[Tagging] Tagging of larger surfaces for rendering and routing

Stefan de Konink stefan at konink.de
Sun Aug 14 20:21:17 UTC 2016


Hi,


As followup for:

http://forum.openstreetmap.org/viewtopic.php?id=55457
https://github.com/gravitystorm/openstreetmap-carto/issues/2282

The problem;

Consider a large area that doesn't have explicit roads. It could be a 
field of grass or a sahara of sand. Typically such surfaces are tagged as 
landuse with objects such as housing on top. It surely looks good on a 
rendered map, but for routers, journey planners, topology cannot be 
inferred by the node, way and relation model. Secondary the wiki[1] 
suggests that routers should only use highway=* and junction=*, which 
makes sense.

As specific example on the forum I am micromapping a campingplace and 
would like to use highway=service to access camp_site=pitch. In real life 
this is sometimes a field of grass passing by pitches that are also fields 
of grass with some barrier=hedge around it to separate it from the field.

As can be seen in the github issue the current rendering of a 
highway=service, area=yes results in a white void where the landuse=grass 
is ignored. Cartographers throw in the argument that the map is not a 
vectorised version of satellite imagery. Which is true of course, on the 
other hand: is a field of grass is not the same as a paved 
plaza tagged as highway=pedestrian, area=yes while, the net effect for an 
unpaved field is generally the same.


The result;

I would prefer that the map looks like its landuse, but this specific 
landuse's primary intention is facilitating access to properties and other 
objects. For journey planners this area topology folds back to a single 
vertice where from multiple locations, sharing a node with the osm-way 
acting as area, can be reached.


My proposal;

Considering that in the camping site example highway=service is primary 
used to facilitate access to pitches, I would like to see 
highway=service, surface=grass, area=yes possibly in combination with 
landuse=grass as indication to render this surface not as a white void, 
but as a green field.

The alternative might be to define a user defined highway tag such 
as highway=grass.


My current workaround;

highway=grass, area=yes is not rendered which basically gives me the best 
of all worlds. Rendering is done by the underlying landuse, routing is 
facilitated by the highway=* match.



Matthijs suggested this was a better fora to discuss the issue, than the 
carto github issue tracker. So here I am.


Stefan


[1] http://wiki.openstreetmap.org/wiki/OSM_tags_for_routing



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