[OSM-talk-be] Ways with identical coordinates on top of each other

[Marc Gemis]

I assume OSM always has been a 2.5D map. I'm thinking about tunnels
and bridges. To properly map them, we always needed the level tag. So
any data consumer that creates a road network from OSM will need to
have knowledge about the level tag.
Of course, the example that you mention, of indoor mapping with
multiple levels, is not properly solved by carto-css (the default
rendering on osm.org). The problem will also occur for POIs on
different floors. People have been experimenting with other
representations to make this type of data understandable.
I guess more and more 3D features will be added to the data, the
question is how fast will the data consumers come up with
representations that are easy to understand.

regards

m.

On Thu, Aug 8, 2019 at 12:22 PM Florian Goetghebeur
<florian.goetghebeur at be-mobile.com> wrote:
>
> Hello,
>
> I recently came across a parking building with multiple floors in OSM, in which ways are tagged with 'level' and 'layer' tags. It struck me that there are ways that have the very same geometry on different levels (see links below). As a result, the map has four arrows (one for each level), indicating the oneway direction, with only little space in between. It looks strange to me. But having nodes and ways stacked on top of each other might have other unwanted consequences, e.g. when you try to process the OSM data to get a road network for routing and you do not take the level and layer tags into account.
>
> So I am now wondering about the community's vision about this 2D vs 3D issue. Can OSM still be seen as a 2D map? In what way is OSM evolving regarding this topic? We now have this strange blend between a 2D visualization and a few 3D tags that can cause issues. The notes and comments for the nodes below show that there have been problems already.
>
> Thanks for sharing your insights!
>
> Four nodes at the same location:
> https://www.openstreetmap.org/node/4359171125
> https://www.openstreetmap.org/node/4359171126
> https://www.openstreetmap.org/node/4359171127
> https://www.openstreetmap.org/node/4359171128
> Two ways with the exact same coordinates:
> https://www.openstreetmap.org/way/438182278
> https://www.openstreetmap.org/way/438182283
>
> Kind regards,
> Florian
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