| Geostationary satellite has many unique characteristics, such as the relatively fixed earth observation location, high temporal resolution, wide observation range, etc. Now the geostationary orbit optical remote sensing is mainly used for meteorology and early warning and its spatial pixel resolution is at kilometer-level, which brings significant limitations when applying to terrestrial, ocean and disaster observations. With the development of sensor craftsmanship and optical design technology, geostationary satellite develops towards higher spatial resolution and begins to be applied to the area of terrestrial observation on the base of keeping high temporal resolution, which is complementary with the globe observation and high spatial resolution of the low earth orbit satellite. It can be predicted that the geostationary remote sensing satellite is an important development direction of the area of future satellite remote sensing, and will play an important role in the earth observation system and space surveillance system. The geostationary satellite is an extendible area of satellite with great development potential.Satellite data preprocessing is an important part of satellite data application system. With the development of geostationary satellite with high spatial resolution, it is a problem to be solved that how to obtain high precision and high quality images, make full use of the remote sensing information and ensure the accuracy of remote sensing applications. In recent years, the high accuracy geometric processing technology has been developed rapidly in the area of medium and low orbit satellite. The construction of geometric model tends to be mature, so as the on-orbit geometric calibration method and the sensor correction technology. However, for geostationary orbit satellite, due to its unique imaging characteristic, the determination of geometric model and the verification of method in ground data processing have become an urgent need.In this paper, we study the theory and method of high accuracy geometric processing of geostationary orbit high resolution area-array camera. The model, method and algorithm in this research can not only provide theoretical and technical support for satellite data ground preprocessing, but also provide reference for the design of the geostationary satellite platform. The main research contents and innovations are as follows:1) Analysis of the geometric imaging characteristic of geostationary orbit high resolution camera and construction of a rigorous geometric imaging modelFirst, the design parameters of geostationary orbit high spatial area-array camera are determined, the imaging differences with the existing aerial area-array camera, low-orbit linear array push-broom camera and geostationary meteorological satellite are analyzed, and the characteristics of high-orbit, narrow field of view, and area-array imaging are summarized, which are the basis and foundation for the following research. Then, several imaging modes of the stationary orbit area-array camera are described, and a simulation experiment about the geometric imaging range of stationary orbit is carried out, based on which we analyze the geometric imaging characteristics of stationary orbit area-array camera quantitatively and make a preliminary conclusion that tiny change of satellite attitude will lead to significant change of the ground resolution. Based on the research object of stationary orbit area-array camera, the time and space datum of the stationary orbit area-array camera is introduced, and the definition of various space coordinate systems and their conversion relationship are represented. Besides that, the model of attitude and orbit parameters is described. Finally, a rigorous geometric imaging model of stationary orbit area-array camera is constructed, which lays the foundation of geometric model for the following geometric calibration and sensor correction.2) Analysis of each error source influencing the geometric positioning of the stationary orbit area-array camera and their laws, and proposition of a geometric calibration model based on two-dimensional direction angleAnalyzing error sources that influence the geometric positioning of the stationary orbit area-array camera is the basis of geometric calibration. First, the effects of various errors on the geometric positioning of the stationary orbit area-array camera are analyzed quantitatively from three aspects:attitude determination error, orbit determination error and camera distortion. Then, we make a comprehensive analysis about the laws of various errors and make a qualitative conclusion that the exterior orientation elements are highly correlated with the interior orientation element in the aspect of geometric error of the area-array camera.After analyzing various error sources that influence the geometric positioning of stationary orbit and their laws, we construct the physical model of geometric calibration of the stationary orbit area-array camera. With the physical model, we propose the key problem of three aspects:the temperature, parameter correlation and the observation error of the star sensor, and give corresponding solutions. Then, focusing on the problem of parameter correlation, we propose a geometric calibration model of stationary orbit area-array camera based on two two-dimensional direction angle, and give the calculation method in terms of implementation. Finally, the experiments conducted in this thesis demonstrate that our model and method are correct and effective, which provide method and technical support for the operation of the ground data processing of the geostationary orbit area-array camera.3) Analysis and verification of the applicability of the RPC model in the stationary orbit area-array cameraAs a general model, RPC model has been widely applied in the medium-low orbit push-broom optical satellite and medium-low resolution SAR satellite. According to the rigorous geometric model of the stationary orbit area-array camera constructed above, the RPC model is generated by the virtual control points, and the fitting accuracy of the RPC model to the rigorous model is verified. The experimental results show that the RPC model can be used to replace the rigorous geometric imaging model of the stationary orbit area-array camera, and can be used as a part of the sensor correction products. It provides a geometric model independent of the sensor parameters for the follow-up image processing.4) Two methods and implementation algorithms for sensor correction based on image projection transformation and object consistency respectivelyBased on the reference to the sensor correction method of the aerial area-array multi-lens camera and multi-line array push-broom camera, the concept of "virtual area-array image" is introduced. On the foundation of this concept, we propose two sensor correction methods based on image projection transformation and object consistency respectively, and give the implementation of the corresponding algorithms. Furthermore, the validity and correctness of the algorithms are verified by the simulation data. Experiments demonstrate that, in the premise of ensuring the accuracy of geometric positioning, the two methods are both able to realize the seamless splicing of multi-area array images in stationary orbit sensor correction products. |
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