Research On The Application Of Vehicle-borne Laser Scanning System In Manhole Covers Detection

With the fast pace of modernization in China,the process of motorization accelerating,public travel has been strongly demanded.The explosive growth of the number of private cars and the development of the city's logistics industry make the burden of the urban road more and more serious.For example,road surface components such as manhole covers are absent,damaged,subsiding,offsetting.Wear of road markings makes identification reduce.What happens has made new challenges to the current road maintenance project.The traditional location and survey of damaged parts is inefficient,such as RTK,which needs much labor force and has high risk.How to detect road surface damage quickly,effectively,timely,non-contact,which needs to be solved urgently.In response to these circumstances,the vehicle-borne laser measurement technology is used to collect the covers information.First of all,according to the characteristics of pavement information,in order to reduce the interference of the ground objects,the conventional vehicle-borne laser measurement system needs to be modified.The panoramic camera is modified to shooting ground simply.Then,the point cloud data is converted to the intensity images on the basis of the difference of the reflection intensity of the point cloud.Improve the random Hough transform based on the characteristics of circular shape and fixed radius,by which manhole covers are extracted from intensity images.Then,the least square fitting is used to calculate the center coordinate accurately.Find the location in the point cloud according to the transformation relation,which makes manhole covers positioning and settlement measurement come true.Finally,through the comparison of GPS-RTK and level measurement,vehicle-borne laser scanning technology can detect the manhole covers and meet the demand.