Coordinate Systems

To accurately map a world like Toril, you need a Coordinate Reference System (CRS). Ours are custom-built on the planet’s known dimensions for maximum precision. We use two types: a Geographic Coordinate System (GCS) that treats the world like a globe (using degrees), and a Projected Coordinate System (PCS) that flattens the globe onto a map for your screen (using meters or feet).

1. The Map You See (Map Window CRS)

The main map view in QGIS uses the Patterson projection. Using a PCS is essential for maintaining a consistent map scale, which allows the project’s “smart” styling to function correctly. This ensures that icons, labels, and symbols resize properly and remain visible as you zoom and pan across the map (see Working with Layers & Styles).

We specifically chose the Patterson projection for its visual similarity to the common form of Plate Carrée (in which the grid of parallels and meridians forms squares), the projection used in most of the original source maps. This allows us to preserve the familiar shapes and proportions of the continents as they were originally depicted. Our Patterson PCS uses the FRIA Prime Meridian, an internal reference line derived from the original Forgotten Realms Interactive Atlas.

2. The Coordinates You Use (Displayed Coordinates CRS)

The technical FRIA meridian mentioned above is arbitrary; it has no significance in the world’s lore and just happened to be in the center of the original source maps. To provide meaningful coordinates for you to use, we created a separate, lore-friendly GCS. This system is based on the Myth Drannor Prime Meridian, which passes through the ancient elven city. This meridian was mentioned by the setting’s creator, Ed Greenwood, and serves as the official “Greenwich” of Toril, making the coordinates you see in the interface truly meaningful.

3. How The Data is Stored (Storage CRS)

“Under the hood,” all geospatial data in the project’s GeoPackage file is stored in a GCS based on the technically convenient, but arbitrary, FRIA Prime Meridian. You don’t interact with this system directly; it’s the internal foundation that ensures everything aligns perfectly with the source material.

Summary

You don’t need to worry about these different systems, as the QGIS project file handles them automatically. Here’s a quick recap:

System	Role	Prime Meridian	Why?
Toril PCS / Patterson	What you see on screen	FRIA	For a stable map scale & “smart” styling in QGIS.
Toril GCS (Myth Drannor)	The coordinates you read	Myth Drannor	For lore-friendly coordinates that you can use.
Toril GCS	How data is stored	FRIA	For technical alignment with the original source maps.

To learn more about the technical details of Toril GIS’s coordinate systems, please read our in-depth blog post: Crafting Coordinate Systems for Faerûn and Beyond.

For detailed examination and customization, the WKT-CRS definition files for all systems are available in the Toril GIS repository on GitHub.