Recognition of online multistroke freehand conic sections based on time-space relationship

A method for interpreting multistroke 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 multistroke 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 multistroke 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 multistroke sketches and the results show that the proposed algorithm achieves a satisfactory interpretative efficiency.