Abstract: Based on the principle of two order B-spline modelling this paper procaseed the terain line of pro-file and modeled alternately to form a under-vertical profile and its curvature figure.Then,using unitsof tangent line and circular curve,the curvature figure was modeled to form a vertical profile thatmeets design demands.At last,the constraint boundaries that restrained the forming of vertical profilewere discussed.

Key words: two order B-spline, vertical profile, under vertical profile, constraints processing

摘要： 本文利用二次Ｂ样条拟合的原理，对路线纵断面地面线作平顺处理，然后进行反复拟合，生成一条“准纵断面线”，并自动生成准纵断面线的曲率图，然后采用直线和圆曲线对曲率图进行拟合，生成满足路线纵面设计要求的纵断面线。文中还对纵面线形生成过程中的约束处理作了讨论。

关键词: 二次B样条拟合, 准纵断面线, 纵断面线, 约束处理