This paper introduces a novel data-driven motion in-betweening system to
reach target poses of characters by making use of phases variables learned by a
Periodic Autoencoder. Our approach utilizes a mixture-of-experts neural network
model, in which the phases cluster movements in both space and time with
different expert weights. Each generated set of weights then produces a
sequence of poses in an autoregressive manner between the current and target
state of the character. In addition, to satisfy poses which are manually
modified by the animators or where certain end effectors serve as constraints
to be reached by the animation, a learned bi-directional control scheme is
implemented to satisfy such constraints. The results demonstrate that using
phases for motion in-betweening tasks sharpen the interpolated movements, and
furthermore stabilizes the learning process. Moreover, using phases for motion
in-betweening tasks can also synthesize more challenging movements beyond
locomotion behaviors. Additionally, style control is enabled between given
target keyframes. Our proposed framework can compete with popular
state-of-the-art methods for motion in-betweening in terms of motion quality
and generalization, especially in the existence of long transition durations.
Our framework contributes to faster prototyping workflows for creating animated
character sequences, which is of enormous interest for the game and film
industry.

通过使用周期自编码器学习到的相位变量，在混合专家神经网络模型中引入了一种新颖的数据驱动的动作插值系统，以达到人物的目标姿势。我们的方法在空间和时间上以不同的专家权重聚类动作，生成一系列自回归方式在当前状态和目标状态之间的姿势序列。此外，为了满足动画师手动修改的姿势或某些末端执行器作为要达到的约束，我们实施了学习的双向控制方案来满足这些约束。结果表明，使用相位进行动作插值任务可以使插值动作更加清晰，并进一步稳定学习过程。此外，在动作插值任务中使用相位还可以合成更具挑战性的运动，超越了行走等基本动作。此外，可以在给定目标关键帧之间进行风格控制。我们的提出的框架在动作质量和泛化性方面可与流行的最先进方法相竞争，特别是在存在较长的过渡持续时间的情况下。我们的框架有助于快速原型工作流程，用于创建游戏和电影行业中的动画人物序列，这是非常有趣的。