将高解析度动作撷取资料校正应用在脸部动画系统(英文)

High Resolution Calibration of Motion Capture Data for Realistic Facial Animation

提出一个新的方法来产生脸部动画 ,即利用动作撷取系统捕捉真人脸上的细微动作 ,再将动态资料用来驱动脸部模型产生动画 .首先 ,利用 Oxford Metrics'VICON8系统 ,在真人的脸上贴了 2 3个反光标记物 ,用以进行动作撷取 .得到三维动态资料后 ,必须经过后继处理才能使用 ,因此 ,提出了消除头部运动的方法 ,并估计人头的旋转支点 ,经过处理后 ,剩余的动态资料代表脸部表情的变化 ,因此 ,可以直接运用到脸部模型 .用 2 .5D的脸部模型来实作系统 ,这样可兼得二维模型与三维模型的优点 :简单、在小角度旋转时显得生动、自然 .在脸部动画的制作中 ,利用一个特殊的内差公式来计算非特征点的位移 ,并将脸部分成数个区域 ,用以限制模型上三维点的移动 ,使动画更加自然 .此动画系统在 Pentium III50 0 MHz的机器上 ,并配有 Open GL的加速卡 ,更新率可以超过每秒 30张 .

A novel technique is proposed to make realistic facial animation driven by motion capture data. First, a person's facial expressions are recorded using Oxford Metrics' VICON 8 optical motion capture system, where 23 optical markers are attached on the person's face. The captured 3D motion data are then processed to eliminate 3D global head motion by finding the pivot point for rotation. These processed 3D motion data can be directly applied to a head model. A two and half dimension facial model is used here for implementation because it combines good features from both 2D mesh and 3D model: simple, vivid and natural, when small scale rotation is applied. An interpolation function is employed to calculate the offsets of other unconstrained mesh vertices. Furthermore, a face is divided into several regions and force constraints are applied to limit the displacement of vertices on the mesh depending on the region to make the animation more natural. The system has an update rate of over 30 frames/second on a Pentium III 500MHz PC with an OpenGL acceleration card.