Thanks Greg,
I don't know in practice if I will need the minutes and seconds, as you
say degrees with decimal information is probably more accurate. If I
store degrees in decimal I will need to convert back and forth though as
people will use GPS to enter lat and long into the system. I need to be
able to work out route lengths for various transport modes as well as
integrating (in the future) with GIS mapping software such as ESRi or
MapInfo.
I have subscribed to the Open Geospatial Consortium and downloaded their
"common architecture" which includes an SQL model... But it is a lot to
take in, so any guidance is appreciated.
Thanks and regards
John
Gregory S. Williamson wrote:
We have had good success with postGIS for storing various spatial data sets (polygons, points and lines).
They can be found at <http://postgis.refractions.net/>.
We store our data in lat/long but postGIS has many different spatial reference systems defined and I would suspect that minutes/seconds exists. You may want to subscribe to and post your question on the postGIS mailing list.
There are windows-ready compiled versions which seem to work well, although I've only played with them for prototypes (our real database servers are all linux so I can't be of any help on the Windoze front).
In general support for this extension of postgres is quite helpful, so I would suggest asking on their general list.
HTH,
Greg Williamson
DBA
GlobeXplorer LLC
-----Original Message-----
From: pgsql-general-owner@xxxxxxxxxxxxxx on behalf of John Tregea
Sent: Sun 6/11/2006 11:18 PM
To: pgsql-general@xxxxxxxxxxxxxx
Cc:
Subject: [GENERAL] Help with storing spatial (map coordinates) data?
Hi,
I have recently switched to PostgreSQL and had no problem bringing our
existing (my)SQL databases and data into the environment. I am now
extending the functionality of our databases and want to start storing
spatial information.
The information is made up of latitude and longitude coordinates that
define a point or location on the earth's surface. e.g. degrees, minutes
and seconds north/south and degrees, minutes and seconds east/west.
I have read up on custom data types (with input and output functions) in
the docs but am not sure if that is the best way to go. Can anyone point
me to a simple, workable implementation of storing and managing this
type of data or advise me on how to structure a series of fields that
could combine to the required string?
I am running postgreSQL 8.1.4 under WinXP Pro and currently evaluating
an X-Talk front end called Revolution for the GUI development and have
only some general experience with SQL.
Thanks in advance
John Tregea
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