The Research On Image Preprocessing And Mosaic Technology Of Sidescan Sonar

In recent years,marine transportation and coastal tourism have developed rapidly.With the increasing number and density of marine activities of ships,aircraft and personnel,the probability of maritime emergencies has increased,and many wrecks of ships and aircraft have sunk to the seabed.Therefore,it is imperative to study seabed target search.Side scan sonar is an important tool for underwater target searching.It detects the seabed by means of underwater carrier.In this paper,by studying the image mosaic method of side scan sonar,the original sonar data collected are mosaic to form a large-scale seabed image,which can provide help for the detection of seabed topography and geomorphology,and support the search of underwater distressed targets.This paper is based on the national science and technology support project "Deep-sea underwater target autonomous search and detection technology".The sonar image preprocessing and mosaic methods are studied,and the side-scan sonar image mosaic and display software is developed.In the aspect of sonar image preprocessing,aiming at the noise in sonar image,an adaptive bilateral filtering method is proposed to denoise the image;the non-uniformity of gray level in the image is eliminated by automatic gain control method;aiming at the geometric distortion of the image and the influence of water column area,a Canny operator is proposed to detect the edge line to obtain more accurate depth(sonar distance).In sonar image mosaic,based on track and attitude angle information,the scanning data are mosaic into a single image(an image formed by a packet)by geographic mosaic method,which solves the triangular and sector gap problems in sonar image.Based on MFC,the image mosaic software of side-scan sonar is developed.The functions of image mosaic,waterfall map display,single mosaic map display,track map display,mosaic map display,image display resolution selection display,center band sonar information display and mouse click point longitude and latitude high display are realized.The function test of side scan sonar image mosaic software has been completed and delivered to users.It can work steadily in many experiments of Zhanghe Reservoir inHubei Province,and the mosaic effect is good,which meets the design requirements.