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
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
