[OSGeo Africa] SRID

[Gavin Fleming]

In PostGIS: SELECT * FROM spatial_ref_sys;

The only problem is, for SA projections like the LOs on Hartebeesthoek
datum, proj4 can't handle a south-facing projection (yet) and be aware
in PostGIS that while their EPSG codes are defined properly, the
matching proj4 strings are undefined (at 1.2 at any rate). 

I have some LO 27 data in PostGIS that QGIS and uDIG couldn't project,
yet GeoServer did. For the South African EPSG LO definitions to apply
though, you have to swap your x and y signs (though not the axes). 

A workaround in South Africa is to use normal Transverse Mercator on
Hartebeesthoek and standardise the axes and signs (i.e. make them look
conventional like the rest of the world) - then just define your own
EPSG (and proj4) code and add a record to PostGIS. 

Here's an Albers one I use a lot:

srid,auth_name,auth_srid,srtext,proj4text
40000,EPSG,40000,PROJCS["South Africa Albers Equal Area
24",GEOGCS["GCS_Hartebeesthoek_1994",DATUM["D_Hartebeesthoek_1994",SPHER
OID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["D
egree",0.0174532925199433]],PROJECTION["Albers"],PARAMETER["False_Eastin
g",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",24.
0],PARAMETER["Standard_Parallel_1",-18.0],PARAMETER["Standard_Parallel_2
",-32.0],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]],+proj=ae
a +lat_1=-18 +lat_2=-32 +lat_0=0 +lon_0=24 +x_0=0 +y_0=0 +ellps=WGS84
+units=m +no_defs 

Gavin 
 
 

-----Original Message-----
From: africa-bounces at lists.osgeo.org
[mailto:africa-bounces at lists.osgeo.org] On Behalf Of Tim Sutton
Sent: 17 February 2009 13:57 PM
To: Africa local chapter discussions
Subject: Re: [OSGeo Africa] SRID

Hi


On Tue, Feb 17, 2009 at 12:10 PM,  <bartvde at osgis.nl> wrote:
> Hi,
>
> SRID is an Oracle term so I assume you are talking about Oracle
Spatial.
>
> It's in a table called CS_SRS in the MDSYS schema:
>
> select * from MDSYS.CS_SRS
>
> Best regards,
> Bart
>
>> Hi All,
>>
>> First posting!!!
>>
>> Where can I get a list of SRID's.
>>
>> Regards,
>>
>> Clinton Papenfus
>> 0833767083



For a user friendly list of CRS's you can also click on the icon in
the bottom right corner of the QGIS window, and you will be presented
with a CRS list. Click on any CRS entry to see its proj4 definition.

Regards

Tim

-- 
Tim Sutton - QGIS Project Steering Committee Member (Release  Manager)
==============================================
Visit http://linfiniti.com to find out about:
 * QGIS programming services
 * Mapserver and PostGIS based hosting plans
 * FOSS Consulting Services
Skype: timlinux Irc: timlinux on #qgis at freenode.net
==============================================
_______________________________________________
Africa mailing list
Africa at lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/africa

This message is intended for the addressee only. 
Information and attachments in this e-mail may contain confidential, proprietary, or legally privileged information. 
If you are not the intended recipient, or responsible for delivery of the message to the intended recipient, 
any disclosure, copying, distribution, or any action taken is prohibited and may be unlawful, 
and could result in a claim against you.