[postgis-users] equal area projection

[Mark Cave-Ayland]

mark balman wrote:

> Hi all
>  
> I am trying to add a new equal area projection into postgis (behrmann 
> and/or Robinson). I am struggling to get this to work. From the 
> "spatialreference.org <http://spatialreference.org>" website I uploaded 
> the following into postgis:
>  
>  INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, 
> srtext) values ( 954017, 'esri', 54017, '', 
> 'PROJCS["World_Behrmann",GEOGCS["GCS_WGS_1984",DATUM["WGS_1984",SPHEROID["WGS_1984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Behrmann"],PARAMETER["False_Easting",0],PARAMETER["False_Northing",0],PARAMETER["Central_Meridian",0],UNIT["Meter",1],AUTHORITY["EPSG","54017"]]');
>  
> After this I add some data in Behrmann projection using shp2pgsql, but 
> trying a transform query such as
>  
> select AsText(transform(GeomFromText('Point(-75 10)',4326),954017))
>  
> does not work and crashes postgis.
>  
> I really need to get a global equal area projection to work for my 
> project (have been using Plate Carree, but obviosly not good 
> for performing area intersects) and would be grateful for any pointers 
> on how to do this.
>  
> Many thanks
>  
> Mark


Hi Mark,

The SRTEXT parameter is actually not used for PROJ.4 transformations - 
it's the proj4text field which is the important part and it appears it's 
blank in your SQL above. If you can find the equivalent PROJ.4 
description, you should be fine.

BTW I'm quite surprised that PROJ.4 crashes with an empty proj4text - 
which version of PostGIS are you using?


ATB,

Mark.

-- 
Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
http://www.siriusit.co.uk
t: +44 870 608 0063