Research On 3D Reconstruction Affected By Flat Refraction

There is a very important problem in the field of computer vision geometry,which is the 3D reconstruction of the scene affected by refraction.There is no mature algorithm for sparse reconstruction or dense reconstruction of refracted scene.The main research object of classical visual geometry is single view point camera model,and the scene affected by refraction is not suitable for single view point camera model,so more and more researches focus on non single view point model which has more extensive applicability than single view point model.In this paper,we study the scene images observed by the projective camera to reconstruct the scene which has been refracted by the media with parallel interface for many times.The main task of this paper is to analyze the geometric constraints between the three views when the scene is observed by three projective cameras after refracting through a variety of media with parallel interfaces,and to try to reconstruct the scene affected by refraction without other additional devices or information.One of the most extensive applications of such scenarios is underwater scene reconstruction.With the development of ocean exploration,Collecting pictures by underwater UAV has a great advantage in exploring the underwater environment,and more and more researches focus on underwater scene reconstruction.In the current research of underwater reconstruction,one is to correct the refraction distortion through the lens distortion model of the pinhole camera,which is often inaccurate.The other is to provide additional devices or information to meet specific geometric constraints to solve,which is cumbersome.The premise of the algorithm in this paper is that three cameras with fixed relative positions are calibrated in advance to know their relative positions and poses.Using the device and algorithm described in this paper can accurately and conveniently reconstruct underwater scenes.Since the refraction interface normal vector is independent of the scene,it can be calculated by the matching points of three cameras in the scene,so this paper uses two-step method to reconstruct the scene affected by refraction.First,two methods of calculating the refraction interface normal vector are derived from the known Trifocal Tensor among three cameras combined with a general constraint in flat refraction,including Direct Linear Transformation equations method and the algorithm based on collinear constraints,these two algorithms are compared and analyzed.Then,the restoration of three-dimensional space structure when the normal vector of refraction interface is known in various cases is deduced.Finally,a nonlinear optimization function is designed for Bundle Adjustment.This paper not only provides simulation experiments,analyzes the stability of each algorithm,but also uses a group of real underwater data to reconstruct the underwater scene to verify the effectiveness of the algorithm.