Читать книгу Imagery and GIS - Kass Green - Страница 63

The imagery spatial resolution requirements of a project are determined by the smallest item to be identified on the ground—the project’s minimum mapping unit (MMU). Smaller MMUs require higher spatial resolutions. For example, mapping forest types with an MMU of 10 acres can easily be accomplished using 30-m Landsat imagery. However, mapping individual trees will require 1-meter or higher spatial resolution imagery. Similarly, mapping four-lane freeways can just barely be accomplished with 30-m imagery, but mapping two-lane residential streets or small unpaved secondary roads will require a higher spatial resolution.