Soil directioal (biconical) reflectance in the principal plane with varied illumination angle under dry and saturated conditions.

Abstract

Change in directional (biconical) spectral reflectance was monitored for three soil samples under air dry and saturated conditions in the laboratory. The illumination angle was set consecutively at θi = -10°, -40°, and -70° (left side of the sample on the principal plane), while the observation angle ranged from θo = -60° to + 60° (both sides of the sample in the principal plane) in 5° increments. The soil samples were chosen to represent a variety of soil properties. Emphasis is on observations that illustrate the changes in the directional and spectral distribution of soil reflectance when the soil is dry or saturated.