Method of preparation of transparent or opaque of representation of a terrain contour simulated

摘要

916,430. Photographic maps. ACF INDUSTRIES Inc. Jan. 21, 1960 [April 7, 1959] No. 2212/60. Classes 97 (1) and 98 (2). Relates to photographic methods of preparing a transparent or opaque map of an area of the earth's surface such that the optical density at any point on the map is proportional to the height of the corresponding point on the earth's surface. In one embodiment, Fig. 1, radiation such as light, X-rays, neutrons or gamma rays is projected from a source 112 on to a photographic plate 110 through a solid three-dimensional model of the area of the earth's surface formed of material whose radiation absorption is proportional to its thickness, e.g. plaster or lead for light of X-rays, respectively. In another embodiment, Fig. 2, the model 8 is painted white and placed in a tank 160 under a camera 161 and when the camera shutter is opened to make a time exposure a dark opaque fluid, e.g. ink, is allowed to flow from a tank 164 through a valve 165 into the tank 160 so that the lower parts of the model are covered before the higher parts and hence the exposure time of any print on the model is proportional to its height; alternatively a dark-coloured model and a light-coloured fluid may be used. Small apertures are formed in the model at the lowest point in any depressions which have no natural drainage paths to the sea level datum plane and the camera shutter and valve 165 may be controlled electrically. In a modification the model comprises cheese cloth or like material formed to the shape of the earth's surface so that the fluid will rise uniformly throughout. The completed map may be scanned photoelectrically to produce a voltage proportional to surface height as described in Specification 916,431, or the height may be read off a calibrated light meter held over the map.