Measurement Indexes of Positional Uncertainty for Plane Line Segment Based on ε_m Model

In this paper,the εm uncertainty model of line segments is studied further.Firstly,the error band boundary line is divided into 4 parts: left boundary line,right boundary line,left error semicircle and right error semicircle.The analytic expression about the 4 parts an of the error band boundary line for the εm uncertainty model of line segments are deduced by algebra method.Secondly,the visual graphics of the error band for the εm uncertainty model can be drawn using the analytic formula.Thirdly,the average error band width and the error band area are gotten which are used to measure the precision of the line uncertainty.