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Currently the wikipage for the layer=* tag has all sort of recommandations. It seems that in practice, layers are hard-ignored in a number of circumstances. In this case I need a grassy area to be on top of the building: this parking garage is built "into the hillside" and at its top can be rolled onto (as can be clearly seen on aerial imagery). However I have been resolutely unable to force the landuse area to layer on top.

Is there a way to actually achieve that or has this been made specifically impossible in the Map style?

asked 05 Apr '12, 22:54

Circeus's gravatar image

accept rate: 7%

When editing osm-data you may want to keep in mind that osm is primarily a geo-database and the map on is only one possible representation out of this data. If you are not happy with the rendering style provided you are free to use the data and render with it another map according to your needs.

The argument not to tag things incorrectly for the renderer is often used to remind mappers that the database and a resulting map are two different things.

With regard to your case I would suggest to consider the "grassy area on a building" as a roof and tag it accordingly. There are various tagging options for building attributes however not widely used an thus not rendered ond (yet). Tagging the building a layer=-1 is factually incorrect as it is a building which is clearly above ground.

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answered 06 Apr '12, 14:33

FischersFritz's gravatar image

accept rate: 0%


I'm going to go on stron record here as saying that if the renderer is willfully displaying correct tagging incorrectly, that's turning a feature into a bug and a terrible thing to have in the system. If layers work for roads and are not explicitly restricted to them features, telling people not to tag for the renderer and then specifically not following the tags in use on semantic grounds (reality is stranger than imagination!) is undermining the entire argument.

(06 Apr '12, 14:56) Circeus

I do have some doubt, if there is such a thing as an objectively "correct tagging" in osm.

I personally, do not see any good reasons to implement any layer-tagging for landuse objects. Landuse typically refers to somewhat larger areas, and in this case one might consider the landuse to be somewhat transportation-related, or somewhat hospital-related.

If landuse may be understood as the way the land is use by humans, then "grassy" doesn't seem to be an appropriate value for the landuse-tag. Grass rather refers to a surface. So why not use the surface=grass with the roof-tagging?

(06 Apr '12, 15:14) FischersFritz

I'm using "grass" because this is private land where no other use is really logical (universities do not have parks in them!). Additionally, the area in question is pretty much outright an extension of the hillside on top of the building, which is most certainly not carried over properly by a roof tag as far as I am concerned.

(06 Apr '12, 17:02) Circeus

Did you try to use the layer=-1 tag for the parking garage ?

(I see you had the parking garage at layer=0 and the grassy area as layer=1 but they shared the same nodes in a couple places, so that may have been a cause of it).

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answered 05 Apr '12, 23:23

skorasaurus's gravatar image

accept rate: 12%

edited 05 Apr '12, 23:28

No. I was worried because of the surrounding amenity=university area, and one can only fiddle so much with layers before the map (or your brain) melts down.

(05 Apr '12, 23:24) Circeus

I see you changed the nodes, thanks for that, but it seems unfortunately not to have helped one bit. Tried to put the building at layer -1 and the landuse at layer 1. If that fails, I'll be at a complete loss.

(06 Apr '12, 14:12) Circeus

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question asked: 05 Apr '12, 22:54

question was seen: 4,420 times

last updated: 06 Apr '12, 17:02

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum