基于时空关系的在线多笔画手绘二次曲线识别

Recognition of Online Multistroke Freehand Conic Sections Based on Time-Space Relationship

综合考虑笔画时空关系对在线多笔画手绘二次曲线进行识别.先对笔画识别结果进行基于时间间断的多笔画预处理将其识别为虚线或实线,然后详细讨论基于空间关系的多笔画手绘二次曲线的识别问题.将基于空间关系的二次曲线多笔画识别分为封闭二次曲线和非封闭二次曲线的多笔画识别,对前者给出采用最小中值二乘的多笔画拟合二次曲线方法.针对非封闭二次曲线提出广义笔画及其对应的旋转角和首尾点的概念,并从多笔画判定、草图生成、旋转角和首尾点的确定这3方面给出其多笔画识别方法.最后通过自主开发的FSR系统对文中算法加以验证.

A method for interpreting muhistroke freehand conic sections is presented based on the time-space relationship. The pretreatment approach based on the time slot is able to interpret the dashed or continuous strokes, and the recognition method is discussed based on space relationship of strokes. The muhistroke interpretation of freehand conic sections is divided into the interpretations of the closed and non-closed conic sections. Using the least median squares method fits conic section for the former. The definitions of the rotation angle and the endpoint of generalized stroke of the non-closed conic section are presented, which consists of three stages： the muhistroke determination, the sketch generation and the rotation angle and endpoints calculation. A human-computer interface prototype system FSR is developed using the proposed theory, which makes system interface easy and friendly to user. The FSR system is tested with a number of muttistroke sketches and the results show that the proposed algorithm achieves a satisfactory interpretative efficiency.