河流自然水体中三维视觉测量  

River underwater 3D vision measurement method

作　　者：许丽 周永昊 陆桂明 周金峰 张帆 罗文宇 XU Li;ZHOU Yong-hao;LU Gui-ming;ZHOU Jin-feng;ZHANG Fan;LUO Wen-yu(School of Physics and Electronics,North China University of Water Resources and Electric Power,Zhengzhou 450046,China;China Mobile Communications Corporation,Beijing 100033,China)

机构地区：[1]华北水利水电大学物理与电子学院,河南郑州450011 [2]中国移动通信集团公司,北京100033

出　　处：《光学精密工程》2021年第10期2465-2480,共16页Optics and Precision Engineering

基　　金：国家自然科学基金项目(No.51609086,No.U1804148);河南省科技攻关项目(No.182102210059)。

摘　　要：针对水体浑浊所造成水下图像退化和多介质引起的光线路径改变等问题,提出了基于径向多线结构光的水下视觉测量方法。首先,建立了基于折射的水下视觉测量模型,在投影仪垂直于折射平面投射且光平面经过投射光轴的条件下,陆上光平面和水下光平面共面,陆上标定可代替水下标定;采用蒙特卡洛模拟方法,分析了像点误差对点云计算精度的影响。其次,设计了黑白交错的中心旋转径向多线编码光模式;采用黑白条纹边缘作为测量点,减弱了编码光解码对图像质量的依赖性;通过中心旋转的方式,提高了表面的测量分辨率。最后,在1 m×1.2 m×0.8 m的水体中加入泥沙模拟自然河流水体环境,实验分析了浑浊水体对条纹提取、编码光解码和三维视觉测量精度的影响。实验结果表明,该方法在1500 mm的测量距离上,对清水条件下的瓷瓶进行了不规则表面的三维表面测量;对清水、含有40,60和90 g泥沙的浑水中规则物体进行三维表面测量,获得了平面残差分别为0.95,1.93,5.43和21.43 mm的测量结果;当泥沙量超过某数值(如60 g)时,条纹提取精度急剧恶化,泥沙量为40和90 g的浑水中测量平面拟合残差从1.93 mm增加到21.43 mm。Aiming to remedy the degradation of underwater images owing to turbidity of mud and sand in the natural river water,and the change of light caused by underwater refraction,an underwater vision measurement method based on radial multi-line structured light is proposed in this study.First,an underwater visual measurement model based on refraction is constructed.When the projector axis is perpendicular to the refracted plane and the light-plane passes through the projected axis,landed light plane is coplanar with underwater ones,which can avoid the underwater calibration processes.The Monte Carlo simulation method is used to analyze the influence of the imaging point errors on the underwater 3D vision measurement model.Next,an interlaced central rotation radial multi-line light mode is designed.Black and white stripes are used as the projection modes to reduce the dependence on the image quality.Measurement stripes are increased,and measurement resolution is improved through central rotations.Finally,3D topography measurement experiments on the surface of underwater objects are made,in which the influence of turbid water on the edge extraction accuracy,coded light decoding,and 3D vision measurement are analyzed.In the experiment,sediments with different weights are added in a water volume of 1 m×1.2 m×0.8 m,which simulates the natural water environment.The experiment shows that at a measurement distance of 1500 mm,the surface of a bottle is measured in clean water,with a plane residual error of 0.95 mm;the plane residual errors are respectively 1.93 mm,5.43 mm,21.43 mm in muddy water with 40 g,60 g,90 g of sediment.When the amount of sediment exceeds a certain value(such as 60 g sediment in this experiment),the accuracy of fringe extraction deteriorates sharply.The residual error of measurement plane fitting in muddy water with 40 g and 90 g of sediment increases from 1.93 mm to 21.43 mm.

关 键 词：三维视觉测量 河流水下测量 结构光 径向多线投影模式 

分 类 号：TP394.1[自动化与计算机技术—计算机应用技术] TH691.9[自动化与计算机技术—计算机科学与技术]