I've been searching for an EPSG code for the coordinates I'm working with: geodetic latitude and longitude (not geocentric) and height above the WGS84 ellipsoid. I don't care about coordinate order. EPGS:7912 is very close but it's based on the GRS80 ellipsoid and my data is with respect to the WGS84 ellipsoid.

Does this EPSG code exist? What is it?


EPSG/WKID number 4326 relates to WGS84 Geographic, with units in degrees. The ellipsoid is extremely similar to GRS80, with only a slight difference in one of the axes. This is the code and system that the Global Navigation Satellite System (GNSS) is based on (also known as GPS, for the American constellation of satellites). GNSS/GPS satellites are positioned based off of this ellipsoid.

Note that for height values in GNSS or WGS84 data, height is represented as being above or below the reference ellipsoid. In many instances, data provided will reference a GEOID, which incorporates gravitational and terrestrial information and applies a change to the ellipsoid at any given grid position. But EPSG refers simply to the horizontal coordinates, in degree units for WGS84, as the system relates to map projection and coordinate information. Height or elevation values are typically treated separately, even though for data such as GNSS/GPS positioning they're all provided together, and reference the same ellipsoid.

In some instances (I have not encountered such a case), if you need an EPSG that specifically references the vertical dimension above or below the ellipsoid, you can use EPSG 4979 (WKT here). This references the same ellipsoid, but if a Set RSID call needs this dimension, it is included.

  • Yes 4326 is good for 2D coordinates but I ultimately need to create a 3D PostGIS geometry object and provide a CRS code for it. Basically I'm looking for a 3D version of 4326 where height above the ellipsoid is the third dimension. Do you know of an existing EPSG code for this?
    – medley56
    Dec 6 '17 at 23:59
  • 4326 applies to the vertical dimension as well - see gis.stackexchange.com/questions/3334/…
    – AlecZ
    Dec 7 '17 at 1:05
  • 1
    No it doesn't. See the WKT here: epsg-registry.org/export.htm?wkt=urn:ogc:def:crs:EPSG::4326
    – medley56
    Dec 7 '17 at 16:28
  • That's interesting - see the updated answer above and let me know if that works
    – AlecZ
    Dec 7 '17 at 19:50

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