DEM-aided Block Adjustment For Satellite Images With Weak Convergence Geometry

Remote sensing earth observation is an important means of human access togeo-spatial informantion,has an irreplaceable role in the development of nationaleconomy.Extensive application of satellite remote sensing technology began in the1970s,the United States in1967launched the first experimental polar orbitmeteorological satellite.Since the1980s,France,ESA,Japan,Russia,Canada and othercountries have also launched a series of satellite,such as the French SPOT series ofsatellites,ESA’s ERS series satellite and ESOURCE-02satellite,Canada’s Radarsatradar satellites,Iapan’s ALOS satellite.In the enterprise,The United StatesSpaceImaging commercial satellite IKONOS was launched in Setember1999.To enterthe21st century,the United States DigitalGlobe launched QuickBird satellite,GeoEyecompany launched GeoEye satellite.Most of these satellites has entered commercialoperarion stage,marking enter the stage of comprehensive development andapplication of remote sensing technology.As an significant national condition,Geographic conditions is themacroscopic,holistic and comprehensive reflecting of human and physical geographicfactors.Satellite surveying and mapping is an important geographic conditionsmonitoring’s technique, which has the remarkable characteristic in large area and fastupdating national fundamental geographic information.Block adjustment model with a combination of rational function model(RFM)and affine transformation is traditionally used in satellite images processing.Themodel achieved good results in block adjustment whose images have strongconvergence geometry.Navigating in space,the satellite’s FOV is small and moststellites’direction of scanning approximately perpendicular to the ground,which led tosmall base-height ratio of the overlay images. Approximately perpendicular to theground projection coupled with overlay images’ small base-height led to satelliteimages with weak convergence geometry.The elevation error of tie point will beamplified in the traditional block adjustment,which leads to the non-convergence ofthe adjustment consequently. This paper proposes an algorithm of block adjustmentwhich use DEM as elevation assist.First, the paper discusses the advantages and reliability of traditional blockadjustment model in linear images processing.Then,by analyzing the reasons offorming the weak geometry,this paper proposed the method of recognizing the weakgeometry images.For the case with the tie point in same oribit led to the irreversibility of normal equation in adjustment, this paper proposed the mothod of disposing it asweak convergence geometry tie point.At last,by analyzing the reasons ofnon-convergence of block adjustment with weak convergence geometry images,thispaper proposes an algorithm of block adjustment which use DEM as elevationassist.Throughout the paper,the main innovative points of this article is as follows:1、Proposing the method of identifying the weak convergence geometry satelliteimages.2、Proposing the method of eliminating impact of the same oribit tie point inblock adjustment.3、Proposing the algorithm of block adjustment which use DEM as elevationassist.4、Experimenting with weak convergence geometry satellite images to test thereliability of this method.