GEOG 2420 Study Guide - Final Guide: Quartzite, Optical Axis, Network Layer
6 Dec 2014
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Document Summary
If you have a single image you can obtain: scale of photograph, object height object length, area of an object perimeter of an object, grayscale tone or color. Multiple overlapping images can obtain: precise object location (x,y) of building footprints, streets, shorelines in standard map projections, precise object heights (z) Scale of aerial photo: expresses relationship between distance on image & actual ground distance (larger the # in scale expression, smaller the scale) Photo-scale reciprocal (psr): inverse of representative fraction (if rf is 1:200,000, then psr is 200,000) Method 1 compare size of object measured in real world (or from map) to same object on an aerial photo (ab is size of object on aerial photo compared to actual length, ab) Method 2 compute relationship between camera lens focal length and altitude of aircraft (f is the camera focal length and h is the flying height above the ground)
