Hi there OSM community,
I have a question concerning the POI layer of OSM and how it is being used in navigation systems that use OSM as a map. I couldn’t really find a clear answer anywhere, so I thought I’d post it here. I’d like to know (or find out how I can look this up) how many navigation apps/systems use the OSM map, and how many of these use the actual OSM POI layer, or if they create their own?
This would help me out enormously, so any help is appreciated!
Thanks in advance.
There is NO poi layer in OSM … OSM is just a database where different services get their data from
See the OSM wiki about http://wiki.openstreetmap.org/wiki/Routing
and pay attention to online or offline solutions.
Hi Stephan, thanks for the reply.
This doesn’t seem right though, since I’ve searched up some things on Navmii (which also seems to use OSM as a baselayer, even though this isn’t mentioned in the wiki), and this doesn’t have the same POI’s as OSM. The POI’s that are in OSM aren’t visible in Navmii, so it seems they have their own POI layer over it.
A couple of points…
Firstly, what stephan75 said is absolutely correct - there is no “POI layer” in OSM. However, it’s perfectly possible for anyone to extract different sorts of data from OSM and display it in “layers” either on a website or in an application.
Secondly, when talking about routing what you see on screen usually isn’t what’s used internally by whatever calculates the routing - though they will be based initially on the same OSM data. This sometimes manifests itelf on online routers when they haven’t updated their routing engine with recent OSM data, but are displaying recent OSM data on map tiles.
Thirdly, when it comes to what POIs are or are not displayed, what’s available within the OSM data is far more than any one online or offline map would ever want to display, so it’s quite common to see OSM-based maps not showing everything within the data, or showing some things within the data that don’t appear on other OSM-based maps. It’s also possible of course to combine OSM data with other suitably-licensed non-OSM data.
If you’ve got a particular question about a particular app you’ll probably need to ask the authors of that app. In the case of closed-source ones they’re the only people who will be able to answer your questions.
Edit: Actually a good example of most of the points above is http://osm-nottingham.org.uk/. It includes OSM data not normally displayed on other maps as well as non-OSM data on the same map.
Also, even when a map rendering displays a particular type of POI from the underlying OSM data, it will only do so to the extent that that can be done without conflicting with the display of other data. E.g. in a parade of shops, some may be suppressed, because they are too close to others, and some may not be named, because the label would conflict with another symbol.