About Projections

About Coordinate Systems

Another name for projections, a discussion of the different ways coordinate systems get specified and the many different standards understood by Manifold.

Projections Tutorial

It's all about flattening a more-or-less round Earth.  Nice essay on what Columbus looked like, too.

Projections Readings

A short, "jump" topic with credits to the USGS publication heavily quoted, originally written by J.P. Snyder.

General Projections Concepts

Snyder's introduction to projections.   Still the best.

The Earth as an Ellipsoid

What an ellipsoid or datum is and why they are used.  

Guide to Selecting Map Projections

Snyder's advice on how to pick a projection for a map.  This is important so you can use the map how you want, not just to create a pretty map.

Projections Album

Extensive collection of topics illustrating the various main projections people use.