Emilie Laffray wrote: > On 23/01/2010 06:38, Sam Vekemans wrote: > >> Mapnik -osm2pgsql layers >> >> Thats awesome visualization! >> >> Is it possable to create a mapnik osm2pgsql set of layers that would >> allow seeing just select features? >> >> I guess im talking about a wmf service. (which i barely understand) >> But wont that require separate hosting of the data? (or rather, a >> rendering of the planet that just has land & sea) where all the other >> features can be added with a osm2pgsql layer? >> >> (if you dont follow, thats ok) >> >> All i need to know if its technically possable :) ~ probably just >> requires oodles of computing power for it. >> >> Cheers, >> Sam >> >> > > You don't necessarily need a WMS server. You can create queries directly > through postgis and add it to a layer; for example, http://beta.letuffe.org/ > I don't know how it is configured but the person behind it Sylvain > Letuffe would glad to explain if need be. It was this server that we use > to overlay the CORINE rendering over the current map. This serveur is > used to visualize boundaries in France. > > Emilie Laffray > Hi Sam, Emilie,
What I did, and what is also done on the site of Sylvain Letuffe, is generating transparent images. Instead of specifying a background color in the XML config for Mapnik, you can also specify "transparent" as background. Furthermore, it is possible to specify the opacity for feature classes, so all sorts of combinations are possible. If you have multiple such layers, and use them as overlays, then you get the effect that you can toggle layers on and off. This requires less processing power and is faster than WMS, because these tiles can be cached or prerendered, which is not really feasible with WMS. (This is unless you use WMS with a tile cache.) Frank _______________________________________________ Talk-ca mailing list Talk-ca@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-ca
