Abstract: This paper presents an attenuation deformation algorithm based on unitization model to solve the problem which is difficult to control object’s deformation model accurately by adjusting controlling-vertices in free-form-deformation of soft tissue.The method models with triangle grid，transform the collision point three-dimension world coordinate into two-dimension vertex coordinate of triangle grid，control attenuation change of vertical offset in region by defining adaptive deformation region within the center of collision point to lead to deform.The offset implements parabolic attenuation with designing proper attenuation function.The experiment shows that the model implements by the algorithm gets the general property，and the effectiveness of parabolic attenuation deformation is obtained accurately in local region.

Key words: soft tissue deformation, unitization model, coordinate transformation, attenuation function

摘要： 针对软组织自由变形中调整控制顶点难以准确控制物体变形的问题，提出了一种基于单位化建模的衰减变形算法。该算法利用三角网格进行单位化建模，将变形软组织碰撞点的三维世界坐标转换为三角网格二维顶点坐标，通过确定以碰撞点所在顶点为中心的自适应变形区域，控制区域内顶点偏移量发生衰减变化，从而直接作用于物体顶点进行形变，同时通过设计合适的衰减函数使偏移量呈抛物线衰减。通过实验证明该算法所建模型具有通用性，变形在局部区域内可取得准确的抛物线衰减效果。

关键词: 软体变形, 单位化建模, 坐标变换, 衰减函数