机载视觉自主着陆过程中的跑道提取方法

A Method to Extract the Runway for Airborne Vision Based Auto-landing

跑道直线参数的准确提取,是机载视觉完成自主着陆过程的重要条件。首先在边缘图像的基础上利用相位编组算法,得到当前边缘图像中大量的线段,根据线段之间的角度,端点距离,以及线段两边的灰度均值,设计了一套规则来定量描述线段之间的亲近性,根据亲近值,将处于同一直线上的短线段首尾连接成长线段。取最长的若干条线段待选,再利用跑道区域的先验知识,主要是跑道内外的灰度对比信息,将位于同一条跑道的两条边缘上的线段识别出来。大量的实际图像结果验证了算法的有效性。

Extracting the linear parameters of the runway is the precondition for airborne vision based auto-landing. Firstly it is required to obtain a lot of short lines by gradient direction grouping on the edge map. Secondly according to the angle between two lines and the distance between the ends of two lines, and the gray average on both sides of lines, a rule to quantitatively characterize the affinity between two short lines is advanced, then the short lines on the same line end-to-end by the value of affinity will be linked. Finally the longest lines are left to choose, and priori knowledge, namely the contrast information of shades between the internal and external runway is applied to distinguish the two lines lying on the two edges of the same runway. The method has been tested valid by many actual images.