ABOUT THE SOIL LINE CONCEPT IN REMOTE-SENSING

The soil line, a linear relationship between bare soil reflectance observed in two different wavebands. is widely used for interpretation of remotely sensed data. The basis on soil line was analyzed using a radiative transfer model in which reflectance was splitted into its single and multiple scattering components. The slope of the soil line corresponded to the ratio of the single scattering albedos corresponding to the two wavebands where the soil line was defined. The intercept originated from the difference in multiple scattering observed in each of the two wavelength bands used. The soil line concept was very robust over the whole optical domain as soon as soil types are separated, and when the effect of the view and source configurations as well as the surf-ace roughness were considered. However, in the middle infrared spectral domain, the soil line concept failed when soil moisture was a factor of variation.