GIS FAQ

Here are some Frequently Asked Questions about Geographic Information Systems.

See other FAQs at FAQ or Category:FAQ.

If you have a question not on this list, feel free to ask it in one of the Contact channels.

What geographic datums are used in OpenStreetMap?

OpenStreetMap uses the WGS 84 lat/lon data exclusively. All uploaded tracks and edits should always be in WGS 84, the default data for GPS receivers.

What is the map scale for a particular zoom level of the map?

Main article: Slippy_map_tilenames#Resolution_and_Scale

Why aren't you using Open Geospatial Consortium (OGC) schemas and software for OpenStreetMap?

We choose technology for openstreetmap.org based on speed & flexibility. Some OGC standards and implementations fit this bill, but others do not. We used to use MapServer for serving static versions of our maps, but unfortunately we found it to be unthreaded, slow, and hard to extend - we replaced it with Mapnik. If you'd like to develop integration with OGC tools, let us know.

See Why not GPX? for a similar discussion about why GPX was rejected as a transport format.

What Geotagging do you use?

Main article: Geotagging