Geological survey

Aerial Photography: Introduction to Photo Interpretation 1955 US Geological Survey

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• published: 24 Jan 2015
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more at http://search.quickfound.net/map_search_and_news.html 'INTRODUCTION TO PHOTO INTERPRETATION FOR THE DISCOVERY AND EVALUATION OF NATURAL RESOURCES... Provides training in the techniques of photo interpretation for the discovery and evaluation of the natural resources of a country or region. The film begins with a summary of the idea of "resources," and their development by mankind for a variety of purposes. Early on in the film the case is presented for the verification of information by a study of the ground area, and an understanding of ground truth. The use of aerial photography is introduced first by showing how trees and vegetation coverage is evaluated and interpreted by the Forest Service. In this sequence, kinds of timber are differentiated and their images on photography examined. The difference between soft pine and hardwood deciduous trees is noted on the photos. Further analysis carried out by use of counting of crowns in measured areas, and by looking at crown size and forest density. A second segment details how Geologic maps can be made and benefit from aerial photographic interpretation. It is noted that color imagery adds a ueful and helpful dimension to the process of detecting certain minerals and formations. Ground Truth observations, and verification for accuracy of interpretation are stressed. The interpreter should have direct familiarity with the various areas he is mapping and interpreting. In the third segment, soil mapping by photo interpretation is covered. Large areas can be quickly and relatively accurately characterized, but an emphasis on ground truth and familiarity with soil types, and soil chemical analysis is given substantial weight. The general correlation of the soils and the chemistry of them with local geological structure and water abundance is also intimated. The fourth segment discusses photo interpretation of hydrologic detail. Again,ground truth is emphasized to allow characterization of hydrology from the specific to the general to be made with confidence. Vegetation and geologic structure also arefactors which are considered in the hydrologic photo-interpretation.' Public domain film from the US National Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied. The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original). http://creativecommons.org/licenses/by-sa/3.0/ http://en.wikipedia.org/wiki/Aerial_photography Aerial photography is the taking of photographs of the ground from an elevated position. Usually the camera is not supported by a ground-based structure. Platforms for aerial photography include fixed-wing aircraft, helicopters, multirotor Unmanned Aircraft Systems (UAS), balloons, blimps and dirigibles, rockets, pigeons, kites, parachutes, stand-alone telescoping and vehicle mounted poles... The first commercial aerial photography company in the UK was Aerofilms Ltd, founded by World War I veterans Francis Wills and Claude Graham White in 1919... Operations began from the Stag Lane Aerodrome at Edgware, using the aircraft of the London Flying School... From 1921, Aerofilms carried out vertical photography for survey and mapping purposes. During the 1930s, the company pioneered the science of photogrammetry (mapping from aerial photographs), with the Ordnance Survey amongst the company's clients. Another successful pioneer of the commercial use of aerial photography was the American Sherman Fairchild who started his own aircraft firm Fairchild Aircraft to develop and build specialized aircraft for high altitude aerial survey missions. One Fairchild aerial survey aircraft in 1935 carried unit that combined two synchronized cameras, and each camera having five six inch lenses with a ten inch lenses and took photos from 23,000 feet. Each photo covered two hundred and twenty five square miles... A year later, Fairchild introduced a better high altitude camera with nine-lens in one unit that could take a photo of 600 square miles with each exposure from 30,000 feet... http://en.wikipedia.org/wiki/Aerial_photographic_and_satellite_image_interpretation Photographic interpretation is “the act of examining photographic images for the purpose of identifying objects and judging their significance” (Colwell, 1997)... Principles of image interpretation have been developed empirically for more than 150 years. The most basic of these principles are the elements of image interpretation. They are: location, size, shape, shadow, tone/color, texture, pattern, height/depth and site/situation/association. These are routinely used when interpreting an aerial photo or analyzing a photo-like image. A well-trained image interpreter uses many of these elements during his or her analysis without really thinking about them...