Research And Application Of The RPC Model Geometry Processing For Spaceborne SAR And Spaceborne InSAR

Synthetic Aperture Radar (SAR) is developed in the late1950s and become one of the fastest growing and most successful microwave sensors, which at present has been an important tool for Earth Observation. The advent of Space-borne SAR is SEASAT mission in1978. Followed by the implementation of Shuttle Imaging Radar (SIR) series in the United States, a series of satellite were launched. For example, the ERS SAR-1/2, JERS SAR, RADARSAT-1SAR and ENVISAT ASAR SAR. In recent years, the new generation of high-resolution SAR satellites was launched including COSMO-SkyMed satellite series of Italy, TerraSAR-X and Tandem-X of German and RADARSAT-2of Canada. On this account, it makes widespread use of SAR data products across such diverse scientific disciplines as forestry, agriculture, ecology, geology, oceanography, hydrology and cartography etc. And it has played an important role in many domains such as environmental monitoring, land cover mapping, nature resource exploration, disaster management and marine surveillance. However, with the increase of SAR satellite, which makes the SAR satellite data becoming more and more diverse, it also led to another problem:auxiliary parameters of various satellites are different, the form of auxiliary parameters is different (inconsistent data format, physical parameter form is inconsistent). Thus it is unfavorable for the development of software for multi-source remote sensing geometry processing. Therefore, this paper will look for a general geometric model, which can achieve general geometry processing of different SAR satellites datas.RPC model is a mathematical sense of the imaging geometry model, which is independent of the sensor and platform. This model can establish the relationship between the ground coordinates of the image and the corresponding geographic coordinates. A lot of work has been done on RPC model for optical sensor by many researchers. Based on the comparison of imaging geometric characteristics between pushbroom satellite images and SAR images, this paper proves that the RPC model can be a replacement for the spaceborne SAR rigorous geometric model (Range-Doppler model), and moreover for the InSAR process, this paper also concludes that InSAR rigorous geometric mode (interferometric phase equation) can replace by the RPC model Subsequently. With the analysis of error in the orientation process about the spaceborne SAR images and the spaceborne InSAR image, affine transformation model and quadratic polynomial model is respectively applied to absorb error, which can ensure the correctness of SAR orientation, stereo SAR orientation and InSAR orientation, finally. This paper states how the RPC model is applied for the DEM generation by spaceborne InSAR technique. On the whole, the main content and innovative point is as follows:1) Based on the comparison of imaging geometric characteristics between pushbroom satellite images and SAR images, this paper proves that the RPC model can be a replacement for the spaceborne SAR rigorous geometric model (Range-Doppler model);2) For the InSAR process, this paper proves that InS AR rigorous geometric mode (interferometric phase equation) can replace by the RPC model;3) With the analysis of error source in the orientation process about the spaceborne SAR images, affine transformation model is applied to absorb error. Finally, it has been verificatied by the monolithic directional SAR orientation experiment.4) With the analysis of error source in the orientation process of spaceborne InSAR images, quadratic polynomial model is applied to absorb error. The simulation experiment has validated that baseline error caused by the interference phase error should use the quadratic polynomial to estimate. It has been verificated that quadratic polynomial can be used for InSAR baseline error correction feasibility by the experiment of concrete SAR datasets in the end.5) This paper states how the RPC model is applied for the DEM generation by spaceborne InSAR technique in detail. RPC model is applied for the orbit registration, flat-earth phase removal, refer DEM phase removal and phase to height conversion.