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Air Mapping isill!»2 per cent on either side. Each roll1 -of film is 380 feet long, six inches wide, and-is sufficient to make l£5;t:pn 1 A-JJ Oai[exposures, of three pictures each,:ureal a i u, oaiu ^ ^ a° ^ °r *7 matelv sntmrp miles.Timber and Water Power Possibilities Axe Clearly Shown—-Much Cheaper Than Other Meansmately 400 square miles.The pictures are taken through a hole in the bottom of the plane, which is fitted with a water-tight hatch. When the plane leaves thej water, the cover is taken off • and camera adjusted. The camera is sus-While complete topographic maps [ pended in the fuselage of the planeare not made from the.photographs Taken by the Alaska aerial survey detachment, under the command of Lieut. Comm, A. W- Radford, U. S. xL. now basing at Juneau, they do supply information by which base maps showing shore lines, streams, lakes and cultural features such as roads, trails, houses, and so forth, may be made, R, H. Sargent, topographic engineer, representing the TJ. S. department of the interior -with the mapping party, said in an interview given to the Juneau £m-Dire.t! s; ri b V a o i Un£hafcsibi1jOther Methods ExpensiveTo secure such information by the ordinary ground methods of topographic mapping is extremely arduous and expensive. The added value of zhese photographs is the great amount of valuable information regarding the timber and water power possibilities to the U. S. forest service, he said.on a huge gtohal ring, the same as( is used'for the compass of a ship. I _ which permits it to be accurately! level.The average mapping Sight, is about four hours. It requires about one hour to reach the mapping altitude of 11,000 feet and the planes travel about 75 miles, more or less, in reaching this elevation.The crew of a mapping plane consists of the pilot, whose business is to fly the plane along the course) “is at a constant altitude and on an even keel; the navigator, who navigates the ship and directs the pilot in the course to be flown; and the photographer, who operates' the camera. All of these men are kept extremely busy with their several duties, especially the photographer, for exposures are made averaging from 12 to 22 seconds apart, de-j pending on the ground speed of the plane. The ground speed varies ac-la addition to the mapping- pic- j cording to whether the plane isj tuxes, which are taken, through the flying with or against the wind, i bottom of the plane, many oblique At the end of a mapping flight, j Pictures are taken over the side of the photographs are brought into IThe plane at lower altitudes, showing in greater detail the timber and water power possibilities. These are taken with large one-lens cameras. he said.Cameras Used The cameras used for aerial-mapping are constructed with three lenses with an auxiliary fourth lens to be used if desired. Three pictures are taken simultaneously with each exposure, the middle lens taking a vertical picture, and the twothe complete laboratory on the barge and axe immediately developed. They are cut into 130 foot strips, developed and placed on a huge reel for drying. They are then csre-tully inspected and numbered so that any of the thousands of photographs may be instantly identified at any time.When the pictures are inspected and numbered, the films are sent to Washington, where the negatives are printed. The central picture isside lenses, which are obliquely set a contact print, while the two end taking distorted pictures which pictures are placed in a transform -must be adjusted at the Washing- er which, produces a keystone-ton, D. C., office by films printed shaped print. The set of three, by means of what is called a trans- representing one simultaneous ex-lOrming printer.For mapping purposes, the pictures must overlap at least 60 perposure of the three lenses., are mounted together as one picture and are ready for the work of -the-cent ui the direction of flight and cartographer, or map maker
Newspaper Details
Fairbanks Daily News Miner
Fairbanks, Alaska, US
Sat, Jul 13, 1929
Page 5
Full Page
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Anonymous
FL, USA 18 Apr 2020
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