Real-time non-contact water-surface ripple measuring method based on visible-light polarization imaging
A technology of polarization imaging and measurement method, which is used in measurement devices, open-air water source survey, surveying and navigation, etc. to achieve the effect of facilitating image correction
Active Publication Date: 2015-07-22
BEIJING INSTITUTE OF TECHNOLOGYGY
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[0007] The purpose of the present invention is to overcome the defects of the prior art, in order to solve the problem of providing real-time two-dimensional distribution of water surface ripple space, and propose a real-time non-contact water surface ripple measurement method based on visible light polarization imaging
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[0027] Such as image 3 As shown, the present invention is based on the real-time non-contact water surface ripple measurement method based on visible light polarization imaging, and the basic implementation process of the method is as follows:
[0028] Step 1. The polarization imaging system acquires multi-polarization images of the reflected light on the water surface, and calculates the degree of polarization DOLP and the polarization azimuth Ψ of the reflected light according to the multi-polarization images.
[0029] The unbiased pan-visible light is incident on the water surface, and at the same time, the 4-channel polarization imaging system images the reflected light from the water surface (that is, the reflected light from the water surface to the unbiased pan-visible light), and obtains four different polarization state image data of the same state of the reflected light in one exposure. 1 , I 2 , I 3 , I 4 ; According to the instrument matrix A of the 4-channel p...
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The invention relates to a real-time non-contact water-surface ripple measuring method based on visible-light polarization imaging. Firstly, a multi-polarization state image of water-surface reflected light is obtained by utilization of a polarization imaging system, and a degree of polarization and a polarization azimuth are calculated based on the multi-polarization state image. Then, an angle of incidence of light that is incident to the water surface is calculated by utilization of the degree of polarization combining with the Fresnel law. Finally, a normal vector of a water-surface microfacet is calculated based on the polarization azimuth and the angle of incidence. The measuring method, which is a non-contact imaging measuring method, is capable of avoiding influences of the measuring method on water-surface ripples, and advance placement of targets or templates, etc. under water during measuring are not required. The measuring method is suitable for practical demands of image rectification of onboard under-water imaging. In addition, the method provides, in real time, two-dimensional spatial gradient distribution of the water-surface ripples, thus facilitating the image rectification of the onboard under-water imaging.
Description
technical field [0001] The invention relates to the technical field of water surface ripple measurement, in particular to a real-time non-contact water surface ripple measurement method based on visible light polarization imaging. Background technique [0002] The observation of ocean waves and water surface ripples has long been concerned by people, and a variety of wave measuring instruments and methods have been developed and adopted at home and abroad. In recent years, the correction of airborne underwater imaging images has been proposed at home and abroad, and the water surface ripple information is an indispensable information in image correction. Therefore, it is particularly important to study the measurement method of non-contact real-time water surface ripple. [0003] The wave measurement methods are classified into single-point, multi-point, and surface types from the measurement range, and can be divided into below the water surface, near the water surface, an...
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IPC IPC(8): G01C13/00
CPCY02A90/30
Inventor 金伟其刘敬王霞裘溯陈振跃管文
Owner BEIJING INSTITUTE OF TECHNOLOGYGY