Animation Compression - Character Tool

Motivation

We want to have assets that take the lowest amount of memory, but that animate at the highest possible quality.

Uncompressed, an animation contains a key for every frame in the animation and for each joint that has been exported. We usually want to reduce the amount of joints and keys to minimize the size. We have separate channels for rotation keys and position keys per joint.

To compress animation character uses the Resource Compiler (RC).

Compression of Existing Animations

To adjust compression settings of the animation load your character by double-clicking on it in Explorer.

Choose your animation in the Animations tree in Explorer. Note that both .i_caf and .animsettings should present and writable.

Now you can see the compression settings in the property panel on the right:

• You can adjust compression settings and instantly see the resulting animation and its size;
• Set "Compression" to "Side by Side" in Display Options to compare original animation with a compressed version;
• You can remove specific bone animation by checking a checkbox next to it:
  
• Click the Save button in the properties panel toolbar, or Save All in the File menu when you're done.

Setting Compression Settings

Removing channels (position/rotation keys) automatically

• You can get huge savings by automatically removing joints that don't contribute to the animation.
• Roughly, for the RC to know if a joint contributes to an animation it finds out how much it moves during the animation and compares it to the provided epsilon values. If it finds that it moves less than what the epsilon specifies it will remove the keys for the joint. Higher values for epsilons will remove more joints.
• The values to tweak for this are 'Position Epsilon' for the position channel and 'Rotation Epsilon' for rotation channel. This means rotation and position keys are considered separately.
• 'Position Epsilon' and 'Rotation Epsilon' are global values for the whole animation.
• Additive animations have smaller movement so you'll need to use smaller values for the epsilons.
• This is an all or nothing process: Either the keys are all kept for a channel(position/orientation), or deleted.

Reducing the amount of keys within a channel

• The previous step has removed joints completely, we now want to reduce the number of keys each channel has, since at this point we have one key per frame.
• For this the RC uses the 'Compression' value. Higher values will remove more keys within a channel.
• The Compression value is a global value so it will affect all joints the same by default (although we can still tweak it later on a per joint detail level).

The goal should be at this point to have an animation that takes as little as possible but looks good. Sometimes though, playing around with global values for a whole animation is not enough, and we will need to fix up individual joints that show choppy motion.

Define Animation Tags

Each animation can have a list of tags associated with it. Tags can be used to:

• Select animations that have to go into a specific DBA by means of an Animation Filter (see below)
• Apply compression to a group of animation files by means of Compression Presets (see below)

You can find Tags in the Properties window when you select animation in the Asset Explorer.

To add a new tag use the context button with tag count and select "Add" in popup menu. Then click on an empty string to enter its name.

To remove a tag you can use use context menu (RMB on the tag name).