NDBSI - Normalized Difference Bare Soil Index

As a component of the Earth’s land surface, bare soil is an important indicator of urbanization and therefore plays an irreplaceable role in regional ecosystems. Given that the spectral signatures of bare soil are complicated and easily confused with impervious surfaces, few soil spectral indices have been purposed and widely used. In the cited study (Deng et al., 2015), a soil index was developed, the normalized difference bare soil index (NDBSI), by analyzing the spectral characteristics of multiple soil types. Using Landsat 8 OLI images from six urban and rural areas in China, we found that NDBSI was more effective in mapping bare soil than currently used indices (i.e. bare soil index (BI), product index for dark soil (PIDS), and biophysical composition index (BCI)), especially in distinguishing between bare soil and impervious surface. Moreover, NDBSI showed good performance in identifying bare soil from red brick, which is helpful for soil mapping in industrial urban areas, where red brick is widely used as roofing materials. 

Generic Formula (R is the reflectance at the wavelengths (nm) denoted by the subscripts):

Formula by Sentinel-2 bands: 

References:

• Li, S., & Chen, X. (2014). A NEW BARE-SOIL INDEX FOR RAPID MAPPING DEVELOPING AREAS USING LANDSAT 8 DATA. ISPRS Annals of Photogrammetry, Remote Sensing & Spatial Information Sciences, 2(4).

• Liu, Y., Meng, Q., Zhang, L., & Wu, C. (2022). NDBSI: A normalized difference bare soil index for remote sensing to improve bare soil mapping accuracy in urban and rural areas. Catena, 214, 106265.