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A brief introduction to map projections By Mark VanderVen vanderm6@cc.wwu.edu. Cartography. No simple, easy definition. We’ll define it as the study, science, history, and art of map-making. . Cartography. Comprised of many techniques and methods.
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A brief introduction to map projectionsByMark VanderVen vanderm6@cc.wwu.edu
Cartography No simple, easy definition We’ll define it as the study, science, history, and art of map-making.
Cartography • Comprised of many techniques and methods. • Includes measuring the earth's shape, distances, and features • Collect and store information about terrain, places and people • Create and design processes for graphical representation of data • Print and publish spatial information. • Adapt three-dimensional features to flat models
A spherical surface (or section of) cannot be transformed to a planar (flat) surface without incurring some distortion
Projection “A mathematical development of one surface onto another. In the cartographic context, one surface is the earth and the other is a flat surface such as a map. The mathematics usually convert from the spherical coordinates of latitude and longitude to a Cartesian coordinate system. The projection is one element of a coordinate system definition.” Norm's GIS Glossaryhttp://www.mentorsoftwareinc.com/resource/glossary.htm
Second Defintion • A map projection is a systematic transformation of the latitudes and longitudes of locations from the surface of a sphere or an ellipsoid into locations on a plane. Maps cannot be created without map projections. All map projections necessarily distort the surface in some fashion. https://www.revolvy.com/main/index.php?s=Orthographic%20projection%20in%20cartography
…more simply put… • A map projection is a flat map surface representing all or part of a spherical surface (Earth).
A spherical surface (or section of) cannot be transformed to a planar (flat) surface without incurring some distortion REMINDER
Map properties that can be distorted • Shape • Area • Distance • Direction
For a web page on coordinate systems see: http://www.colorado.edu/geography/gcraft/notes/coordsys/coordsys.html
Comparisons ESRI “No Projection” (Lat/Long) Mercator
Conclusions Different projections are used to preserve • Shape • Area • Distance • Direction No projection can do all simultaneously.
For More • What on Earth are Map Projections Prof. Alan Saalfeld Geography Ohio State University Click Here for pdf