Photogrammetry

Excerpt

Photogrammetry can be defined simply as the science of making reliable measurements from photographs. Unlike a map, however, a photograph contains a number of distortions that require correction before accurate measurements can be made. A number of photogrammetric techniques can be employed to remove these distortions and obtain useful measurements. In coastal studies, photogrammetric techniques are commonly employed to establish the positions of historical and modern featuresof- interest (e.g., shorelines (defined as the high-water line or wet-dry boundary), cliff edges, dune positions, etc.). Historically, the focus of study has been overwhelmingly on the use of vertical aerial photography to derive accurate shoreline positions, although photogrammetric applications using ground-based photography, videography and integration with other types of remotely sensed data (e.g., lidar) are becoming widespread. Most often, a time series of feature positions is compiled for the purpose of studying coastal dynamics, such as the evolution of geomorphic features, or determining rates of coastal change (e.g., shore erosion and accretion). These time series have also been used to guide the delineation of coastal erosion or flood hazard areas and building setback lines. …