Trimetrogon is an aerial photographic survey method that involves the use of three cameras in one assembly. One camera is pointed directly downwards, and the other two are pointed to either side of the flight path at a 30° depression angle (60° from vertical). The images overlap, allowing the use of stereographic interpretation of the

topography Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary s ...

. The name comes from the

Metrogon Metrogon is a high resolution, low-distortion, extra-wide field (90 degree field of view) photographic lens design, popularized by Bausch and Lomb. Variations of this design are said to have been used extensively by the US military for use in aeria ...

cameras used in the original montages.

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Further reading