当前位置: X-MOL 学术Int. J. Appl. Earth Obs. Geoinf. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
The radiometric accuracy of the 8-band multi-spectral surface reflectance from the planet SuperDove constellation
International Journal of Applied Earth Observation and Geoinformation ( IF 7.5 ) Pub Date : 2022-09-25 , DOI: 10.1016/j.jag.2022.103035
Yu-Hsuan Tu, Kasper Johansen, Bruno Aragon, Marcel M. El Hajj, Matthew F. McCabe

Advances in the capabilities of commercial CubeSat constellations have enabled the retrieval of multi-spectral surface reflectance data over the Earth’s terrestrial surfaces on an almost daily basis. For example, while the earliest versions of Planet’s CubeSats provided tri-band and then quad-band optical image data, the most recent iterations deliver imaging capabilities with eight unique spectral bands for Earth system monitoring. To determine the utility of these rich geospatial data collections for a range of applications, it is necessary to characterise their radiometric accuracy. Leveraging on-ground spectroradiometer measurements of radiometrically pseudo-invariant features, we assess the absolute accuracy of an annual sequence of Planet SuperDove surface reflectance data. Date-coincident and spectrally overlapping Sentinel-2 image data were also used to assess the relative radiometric accuracy of the CubeSat reflectance data. Additionally, confidence levels for acquiring consistent SuperDove surface reflectance data were calculated, and the multi-temporal patterns of surface reflectance between the SuperDove and Sentinel-2 surface reflectance products were evaluated by examining their rank correlation. Our findings demonstrate that (1) the average accuracy of the Coastal-Blue, Blue, Green I, and Green II SuperDove surface reflectance bands was 5% higher than for the Yellow, Red, Red-Edge, and Near-Infrared bands; (2) the SuperDove surface reflectance data was on average almost identical to the surface reflectance derived from the coincident Sentinel-2 data; and (3) the radiometric accuracies (i.e., mean errors) can be improved by using band combinations (e.g. normalised difference vegetation index). However, due to the different radiometric performance between the spectral bands, some vegetation indices (e.g. the Yellowness Index) did not provide a linear relationship between the SuperDove and reference data. The probability of acquiring surface reflectance data with less than 5% reflectance variation was approximately 90% for the annual multi-satellite dataset. On average, 68% of the data derived from a single satellite had at least 95% probability of acquiring surface reflectance with less than 5% variation. The time series patterns of the SuperDove reflectance data had an average rank correlation coefficient of 0.67 for all types of surface units and 0.77 for vegetated surfaces when compared with the spectrally overlapping bands of the Sentinel-2 surface reflectance data. In addition to providing confidence levels for users to directly assess the radiometric accuracies of SuperDove surface reflectance products, we also provide suggestions to improve the data quality from an end-user’s perspective.



中文翻译:

来自行星 SuperDove 星座的 8 波段多光谱表面反射率的辐射精度

商业 CubeSat 星座能力的进步使得几乎每天都能检索地球陆地表面的多光谱表面反射率数据。例如,虽然 Planet 的 CubeSat 最早版本提供了三波段和四波段光学图像数据,但最近的迭代提供了具有八个独特光谱波段的成像能力,用于地球系统监测。为了确定这些丰富的地理空间数据集合在一系列应用中的效用,有必要描述它们的辐射精度。利用对辐射伪不变特征的地面分光辐射计测量,我们评估了每年的 Planet SuperDove 表面反射率数据序列的绝对精度。日期重合和光谱重叠的 Sentinel-2 图像数据也用于评估 CubeSat 反射数据的相对辐射精度。此外,计算了获得一致 SuperDove 表面反射率数据的置信度,并通过检查它们的等级相关性来评估 SuperDove 和 Sentinel-2 表面反射率产品之间的表面反射率的多时间模式。我们的研究结果表明(1)Coastal-Blue、Blue、Green I 和 Green II SuperDove 表面反射波段的平均精度比黄色、红色、红边和近红外波段高 5%;(2) SuperDove 地表反射率数据平均与 Sentinel-2 重合数据得出的地表反射率几乎相同;(3) 辐射精度(即,平均误差)可以通过使用波段组合(例如归一化差异植被指数)来改善。然而,由于光谱带之间的辐射测量性能不同,一些植被指数(例如黄度指数)没有提供 SuperDove 和参考数据之间的线性关系。对于年度多卫星数据集,获得反射率变化小于 5% 的表面反射率数据的概率约为 90%。平均而言,来自单颗卫星的 68% 的数据具有至少 95% 的概率获得表面反射率且变化小于 5%。SuperDove 反射率数据的时间序列模式对于所有类型的表面单元和 0 的平均秩相关系数为 0.67。77 与 Sentinel-2 表面反射率数据的光谱重叠带相比,植被表面。除了为用户提供置信度以直接评估 SuperDove 表面反射产品的辐射测量精度外,我们还从最终用户的角度提供改进数据质量的建议。

更新日期:2022-09-25
down
wechat
bug