Geographic Coordinate Systems 101: A Primer for Software Generalists
Before I started working on the project, I thought that all coordinate formats were the same, with Google maps being the standard. However, I shockingly learned that there are hundreds of geospatial systems discovered a whole new world full of pain, abbreviations, unknowns, and more abbreviations.
All of the different standards and systems have a different approach to the same problem: how to present the surface of the Earth.
In this post, I'll take a shallow dive into geographic coordinate standards and systems to explain the differences between them and introduce the most popular ones. Then I’ll build on that knowledge to talk about GeoJSON to help you choose the right tools for your project.
There are four main factors to every coordinate system: an ellipsoid model, a horizontal datum, a vertical datum, and units. The differences often depend on the map's purpose — a map for military missions at sea should optimize for different factors than a cadaster.
As the Earth is not perfectly spherical, a map needs to create a model of an ellipsoid that approximates the Earth's curvature. Various systems differ based on the shape of this ellipsoid — the radius at the equator and the flatness at the poles are two main variances.
