UserAndre Castro/maps01

Maps

I have recently found open street maps, an alternative to googlemaps. Not only it is a open-source project that allows anyone to contribute for the improvement of the maps, but it has a great feature of allowing data inserted by the users to be retrieved.

I would like to use in to create non-functional maps or trajectories that could open new perspectives on on the city space. (situationists echos)

OSM Elements

source: http://wiki.openstreetmap.org/wiki/Map_Features

maps are made up of a few simple elements (Data primitives): 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). (All editing interfaces use the elements and allow the input of tags. )

NODE - the basic element, building block. Nodes consist of latitude and longitude (Nodes are needed to define a way, but a node can also be a standalone unconnected point representing something or points of interest (POI). Standalone nodes should always have at least one Tag such as amenity=telephone). Example <node id="25496583" lat="51.5173639" lon="-0.140043" version="1" changeset="203496" user="80n" uid="1238" visible="true" timestamp="2007-01-28T11:40:26Z"><tag k="highway" v="traffic_signals"/> </node>

WAY - ordered interconnection of at least 2 or more nodes can describe a street, footpath, railway line, river, fence, power line, area or building outline. CLOSED WAY - the first and last nodes are identical, enclosing an AREA eg:

 <way id="5090250" visible="true" timestamp="2009-01-19T19:07:25Z" version="8" changeset="816806" user="Blumpsy" uid="64226">
   <nd ref="822403"/>
   <nd ref="21533912"/>
   <nd ref="821601"/>
   <nd ref="21533910"/>
   <nd ref="135791608"/>
   <nd ref="333725784"/>
   <nd ref="333725781"/>
   <nd ref="333725774"/>
   <nd ref="333725776"/>
   <nd ref="823771"/>
   <tag k="highway" v="unclassified"/>
   <tag k="name" v="Clipstone Street"/>
   <tag k="oneway" v="yes"/>
 </way>

Retrieve Data

To acess data of a given area in http://www.openstreetmap.org/ go to Export Menu and check the coordinates. they organized as [bbox=lat,long, lat++, long++] area[1,3,2,0] or in other works [lat,long, lat++, long++]

EXAMPLES: search a small are in west Rotterdam: http://open.mapquestapi.com/xapi/api/0.6/node[bbox=4.4552603823670465,51.91739525301985,4.46384345121436,51.920373035178464] -O rotterdam-west-test.osm

search pubs in Rotterdam wget http://open.mapquestapi.com/xapi/api/0.6/node[amenity=pub][bbox=4.3142405612056836,51.87797066611181,4.588898764319719,51.973245376533505] -O rotterdam-pub-test.osm

search for libraries in the London: wget http://open.mapquestapi.com/xapi/api/0.6/*[amenity=library][bbox=-0.57,51.24,0.31,51.75] -O london.osm

I am having trouble finding the ways in the xml data

Ways get rendered as streets/railways/footpaths/canals etc according to the tag(s) indicating what type of way it is.'´' Ways are contiguous and non-branching. (You can get from beginning to end by following segments of the way, without "jumping" or backtracing)

eg: <tag k="addr:street" v="Mauritsstraat"/>

relevant links:

http://derickrethans.nl/what-is-openstreetmap.html Good explanation of OSM project

http://weait.com/content/openstreetmap-planet-file

http://derickrethans.nl/spatial-indexes-data-sqlite.html

SVG

osmarander is an applicaiton to create svgs out of osm data http://wiki.openstreetmap.org/wiki/Osmarender

Gave it a try with XMLstarlet, but didn't menage to get it. Try another evening

Mapgen is another possibility http://wiki.openstreetmap.org/wiki/Mapgen.pl