QGIS: Becoming a GIS Power User

Defining custom projections

Map projections stump just about everybody at some point in their GIS career, if not more often. If you're lucky, you just stick to the common ones that are known by everyone and your life is simple. Sometimes though, for a particular location or a custom map, you just need something a little different that isn't in the already vast QGIS projections database. (Often, these are also referred to as Coordinate Reference System (CRS) or Spatial Reference System (SRS).)

I'm not going to cover what the difference is between a Projection, Projected Coordinate System, and a Coordinate system. From a practical perspective in QGIS, you can pick the one that matches your data or your intended output. There's lots of little caveats ...