The process by which a person extracts information from an image. A series of clues is assembled in an orderly fashion and a solution arrived at that best fits the clues. The interpreter uses seven criteria in interpretation of photo images: tone, texture, pattern, shape, shadow, size, and location (or association).
A series of unmanned earth-orbiting satellites, a joint initiative of the United States Geological Survey (USGS) and the National Aeronautics and Space Administration (NASA). Landsats 1-7 have aquired over 2 million images of the earth's surface since 1972.
One of the air photo interpretation criteria. Regular repetitions of tonal variations on an image or photograph. Some elements of the natural landscape form patterns, for example, river channels may be arranged into distinctive drainage patterns. The human landscape also exhibits patterns, for example the squares of the DLS system.
An optical illusion that may occur on images with extensive shadows. Ridges appear to be valleys and valleys appear to be ridges. The illusion can be corrected by arranging the image so that the shadows trend from the top margin of the image to the bottom
Ratio of distance on an image to the equivalent distance on the ground. It is usually expressed in the form 1:20,000, meaning that one unit of measurement on the photo represents 20,000 of the same units on the ground.
One of the air photo interpretation criteria. As photographs are usually taken when the sky is cloud-free, ground objects will throw shadows. Some shadows are a distinctive shape enabling identification of the ground object.
People see things in three dimensions (i.e., they see stereoscopically) because they see objects from two different viewpoints – the right eye and the left eye. The two sight lines converge on the object being viewed and the two images are processed in the brain to give a three dimensional impression.
One of the air photo interpretation criteria. Technically it is the frequency of change and arrangement of tones on an air photograph. It is best described by reference to the texture of cloth, so photo surfaces may be rough, mottled, silky, etc.
One of the air photo interpretation criteria. A measure of the amount of light reflected by an object and recorded on a panchromatic (black and white) photograph. It is recorded in shades of grey from almost black to almost white.