Abstract: This paper presented a novel method for interpreting multistroke freehand sketching with polylincs.The multistrokes were interpreted as sketch content and were used to generate 2D geometric primitives. The pretreatment approach proposed is able to interpret the dashed or continuous strokes. The polylines multistroke interpretation is classified as two parts. Onc is made of the polylines and straight lines and the other is made of polylines and polylines. Some new conceptions are defined for discussing the latter. The corresponding algorithms are given for interpretation of online multistroke sketching. I}his paper developed a human-computer interface prototype system FSR using the proposed theory, which makes system interface easy to use.The FRS system was tested with a number of multistroke sketches. And the test results show that the algorithm achieves a satisfactory interpretative efficiency.

Key words: Online, Freehand sketching, Multistroke interpretation, Polyline, Time-space relationship