On 28 March 2008 at 15:54 Artem Pavlenko wrote:
> On 28 Mar 2008, at 15:29, Tom Chance wrote:
> > I'd like to show symbols in the center of certain areas, like the
> > parking symbols in OpenStreetMap:
> > http://www.openstreetmap.org/?
> > lat=51.46993&lon=-0.06831&zoom=16&layers=B
> > 0FT
> >
> > It's not immediately obvious to me how this is achieved, looking at
> > the style sheet:
> > http://svn.openstreetmap.org/applications/rendering/mapnik/osm.xml
>
> > Can anyone enlighten me?
> >
>
> You should be able to use PointSymbolizer/TextSymbolizer/
> ShieldSymbolizer for polygons. Positions are simply centroids atm:
> ....
> <Rule>
> <MaxScaleDenominator>20000</MaxScaleDenominator>
> <Filter>[amenity]='parking'</Filter>
> <PointSymbolizer file="parking.png" type="png" width="16"
> height="16" allow_overlap="false"/>
> </Rule>
> ...
>
> In OSM there is an extra step (I think) in osm2pgsql to
> extract centroids and put them into separate layer.
OK, thanks, so I need to duplicate the add_parking_node function for
other areas, or make it more generic so it works for several different
features? For example power=generator, leisure=sports_centre and so on?
I'm not a C hacker but I'll play around a bit with this part of
output-pgsql.c from osm2pgsql:
void add_parking_node(int id, struct keyval *tags, double node_lat,
double node_lon)
{
// insert into planet_osm_point(osm_id,name,amenity,way) select
osm_id,name,amenity,centroid(way) from planet_osm_polygon where
amenity='parking';
const char *access = getItem(tags, "access");
const char *amenity = getItem(tags, "amenity");
const char *name = getItem(tags, "name");
struct keyval nodeTags;
if (!amenity || strcmp(amenity, "parking"))
return;
// Do not add a 'P' symbol if access is defined and something
other than public.
if (access && strcmp(access, "public"))
return;
initList(&nodeTags);
addItem(&nodeTags, "amenity", amenity, 0);
if (name)
addItem(&nodeTags, "name", name, 0);
if (access)
addItem(&nodeTags, "access", access, 0);
pgsql_out_node(id, &nodeTags, node_lat, node_lon);
resetList(&nodeTags);
}
Kind regards,
Tom
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