|This page is about the "old" Osmium. For the new version see http://osmcode.org/libosmium .|
Most OSM conversion and exporting tools give you some kind of config file that allows you to map OSM tags to output attributes. But this is often not enough. Think of two examples:
- Roads can have oneway tags. Allowed and often used values include "1", "yes", "true", "false", and "-1". In the output (say a Shapefile or PostgreSQL table you just want boolean (yes or no). You have to map "1", "yes", "true", "-1" to yes and "false" to no. In addition you have to turn the order of the nodes in the way around if it is "-1".
- If you want to generate maps for specific languages, you have to look at several different tags to decide which name you want to use for labelling: "name", "name:LANGUAGE", "local_name", etc. Depending on what you want to do exactly, you might prefer one of the other name, etc.