Differing in the method of the Trim in AutoCAD,on the base of researching the method of rate of slope,a basic idea of the method of vertical line is proposed,which can trim a lot of linear drawings and divide the relief map exactly and availably.

• 区分于AutoCAD中的Trim方法 ,在研究斜率法的基础上 ,提出了一种可对大量线性图元进行修剪的垂线法的基本思想 ,并对地形图进行了准确有效的分割