[mapserver-users] Finding the centroid given the feature

Steve Lime Steve.Lime at dnr.state.mn.us
Thu May 28 14:12:29 EDT 2009


What version are you using? What data source?

Steve

>>> On 5/28/2009 at 10:01 AM, in message
<6db14d250905280801q3660a6a7ycbcd5f5a238c595c at mail.gmail.com>, Varun saraf
<vsaraf.gmu at gmail.com> wrote:
> Hi,
> 
> I know mapserver uses a point-in-polygon method to find a feature
> given a set of co-ordinates, but can it do the same thing reversed?
> For example. Each polygon I draw has a number associated with it which
> is in a "dbf" file with the same name as the "shp" file that mapserver
> uses to draw the polygons. My current map file allows me to fetch that
> unique number whenever I pass the co-ordinates of any point inside
> that polygon (mapserver uses the point-in-polygon method to fetch me
> the polygonID). The query I use is
> 
> http://127.0.0.1:8123/cgi-bin/mapserv.exe?&map=C:/ms4w/apps/workshop-5.0/testMa 
> p.map&mode=query&mapxy=-77.098617
> 38.87795
> 
> where mapxy keeps changing based on the user's click. The html
> template I send just has the variable name [polygonID] which helps me
> get the polygon ID of the point I specify in the mapxy variable. Now,
> is there a way in which I can send this polygonID to mapserver and get
> hold of any point (perhaps the centroid) inside of this polygon? Can
> someone point me in the right direction here?
> 
> Thanks a lot.
> 
> -Varun
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