Reflectance brightness measured over agricultural areas

Remote-sensing signals from agricultural scenes result from the interaction of light with soil and plants. A plant in full sunlight has some of its leaves exposed to direct solar irradiation, whereas other leaves are wholly or partially shaded and are exposed to various intensities of diffuse light. Reflectance from a plant canopy is made up of an integration of reflectances from the various components of the canopy. Measurements made with image analyzer equipment showed that a wide range of soil and of plant canopy geometries had a similar range of reflectance intensities, although the area distribution was different between soil and crop canopies.