卫星成像仿真中零视距标准图的获取方法

Acquisition Method of Zero Stadia Standard Image for Satellite Imaging Simulation

高分辨率卫星成像全链路仿真是卫星发射前效果评估的主要手段,零视距标准图是验证成像仿真链路基础环节准确性的必要标准。地面设备获取零视距图像时,由于存在成像视场受到限制、观测角度与卫星不一致、工作量大、难以定量化等问题,难以直接获取垂直对地观测的零视距标准图。通过建立地面零视距标准图测量系统,利用轨道逐行拍摄、几何校正、图像拼接,得到较大幅宽垂直向下图像。并且通过同步辐射校正法进行定量化,得到零视距反射率图像。最终,在距离地面2.6m的观测平台上,获取了面积为10m×10m,分辨率为亚米级的零视距标准图(反射率图)。与地面实测反射率对比,结果表明零视距标准图(反射率图)误差小于5%,可为亚米级高分辨率卫星成像仿真链路基础环节的精度验证提供标准。

Full link simulation of high resolution satellite imaging is the main means to evaluate the effect of satellite pre-launch.The zero stadia standard image is the necessary standard to verify the accuracy of the basics on imaging simulation link.When the ground equipment acquires zero stadia image,it is difficult to obtain zero stadia standard image directly by vertical observation to earth because of the problems such as the inconformity of the observation angle and the satellite,the heavy workload and difficulty of qualification.Through the establishment of ground zero stadia standard measurement system,vertical image with wide width is obtained by rail line shooting,geometric correction and image mosaic.Then,the zero stadia reflectance image is obtained by quantifying the synchrotron radiation correction method.Finally,on the observation platform 2.6 m away from the ground,the zero stadia standard image（reflectivity image）with the area of 10 m×10 mand the resolution of sub-meter level is obtained.Compared with the reflectance of the ground testing,the results show that the error of the zero stadia standard image（reflectivity image）is less than 5%,which can provide a standard for the accuracy verification of basic link of sub-meter high resolution satellite imaging simulation link.