The isoline parameters used in Eqs. (9) and (19) were computed from and , which were determined using the algorithm described in Ref. 34. This algorithm required two hypothetical simulations in which the soil was assumed to be “spectrally flat,” with a zero reflectance value, or the soil was assumed to have a medium reflectance value over the entire wavelength range. In addition to and , the asymmetric order approximated isoline, Eq. (19), required a value of to define . was determined by conducting an additional simulation in which the soil was assumed to be spectrally flat and even brighter than was assumed in the simulation used to determine . The assumption of brighter soil increased the photon contributions of the higher-order interactions. The parameter was determined by solving Eq. (17) for and using and , which were computed prior to . With these variables in hand, the isoline parameters , , , , , , and were obtained. In summary, three hypothetical simulations were conducted to determine the isoline parameters that corresponded to spectrally flat soil at three different brightness levels.