vertical air photograph — A photograph taken from the air with the optical axis of the camera perpendicular to the surface of the earth. Vertical photographs have practically a constant scale and are used to prepare maps and detect camouflaged objects. See aerial… … Aviation dictionary
principal vertical — On an oblique photograph, a line perpendicular to the true horizon and passing through the principal point … Military dictionary
ground nadir — The point on the ground that is vertically beneath the perspective center of the camera lens. On a true vertical photograph, this coincides with the principal point … Aviation dictionary
Coastal management — This article is about coastal management aimed to prevent erosion and flooding. For broader management issues, see Integrated coastal zone management. Oosterscheldekering sea wall, the Netherlands. In some jurisdictions the terms sea defense and… … Wikipedia
History of the single-lens reflex camera — The history of the single lens reflex camera predates the invention of photography in 1826/27 by one and a half centuries with the use of a reflex mirror in a camera obscura first described in 1676. Such SLR devices were popular as drawing aids… … Wikipedia
principal parallel — i. On an oblique photograph, a line parallel to the true horizon and passing through the principal point. See photograph parallel. ii. On a vertical photograph, a parallel passing through a photo nadir. Also known as a photo nadir parallel … Aviation dictionary
radial displacement — On vertical photographs, the apparent “leaning out,” or the apparent displacement of the top of any object having height in relation to its base. The direction of displacement is radial from the principal point on a true vertical, or from the… … Military dictionary
Mechanical filter — Figure 1. A mechanical filter made by the Kokusai Electric Company intended for selecting the narrow 2 kHz bandwidth signals in SSB radio receivers. It operates at 455 kHz, a common IF for these receivers, and is dimensioned 45×15×15 mm ( … Wikipedia
painting, Western — ▪ art Introduction history of Western painting from its beginnings in prehistoric times to the present. Painting, the execution of forms and shapes on a surface by means of pigment (but see also drawing for discussion of depictions in … Universalium
climate — /kluy mit/, n. 1. the composite or generally prevailing weather conditions of a region, as temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds, throughout the year, averaged over a series of years. 2. a region or… … Universalium
P in this case is photo nadir, ground nadir and the principle point of the photograph.