高分辨率光学遥感器辐射定标与归一化技术研究

With the successful launch of china high resolution series satellites, remote sensing satellite images have been widely used in different quantitative remote sensing applications for departments and districts. In present, on-orbit radiometric calibration for national optical remote sensor is still using vicarious calibration method with ground calibration site. Impacted by weather and measuring technique，the frequency of absolute radiometric calibration is limit so that the accuracy is relatively low, about 7%. The relative radiometric calibration of optical remote sensor mainly focuses on the stripping removal; the accuracy is around 3%. High resolution remote sensor launched recently has features of large swath, multi-camera mosaic, and jointly constellation. In order to ensure the wideness and deepness of quantitative remote sensing applications, improving and proposing new approaches for radiometric calibration and normalization is necessary. . According to special imaging pattern of China high resolution optical remote sensor, this project performs the absolute radiometric calibration for a single camera with high frequency by using cross-sensor calibration method and studies the no-linear response phenomenon at both ends of dynamic range. The relative radiometric calibration for large-swath camera is also executed with multi-scene approach and response at different scan angle is corrected. Based on radiometric calibration results of a single camera, we propose inter-sensor calibration approach to accomplish the normalization for multi-camera mosaic imaging sensor and furthermore the normalization for remote sensors in a constellation.

随着我国高分辨率系列卫星的陆续成功发射，遥感卫星影像被广泛的使用到各个行业、区域定量化遥感应用中。现阶段国产光学遥感器在轨辐射定标仍采用场地定标方法，受天气和测量技术影响，绝对辐射定标频次有限且精度相对较低，约7%左右。相对辐射定标则主要针对遥感器的条带噪声去除，精度约3%左右。我国最近发射的高分辨率光学遥感器具有大幅宽、多相机拼接、星座组网等特点，为确保定量化遥感应用的广度与深度，必须改进并研究新的辐射定标与归一化技术。 .项目针对高分辨率光学遥感器成像特点，基于交叉辐射定标实现了单相机的高频次绝对辐射定标，并对相机高低端辐射响应非线性开展研究。利用分视场法开展宽幅相机相对辐射定标并开展不同观测角的辐射差异校正。基于单相机的辐射定标结果，提出自交叉辐射定标方法实现多相机拼接成像遥感器相机间的辐射归一化并进而扩展到组网星座遥感器间的辐射归一化。

卫星遥感器的辐射定标精度水平很大程度上决定了遥感定量化数据产品的质量及应用的广度和深度，只有开展长期在轨辐射定标工作才能监测遥感器辐射性能变化，评估其辐射质量，及时校准卫星遥感数据的质量和稳定性，从而确保地物信息被遥感器及时准确的监测。.项目针对高分一号、高分四号、高分六号高分辨率光学遥感器成像特点，基于交叉辐射定标实现了单相机的高频次绝对辐射定标，并对相机高低端辐射响应非线性开展研究。利用分视场法开展宽幅相机相对辐射定标并开展不同观测角的辐射差异校正。基于单相机的辐射定标结果，提出自交叉辐射定标方法实现多相机拼接成像遥感器相机间的辐射归一化并进而扩展到组网星座遥感器间的辐射归一化。研究表明，GF-1卫星定标精度较高，但是动态范围相较MODIS略差，GF-1/PMS1全色传感器的信噪比优于43.86dB、多光谱传感器各谱段的信噪比优于42.71dB，GF-1/WFV1各谱段的信噪比优于39.45dB，均符合了28dB的卫星研制总要求。基于MODIS和LANDSAT的影像，我们计算出GF-1宽幅相机各谱段交叉辐射定标系数，精度都达到6.5%。针对GF-6，我们通过采用单场地法和多场地法进行比对分析，4个波段的不确定度分别为3.88%、4.00%、3.84%和3.59%。当采用多场地法进行定标时，波段的不确定度为1.94%、1.91%、1.92%和2.77%，不确定度都在3%以内。.通过本项目的研究，创新性提出了GF-1自交叉辐射定标方法，取得了很好的结果，很好的解决了GF-1宽幅相机多相机拼接时产生的色差问题。此外，通过研究，首次有效的发现了GF-1 宽幅相机的RVS（不同观测角的辐射响应差异）的问题，为今后进一步开展提高GF-1 宽幅相机定标精度奠定基础。.