Calibration method for flow field of water surface of river based on lens imaging model at inclined visual angle

Abstract

The invention discloses a calibration method for a flow field of the water surface of a river based on a lens imaging model at an inclined visual angle. The method comprises the following steps: setting two marker posts on a measuring section of the river for orientation; then fixedly connecting a laser range finder with an industrial camera to form an imaging measurement apparatus and erecting the imaging measurement apparatus on the measuring section at one riverbank; measuring the distance between the apparatus and an intersection of the marker posts and the water surface by using the laser range finder and calculating the elevation of the apparatus above the water surface according to a pitch angle measured by a built-in sensor; and separately solving object image scale factors of each velocity measurement line of an image on the section and in a fair current direction by using the lens imaging model at an inclined visual angle, and then calibrating corresponding starting point distance and flow velocity values to finish calibration of the flow field. Compared with the prior art, the method provided by the invention has the advantages that laying of control points at the two banks of the river and exploration of the coordinates of the control points with complex equipment like a total station are not needed, so workload and requirements on equipment are substantially reduced; and the calibration method is especially applicable to regular tour-measuring of the flow velocity and flow quantity of rivers and to emergency monitoring under extreme conditions.

Description

technical field [0001] The invention relates to a method for calibrating the flow field of a river water surface, in particular to a method for calibrating a water surface flow field for imaging speed measurement of a river water surface, and belongs to the field of visual measurement. Background technique [0002] In the river water surface imaging velocimetry technology that uses video images to measure the river surface velocity field, the flow field calibration is to convert the motion vector in the image optical flow field from the image coordinate system to the world coordinate system, and divide it by the frame interval to obtain the velocity vector field the process of. Compared with machine vision in industrial inspection, the visual measurement of river water surface has the following difficulties: ①The object to be measured is the water surface with dynamic changes in elevation, and the water level of mountain stream rivers during high flood periods has skyrockete...

AI Technical Summary

Problems solved by technology

[0006] To sum up, in view of the difficulties in the visual measurement of river water surface, the existing methods are either not accurate enough to be practical, or time-consuming and labor-intensive, and difficult to deploy quickly.

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