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missing spatial data CRS format SRID 4978? RRS feed

  • Question

  • Hi,

    I have point coordinates in EPSG CRS 4978 format. However there is no any SRID 4978 in

     

     

    spatial_reference_systems

    How do I create table and insert data then?

    Regards

    Valko

    Saturday, April 17, 2010 5:33 PM

Answers

  • Hi Valko -

    From what I can determine , EPSG 4978 is functionally equivalent to EPSG 4326 from SQL Server's standpoint.  Here are the well-known text strings for each CRS:

    EPSG 4978
    GEOCCS["WGS 84",DATUM["World Geodetic System 1984",SPHEROID["WGS 84",6378137.0,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0.0,AUTHORITY["EPSG","8901"]],UNIT["m",1.0],AXIS["Geocentric X",OTHER],AXIS["Geocentric Y",EAST],AXIS["Geocentric Z",NORTH],AUTHORITY["EPSG","4978"]]

    EPSG 4326
    GEOGCS["WGS 84", DATUM["World Geodetic System 1984", ELLIPSOID["WGS 84", 6378137, 298.257223563]], PRIMEM["Greenwich", 0], UNIT["Degree", 0.0174532925199433]]

    Both are defined as WGS 84 and both use the idential SPHEROID/ELLIPSOID definitions.  Note, however, that EPSG 4978 is defined with a GEOCCS keyword while EPSG 4326 uses a GEOGCS keyword. From an ESRI web site describing coordinate systems, "A dataset's coordinate system is identified by the PROJCS keyword if the data is in projected coordinates, by GEOGCS if in geographic coordinates, or by GEOCCS if in geocentric coordinates."

    Do note that EPSG 4978 units are in meters and EPSG 4326 units are in degrees. I'd have to take a look at your coordinates to be absolutley certain, but it appears that you should be able to load your EPSG 4978 point coordinates into SQL Server as EPSG 4326 with no loss in data fidelity.

    Can anyone else provide additional detail or correction to my response?

    Thanks,

    - Ed

    • Proposed as answer by Spatial Ed Tuesday, April 27, 2010 8:52 PM
    • Marked as answer by Tom Li - MSFT Friday, April 30, 2010 9:48 AM
    Tuesday, April 27, 2010 8:13 PM