Interpolation is a method of calculating character poses in the frames between two keyframes to create smoother motion.
Interpolation is applied to groups of sequential frames known as Interpolation Intervals.
An interpolation interval is always limited by two key frames: one marking the beginning of the interval and another at the end of it.
To create an interpolation interval:
1. Select several frames on the Timeline.
2. Choose a type of interpolation from the menu.
The in-between frames will be generated automatically
Each interval on the Timeline can use a particular type of interpolation:
Note how different types of interpolation affect the trajectory of the object
A type of interpolation can be described as a rule used to create in-between frames on an interval. Keyframes set start and end positions, but how the object moves between these positions is defined by the type of interpolation.
Cascadeur supports several types of interpolation:
In-between values are not calculated, animated objects only change their positions and poses in keyframes.
Frames with Step interpolation are colored white on the timeline
Objects move between the specified the keyframes with constant speed.
Frames with Linear Interpolation are colored beige on the timeline.
Objects move along a curve defined by their positions in the key frames, accelerating at the beginning of the trajectory and decelerating near the end of it.
When this type of interpolation is selected on multiple intervals, character movements on previous intervals can influence subsequent ones, producing an effect similar to moving by intertia. This can make movements look more realistic, but in case this effect is not desired, use Bezier viscous interpolation type instead.
Frames with Bezier Interpolation are colored with a light blue shade.
This type works in the same way as the Bezier interpolation, but previous movements influence subsequent ones to a lesser degree.
Bezier (left) and Bezier clamped (right) types of interpolation
Objects move linearly (like under Linear interpolation), but with acceleration and deceleration (like under Bezier). Any angles in the trajectories are heavily smoothed.
Frames with Bezier clamped interpolation are colored teal on the Timeline.
This type of interpolation should be used for:
- Ground-level movements
- Fulcrum Points
This type can be used when you want to edit a character pose on a regular frame of the interpolation interval, instead of the keyframe. This way you can adjust poses between key frames without creating additional keys.
Frames with Fixed Interpolation are colored green.
Frames with Mixed interpolation are colored light pink:
Cascadeur supports both IK (inverse kinematic) and FK (forward kinematic) interpolation, and you can use any of these on any Interval.
To switch between IK and FK:
- Select an interval.
- Click IK or FK button at the top of the Timeline.
If tracks on this interval have different types of interpolation, Mixed mode will be used.
To learn more about using IK and FK, see Kinematics in Cascadeur.