Spectral Reflectance Properties Remote sensing is based on the measurement of reflected or emitted radiation from different bodies. Objects having different surface features reflect or absorb the sun's radiation in different ways. The reflectance properties of an object depend on the particular material and its physical and chemical state (e.g. moisture), the surface roughness as well as the geometric circumstances (e.g. incidence angle of the sunlight). The most important surface features are colour, structure and surface texture. These differences make it possible to identify different earth surface features or materials by analysing their spectral reflectance patterns or spectral signatures. These signatures can be visualised in so called spectral reflectance curves as a function of wavelengths. The figure in the right column shows typical spectral reflectance curves of three basic types of Earth features: green vegetation, dry bare soil and clear water. The spectral reflectance