[Tagging] Comparison of tag support: Mapnik, Osmarender, Potlatch, JOSM, Kosmos, Map Features (wiki)

Ulf Lamping ulf.lamping at googlemail.com
Mon Dec 14 20:47:47 GMT 2009

Am 14.12.2009 11:02, schrieb Pieren:
> What is "core" and what is not ? What is in the wiki Map Features ?
> But anyone can add his tag, approved by 10 or 12 voters in the Map
> Features...
> You cannot fix priorities for other people creating the data or other
> applications using the data. What is the "core" for OpenCycleMap is
> not the same as the "core" for OpenWaterwayMap, OpenCrimeMap,
> OpenHikingMap, OpenShopMap, OpenTourismMap, OpenSchoolMap, etc...
> You are really expecting too much from the "rendering" side of the
> project.

At least for the OSM based maps I've seen so far, the "core" of features 
that a map "wants" to display is often very similiar: streets, rivers, 
forest, ... plus some special interest stuff specific to this map. This 
isn't true for all maps and obviously maps will use different styles 
(colors, thickness, ...) to display these "core" features in different ways.

However, having a list of features that a lot of other maps are 
displaying will very certainly help map makers in choosing the things 
they want to display. I don't see this as a "has to be implemented" but 
as a toolbox for mapmakers. Just don't underestimate the amount of time 
to get such a knowledge.

> What we need is a clear definition of the tags and this is
> done by searching a consensus on the wiki and on this list and we see
> if we succeed or fail with the statistics.

We have e.g. lot's of highway=path in the database and no one (except 
the mapper) really knows what this *exactly* means in a specific case, 
as there is more than one definition out there. But statistics just 
can't tell you anything about this semantic.

> If we don't have a common
> definition of the tags, we end up with different rendering rules and
> even worst, with different tagging presets in the editors.

The rendering rules doesn't matter a lot in this regard. It only 
displays a cycleway with a certain color, thickness and such - so it can 
be recognized as a cycleway. What the mapper wants to describe with 
highway=cycleway and what a map user understands out of this is 
basically out of the scope of the map display.

> So, what we have to do first, if we have to fix priorities, is to
> improve the definitions of the tags, avoid duplicates or changes in
> the meaning of the tags one year or two after their creation (e.g. the
> other thread about cycleway on this ML).

I just don't know how to stop mappers from using a tag in a way they 
want to use it :-)

Regards, ULFL

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