Photogrammetry

Photogrammetry is the science of making measurements from photographs, especially for recovering the exact positions of surface points. It may also be used to recover the motion pathways of designated reference points on any moving object, on its components, and in the immediately adjacent environment. Photogrammetric analysis may be applied to one photograph, or may use high-speed photography and remote sensing to detect, measure and record complex 2-D and 3-D motion fields (see also sonar, radar, lidar, etc.). Photogrammetry feeds measurements from remote sensing and the results of imagery analysis into computational models in an attempt to successively estimate, with increasing accuracy, the actual, 3-D relative motions within the researched field.

Its applications include satellite tracking of the relative positioning alterations in all Earth environments (e.g. tectonic motions etc.), research on the swimming of fish, of bird or insect flight, and other relative motion processes (International Society for Photogrammetry and Remote Sensing). The quantitative results of photogrammetry are then used to guide and match the results of computational models of the natural systems. They help to invalidate or confirm new theories, to design novel vehicles or new methods for predicting or/and controlling the consequences of earthquakes, tsunamis or other events, or to understand the flow of fluids next to solid structures and many other processes.

Photogrammetry is as old as modern photography, dating to the mid-19th century. Its detection component has been emerging from radiolocation, multilateration and radiometry. Its 3-D positioning estimative component (based on modeling) employs methods related to triangulation, trilateration and multidimensional scaling.

In the simplest example, the distance between two points that lie on a plane parallel to the photographic image plane, can be determined by measuring their distance on the image, if the scale (s) of the image is known. This is done by multiplying the measured distance by 1/s.

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