高分辨率光学遥感卫星小目标法在轨辐射定标

辐射定标是卫星遥感信息定量化的关键技术之一。高分辨率光学遥感卫星小目标法在轨定标将目标反射率的现场测量转换为实验室高精度测量，以实际测量代替气溶胶散射特性假设，通过简化辐射传输计算获取大气透过率与遥感器入瞳辐亮度，根据遥感器系统PSF检测结果将小目标的辐射响应与背景辐射相分离，降低对场区背景环境要求的同时提高了绝对辐射定标精度。试验结果分析表明，高分辨率光学遥感卫星传感器小目标法在轨辐射定标不确定度优于3%，与大面积辐射校正场或灰阶靶标法的定标结果差异3.65%，小目标法有望在全谱段范围实现高分辨率光学遥感卫星传感器的全动态范围定标与几何检校。

In-flight radiometric calibration of high spatial resolution satellite optical sensor using small targets

Radiometric calibration is one of the key technologies for quantification of satellite remote sensing information. A calibration method for high resolution optical remote sensor was presented based on small targets. At the same time, the reflectance test on site was changed to accurate measurement in laboratory. It substituted the field actual determination to the assumption of aerosol scatter. The atmospheric transmittance and at-sensor radiance could be calculated by simplified radiometric transfer code. And the approach could isolate the digital number(DN) signal created by little targets from response produced by background radiance through system's point spread function PSF estimation, which reduced the background requirement and improved the absolute radiometric calibration accuracy. The experimental results show that the calibration uncertainty is less than 3% for high spatial resolution satellite. The difference of calibration coefficient is less than 3.65% compared with large test site or gray-scale targets method. The small target approach is expected to achieve full dynamic calibration and geometric calibration in the full spectrum range for high resolution satellite optical sensor.