I'm new to GIS and learning about SRIDs.

Are there still other relevant or commonly used SRIDs than WGS 84 (SRID 4326) or Web Mercator (SRID 3857)?


2 Answers 2


Having different representation systems was indispensable when only paper maps were produced.

Now, with digital maps, that need was divided into two:

  • One is to define geometric properties on objects located on a curved reference surface, such as defining the length of the shortest line on that surface between two points, the area of a polygon defined by its vertices, the location of a point knowing its distance and direction with respect to another, the location of the intersection between two lines, etc. This need can be solved digitally without converting coordinates to other systems, although in practice it is easier to use a different reference system.

  • The second and most important is that the maps are still represented and are still viewed in two dimensions. And whoever looks at a map does not have enough information to convert it to 3D in they mind. So when you see a map in geographic coordinates, you have a very wrong perception about all the geometric properties of the represented objects. And when you view a map in Web Mercator, you have a very wrong perception of the distance between the objects on a curved surface, and therefore also the area that polygons span.


Everyone on the web is using one of those 2 coordinate systems. Google pretty much invented 'web mercator' for its maps, while ESRI maps at the time were using all the other coordinate systems as everyone publishing maps using their own local data and coordinate systems did whatever they wanted. Eventually everyone started standardizing their maps to web mercator to fit onto Google Earth or Google Maps. Then ESRI converted their basemaps from WGS84 to Web Mercator and the rest is history.

As my answer links to above, our system requires measurements in feet, miles, acres, etc. so while we store our data in WGS84 we translate our data to the State Plane Colorado coordinate system via ST_Transform() in PostGIS, but only when we need it via a query or update, etc.

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