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 On 11/07/2011, at 10:40 PM, Gheorghiu, Mihai wrote: > 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 > > 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. _______________________________________________ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users
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