基于反射点源的高分辨率光学卫星传感器在轨辐射定标方法

In-Flight Radiometric Calibration of High Resolution Optical Satellite Sensor Using Reflected Point Sources

在轨绝对辐射定标是遥感信息定量化应用的关键技术之一。基于反射点源的在轨定标新方法将目标反射率的场地多点测量转换为实验室高精度检测,结合同步大气光学特性参数测量,通过简化的辐射传输计算获取星载遥感器的入瞳辐亮度;根据点源法在轨点扩展函数检测,有效分离目标反射辐射与程辐射、背景辐射,消除了对气溶胶散射特性的假设,并突破场地替代定标易受时空及天气条件的限制,能够在复杂环境条件下实现高分辨率光学卫星传感器高精度、高频次的移动定标。初步实验结果表明,基于反射点源的光学卫星传感器在轨绝对辐射定标不确定度优于3%,与基于大面积灰阶靶标的定标结果差异为3.02%,简化定标流程的同时提高了定标精度与效率。

In-flight absolute radiometric calibration is one of critical techniques for quantified information application of remote sensing.A novel calibration approach is presented based on reflected point sources.At the same time,the reflectance measurement on site is changed to accurate determination in laboratory.The top-of-atmosphere radiance of satellite-borne remote sensors can be calculated by simplified radiometric transfer code and measurement of the atmospheric optical properties.The calibration method can also isolate the response value of remote sensing image created by the targets from the response produced by sky path radiance and background radiance through in-flight point spread function estimation by point source method,which can eliminate the assumption of aerosol scattering properties.The approach can break the limit of time,locale and weather conditions at vicarious calibration sites and achieve high precision,high frequency mobile calibration for high spatial resolution satellite sensor in complex environments.Preliminary results show that its uncertainty is less than 3%.The difference of calibration coefficient is 3.02% between the proposed method and the method based on large-area gray-scale target.Simultaneously,the method can simplify the process and improve the calibration accuracy and efficiency.