3D Practice: Houdini 11 – Pose-to-pose animation
I have been reading up on character animation in various books and other sources. First I am trying to learning the basic technical aspects in Houdini, like what buttons to press to create key-frames, how to work with graphs etc.
However:
- Animation is the art of observation, interpretation, and implementation. Learning to see how things move, deciphering why they move as they do, and then applying all that to your scene is what animation is all about.
- Movement and timing are what make animation good, not setup or the model.
(Note on blocking out animation for a walk-cycle, books I’ve studied says keyframe every 5 – 6 frames)
Notes on Pose-to-pose animation (Keyframe Animation) in Houdini
This involves keying the important poses where they occur in time, then filling in the tweens. This is the common method for doing 3D computer-based animation.
This is a newer style of animation, dating from the 1960s: the master animator would create main cells (two or three per shot), additional cells (between 5 and 10) would be filled in “from storybook”, and then the remaining in-between cells would be created.
This style involves two phases:
Blocking
- Lay out the rough animation by creating the important poses where they occur on the timeline.
- Set keyframes on everything that’s key-able. This is for control and predictability: you don’t want to accidentally leave something un-keyed. This is also much faster than selecting the parameters to key.
- Use constant (straight) or sometimes linear transitions between keyframes in the channel editor. This makes the character jump between poses.
Keying everything gives quick, immediate results, but it can become difficult to tweak the animation later, especially for complex characters.
To set up Houdini for blocking:
- Choose Edit > Preferences > Animation and set Global set key to Set keys on all scoped channels.
- Turn off Autokey: Add keyframes on parameter change.
- Create a channel group containing the parameters of the character’s world space controller Nulls. Use the channel group to scope the parameters to keyframe.
- Copy the current pose to create the next one: pose the character, key everything, then copy the keyframe in the playbar to another frame, and key everything at that frame.
- Use flipbook blocking to move the blocked poses around in time.
Posing
In this phase, you clean up the animation by deleting unused animation (delete keys on straight curve segments) and set up transitions between keyframes (convert constant transitions to ease, constant, or spline).
As the characters transition between the main poses, you add keyframes for finer controls, keying only the affected parameters.
A good workflow for this phase is to work on the hips down to the feet on the first pass, and the neck down to the arms on the second pass.
In this phase you will often run into a series of diminishing returns for tweaking the character. After much tweaking, making small changes begins to take a lot of effort.
Shortcut Keys:
Set Keyframe: Alt + LMB
Translations Tools: T
Rotations Tools: R
Scaling Tools: E
Channel Editor: K
Only scoped channels will appear
Home on curve: H
Hover over key: Shows Frame / Value
Navigating: H (home), Right-Click (Zoom), Mouse Left/Right (Zoom in Time). Mouse Up/Down(Zoom in Value). Middle Mouse (Pan).
Tie/Un-tie tangents: T (individual basis)
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