前言平曲线与凸型竖曲线(或凹型竖曲线)重叠的问题,在生产实践中经常会遇到。当平曲线与凸型竖曲线重叠时,由手透视成像作用,显然使视觉距离缩短了(即所谓凸曲线效应),而凹曲线则明显地引起延长作用 Preface The problem of overlapping of flat curves with convex vertical curves (or concave vertical curves) is often encountered in production practice. When the flat curve overlaps with the convex vertical curve, the apparent distance is apparently shortened by the hand-perspective imaging (the so-called convex curve effect), while the concave curve obviously causes the prolongation