一种不定长水尺图像水位测量方法  

A water level measurement method for indefinite water gauge image

作　　者：刘铭辉 车国霖[1] 张衎 王剑平[1] 欧阳鑫[1] Liu Minghui;Che Guolin;Zhang Kan;Wang Jianping;Ouyang Xin(Faculty of Information Engineering and Automation,Kunming University of Science and Technology,Kunming 650500,China)

机构地区：[1]昆明理工大学信息工程与自动化学院,昆明650500

出　　处：《仪器仪表学报》2021年第7期250-258,共9页Chinese Journal of Scientific Instrument

基　　金：国家重点研发计划(2017YFB0306400);国家自然科学基金(51709083);云南省科技计划(2018BA070)项目资助。

摘　　要：针对水尺图像水位识别中存在的多根水尺拼接、水尺拍摄不完整以及环境适应性差等问题,从摄影测量学角度提出一种复杂光照条件下不定长水尺图像水位测量方法。首先通过人工选取的标识点构建水尺在像素坐标系和世界坐标系之间的透视投影关系;然后利用水尺的颜色特性将水尺与背景分割并二值化;再根据二值化图像使用方差均值阈值法检测水位线位置;最终通过投影关系计算出水尺图像中水尺中线的表达式,并结合水位线位置计算出水面上水尺中线的真实长度,获得水位值。本文对水文站真实水尺图像进行了测量实验,将检测结果与遥测水位值进行对比,结果表明本方法提高了不定长水尺图像水位检测的可靠性,测量精度达到1 cm,检测分辨率为1 pixel,基本满足水文站水位监测要求。To solve the problems of multiple water gauge stitching,incomplete water gauge shooting and poor environmental adaptability in water level recognition of water gauge images,a photogrammetric method is proposed to measure the water level of indefinite water gauge image under complex lighting conditions.Firstly,the perspective projection relationship of the water gauge between the pixel coordinate system and the world coordinate system is constructed through the manually selected identification points.Then,the water gauge and the background are segmented and binarized by the color characteristics of the water gauge.According to the binarized image,the average and variance threshold method is used to detect the position of the water level.Finally,the expression of the middle line on the water gauge in the water level image is calculated through the projection relationship.The length of the middle line on the water gauge on the water surface is calculated by combining the position of the water level line to obtain the water level value.In this paper,the measurement experiment is carried out on the real water gauge image of the hydrological station,and the detection results are compared with the remotely measured water level value.Results show that this method could improve the reliability of the water level detection of the indefinite water gauge image.The measurement accuracy is up to 1 cm and the detection resolution is 1 pixel,which basically meet the water level monitoring requirements of hydrological stations.

关 键 词：水位测量 不定长水尺 图像法测量 透视变换 水位线检测 

分 类 号：TH815[机械工程—仪器科学与技术]