Soil line automatic identification algorithm based on two-dimensional feature space

Soil line is a straight line in two-dimensional spectral space, which is generated from a series of pure soil pixels ranged by reflectance. It is a comprehensive reflection of the soil’s characteristic in different water conditions, and helps to understand the physical, chemical and ecological properties of soil and vegetation. For a long time, the soil line has been manually identified with low efficiency and large variability, which limits the further application and promotion of soil line based models. Aimed to solve these problems, the paper proposed an soil line automatic identification algorithm and stated the details of its procedure. With this algorithm, the soil line and its fitting parameters can be automatically identified in the two-dimensional spectral space and calculated based on the reflectance of pixels in the remote sensing image. Through the validation of field experiments and time series data, the algorithm was proved to be a stable and accurate way to identify soil line. The algorithm was applied in drought monitoring model, such as PDI, MPDI and SPSI. The results show that the automatic algorithm can greatly raise the efficiency, improve the accuracy of soil line identification, and contribute to the widespread application of the drought models.