:00:57 --> 00:01:00
Select the base triangular node and go to the Motion Panel.

00:01:01 --> 00:01:04
In the Clip Manager, click the Browse button,

00:01:05 --> 00:01:11
set the Filter to Bip Files and locate and select the IceSlip.bip file
you downloaded for this tutorial.

00:01:12 --> 00:01:18
Actually, this motion capture file was initially a Motionbuilder .FBX
file that was converted to a .BIP file.

00:01:18 --> 00:01:22
At this time, CAT doesn't recognize .FBX files natively.

00:01:23 --> 00:01:30
In the dialog that appears, notice the Biped Height value.
You need to match this value to your rig's height.

00:01:30 --> 00:01:32
Go to the Front view.

00:01:32 --> 00:01:36
From the Tools menu, choose Measure Distance.

00:01:38 --> 00:01:42
Click a point on the floor between the character's feet and then click
another point at the top of its head.

00:01:43 --> 00:01:48
Notice the Distance specified on the status bar. It should be around 146.

00:01:49 --> 00:01:53
Enter 146 as the Biped Height value and click OK.

00:01:54 --> 00:01:59
The Capture Animation dialog appears and your rig is now retargeted
to the Motion Capture file.

00:01:59 --> 00:02:05
Do not dismiss the dialog just yet. Notice that the Motion Capture file
is 132 frames long.

00:02:05 --> 00:02:13
Adjust your animation length accordingly. If you wish, you can even set
it a bit longer, at 150 frames.

00:02:15 --> 00:02:22
Scrub the animation. Your character is now animated to walk a few steps
and then slip and fall.

00:02:26 --> 00:02:31
As you look closely, there are a few discrepancies
such as the feet floating slightly above the ground.

00:02:32 --> 00:02:38
The head, neck and shoulders could also use some adjustments.
This is where Adjustment Layers come into play.

00:02:38 --> 00:02:46
At this time, your rig is still dependent of the motion capture file.
To make it independent, you first need to bake the motion to the rig.

00:02:46 --> 00:02:54
This is done by clicking the Capture Animation button, which essentially
bakes the animation by creating keyframes for all bones in the skeleton.

00:02:54 --> 00:03:01
If you select any bone in the skeleton at this time,
you'll see that it has a keyframe for every frame of the animation.

00:03:01 --> 00:03:06
This makes it very hard to edit, but adjustment layers make it easy
to offset the animation.

00:03:07 --> 00:03:10
In the Motion panel, add a World Adjustment Layer.

00:03:10 --> 00:03:17
Notice that unlike an Absolute Layer, this doesn't overwrite or cancel
the underlying animation.

00:03:22 --> 00:03:23
Enable Auto Key.

00:03:24 --> 00:03:26
Make sure you are at Frame 0.

00:03:29 --> 00:03:34
Select the Foot Platforms, and move them down to the ground level.

00:03:41 --> 00:03:48
Again, notice how the change you introduced is only a slight offset
of the feet positions. The underlying animation is still intact.

00:03:49 --> 00:03:54
Similarly, make small adjustments to the head and chest at frame 0.

00:03:58 --> 00:04:05
Make more adjustment at other frames if you need them. Possibly,
a slight adjustment of the head may be needed around frame 20.

00:04:08 --> 00:04:10
Disable Auto Key when done.

00:04:11 --> 00:04:19
At this time, the Motion Capture skeleton that was used for retargeting
your rig is still in the scene, but is no longer needed.

00:04:19 --> 00:04:25
You have already baked the animation to the skeleton and adjusted
the animation through the Adjustment Layer.

00:04:25 --> 00:04:29
As you close the Capture Animation dialog, a warning appears.

00:04:29 --> 00:04:36
Click Yes to remove the Retargeting Mapping information
and to get rid of the no longer needed skeleton.

00:04:36 --> 00:04:43
You can keep fine-tuning the existing Adjustment Layer
or add more as they all work in an additive, non-destructive way.

00:04:44 --> 00:04:51
In the next movie, you revisit the CAT Motion Layer and learn
how to adjust its parameters to alter the dynamics of the motion.
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  • 3ds Max
  • Animation
  • Character
  • 2011
  • Character Animation
  • Character Effects
  • Workflow
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