principal point


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principal point

[′prin·sə·pəl ′pȯint]
(optics)
The intersection of a principal plane with the optical axis.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

principal point

As it relates to photography, it is the foot of the perpendicular to the photo plane through the perspective center. Generally, it is determined by the intersection of the lines joining opposite or diagonal collimating or fiducial marks. See also collimating marks.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved
References in periodicals archive ?
Above it the digradato foreshortens the grid by extending the vertical lines back toward the principal point E.
Le principal point de passage frontalier du Nigeria avec le Benin, le poste frontalier de Seme, qui est le point de passage terrestre le plus frequente du Nigeria et le principal couloir commercial d'Afrique de l'Ouest, a ete ferme sans preavis mardi apres que des camions de produits medicaux interdits, de tramadol et de codeine, ont ete interceptes a Lagos le 16 aout.
Il a indique que le principal point de contentieux demeurait la composition de la future instance devant diriger la transition.
"The principal point in our review petition today was that having accepted our principle, the court has increased the number in a manner which has no real-life or practical application.

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