I’ve been thinking about a mapping idea and wanted to ask if anyone has seen something like this before — or if it could make sense to explore together.
You know those little Hinweisschilder (DIN 4066) you see on walls and fences — the blue or yellow plates showing the distance and direction to hydrants, gas or water lines (e.g. “H100 2.3 → 1.8 ↑”)?
They’re everywhere in Germany, and they encode quite a bit of positional information. I’m wondering if anyone has ever tried to collect and interpret those signs to estimate where underground connections or short pipe segments might run.
My rough thought:
Take geotagged photos of the plaques (they’re publicly visible).
Use OCR to read the numbers and arrows.
Combine that with GPS location to approximate the buried line or hydrant connection.
Visualize it on a map
Before I go too far, I’d love to know:
Has anyone in the OSM community already done something similar?
Are there existing tags or conventions for mapping these plaques themselves?
Do you see any red flags (legal, data policy, practicality)?
I’ve seen OpenFireMap and OsmHydrant, but not something that uses the plaques’ geometry.
Has anyone come across this idea or is interested in exploring it?
A total of over 30,000 marker have been added in Germany to date. Source
If I’m not mistaken, @flohoff has already developed a specific process for capturing and processing these. Perhaps he can contribute something here.
Hallo Sebastian, auch von mir ein Willkommen. Das Mappen von Erdeinbauten (Ventile für Wasser und Gas, Hydranten etc.) ist nichts ungewöhnliches. Die gängigsten Elemente sind
Die Hinweisschilder, diese können als marker=plate (+ Zusatztags) erfasst werden.
Die Straßenkappen für die darunter liegenden Einbauteile. Diese lassen sich mit pipeline=valve + utility=* mappen.
Die Hydranten, die als emergency=fire_hydrant (+ Zusatztags) erfasst werden.
Siehe dazu auch die von @mcliquid verlinkten Wikiseiten.
Gruß Mikke
PS: Ich denke auch, Deine Frage ist im deutschen Subforum besser aufgehoben …
At least a few hints, especially in the context of emergency=fire_hydrant.
The plaques are just a help for the fire service and other authorised persons when searching for the hydrant. Relevant is finally the position of the hydrant, not the mark.
There are numerous possible errors:
A slightly horizontal-turned mark results in a completely different position. It can be turned due to vehicles hitting it accidently, vandalism etc.
The distances signed on the mark can vary from the actual position. Because of incorrect measurement, moved signs to another pole without adjustment of the mark etc.
Sometimes there are marks, but no hydrant
Often there are hydrants, but no signs
For this use cases, the mark is not really relevant.
