The potential use of the interferometric coherence measured with Sentinel-1 satellites as input feature for crop classification is explored in this study. A one-year time-series of Sentinel-1 images acquired over an agricultural area in Spain, in which 17 crop species are present, is exploited for this purpose. Different options regarding temporal baselines, polarization, and combination with radiometric data (backscattering coefficient) are analyzed. Results show that both radiometric and interferometric features provide notable classification accuracy when used individually (overall accuracy lies between 70% and 80%). It is found that the shortest temporal baseline coherences (6 days) and the use of all available intensity images perform best, hence proving the advantage of the 6-day revisit time provided by the Sentinel-1 constellation with respect to longer revisit times. It is also shown that dual-pol data always provide better classification results than single-pol ones. More importantly, when both coherence and backscattering coefficient are jointly used, a significant increase in accuracy is obtained (greater than 7% in overall accuracies). Individual accuracies of all crop types are increased, and an overall accuracy above 86% is reached. This proves that both features provide complementary information, and that the combination of interferometric and radiometric radar data constitutes a solid information source for this application.

中文翻译：

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作物类型映射的 Sentinel-1 干涉相干和反向散射的时间序列

本研究探讨了使用 Sentinel-1 卫星测量的干涉相干性作为作物分类输入特征的潜在用途。为此目的，利用在西班牙一个农业区采集的一年时间序列的 Sentinel-1 图像，其中存在 17 种作物物种。分析了关于时间基线、极化和与辐射数据（反向散射系数）组合的不同选项。结果表明，辐射测量和干涉测量特征在单独使用时都提供了显着的分类准确度（总体准确度在 70% 到 80% 之间）。发现最短时间基线相干性（6 天）和所有可用强度图像的使用效果最好，因此证明了 Sentinel-1 星座提供的 6 天重访时间相对于更长的重访时间的优势。还表明双极数据总是比单极数据提供更好的分类结果。更重要的是，当相干系数和后向散射系数同时使用时，精度会显着提高（总体精度超过 7%）。提高了所有作物类型的个体准确度，总体准确度达到了 86% 以上。这证明这两个特征提供了互补的信息，并且干涉测量和辐射测量雷达数据的组合构成了该应用的可靠信息源。当相干系数和后向散射系数同时使用时，精度会显着提高（总体精度大于 7%）。提高了所有作物类型的个体准确度，总体准确度达到了 86% 以上。这证明这两个特征提供了互补的信息，并且干涉测量和辐射测量雷达数据的组合构成了该应用的可靠信息源。当相干系数和后向散射系数同时使用时，精度会显着提高（总体精度大于 7%）。提高了所有作物类型的个体准确度，总体准确度达到了 86% 以上。这证明这两个特征提供了互补的信息，并且干涉测量和辐射测量雷达数据的组合构成了该应用的可靠信息源。