SAR影像的几何精纠正
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摘要
SAR影像几何纠正中的一个重要问题是建立其构像模型。在阐述F.Leberl模型的基本原理和方法的基础上,针对星载SAR成像处理过程中多普勒中心频率不为零的现象,采用多项式拟和多普勒中心频率的方法,修正零多普勒条件方程,建立起既适合星载又适合机载SAR传感器的F.Leberl构像模型。机载和星载SAR影像的实验结果表明,文中提出的改进算法能显著地提高F.Leberl模型对星载SAR影像的定位精度,同时也适合于对机载SAR数据的处理,并且解算过程稳定,收敛很快,精度较高。
With the development of SAR(Synthetic Aperture Radar) remote sensing techniques,SAR images have been widely applied in a lot of fields.But because of its side-looking character,we have to rectify the images into orthoimages before we use them.Building mathematical models is an important step in SAR rectification.In this paper we first recapitulate some mathematical models used for SAR image rectificaion,including Soviet Model,Polynomial Model and G.Konecny Model.The characteristics of these models are analyzed.Then we introduce the F.Leberl Model in detail,which is based on the distant condition and the zero-Doppler condition.In airborne condition the range direction is perpendicular to the flight track so the Doppler center frequency is zero.But in spaceborne condition,the Doppler center frequency does not always equal to zero,so the zero-Doppler condition needs to be corrected.In this article we use a polynomial to substitute the value of the Doppler center.By this way we corrected the zero-Doppler condition.In the experiments we used both the original F.Leberl Model and the corrected model to validate the precision of our model.From the results we come to the conclusion that the new model is acceptable to both the airborne SAR and the spaceborne SAR,at the same time it can get higher precision than the original model in spaceborne condition.
With the development of SAR(Synthetic Aperture Radar) remote sensing techniques,SAR images have been widely applied in a lot of fields.But because of its side-looking character,we have to rectify the images into orthoimages before we use them.Building mathematical models is an important step in SAR rectification.In this paper we first recapitulate some mathematical models used for SAR image rectificaion,including Soviet Model,Polynomial Model and G.Konecny Model.The characteristics of these models are analyzed.Then we introduce the F.Leberl Model in detail,which is based on the distant condition and the zero-Doppler condition.In airborne condition the range direction is perpendicular to the flight track so the Doppler center frequency is zero.But in spaceborne condition,the Doppler center frequency does not always equal to zero,so the zero-Doppler condition needs to be corrected.In this article we use a polynomial to substitute the value of the Doppler center.By this way we corrected the zero-Doppler condition.In the experiments we used both the original F.Leberl Model and the corrected model to validate the precision of our model.From the results we come to the conclusion that the new model is acceptable to both the airborne SAR and the spaceborne SAR,at the same time it can get higher precision than the original model in spaceborne condition.
引文
[1]Zhu C Y,Xu Q,W u C H,et al.Study on MathematicalModelsfor A irborne SAR Image Rectification[J].Journal of Rem oteSensing,2003,7(2):112—117.[朱彩英,徐青,吴从晖等.机载SAR影像几何纠正的数学模型研究[J].遥感学报,2003,7(2):112—117.]
[2]Lu J G,L i J P.The Research and Realization of Satellite SARImage O rtho-Rectification A lgorithm[J].Rem ote SensingTechnology and Application,2002,17(4):230—234.[吕京国,李建平.星载合成孔径雷达影像正射纠正算法的研究与实现[J].遥感技术及应用,2002,17(4):230—234.]
[3]X iao G C,Zhu C Y.Radar Photogramm etry[M].Beijing:TheEarthquake Pub lish ing House,2001.[肖国超,朱彩英.雷达摄影测量[M].北京:地震出版社,2001.]
[4]Yuan X K.Introduce to the Spaceborne Synthetic Aperture Radar[M].Beijing:National D efense Industry Pub lish ing House,2003.[袁孝康.星载合成孔径雷达导论[M].北京:国防工业出版社,2003.]
[2]Lu J G,L i J P.The Research and Realization of Satellite SARImage O rtho-Rectification A lgorithm[J].Rem ote SensingTechnology and Application,2002,17(4):230—234.[吕京国,李建平.星载合成孔径雷达影像正射纠正算法的研究与实现[J].遥感技术及应用,2002,17(4):230—234.]
[3]X iao G C,Zhu C Y.Radar Photogramm etry[M].Beijing:TheEarthquake Pub lish ing House,2001.[肖国超,朱彩英.雷达摄影测量[M].北京:地震出版社,2001.]
[4]Yuan X K.Introduce to the Spaceborne Synthetic Aperture Radar[M].Beijing:National D efense Industry Pub lish ing House,2003.[袁孝康.星载合成孔径雷达导论[M].北京:国防工业出版社,2003.]
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