Cinema 4D Prime Animate Menu Timeline Menu Functions
Function available in CINEMA 4D Prime, Visualize, Broadcast, Studio & BodyPaint 3D


The KeyReducer is an essential tool when editing Motion Capture tracks. MoCap systems always save one keyframe per frame of animation. This will put gray hairs on any animator’s head because it is impossible to tell what is happening where in the animation – the entire timeline is crammed with keyframes!

Keyframes from a Motion Capture recording before (top) and after (bottom) applying the KeyReducer.

What the KeyReducer does is thin the thicket of keyframes. To do so it uses an algorithm adapted to the algorithm of the RM Curves (see Reset RM Curve) that in essence also create simplified F-Curves for control.

And it does this intelligently! It differentiates between keyframes that are relevant to the animation and those that are used as fillers.


Select the Tracks (Dope Sheet mode) or F-Curves (F-Curve mode) whose keys should be reduced before activating the KeyReducer. As soon as the mouse button is released the Keys will be removed and the animation can be played.

The following sliders can be used to adjust reduction:

As soon as one of the sliders is released the Reduction value will return to 0% (also after a value has been entered manually and the Enter-key pressed). If you are still not satisfied with the result you can either define another value or undo the reduction via the Timeline’s Edit menu.

Editing tracks using the KeyReducer is especially useful in conjunction with Cinema 4D Studio’s Cappuccino functions since these functions generally create a great number of keyframes.

The KeyReducer should be used carefully when editing motion capture files that were recorded using certain motion capture systems. Editing all tracks at once will probably never achieve the desired end-result. In fact, a bone / joints skeleton will practically be decimated because the KeyReducer will ignore such settings as the spacing between bones. The KeyReducer edits each object independently. The KeyReducer should therefore be applied to individual tracks, one at a time!