Formulas of several commonly used vegetation indices.

Note: B, R, NIR, and SWIR are the surface reflectance in the blue, red, near infrared, and shortwave infrared bands, respectively. SWIRmax and SWIRmin are the maximum and minimum surface reflectance in the SWIR band, respectively. SWIRmax and SWIRmin are defined as the 1% minimum and maximum cutoff points in the histogram of the SWIR band reflectance here. a and b are the slope and intercept of the soil line, respectively. L, X, Y, and Z are soil background adjusted factors. γ is an atmospheric self-correcting factor which depends on aerosol types.

备注：B、R、NIR、SWIR分别对应蓝波段、红波段、近红外（Near Infrared, NIR）、短波红外（Shortwave Infrared, SWIR）波段的地表反射率。SWIRmax与SWIRmin分别为SWIR波段的地表反射率最大值与最小值，本文中将二者定义为SWIR波段反射率直方图中的1%最小截断点与1%最大截断点。a、b分别为土壤线的斜率与截距。L、X、Y、Z为土壤背景校正因子。γ为依赖于气溶胶类型的大气自校正因子。