夸张是角色动画中的重要运动规律之一,它来源于现实,又高于现实.根据这一原则,把"夸张"的运动学特性理解为运动速度的缩放,提出了在真实自然的动作捕捉数据的基础上来编辑合成夸张动作的方法.首先从原始动作数据中提取角色骨骼各节点的速度信息;然后以少量直观的参数输入计算出合理的运动速度缩放因子曲线,对速度进行合适的缩放并重新映射回原始的动作数据表达形式,从而以统一的算法框架实现了多种卡通风格和空中特技等夸张动作.此外,还引入了部分物理约束进行后处理,有效地增强了夸张结果的视觉合理性.实验结果表明,该方法能够较好地生成夸张效果,可以应用于实际的动画创作.
As a significant principle of the character animation,exaggeration originates from the reality and goes beyond it.According to the principle,this paper construed the motion exaggeration as a kind of "scaling" of velocities from the perspective of kinematics and presented a velocity scaling based approach to create exaggerated motion from the real motion capture data.In the process,scaling factor curves are calculated from few intuitive parameters set by users to scale velocities that extracted from the skeletons' joints.And then,the exaggerated motion can be reconstructed by mapping the new velocities back to the original motion data expression.Three cartoon effects and complex acrobatic motions can be generated by the unified method.In order to make the exaggeration more convincing,a constraint-based solver was employed to reinforce the visual plausibility in the resultant motions.The experimental results show that our method can generate motion exaggeration for character animation and can be used in the animation creation.