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Cartographical Map Projections

Cartography, the science of map-making, comprises many problems and techniques, including:

South America in selected projections at the conventional aspect and identical scaling factor. Which projection is best? Which is right? The short answer is none, at least not all the time. Even if a single projection is used, just switching the aspect can radically reshape the continents. But if you want an educated answer, please keep reading.

There is an endless variety of geographic maps for every kind of purpose. When looking at two different world maps one can wonder why the differences: do we draw the world as a rectangle, or an oval? Shouldn't it be a circle? Must coordinate grid lines be parallel? Straight or curved? Does South America's “tail” bend eastwards or westwards? What's the “right” way (or, more properly, is there a right way?) to draw our unique planet?

One important concern of cartography is solving how to project, i.e. transfer points from an almost spherical lump of rock — our Earth — onto flat surfaces, either paper pages or computer screens.

Here are informally described important cartographic concepts, how maps are drawn and why there are so many different kinds of projections for world maps. You may start reading here and follow the Click buttons like this one to go ahead buttons, or use this table of contents:

Introduction Introduction A gentle introduction to tinkering with maps
Definitions Basic definitions and concepts about the Earth, maps and the mapmaker's choices
Fitting Map to Purpose Useful properties Useful map properties:
Mathematics of Cartography Creating projections How projections are created, including equations for:
Main Projection Groups Azimuthal Azimuthal projections, perspective or not
Cylindrical Cylindrical projections, arbitrary or perspective
Pseudocylindrical Pseudocylindrical projections, pure, continued or crossbred
Conic projections Conic projections, non-perspective and polyconic
Pseudoconic projections Pseudoconic projections
Modified azimuthals Modified azimuthal projections
Conformal Conformal projections
Others Other interesting projections
Coping with Distortion
Oblique Tilted and crooked projections: oblique maps
Interrupted maps Tearing Earth's skin: interrupted maps
Polyhedral projections Rebuilding the Earth into an exotic planet: polyhedral maps
Pieces of History Premodern projections Projections developed before the Modern Age
Projections at Work Specialized Projections which helped making the world smaller: the Mercator and azimuthal equidistant
Applications of Projections Some unusual applications of map projections (in construction)
Conclusion Summary of projections Summary and list of featured projections
Resources and Links Resources and links
Quick answers and personal rants

HomeSite MapSelect ColorsIntroduction — June 16, 2018
Copyright © 1996, 1997 Carlos A. Furuti