The Research Of Underwater Positioning In Fisheye Stereovision System

With the development of computer vision technology constantly,this technology is widely used in underwater detection,robot localization,and the direction of 3D reconstruction.Gradually with land resources reduce available.The development and utilization of marine resources has been put on the agenda of future development.The current mainstream underwater detection using the ordinary camera,but when an ordinary camera gets enough image information underwater,requires a larger horizon.Due to the large amount of impurities suspended in seawater,large amount of interference(noise,blur)is added to the image,removal of these interference becomes particularly difficult.Fisheye lens is a kind of super wide-angle lens,its optical properties are relatively special its vision in theory has 180 degrees ~270 degrees,to get the same amount of information in the case of fisheye camera is common horizon camera 1/40,the images obtained by this method can greatly reduce the interference of underwater impurities due to the small visibility.I mainly do research in the fisheye camera imaging process,imaging model and underwater imaging model of multimedia.The research contents are as follows.Firstly,the current camera equipment is not suitable for direct underwater shooting,when entering the water,the sealing glass and other auxiliary equipment must be used.The introduction of external media also introduced in addition to water and air outside the refraction of the glass,this makes the traditional imaging model is no longer valid.This paper is based on the basic imaging camera,taking into account the imaging of the camera in the air and in the water,the establishment of a free model of underwater optical axis parallel to the optical axis and ideal imaging model under water.Secondly,Due to the introduction of a variety of media,the light has occurred many times in front of the camera into the refraction,the change of the light path,the traditional camera calibration method can not be used to calculate the camera internal and external parameters.According to the above problems,in this paper,the whole calibration process is divided into two parts,the camera to the inside of the cover glass and the glass cover to a body of water,the camera to the inside of the cover glass can be equivalent to air imaging,the checkerboard we used Zhang Zhengyou calibration method to get camera internal and external parameters,then use the free model of underwater optical axis,Reference points of known world coordinate system in water,by the imaging model of underwater image to calculating point coordinates,by comparing the actual reference point in the image point and the image point model to establish the evaluation function,The final calibration results are obtained by optimizing the optimization functionLast,according to the binocular vision positioning system for underwater fisheye lens,study on the spatial positioning algorithm of underwater.First,according to the method of trigonometry,use the trigonometric function,then push the corresponding formula of the incident point derived refracting surface with imaging between points.Then vector geometry method,using four numbers to solve vector refraction gives the derivation method of space point positioning.The establishment of optical refraction imaging model of fisheye lens under water,it provides a reference for the exploration,location and measurement of underwater environment.