Processing Digital Maps - Programming GPS and OpenStreetMap Applications with Java - page 91

Map feature Extraction (ms) File name File size

places 2496 RGB-NW place.osm 4,363,790

highway.trunk 2303 RGB-NW hw.tr.osm 917,613

highway.primary 2334 RGB-NW hw.1.osm 976,845

highway.secondary 2289 RGB-NW hw.2.osm 930,736

highway.tertiary 2529 RGB-NW hw.3.osm 1,099,032

highway.unclassified 2369 RGB-NW hw.un.osm 1,070,351

highway.road 2655 RGB-NW hw.rd.osm 958,407

highway.track 2696 RGB-NW hw.tk.osm 1,669,279

waterway.river 2565 RGB-NW ww.rv.osm 957,725

railway.rail 2430 RGB-NW rw.rl.osm 933,845

natural.wood 2991 RGB-NW na.wd.osm 970,275

natural.water 2412 RGB-NW na.wt.osm 943,960

30069 15,791,858

RGB-NW.osm 6,092,583

Table7.3. Extracting map layers from RGB-NW.

7.8 Parsing OSM Files with the OSMparser

JOSM and osmosis are part of the openstreetmap map-production process.
The tools can be used to check-out map data, modify it, and check it back in
to the map server. Due to the large number of users and contributors, these
standard tools should be used when possible. On the other hand, XML is
also a well-defined standard and OSM files have a simple structure:

wiki.openstreetmap.org/wiki/Elements

Our maps are made up of only a few simple elements,
namely nodes, ways, and relations. Each element may have an
arbitrary number of properties (a.k.a. Tags) which are Key-
Value pairs (e.g., highway=primary).
A tag is not an element but a property attached to a node,
way or relation.

A look at the file RGB-NW.osm (OSM version 0.5) with a text editor reveals
a lot of map-production-related information:

1: <node id="232389894" uid="109925" changeset="2150422"
user="hajopei" timestamp="2009-08-15T08:35:28Z"
version="2" lat=49.0455424 lon=12.13113>
2: <tag k=created_by v=JOSM />
3: </node>