基于模糊理论的在线手绘图识别

Online Freehand Sketching Recognition Using Fuzzy Theory

分别讨论基于几何特征和基于混合特征的手绘图模糊识别方法.给出各线元对应的模糊特征及其特征提取方法.构造笔划模糊识别的统一隶属函数,通过大量实验给出模糊隶属函数的参数值.采用对隶属函数取截值的方法控制模糊识别中人为参与的程度,在必要时通过人机交互判定识别结果.可识别的线元包括:直线、折线段、椭圆、椭圆弧、圆、圆弧、抛物线、双曲线.该方法有效实现在线手绘图识别,为后期手绘图的三维重建及支持概念设计CAD 系统的研究奠定基础.

Based on geometric features and hybrid features, the fuzzy recognition methods of online freehand sketching are discussed. The fuzzy features and corresponding extraction methods of geometric primitives are introduced, and a general fuzzy membership function is designed by analyzing the triangle membership function. The possibilities of geometric primitives which the stroke belongs to are obtained through numerous experiments. The system supplies the human-computer interactive determinant of the stroke through cutting the value of membership function. If necessary, the designer can help the system make the proper inference when either wrong choice is made by the system, or plural possibilities are analyzed. By the methods, designers＂ intentions can be inferred and input sketches can be interpreted into more exact 2D geometric primitives, including straight line, polyline, circle, circular arc, ellipse, elliptical arc, hyperbola and parabola. The effectiveness of the algorithm is demonstrated preliminarily by experiments. It lays the foundation for 3D object recovering and conceptual design of freehand sketching.