[postgis-users] Coordinate format for SRID:4326

[Gheorghiu, Mihai]

I am confused by the references to "sexagesimal degrees" that I found on this list and elsewhere on the Web.

SRID:4326 used for geography representation in postgis is based on EPSG:4326 (http://spatialreference.org/ref/epsg/4326/postgis/):

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 94326, 'epsg', 4326, '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs ', 'GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4326"]]');

If I query Oracle 10g

SELECT * FROM MDSYS.SDO_CS_SRS WHERE SRID='4326';

WGS 84                4326       4326       EPSG. See 3D CRS for original information source.             GEOGCS [ "WGS 84", DATUM ["World Geodetic System 1984 (EPSG ID 6326)", SPHEROID ["WGS 84 (EPSG ID 7030)", 6378137, 298.257223563]], PRIMEM [ "Greenwich", 0.000000 ], UNIT ["Decimal Degree", 0.01745329251994328]]

My understanding of "decimal degrees" is that 72 degrees 30 minutes are represented as 72.5, and that's the way I used to input coordinates in Oracle.

Now if I want to input the same value in postgis, do I have to use a format such as 72d30m00s00 ("sexagesimal degrees"), or 72.5 ("decimal degrees")?

To add to the confusion, in postgis there is SRID:900914, which is the exact replica of Oracle's 8307, and both use the term "decimal degrees".

 

Thank you very much for your support.

 

Michael

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[Ben Madin]

Michael,

On a computer, use decimal degrees. x axis first (abscissa - Eastings or Longitude), y axis second (ordinate - Northings or Latitude).

In the cockpit, you may find yourself using sexagesimal degrees, and you may hear people quote 'Lat-lon', but if you look at the def's below, you will see +proj=longlat

just my opinion...

cheers

Ben

The information contained in this transmission is to be considered CONFIDENTIAL and PROPRIETARY to Consortium Health Plans, Inc. and intended for the use of the Individual or Entity named above. If the reader of this message is not the Intended Recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is Strictly Prohibited. If you have received this transmission in error, please notify us immediately by telephone at 410-772-2900 or return email to sender immediately. Thank You. _______________________________________________
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