On-orbit Internal Calibration Based On The Cross Image Pair For An Agile Optical Satellite Under The Condition Without Use Of Calibration Site

With the development of spatial information science in China,the mobility of optical remote sensing satellites and the resolution of the acquired images are increasing continuously.In the 13th Five-Year plan,the development of the agile optical satellite(AOS)with the ability of dynamic imaging and resolution better than 0.5m has been put on the agenda.Due to the high mobility,the AOS has been widely used in the fields such as stereo mapping,target detecting and disaster warning,provides the users with high precise and high-time-asked images.For the present application of AOS,improving the geometric quality of images based on the precise texture information has been a key problem for further giving full play to the satellite image performance and application potentialAs an important approach of improving the geometric positioning accuracy and ensuring the geometric quality of optical satellite images,the on-orbit geometric calibration has been widely used in the geometric process of lots of satellite sensors.However,the conventional geometric calibration method critically depends on the high-precise reference data covering the calibration site,thereby results in the inherent limitations of high cost and poor efficiency.In addition,this approach usually requires the resolution of the reference data higher than the satellite images,which limits the applicability of this method to 0.3m or even 0.1m resolution satellites.Since the reference data of calibration site are usually acquired by aerial platforms,the matching error of the heterogeneous data between the reference and satellite data will also reduce the calibration accuracy.Aiming to the limitations of the conventional calibration approach,this paper focuses on the investigation of geometric calibration using a cross imagery pair under the condition without use of calibration site.Based on the calibration model constructed using a viewing-angle model,a bundle adjustment is adopted to achieve the high-accuracy calculation of internal parameters.The experimental results indicated the presented method is effective for calibrating the systematic error of internal parameters,which provides a practical method for the calibration of AOS.The performance of this investigation may also provide some guiding significances for the design of the successive domestic satellite platform.The main research contents and innovations are as follows:1)This paper systematically analyzes the geometric errors of the agile optical satellite,so as to realize the modeling of the error parameters,and construct the corresponding error compensation model.2)An elevation aided calibration model was constructed.Based on the model,the non-convergence of estimation and the rank-defect of normal equation resulted from the correlation among parameters were also solved,so as to ensure the accuracy of on-orbit geometric calibration.3)The robust calculation method of calibration parameters was investigated.In the method,a weights update stategy was determined and a least-square adjustment was used to estimate the calibration parameters under the constraints of corresponding bundles and the reference elevation.4)Based on simulation data,a set of experiments were conducted to validate the method presented in this paper.The experimental results show that the calibration model and method is effective and reliable,and can greatly improve the geometric accuracy of optical satellite image,so as to reduce the difficulty and cost of follow-up process.