PLAN281 Lecture Notes - Lecture 4: Nicolas Auguste Tissot, Spatial Reference System, Developable Surface
27 May 2016
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Document Summary
Flatten the earth"s curved surface : map projections are an important aspect of all mapping, all maps require the transformation of the surface of the spherical earth to a flat surface. There will always be a loss of accuracy. Easier to calculate distance with a ruler on a flat map than using an actual globe. Map projections how: perspective projections can be constructed geometrically, ray tracing, all projections can be represented by mathematical equations, computer generation. Perspective projections: transparent globe with a light source, light rays projected on surface (shadows cast on projection surface) Projection parameters: map projection equations have many parameters. Information about the projection parameters is required to define a country"s spatial reference system. Projection properties: all projections have distortions since it"s impossible to represent all geometric relationships among locations on the earth"s surface accurately on a flat 2d map. Tissot"s indicatrix: helps us assess amount of distortion, nicolas auguste tissot, ellipse of distortion.
