principal distance

principal distance

[′prin·sə·pəl ′dis·təns]
(graphic arts)
The perpendicular distance from the internal perspective center to the plane of a particular finished negative or print, or of a drawing.

principal distance

A standard by which photographic print is measured in terms of the focal length of the camera used at the time of film exposure. It is said to be of the same length as the focal length. Such a standard applied to an enlarged, reduced, or shrunken photographic print is determined by the ratio of the enlargement or reduction.
References in periodicals archive ?
The camera calibration necessitates estimating the interior orientation parameters (IOPs) of each camera, which include the principal distance, the principal point offset, and any necessary distortion or additional parameters.
contains the distortion-free coordinates of image space point, i, or the distortion-free projection of point I in the frame of camera [c.sub.k], where ([mathematical expression not reproducible]) are the observed or distorted image coordinates for point i; ([mathematical expression not reproducible]) is the principal point offset; [mathematical expression not reproducible] is the principal distance; and ([mathematical expression not reproducible]) are the image space distortions for point i.
The nominal principal distance of the cameras varied between 22 mm and 28 mm.

Full browser ?