[OSM-talk] Advanced highway tagging

[Karl Newman]

On Nov 20, 2007 8:32 AM, Martijn van Oosterhout <kleptog at gmail.com> wrote:
> On Nov 20, 2007 4:51 PM, Andrew MacKinnon <andrewpmk at gmail.com> wrote:
> > As for the "zoom level" tag which I proposed, and which has already
> > been criticized, it isn't really a strict tag telling the renderer to
> > "render road X starting at zoom level Y" but rather a tag indicating
> > the "relative importance" of the road, i.e. how important a road is
> > relative to others in the area, so that minor roads in isolated areas
> > are shown at low zoom levels but not all the arterial roads in Central
> > London.
>
> FWIW, the AND data has an importance level, but that's for relative
> *routing* importance.
>
> TBH, I get a little tired of the "the renderer is dumb" argument.
> Sure, they're not smart now but they are just beginning. They will get
> smarter... If we could come up with a way for the renderer to solve
> your problem then the entire issue goes away...
>
Fully agree. I'm actually planning on creating a nice little Java
library for taking a rules file very similar to Osmarender's which
will match rules against OSM elements based on their tags, and apply
an "action" if the rule matches. Initially I plan to contribute it to
Osmosis so it can be used for filtering on tags, but I hope to make it
generic enough so that I can use it for creating GPS maps (yes, I know
about the other projects), where one of the attributes of the "action"
would be a zoom level at which to show the element. Then you could do
something like highway=tertiary (with no other tags) will show at zoom
level 12 and higher, but highway=tertiary, abutters=residential won't
show up until zoom level 14. That should help make the renderers more
"intelligent".