Combined Adjustment Of Space-borne Laser Ranging Data And Linear Array Images

With the development of national interests and the implementation of the national strategy of "the Belt and Road Initiative",overseas high-precision geographic information become more and more urgent to national economic construction and military defense,and optical three-dimensional surveying and mapping satellite using uncontrolled mapping technology become effective means to obtain foreign geo-graphic information.In the application of optical three-dimensional sur-veying and mapping,compared with flat accuracy,the accuracy of the elevation can not meet the requirement of 1:10000 scale global topo-graphic map without ground control points due to the influence of the base-height ratio and orbit and attitude accuracy.Therefore,it is pro-posed to carry the laser altimeter on the satellite to eliminate the system error and improve the positioning accuracy of the linear-array images.In the paper,a preliminary study of bundle adjustment on the laser ranging data and the linear array data is developed,the main work and innovations are as follows:1.The line-array CCD sensor constellation model and laser ranging principle are introduced in detail.The laser ranging data and line-array image data are used to establish the observation equation on image points,the constrained equation on laser ranging and the virtual observation equation,so as to construct an adjustment model combined laser ranging data and linear array image data.2.The experimental data are simulated by satellite parameters and technical indicators of laser altimeter.The tie points and check points are simulated based on the satellite attitude and orbit data,DEM of the simulation area and the measurement error of the image points,the simulated laser ranging data are obtained by DEM,Attitude and orbit data,line-time data,pulse number of laser altimeter,and angles between adjacent pulses and laser ranging errors,and the initial attitude and orbit data are obtained according to the simulation error of attitude and orbit.3.The simulated laser ranging data are added as a constraint to the bundle adjustment model.Under the uncontrolled condition,the influence of the laser ranging data on the positioning accuracy of the line-array image is studied,especially for the influence of the elevation accuracy.On the current simulation index requirements,the accuracy of the elevation reached 0.88 meters,which satisfies the accuracy of 1:10000 mapping accuracy without control points,verifying the validity of laser data for improving elevation accuracy.4.Other factors that may affect the positioning accuracy(Satellite attitude error,laser pulse number,laser emission frequency,laser tilt an-gle,laser point number and laser ranging accuracy)are studied next.Explore the index requirements of each influencing factor when the po-sitioning accuracy meets 1:10000 mapping index requirements in the absence of control points,thus providing theoretical support for the subsequent launch of stereographic satellites.