The Research On Georeferencing Methods Based On Multi-Primitives

Three-Dimensional Laser Scanning technology is known as a breakthrough technology of surveying and mapping after GPS spatial positioning technology.It can scan object surface by high-speed laser,and acquire large point clouds with the 3D coordinate,reflectivity,texture and other information.Terrestrial Laser Scanning(TLS)has been widely used in many fields,such as cultural relics protection,building monitoring,traffic accident handling and digital cities with the advantage of fast,high precision and high mobility.In the current digital age,it is multi-source data fusion but not single-source data can meet the needs of human production.Multi-source data fusion can complement the advantages of two or more types of data.The conversion of point cloud data from the scanning coordinate system to the geographic coordinate system is the basis of fusing point cloud data with other geographic data.In the existing georeferencing method,direct georeferencing is complicated and low accuracy.Indirect georeferencing based on point has high accuracy but also requires more time and effort to deploy more targets.Indirect georeferencing based on line or plane has low accuracy.In order to balance both accuracy and workload of georeferencing better,the generalized laser beam georeferencing method based on multi-primitives is proposed in this paper,and the accuracy evaluation models based on line and plane are deduced.The main works are as follows:(1)Reading references widely,then summarizing the existing georeferencing methods and accuracy evaluation index.(2)According the translation model of 3D point and the properties of Rodrigues matrix,the direct solutions of georeferencing based on four different combinations of primitives are deduced,and the initial values of georeferencing parameters are obtained.(3)Analyzing the advantages and disadvantages of expressions about line and plane,and the classified expression by main axis is selected in this paper,then the translation models of line and plane based on the classified expression are builded.(4)The generalized laser beam georeferencing method based on multi-primitives is proposed.The method takes parameters of georeferencing primitives in scanning coordinate system and geographic coordinate system as adjustment paramenters,and takes the relationship about parameters of common primitives in different scanning coordinate stations as constraint parameters,then the georeferencing parameters of all scanning stations are calculated as a whole by condition adjustment with parameters.(5)The accuracy evaluation index system of georeferencing is established that contains theoretical accuracy and actual accuracy of point,line,and plane.The first accuracy is divided into the theoretical accuracy of georeferencing parameters,check point,check line and check plane.The actual accuracy is divided into internal compliance accuracy and external compliance accuracy.(6)Taking a building in the school as an experimental object,the generalized laser beam georeferencing method is verified by two multi-primitives methods,one is point and line multi-primitives,other is point,line and plane multi-primitives.The experiments show that the accuracy of first method is cm,and the accuracy of last method is dm.