[OSM-talk] Enabling communities to use OSM as a planning tool

[Jon Burgess]

On Wed, 2008-06-04 at 11:09 -0400, simon at mungewell.org wrote:
> At present they can achieve the same effect using off line file and
> merging layers before rendering.
> 
> To make the process more smooth maybe some (or all) of the following
> can
> be implemented:
> 
> 1) Enable the render to use multiple '.osm' files for rendering,
> automatically merging or laying onto the output.

The osm2pgsql code used for the mapnik layer can already load multiple
osm files into a single render database (see the --append option).

Alternatively the Mapnik osm.xml file can easily pull in data from many
different sources when rendering. The existing style already uses
multiple database connections and shapefiles to build up the main map.

If the data was in the DB then it would be a bit tricky to exclude data
from the rendering. We would need to have prior knowledge of what tags
to exclude from rendering.  I personally think it would make more sense
to keep the data out of the main OSM DB. 

For simple route planning it perhaps makes more sense to do a simple
overlay. It should be fairly simple to overlay a GPX file to show the
new routes and is compatible with non-OSM tools.

The only disadvantage I can see with an overlay approach is that you
can't show how the map would look if you took away features that were
already mapped in the OSM layer.

	Jon