Calibration Definitions for Land Surveyors

calibration—The act or process of determining certain specific measurements in an instrument or device by comparison with a standard, for use in correcting or compensating for errors or for the purposes of record.

calibration, camera— In photogrammetry, the determination of: (a) the calibrated focal length; (b) the location of the principal point with respect to fiducial marks; (c) the point of symmetry; (d) the resolution of the lens; (e) the degree of the flatness of the focal plane; and (f) the effective lens distortion in in the focal plane of the camera, referred to the particular calibrated focal length.  In a multiple-lens camera, the calibration includes the determination of the angles between the component perspective units.  The setting of the fiducial marks and the positioning of the lens are considered as “adjustments” although they are sometimes performed during the calibration process. The distortion and other optical characteristics of a lens are determined in a focal plane, at the equivalent focal length; lens calibration.

calibration constants—The results obtained by calibration which give the relationship of the principal point to the fiducial marks of a camera and the calibrated focal length of the lens-camera unit.

calibration correction— 1 The value to be added to or subtracted from the reading of an instrument to remove a bias in the measurements. 2 The correction to the nominal length between to graduations on a tape needed to account for the difference (calibrated-minus-nominal) between the nominal length and the length found by calibration

Source: NSPS “Definitions of Surveying and Related Terms“, used with permission.

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