DEM Extracted By Stereo Images Of High Resolution Satelliteand Accuracy Analysis In Plateau

DEM is a mathematical representation of the earth's surface topography, which is widely used in scientific research and practical production. Traditional method for obtaining DEM by topographic map digitalization and topographic survey has some shortcomings, such as acquisition delay, long acquisition cycle, small obtain area, difficult information collection of special region. Due to bad terrain conditions in plateau area, the traditional measurement method is more difficult to be implemented and selection and measurement of control points is difficult. According to the high resolution satellite advantages of real-time and high precision, digital photogrammetry can overcome the difficult information collection of special region and obtain a large area of DEM in real time with a few control points. Therefore, It is necessary to study and discuss the factors that affect the DEM accuracy extracted by the high resolution stereo images, which has important significance in the practical production and application.LPS as software platform, DEM is extracted based on panchromatic stereo images of WorldView and GeoEye in plateau and the field surveying control point. The accuracy of DEM extracted by high resolution stereo images is analyzed from three aspects: relationship between control point and positioning accuracy, relationship between tie point and the accuracy of map junction, the position accuracy of across-track stereo images.The main research contents of this paper are as follows:(1) DEM extracted solution of high resolution stereo images is designed to obtain DEM of measurement area by relative orientation under condition of rigorous sensor model(RSM) and rational function model(RFM), absolute orientation based on control points, nuclear line image generation based on tie points, aerial triangulation, gross error detection and rejection.(2) The relationship between the DEM accuracy extracted by high resolution stereo images and control points is analyzed. Under none control points, the accuracy of RFM is higher, and the plane accuracy is better than the elevation precision. The plane precision and elevation precision of RSM is very high, but X direction accuracy is relatively lower. The accuracy of RSM is higher than that of RFM. Under the condition of control points, only one control point can be a very good control of the position accuracy of stereo images. The accuracy of the two models is similar, and the plane precision is slightly higher than the elevation accuracy. Sensitivity about the unenven distributioncontrol points of RSM is higher than that of RFM, and the error of RSM exponentially increase.(3) The law between tie points number and the accuracy of map junction of the overlapping area of high resolution stereo images in condition of same strips and different strips. Due to the same access conditions of stereo images of same strips, when there is no tie point in the overlapping area, the accuracy of map junction is higher and there is no obvious joint seam. When there is no tie point in the overlapping area of different trips, the accuracy of map junction is low and edge seam is obvious. However, when two tie points are added to the overlap area, the image edge precision is equal to that of the same strips.(4) Optimal selection scheme of across-track stereo images is obtained by discussing the DEM accuracy extracted high resolution across-track stereo images. Across-track stereo imagescan also obtain a better accuracy of DEM, which can extract higher accuracy DEM by composing of two images of real-time and short acquisition time interval.