Difference between WGS84 and EPSG:4326?

  • What is the difference between WGS84 and EPSG 4326?

    It seems like for a given dataset it might be both WGS84 and EPSG:4326.

  • underdark

    underdark Correct answer

    10 years ago

    4326 is just the EPSG identifier of WGS84.

    WGS84 comprises a standard coordinate frame for the Earth, a datum/reference ellipsoid for raw altitude data, and a gravitational equipotential surface (the geoid) that defines the nominal sea level. [WP]

  • If you're really going to pick a nit: EPSG 4326 defines a full coordinate reference system, providing spatial meaning to otherwise meaningless pairs of numbers. It means "latitude and longitude coordinates on the WGS84 reference ellipsoid."

    The term WGS84 is sometimes used the same way, but also it can refer to the ellipsoid only. For example, you can have "meters northing and easting as measured upon the cylinder formed by projecting the WGS84 ellipsoid using a transverse mercator projection with a central meridian of -123 degrees". (http://spatialreference.org/ref/epsg/32610/)

    In any case: No difference, just like everyone else is saying, except in the very nitty gritty details of how they are used.

    TLDR: No one says "the EPSG 4326 ellipsoid" as part of a coordinate system definition.

  • As far as I can see the two are the same thing. Our definition (in FME) is:

    Coordinate System Parameters

    CS_NAME: LL84
    DESC_NM: WGS84 datum, Latitude-Longitude; Degrees
    DT_NAME: WGS84
    EPSG: 4326
    MAP_SCL: 1
    PROJ: LL
    QUAD: 1
    SCL_RED: 1
    SOURCE: Mentor Software UNIT: DEGREE

    Datum Parameters

    DESC_NM: World Geodetic System of 1984
    SOURCE: US Defense Mapping Agency, TR-8350.2-B, December 1987
    USE: WGS84

    Ellipsoid Parameters

    DESC_NM: World Geodetic System of 1984, GEM 10C
    E_RAD: 6378137
    P_RAD: 6356752.3142
    SOURCE: US Defense Mapping Agency, TR-8350.2-B, December 1987

    OGC WKT Description GEOGCS["WGS84 datum, Latitude-Longitude; Degrees", DATUM["WGS_1984", SPHEROID["World Geodetic System of 1984, GEM 10C",6378137,298.257223563, AUTHORITY["EPSG","7030"]], AUTHORITY["EPSG","6326"]], PRIMEM["Greenwich",0], UNIT["degree",0.0174532925199433], AUTHORITY["EPSG","4326"]]

    ESRI WKT Description GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]]

  • They are certainly not the same. WGS is a datum(for lat/loong specifations) while EPSG is a database of CRS and related information. Those who think these are same actually ignore the basic purpose of EPSG. The main purpose of EPSG is to assign a code for Geodetic Parameter Dataset that contains a repository of parameters needed to define a CRS. This ensures that coordinates describe position unambiguously.

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Content dated before 6/26/2020 9:53 AM