How is land cover derived from satellite imagery?
All surfaces reflect, absorb, or transmit incident light. Different materials reflect and absorb different amounts and wavelengths of light along the electromagnetic spectrum. This is the basis for identifying surface components with 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 is an example of using 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 electromagnetic spectrum 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. Digital raster images are analogous to spread
