Hi!
Jon Burgess schrieb:
> The odd thing is that the main OSM site interprets the same data
> correctly so I believe there must either be a difference in the style or
> newer osm2pgsql version.
Now everything is clear. The behaviour in my case is caused by the line
node,way highway text polygon
in the style file. The polygon type was introduced when I added the area
type highway=pedestrian_area to the rendering rules.
With the default style, the roundabouts come out fine, but I would
assume that all squares tagged with highway=pedestrian_area but not with
an area=yes tag do not show on the standard maps.
So basically, what I need to do is
- change highway back to linear
- either make sure pedestrian areas all have an area=yes or map
pedestrian_areas to an arbitrary tag which is imported as a polygon
The difference in behaviour to the standard maps is caused by a
different principle for the rendering rules.
In the standard setup, you import the whole planet file and all the
filtering is done by the rendering rules. This causes some quite complex
rendering rules with long exclusions in order to avoid multiple
renderings that are triggered independently by different tags. E.g. when
I have a rule for bridges and a rule for tunnels and a rule for
roundabouts, all other road rendering rules must have a tunnel != 'yes'
and bridge != 'yes' and junction != 'roundabout'.
To simplify this, in my setup the rendering rules are already applied to
the data in a preprocessing step and the tags that would trigger
unwanted copies are removed. The mapnik style file contains only the
positive rules. This makes the mapnik style much easier to understand
and results in simpler and theoretically faster SQL queries at render
time. But of course it only works if my understanding of the behaviour
of osm2pgsql and mapnik are correct. Sometimes it is not, but we're
getting there. :-)
Thanks for the information, I'm sure I'll get this working now.
Nop
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