Don, 4030 is missing datum information so I think when you transform the datum gets ignored which means best proj can guess is that 4030 and 4267 should return same number since it can't tell if they are the same or different datum
4030 looks like this - "+proj=longlat +ellps=WGS84 +no_defs " I suspect you should be using 4326 which looks like this "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs " When I use 4326 with your example select X( Transform( SetSRID(MakePoint(-86.123456789::double precision,34.123456789::double precision),4326),4267 ))::double precision, Y( Transform( SetSRID(MakePoint(-86.123456789::double precision,34.123456789::double precision),4326),4267 ))::double precision; I get the below which accounting for rounding differences is about the same -86.1234814621629;34.1233611276746 Hope that helps, Regina -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Don Sent: Thursday, October 30, 2008 11:11 PM To: PostGIS Users Discussion Subject: [postgis-users] different answers for Transform and cs2cs I have basically the same transformration encoded below in 2 different ways. One uses transform the other the program cs2cs. I am just trying to convert a latlong to a different datum. It seems that I am getting the wrong answer with Transform. select X( Transform( SetSRID(MakePoint(-86.123456789::double precision,34.123456789::double precision),4030),4267 ))::double precision from al_ent; x --------------- -86.123456789 -86.123456789 >cs2cs +proj=latlong +datum=NAD83 +to +proj=latlong +datum=NAD27 -f %.12f<<EOF > -86.123456789 34.123456789 > > -86.123481462163 34.123361126798 -0.000032913871 _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users ----------------------------------------- The substance of this message, including any attachments, may be confidential, legally privileged and/or exempt from disclosure pursuant to Massachusetts law. It is intended solely for the addressee. If you received this in error, please contact the sender and delete the material from any computer. _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
