鱼眼星图中的水天线自动提取算法  

A New Automatic Extraction Algorithm for Sea-sky Horizon Line in Fisheye Star Map

作　　者：陈张雷 李崇辉[1] 郑勇[1] 陈冰[1] 何东汉 CHEN Zhanglei;LI Chonghui;ZHENG Yong;CHEN Bing;HE Donghan(Information Engineering University, Zhengzhou 450001, China)

机构地区：[1]信息工程大学,河南郑州450001

出　　处：《测绘科学技术学报》2021年第3期221-227,共7页Journal of Geomatics Science and Technology

基　　金：国家自然科学基金项目(41604011,11673076);信息工程大学优秀青年基金项目(2016611705)。

摘　　要：鱼眼星图中水天线的检测是实现小型化舰载天文导航系统和海面目标侦测系统的关键技术,然而夜间拍摄的鱼眼星图背景复杂,整体灰度值较低,使用传统的边缘检测算法无法准确提取水天线。本文提出一种鱼眼星图水天线自动提取算法,分为预处理和水天线自动提取两部分。预处理策略中,针对背景复杂问题,设计了四边框分块法,简化图像中水天线所在区域的背景;针对噪声问题,引入了修正的阿尔法均值滤波器对分块之后的图像进行平滑处理。水天线自动提取中,针对水天线为单向弧段的特点,设计了特定的线状模板进行卷积以获得连续的水天线;针对水天线上舰船灯光等小目标的干扰,采用设定阈值的方式剔除异常特征点以获得准确的水天线。在此基础上,拟合估计出实测鱼眼星图中的水天线检测精度。基于多种复杂实验条件下的拟合结果表明,水天线的检测中误差平均值为0.77像素,能够满足舰船天文导航和海面目标侦测对水天线提取的精度需求。Automatic extraction of sea-sky horizon line in fisheye star map is a key technology for the achievement of miniaturized ship-bone celestial navigation system and sea surface target detection system.Due to the complicated background and low gray value,it’s hard to extract sea-sky horizon line by applying conventional edge detection algorithm.An automatic sea-sky horizon line extraction algorithm for fisheye star map is proposed in the paper,which consists of pretreatment and automatic sea-sky horizon line extraction.In pretreatment,aiming at the complex background,a four-frame block method is designed to simplify the background of the area where the sea-sky horizon line is located.Aimed at the noise,a modified alpha-trimmed mean filter is introduced to smooth the image after segmentation.Aimed at the characteristics of the sea-sky horizon line as a one-way arc,a specific linear template is designed for convolution to obtain a continuous sea-sky horizon line in automatic sea-sky horizon line extraction.Aimed at the interference of small targets such as ship lights on sea-sky horizon line,the threshold is used to eliminate the abnormal feature points to obtain an accurate sea-sky horizon line.On this basis,the detection accuracy of sea-sky horizon line in the observed fisheye star map is estimated by fitting.Based on a variety of complex experimental conditions,the fitting result shows that the average root mean square error of sea-sky horizon line detection is 0.77 pixel,which can meet the requirements of the accuracy for celestial navigation and surface target detection of ships.

关 键 词：鱼眼星图 水天线 图像分块 修正的阿尔法均值滤波器 边缘提取 

分 类 号：P221[天文地球—大地测量学与测量工程]