[OSM-talk] Suggestion: fallback tag
frederik at remote.org
Thu Dec 17 13:03:38 GMT 2009
Steve Bennett wrote:
> Solution: tag it like this:
This makes only sense if there are certain landuse=reserve areas that
you want to fall back to leisure=park and other landuse=reserve areas
that are more like a natural=grass. And this would then mean that
landuse=reserve is somehow underspecified.
If you have a certain fallback hierarchy that says "dear renderers of
the world, if you encounter something tagged landuse=reserve and you
don't know what to do, then treat it as leisure=park", then it makes
more sense to create this hierarchy externally and feed it to the
renderers, instead of putting bits and pieces of it all over the database!
There are some technical problems, too. Mapnik, for example, renders by
going through the rules one by one, fetching the matching objects, and
Your thinking is obviously the other way round: Take each object in turn
and decide how to render it.
With your approach it is quite easy to have an "else" case that renders
things differently if none of the other rules apply. With Mapnik that is
not so easy.
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