Classification of projections by the nature of distortion.
• Conformal (conformal) - in these projections, the angles between the directions displayed without any distortion , but there is a curvature of space.
• Equivalent (equivalent) - the projections , which are stored in a ratio of areas on the Earth's surface and in the image. These projections have the distortion angles and lengths.
• equirectangular (equidistant) - is the projection in which the particular scale , one of the main areas is ongoing and is generally one.
• Custom - this projection, for which none of the above conditions is not satisfied, that is curvature , there are at the corner, and on the area, and distance .
Analysis of attributes classification of map projections indicates that the map may not be the angles or distortion or warping space and distance , but at the same time lacking all of these types of distortions can not . The size and distribution of these distortions on a particular piece of card are the main features of the suitability of the map to the solution of a navigation or surveying tasks .
The use and choice of map projections depend mainly on the purpose of the map and its scale, which is often determined by the nature of the allowable distortion in map projections elected maps of large and medium scale, designed to solve the metric tasks usually conformal projection, and small scale maps are used to general review and determine the ratio of the areas of territories - in equal size.
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