水电枢纽水下摄像数据的畸变机理及标定研究

Research on Distortion Mechanism and Calibration of Underwater Photography of Dam

水电枢纽建筑物水下检测的方法中,水下摄像是一种易用和直观的方法,但水下摄像数据研究往往忽视水下畸变,给水下缺陷分析和水下三维重建带来不可忽视的偏差。从成像原理的角度分析了水下成像过程中畸变的产生原理和基本特性;以某电站消力池边墙水下拍摄为试验目标,采用张正友标定法和MatLab工具箱进行了水下相机的参数标定,并使用相机参数对水下拍摄的边墙图像进行了矫正。通过重投影误差偏差和露骨料像素值偏差的对比分析,证实该标定方法有效性以及水下畸变的径向特征,为进一步的精确量化分析提供了基础。

Underwater photography was an easy and intuitive method in underwater detection of hydropower junction buildings,but in the study of underwater photographic data,underwater distortion was often neglected,which brings undeniable deviation to underwater defect analysis and underwater three-dimensional reconstruction.In this paper,the principle and basic characteristics of distortion in underwater imaging were analyzed from the perspective of imaging principle.Taking underwater photography of side wall of stilling basin of a power station as experimental object,the parameters of underwater camera are calibrated by Zhang Zheng-you calibration method and MatLab toolbox,and the parameters of the camera are used to correct the underwater side wall images.The validity of the calibration method and the radial characteristics of underwater distortion are verified by comparing the re-projection error deviation with the exposed aggregate pixel value deviation,which provides a basis for further accurate quantitative analysis.