[postgis] How to Zoom out from an Extent and do a Query feature

Paul Ramsey pramsey at refractions.net
Fri Dec 21 09:08:40 PST 2001


Very slick!

WRT your question, your current solution is what I would suggest from a
postgis point of view. A slightly more naive thing would be to just take
the extent() of the selected geometry and mathematically enlarge the
bbox by 30% or so in all directions.

"Obe, Regina DND\\MIS" wrote:
> 
> I want to thank you all again for the great support I've been given and I've
> been really impressed with the speed and functionality I have achieved using
> mapserver and postgis.
> 
> Below is my first app that uses postgis and Mapserver and there was one
> change that I have been asked to do.  I'm not sure if it is easier to do in
> the mapserver domain or Postgis.
> 
> I would like to generate a map view that is a 300 square radius around the
> parcel that is being focused on or at least be able to zoom out from an
> extent I give to mapserver
> 
> http://www.cityofboston.gov/dnd/REMSfind/PropDetailMP.asp?ParcelID=120138300
> 0
> 
> Right now what I am doing is using the postgis functions to list the nearby
> available parcels below and the extent function to get an extent of the map
> that contains the nearby parcels.
> 
> P.S. I apologize if it is a bit slow - the city hall's webserver is
> sometimes a bit tempermental and also my SQL Server box is inside the
> firewall (also since I was only allowed to have one port opened and not
> allowed to install anything on the city's webserver I am querying the
> Postgis server via my SQL Server box (using it as a linked server to SQL
> Server). Surprisingly even in a linked server mode - the speed is pretty
> decent and superfast in my intranet app.
> 
> The main page is
> http://www.cityofboston.gov/dnd/REMSfind/FindProperty.asp  if you wanted to
> try a search of other parcels
> 
> Also if you wanted to list this application as a sample app using
> postgis/mapserver, we would be very honored.
> 
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> 
> 
> 
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