distortion—Any shift in the position of an image on a photograph which alters the perspective characteristics of the photograph. Causes of image distortion include lens aberration, differential shrinkage of film or paper, and motion of the film or camera. Frequently referred to as “lens distortion.”

distortion, angular—Distortion in a map projection because of non-conformality. See also conformality.

distortion, radial lens—The change in scale, in an image, with radial distance from the center of the image (optical axis).

distortion, tangential lens—The change in scale, in an image, in a direction tangent to a circle about the optical axis (i.e., perpendicular to the radial direction).

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

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