Tangent-space optimization for interactive animation control
Tangent-space optimization for interactive animation control
复制标题
交互式动画控制的切线空间优化
DOI：
10.1145/3306346.3322938
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
R. Sumner
中科院分区：
文献类型：
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作者：
Loïc Ciccone;Cengiz Öztireli;R. Sumner
角色动画工具基于关键帧比喻，即艺术家在选定的关键帧设置角色姿势，软件会自动在其间插入帧。尽管插补的质量对于实现流畅且引人入胜的动画至关重要，但可用于调整自动插补结果的工具非常简单，通常需要手动编辑样条线参数。因此，艺术家花费了大量的时间来摆姿势和设置更多的关键帧。在这个以姿势为中心的工作流程中，动画制作人使用正向运动学和反向运动学的组合。虽然正向运动学会产生直观的插补，但它并不自然地支持位置约束，例如固定接触点。反向运动学可以用于在关键帧固定空间中的某些点，但可能会导致较差的插补，计算速度较慢，并且不允许在非关键帧处进行位置约束。在本文中，我们通过将具有位置约束的插补的控制随时间表述为驱动控制的动画曲线的切线空间中的时空优化问题来解决这些问题。我们的方法的关键特性是：(1)允许随着时间的推移操纵位置和方向，扩展反向运动学；(2)不添加可能与艺术家首选的关键帧样式冲突的新关键帧；(3)在艺术家可编辑的动画曲线空间中工作，因此与当前管道无缝集成。我们通过不同的例子和用例演示了该技术在实践中的实用性。
Character animation tools are based on a keyframing metaphor where artists pose characters at selected keyframes and the software automatically interpolates the frames inbetween. Although the quality of the interpolation is critical for achieving a fluid and engaging animation, the tools available to adjust the result of the automatic inbetweening are rudimentary and typically require manual editing of spline parameters. As a result, artists spend a tremendous amount of time posing and setting more keyframes. In this pose-centric workflow, animators use combinations of forward and inverse kinematics. While forward kinematics leads to intuitive interpolations, it does not naturally support positional constraints such as fixed contact points. Inverse kinematics can be used to fix certain points in space at keyframes, but can lead to inferior interpolations, is slow to compute, and does not allow for positional contraints at non-keyframe frames. In this paper, we address these problems by formulating the control of interpolations with positional constraints over time as a space-time optimization problem in the tangent space of the animation curves driving the controls. Our method has the key properties that it (1) allows the manipulation of positions and orientations over time, extending inverse kinematics, (2) does not add new keyframes that might conflict with an artist's preferred keyframe style, and (3) works in the space of artist editable animation curves and hence integrates seamlessly with current pipelines. We demonstrate the utility of the technique in practice via various examples and use cases.
DOI：
10.1109/tvcg.2003.1207443
发表时间：
2003-07
期刊：
IEEE Trans. Vis. Comput. Graph.
影响因子：
--
作者：
K. Yamane;Yoshihiko Nakamura
通讯作者：
K. Yamane;Yoshihiko Nakamura