How is land cover information derived from aerial and satellite imagery?
All surfaces reflect, absorb, or transmit 100 percent of incident light. Different materials reflect and absorb different amounts and wavelengths of light along the electromagnetic spectrum (EMS). This is the basis for identifying surface components from remote sensing. High-resolution analog aerial photography can be used to delineate geographic themes of information, such as wetlands. The National Wetlands Inventory (NWI) Program, for example, uses aerial photography to delineate wetlands in the landscape by manual interpretation and delineation. Digital sensors, such as most satellite-based sensors, can collect multiple wavelengths of light in regions of the EMS not possible with an analog photographic medium. It is possible to manipulate and statistically analyze these wavelengths of light to determine unique characteristics of the landscape and ground surface. These characteristics can be turned into information such as land cover.
