orthodrome—See great circle.
orthogonal—At right angles; rectangularly; meeting. crossing, or lying at right angle.
orthographic projection—See projection, orthographic.
orthometric correction—See correction, orthometric.
orthometric elevation—See height, orthometric.
orthometric error—See error, orthometric.
orthophotograph—A photograph prepared from a perspective photograph by removing those displacements of points caused by tilt, relief, and central projection (perspective).
orthophotograph, digital—An orthophotograph produced through differential rectification in a softcopy plotter.
orthophotomap—Map made by assembling a number of orthophotographs into a single, composite picture; orthophotomosaic. See also orthophotograph.
orthophotomosaic—An assembly of orthophotographs forming a uniform-scale mosaic.
orthophotoscope—A photomechanical device, used in conjunction with double- projection anaglyphic instrument, for producing orthophotographs
orthorectification—See rectification, differential.
Source: NSPS “Definitions of Surveying and Associated Terms“, used with permission.