Animating human bodies becomes one of the most active research fields in virtual human modeling. Animating an articulated three dimensional human model currently requires manual rigging to specify its internal skeletal structure and to define how the input motion deforms its surface. Manual rigging is too tedious, and sensitive to the pose of the model. So in this paper, we present an automatic pose-independent method to extract skeleton of human model. This method based on geodesic distance of human body model first extracts and recognizes five feature points at the end points of head and limbs on human body surface, and calculates the geodesic distances of vertices in the model from the feature points. It then constructs the central lines through the centers of geodesic distance isolines, and finds joint positions by analyzing the angles or circularity function of geodesic isolines of the model according to bent or unbent joints. Our experiments show that, this method can identify joint positions and extract the skeleton automatically, with high precision, and in a poseindependent manner.%人体骨骼动画技术是虚拟人物建模中的研究重点.在现有人体骨骼动画的制作过程中,动画师必需手工标定人体各主要关节点位置及人体骨架每一关键帧的姿态,工作量巨大.因此提出一种自动提取人体任意姿态网格模型骨架结构的方法.该方法首先利用模型各顶点间测地距离的几何关系自动识别人体位于四肢和头顶末端的5个特征点,再以特征点为起点生成等测地距离曲线族,利用等测地距离曲线将人体四肢和躯干区分开来,将这些相邻等测地线中心连接起来生成5条骨骼中心线,最后在中心线上根据中心夹角极小值及等测地距离曲线似圆率来确定人体关节的确切位置.实验结果表明,该算法能适应不同姿态的人体模型,计算结果准确性高,能完全自动实现关节点定位和骨骼提取.
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