DEM Precision Improving Techniques of Spaceborne Interferometric Synthetic Aperture Radar Data Processing
|School||National University of Defense Science and Technology|
|Course||Information and Communication Engineering|
|Keywords||Synthetic Aperture Radar InSAR Interferogram Statistics Correlation DEM Prominent Point scatterers|
As an active microwave remote sensing tools, space-borne Synthetic ApertureRadar (SAR) becomes more and more essential for mankind for its capability of beingable to observe the earth in all weather conditions and all-time. Space-borne SAR isnow being developed towards high spatial and temporal resolution, wide swath,multi-band, multi-polarization, multi-mode, distributed satellite constellation and has abright prospect. As an extension of space-borne SAR, SAR interferometry InSARhas been developed into an important branch of remote sensing technique in past twodecades, with its great advantage in high speed, wide coverage, high accuracy and lowcost in topographic mapping, surface deformation measurements, landslide monitoring,ocean current speed estimation, volcanic seismic studies, etc.With the deepening of research on space-borne SAR Interferometry, some basicand important issues such as data with low correlation, phase unwrapping, atmospherephase delay which hinder the development of space-borne SAR interferometrytechnology have been discovered. For the sake of acquiring more precise DegitalElevation Models (DEM), based on research carried out by former reseachers, signalprocessing theory and data processing methods were detailed studied with largeamounts of SAR data.The main work of this thesis is as follows:Chapter II, SAR Interferometry processing and SAR interferogram modeling isdiscussed. The principles of space-borne SAR interferometry are introduced first.Statistical properties of complex SAR interferogram are then studied carefully. Themain process and ideas of our InSAR processing platform developed based on thisthesis are then studied with a pair of real SAR data.Chapter III, SAR Interferometry based on coarse DEM is discussed. Firstly,accurate corregistration problem of coarse DEM and SAR image is carried out.Accurate SAR data pair registration method, accurate baseline estimation method,accurate coherence estimation methods are then studied accordingly. At last, layoverand shadow areas identify method using coarse DEM is introduced.Chapter IV, SAR Interferometry processing method based on prominent pointscatterers. First, the statistical property of prominent point scatterers is derived and basicidea of prominent scatter processing is described. New interferogram filter method andphase unwrapping method based on prominent point scatterers is introducedsubsequently.Chapter V, SAR Interferometry signal processing based on multi-channel SAR data.For multi-channel SAR data characteristics, different SAR Interferometry processingmethods are evaluated with multi-baseline, multi-frequency, multi-polarization and multi-time data.Chapter VI, Conclusion, innovations and summary for next steps are discussed.The main innovations are as follows:(1) Statistical properties of complex interferograms from homogenous simplescene (SAR background obeys Gamma law) and homogenous complex scene (SARbackground obeys K or G0law) are studied. Our model for homogenous simple sceneis equivalent to but much simpler than the distribution that aready exsit. The study ofmodels for homogenous complex scene extend the statistical theory of complexinterferograms and layed a solid theoretical basis for the further discussion of highresolution SAR interferometry processing methods.(2) Interferometric SAR processing technique using coarse DEM are proposed forsolving difficulties in SAR interferogram filtering and phase unwapping. Our methodshave a great advantage in some respects such as SAR data registration, baselineestimation, correlation estimation. The stability and accuracy of InSAR processing isimproved.(3) Phase maintenance capability of Prominent Point scatterers is discovered. Thestatistical model for Prominent Point scatterers is derived which layed a solid basis forProminent Point scatterers SAR interferometry (PP-InSAR).(4) Anisotropic diffusion equation method based on PP-InSAR technique is appliedto phase filtering problem of SAR interferometry. Our method is clear and simple inphysical and has the advantage of accuracy and robustness for InSAR processing.