Range-Doppler(RD)methodandReverse-Range-Doppler(RRD)methodarecombinedtogethertoachieveautomaticgeocodingofSyntheticApertureRadar(SAR)imagequicklyandaccuratelyinthepaper.TheRDmethodisfirstlyusedtolocatethefourcornersoftheimage,thentheotherpixelsoftheimagecanbelocatedbyReverse-Range-Doppler(RRD)method.Resamplingisperformedatlast.Theapproachhasanadvantageoverprevioustechniquesinthatitdoesnotrequiregroundcontrolpointsandisindependentofspacecraftattitudeknowledgeorcontrol.ItcancompensatetheshiftduetotheassumedDopplerfrequencyinSARimagepreprocessing.RRDsimplifiestheprocessofRD,thereforespeedsupthecomputation.TheexperimentalresultsshowthataSARimagecanbeautomatedgeocodedin30susingthesingleCPU(3GHz)with1Gmemoryandanaccuracyof10misattainablewiththismethod.
