【摘要】 河流水面成像测速是一种非接触式测流技术,其中流场的定标主要基于直接线性变换法(DLT)。由于严重依赖于河流两岸控制点的数量、分布及坐标勘测精度,现有测量系统受到野外复杂施测条件的制约而难以快速安全布设。对此提出了一种基于物像尺度变换(OIS)的流场定标方法。在考虑相机倾角及水位变化的基础上,通过建立倾斜视角下变高平面的成像模型,推导出像平面和河流水面间"点-距离"的变换关系。进而设计一种激光测距仪辅助的测量装置及其检校方法用于模型参数的获取。实验结果表明,OIS法在精度方面与DLT法相当,但无需在现场采用全站仪布设控制点,显著提高了野外作业的效率和安全性。研究有望为新型集成一体化光学测流仪器的设计提供理论和技术方法上的支撑。更多还原

【Abstract】 River surface imaging velocimetry is a non-intrusive flow measurement technology,in which the flow field calibration mainly uses the Direct Linear Transform(DLT) method. Since DLT is greatly limited by the quantity,distribution and accuracy of ground control points(GCPs) set on the river banks,the current measurement systems cannot layout fast and safely under complex field conditions. To handle this problem,a flow field calibration method based on Object-Image Scaling(OIS) is proposed. An imaging model of variable-height plane under oblique angle is built by introducing the tilt of camera and variation of water level. Then,a"pointsdistance"transformation between image plane and river surface is derived. Finally,a measuring device assisted by a laser range finder is designed and calibrated to obtain the model parameters. Experimental results show that the accuracy of OIS is close to the DLT,and no control points are needed to be deployed or surveyed with a total station,which significantly improves the efficiency and security of the field work. This study is expected to provide theoretical and technical support for the design of new integrated optical instrument for river flow measurement.更多还原