Re: [postgis-users] Create circles using a formula
Hi Brent, I am really thankful for your reply. The equation I am to use for calculating radius is radius=(lambda/4*pi)*sqrt((Pt*Gt*Gr)/Pr) My towers table contains the following columns tid,lat,lon,lambda,Pt,Gt,Gr,Pr so as you said the query should be CREATE VIEW circles AS SELECT tower_id, ST_BUFFER( ST_Transform( ST_SetSRID( ST_MakePoint(lon,lat), 4326), 900913, (lambda/4*pi)*sqrt((Pt*Gt*Gr)/Pr) ) AS tower_circle FROM towers Now for geoserver to generate the circles , creating the postgis store with table data as layer is enough I guess. Am I going in a right way? pcreso wrote: > > I'm not conversant with geoserver but have used mapserver to do this sort > of thing often enough. > > I assume your data is in PostGIS, which means your mapserver DATA > statement can be an embedded SQL query or a PostGIS view. > > You can create a view on your table, along the lines of: > > create view v_table > as select *, buffer(setsrid(makepoint(lon, lat),4326), calculate radius>) as geom > from table; > > (assuming you want the output data in EPSG:4326) > > or you can set up your process to build the geometry in a physical table > doing much the same thing, perhaps as an update or insert trigger? > > Use this view, or table as the "table" you provide the WFS service from, & > the geometries you are providing will be suitably sized circles. > > Note this assumes a constant signal strength unchanged by topography, > which is very simplistic. > > Tools like GRASS allow you to apply a terrain model to the sites & carry > out a line-of-sight analysis to generate more accurate polygons descibing > the expected coverage from a tower. > > If you are displaying thousands of features, you might find WMS with > srever side rendering gives a better response time than WFS. Geoserver can > provide both WMS & WFS services, but I think mapserver has some advantages > in the WMS arena. > > HTH, > > Brent Wood > > > On 02/06/2011, at 3:55 AM, vikashvikky wrote: > >> >> Hi, >> >> I am doing a project for a telecom company. I have to render circles on >> the >> map(assuming the center of the circle as tower and circle as the area >> covered by that signal), I am using base layers as Google Maps,Yahoo >> maps(Spherical Mercator) So I have used CreateGeodesicPolygon() >> successfully >> to create circles by reading the values from DB. >> >> Now Since I have to render lot of circles, it made me switch to >> geoserver. >> Since the data is being provided by telecom company , they provide >> Lat,Lon,Gt,Gr,Pt,Pr,lambda(I think their meaning is irrelevant here) >> values. >> These values are stored in the database as they are. Now should use a >> equation(FRIIS transmission equation) and substitute each row(of a tower) >> values to find the distance covered by the tower.Then I have to create >> circles with that distance(considered as radius) and lon/lat and render >> them >> on map using geoserver. >> >> Please suggest me any ideas of how to carry on this task I wud be >> thankful to your guidance >> -- >> View this message in context: >> http://old.nabble.com/Create-circles-using-a-formula-tp31752667p31752667.html >> Sent from the PostGIS - User mailing list archive at Nabble.com. >> >> ___ >> postgis-users mailing list >> postgis-users@postgis.refractions.net >> http://postgis.refractions.net/mailman/listinfo/postgis-users > > ___ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users > > ___ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users > > -- View this message in context: http://old.nabble.com/Create-circles-using-a-formula-tp31752667p31758593.html Sent from the PostGIS - User mailing list archive at Nabble.com. ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] Create circles using a formula
You could try : http://postgis.refractions.net/documentation/manual-1.5/ST_Buffer.html You might need something like : ST_MakePolygon(ST_ExteriorRing(ST_Buffer(tower.point, resultOfDistanceFunction))) cheers Ben On 02/06/2011, at 3:55 AM, vikashvikky wrote: > > Hi, > > I am doing a project for a telecom company. I have to render circles on the > map(assuming the center of the circle as tower and circle as the area > covered by that signal), I am using base layers as Google Maps,Yahoo > maps(Spherical Mercator) So I have used CreateGeodesicPolygon() successfully > to create circles by reading the values from DB. > > Now Since I have to render lot of circles, it made me switch to geoserver. > Since the data is being provided by telecom company , they provide > Lat,Lon,Gt,Gr,Pt,Pr,lambda(I think their meaning is irrelevant here) values. > These values are stored in the database as they are. Now should use a > equation(FRIIS transmission equation) and substitute each row(of a tower) > values to find the distance covered by the tower.Then I have to create > circles with that distance(considered as radius) and lon/lat and render them > on map using geoserver. > > Please suggest me any ideas of how to carry on this task I wud be > thankful to your guidance > -- > View this message in context: > http://old.nabble.com/Create-circles-using-a-formula-tp31752667p31752667.html > Sent from the PostGIS - User mailing list archive at Nabble.com. > > ___ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] Create circles using a formula
I'm not conversant with geoserver but have used mapserver to do this sort of thing often enough. I assume your data is in PostGIS, which means your mapserver DATA statement can be an embedded SQL query or a PostGIS view. You can create a view on your table, along the lines of: create view v_table as select *, buffer(setsrid(makepoint(lon, lat),4326),) as geom from table; (assuming you want the output data in EPSG:4326) or you can set up your process to build the geometry in a physical table doing much the same thing, perhaps as an update or insert trigger? Use this view, or table as the "table" you provide the WFS service from, & the geometries you are providing will be suitably sized circles. Note this assumes a constant signal strength unchanged by topography, which is very simplistic. Tools like GRASS allow you to apply a terrain model to the sites & carry out a line-of-sight analysis to generate more accurate polygons descibing the expected coverage from a tower. If you are displaying thousands of features, you might find WMS with srever side rendering gives a better response time than WFS. Geoserver can provide both WMS & WFS services, but I think mapserver has some advantages in the WMS arena. HTH, Brent Wood On 02/06/2011, at 3:55 AM, vikashvikky wrote: > > Hi, > > I am doing a project for a telecom company. I have to render circles on the > map(assuming the center of the circle as tower and circle as the area > covered by that signal), I am using base layers as Google Maps,Yahoo > maps(Spherical Mercator) So I have used CreateGeodesicPolygon() successfully > to create circles by reading the values from DB. > > Now Since I have to render lot of circles, it made me switch to geoserver. > Since the data is being provided by telecom company , they provide > Lat,Lon,Gt,Gr,Pt,Pr,lambda(I think their meaning is irrelevant here) values. > These values are stored in the database as they are. Now should use a > equation(FRIIS transmission equation) and substitute each row(of a tower) > values to find the distance covered by the tower.Then I have to create > circles with that distance(considered as radius) and lon/lat and render them > on map using geoserver. > > Please suggest me any ideas of how to carry on this task I wud be > thankful to your guidance > -- > View this message in context: > http://old.nabble.com/Create-circles-using-a-formula-tp31752667p31752667.html > Sent from the PostGIS - User mailing list archive at Nabble.com. > > ___ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
[postgis-users] Create circles using a formula
Hi, I am doing a project for a telecom company. I have to render circles on the map(assuming the center of the circle as tower and circle as the area covered by that signal), I am using base layers as Google Maps,Yahoo maps(Spherical Mercator) So I have used CreateGeodesicPolygon() successfully to create circles by reading the values from DB. Now Since I have to render lot of circles, it made me switch to geoserver. Since the data is being provided by telecom company , they provide Lat,Lon,Gt,Gr,Pt,Pr,lambda(I think their meaning is irrelevant here) values. These values are stored in the database as they are. Now should use a equation(FRIIS transmission equation) and substitute each row(of a tower) values to find the distance covered by the tower.Then I have to create circles with that distance(considered as radius) and lon/lat and render them on map using geoserver. Please suggest me any ideas of how to carry on this task I wud be thankful to your guidance -- View this message in context: http://old.nabble.com/Create-circles-using-a-formula-tp31752667p31752667.html Sent from the PostGIS - User mailing list archive at Nabble.com. ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users