Photo Definitions for Land Surveyors
Photoalidade—An instrument similar to the plane-table alidade by the use of which the horizontal direction and the depression angle to any point on an oblique aerial photograph can be obtained. It is used for making a map from oblique photographs.
photo control—See control, photo.
photocontrol point—See control point [PHOTOGRAMMETRY].
photograph—1 A positive or negative image of an object produced on a photosensitive material by the chemical action of light or other radian energy. 2 The print made from the negative or positive. Photograph may be exposed or printed using any one of these types of emulsion panchromatic, negative or positive color, infrared color, or infrared black and white.
photograph, rectified—1 A conventional vertical photograph which has been corrected for the effects of tilt. 2 A digital vertical photograph which has been rectified. A rectified photograph is not corrected for relief displacement since there is only one average elevation used in the corrective process.
photograph center—The center of a photograph as indicated by the fiducial mark or marks of the camera. In a perfectly adjusted camera, the photograph center and the principal point are identical.
photograph meridian—See principal plane [PHOTOGRAMMETRY].
photograph nadir [PHOTOGRAMMETRY]-See nadir.
photograph parallel—See principal plane [PHOTOGRAMMEURY).
photograph perpendicular—The perpendicular from the interior perspective center to the plane of the photograph.
photograph plumb point—Synonymous with “photograph nadir,” which is preferred. See nadir.
photographic interpretation—The determination of the nature of objects imaged on a photograph.
photographic mission—The process of taking a series of consecutive aerial photographs over one area and on the same day.
photoidentification—1 The detection, identification. and marking of survey stations on aerial photographs. Positive identification and location are required if survey data are to be used to control photogrammetric compilation of maps. 2 The process of showing the location, on a photograph, of ground points in relation to surrounding detail and identifying on the ground the points marked and described on the photograph.
photo scale—The ratio of a specified distance on a photograph to the corresponding distance on the ground. Due to the nature of aerial photographs, photo scale can vary according to elevation; therefore, an average photo scale is often used.
Phototheodolite—A survey instrument combining a theodolite and a metric camera. in which the relationship between the camera axis and the line of collimation of the theodolite can be measured. See also camera, terrestrial.
phototriangulation, analytical—A procedure in which the spatial solution is obtained by computational routines. When performed with aerial photographs, the procedure is referred to as “analytical triangulation.”
Source: NSPS “Definitions of Surveying and Related Terms“, used with permission.
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