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I'm interested in using OSM infrastructure and tools (e.g.: database schema and software) without the standard global dataset--to map and perform routing calculations on a local dataset (private/offline database) of an area that's small enough that using planar coordinates measured relative to a local origin (e.g.: a corner inside a large building) is much more straightforward than using global lat/lon coordinates (it's difficult to measure where a reference point at the site is actually located in global lat/lon, and all measurements of site features/positions will necessarily be done using planar survey techniques (e.g.: using theodolites, or tape measure and taut string...); and the local curvature of the earth is negligible on this scale, so...). Is it possible to just do this with local planar coordinates? Or do I need to pick a (probably arbitrary) global frame of reference and convert my planar measurements into lat/lon? |
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No problem at all. I regularly load OSM data into PostGIS using osm2pqsql a variety of such co-ordinate systems (British National Grid, Swiss National Grid, Irish Grid, some US State Planes etc). osm2pgsql has flags to change the co-ordinate system used. For raw OSM data you may need to do more work (e.g., load in WGS84, and add additional columns in PostGIS for your favoured system). Another option is to use Geography datatypes in PostGIS. With very small datasets you may be able to do such re-projections on the fly in a tool such as QGIS. Other options include using OSGeo's ogr range of tools. The actual choice will depend on what specific issues you are interested in, what type of data you want to consume, and what outputs are desired. Notably anything to do with route calculations will involve options other than those described here. |
