Highway bridges as 3D buildings?

General talk
1

Several bridges in Hannover are mapped as 3D buildings. I noticed them because the Mapbox/Maplibre GL renderer shows them as buildings on the highway.

Examples:
https://www.openstreetmap.org/way/715002669
https://www.openstreetmap.org/way/714027954
https://www.openstreetmap.org/way/712600320

This seems very unusual to me. If I understand the wiki correctly instead the bridge outline should be mapped as

man_made=bridge.

.
https://wiki.openstreetmap.org/wiki/Key:bridge

I would like to find out how 3D mappers are mapping road bridges (for vehicles) usually but so far I haven’t found anything (only bridges as part of a building).

Is there a renderer which shows these bridges nicely? How can Maplibre GL be improved? Is there a tag to distinguish buildings from bridges?

2

well, it may be unusual, but it works somehow.

1st question

checkout https://osmbuildings.org/?lat=52.37930&lon=9.74493&zoom=17.0&tilt=30 for H-town-bridge.
checkout https://osmbuildings.org/?lat=51.50552&lon=-0.07537&zoom=17.2&tilt=30 for Tower-Bridge also.
f4mapDemo wont show anything if there are only building:parts with no surrounding outline. :frowning:
so the trusses on Tower-Bridge are missing https://demo.f4map.com/#lat=51.5056920&lon=-0.0752519&zoom=18

2nd question

Hmm? I dont know. You better ask the developers. :slight_smile:

3rd question

Hmm? You can add [https://wiki.openstreetmap.org/wiki/Tag:man_made%3Dbridge] if you like.

EDIT: !! some warning on trying your own 3D-experiments !!

its sad, but the osmbuildings rendering engine is broken, causing incorrect output on handling of building relations, heights and roof orientations. https://github.com/OSMBuildings/OSMBuildings/issues/250. so dont rely on it. … I dont believe that there will be a retrogressive update, cause of going commercial with https://3dbuildings.org/.

3

Concerning 1:
I didn’t know about osmbuildings.org – that looks awesome, thanks!

Concerning 2:
You are right, this is up to the developers. However, they would need to know how to distinguish a building from a bridge.

Concerning 3:
If I understand the wiki correctly you would either map an element as a bridge using “man_made=bridge” or as a building using “building” or “building:part”. So it seems to me as if mapping bridge parts as building:part is a new tagging scheme which is not documented yet in the wiki.

Actually, the wiki page about bridges mentions tags about the structure :

I think it would be better to extent the tags of “man_made=bridge” to include “bridge:part” instead of reusing “building:part” only to display it on osmbuildings.org

4

There is a proposal on 3d bridges but it seems to be stale: https://wiki.openstreetmap.org/wiki/Bridge3D

5

We need a bridge tag or a structure tag acting like the building tag, I think. And NO, cause it’s common technology it works on https://demo.F4map.com and possibly http://maps.osm2world.org/ too. see given examples.

good proposal, but not the end-of-the-road, i think.

EDIT: some thoughts about 3D bridges.

Its true that a bridge is a (man_made) structure, not a building (will say: no walls, no roof, no levels). But we haven’t a concept about that. So if you wanna add some 3D features, simple 3D buildigs (S3DB) is the only method to support this actually. We can use parts, heights, materials and colours here. The result is simple 3D bridges or simple 3D structures (S3DS). But as I say, there’s no tagging concept for that. To come to more complex structures (will say: trusses, arches, cables, sloped pillars) we need a 3D expansion like the https://3dmr.eu/. But that’s experimental too, and definitely harder to support.

6

take a look at [https://wiki.openstreetmap.org/wiki/OSM2World/WebGL_client].

there’s a video about the ongoing development on https://wiki.openstreetmap.org/wiki/OSM2World at FOSSGIS 2019 (de). No bridges mentioned in SOTM 2019 (en) but some ideas on roads, signs and street funiture. You can contact the developer for beta-testing.