Applying Animation
Take animation and apply it to your characters.
Overview
We've made strides to implement an animation transfer system and in its current form we feel that it can automate transfers from many types of animation to various sizes of characters. This does not replace accurate animation and rigging and animating of bones, it does offer a system where a simplistic transfer of animation can happen and deliver results for a muscle simulation. This is a work in progress since we will value your feedback on this system.
Node Structure
This part of the toolset is designed to fit into Houdini's existing workflow with KineFX. It enables users to take multiple characters and multiple animations, transfer the animation to each character with it prepared for simulation and save out files for each character and animation variation.
TOPs and Local Variables
In the Character tab and Animation tab we have index parameters. These enable you to choose your current character or animation to view through the toolset. The default value is however a local variable, @char_index and @anim_index respectively. These default values are used with TOPs and could be deleted if you want to control these values.
Timeline, Preroll and Your Animation Clip
Procedural Anatomy doesn’t expect a certain range but it is setup to use frames as the default way to count for simulations. The alternative, time ($T) should be acceptable but is untested at the moment. In the future we would like to support both but frames will stay Procedural Anatomy’s preferred count format for the foreseeable future.
T-Pose / Rest Frames
These frames fall ahead of the start of your animation and define when the character will be at a rest state or t-pose state depending on the animation.
For muscle simulation you always need to start from the rest state and for animation matching, this is also known as Preroll. You can use as many or as few frames as you want, 30 frames at 24fps solves quickly to the first animation frame. The reason we blend so much is to allow the muscles to loosen and then flex into position before the first few frames of animation.
Typically we start our animations re-mapped to the starting frame to frame 1001. This is because we can then step backwards 30 frames (to frame 971 as our T-Pose/Rest frame) and not have negative numbers as if we started at frame 1 (to frame -29). This is important because our system is not designed to support negative frame numbers.
Example:
T-Pose Frame - 0971
Animation Start Frame - 1001
Animation End Frame - 1390 (or whatever the duration of your file is)
How T-Pose And Rest Pose Work
T-Pose and Rest Pose are used at the same time but work in two different ways. T-Pose is used in animation and motion capture files as a rest position or for retargeting animation. Rest pose in procedural Anatomy is the pose from the Anatomy Output. We smoothly interpolate between the T-Pose or Animation Start Frame and the same for Rest Pose and Animation Start Frame.
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