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osm2pgsql ========= Converts OSM planet.osm data to a PostgreSQL database suitable for rendering into map tiles by Mapnik. The format of the database is optimised for ease of rendering by mapnik. It may be less suitable for other general purpose processing. For a broader view of the whole map rendering tool chain see http://wiki.openstreetmap.org/index.php/Mapnik http://wiki.openstreetmap.org/index.php/Osm2pgsql http://wiki.openstreetmap.org/index.php/Slippy_Map You may find that the wiki pages are more up to date than this readme and may include answers to issues not mentioned here. Any questions should be directed at the osm dev list http://wiki.openstreetmap.org/index.php/Mailing_lists Features ======== - Converts OSM files to a postgresql DB - Conversion of tags to columns is configurable in the style file - Able to read .gz, .bz2 and .pbf files directly - Can apply diffs to keep the database up to data - Support the choice of output projection - Configurable table names - Gazetteer backend for Nominatim http://wiki.openstreetmap.org/wiki/Nominatim - Support for hstore field type to store the complete set of tags in one database field if desired Source code =========== The latest source code is available in the OSM SVN repository and can be downloaded as follows: $ svn co http://svn.openstreetmap.org/applications/utils/export/osm2pgsql Build requirements ================== The code is written in C and C++ and relies on the libraries below: - libxml2 http://xmlsoft.org/ - geos http://geos.refractions.net/ - proj http://www.remotesensing.org/proj/ - bzip2 http://www.bzip.org/ - zlib http://www.zlib.net/ - PostgreSQL http://www.postgresql.org/ - PostGIS http://postgis.refractions.net/ To make use of the database generated by this tool you will probably also want to install: - Mapnik from http://mapnik.org/ Building ======== Make sure you have installed the development packages for the libraries mentioned in the requirements section and a C and C++ compiler. e.g. on Fedora: # yum install geos-devel proj-devel postgresql-devel libxml2-devel bzip2-devel gcc-c++ on Debian: # aptitude install libxml2-dev libgeos-dev libpq-dev libbz2-dev proj autoconf automake libtool make g++ On most Unix-like systems the program can be compiled by running './autogen.sh && ./configure && make'. Operation ========= You must create a PostgreSQL user and a database with the postgis functions enabled. This requires access as the database administrator, normally the 'postgres' user. The default name for this database is 'gis' but this may be changed by using the osm2pgsql --database option. If the <username> matches the unix user id running the import and rendering then this allows the PostgreSQL 'ident sameuser' authentication to be used which avoids the need to enter a password when accessing the database. This is setup by default on many Unix installs but does not work on Windows (due to the lack of unix sockets). Some example commands are given below but you may find this wiki page has more up to data information: http://wiki.openstreetmap.org/wiki/Mapnik/PostGIS $ sudo -u postgres createuser <username> $ sudo -u postgres createdb -E UTF8 -O <username> <dbname> $ sudo -u postgres createlang plpgsql <dbname> Adding the postgis extensions. Note the location of the files may vary. $ sudo -u postgres psql <dbname> < /usr/share/postgresql/8.4/contrib/postgis-1.5/postgis.sql $ sudo -u postgres psql <dbname> < /usr/share/postgresql/8.4/contrib/postgis-1.5/spatial_ref_sys.sql Next we need to give the <username> access to update the postgis metadata tables $ sudo -u postgres psql -d <dbname> -c "ALTER TABLE geometry_columns OWNER TO <username>" $ sudo -u postgres psql -d <dbname> -c "ALTER TABLE spatial_ref_sys OWNER TO <username>" The 900913 is not normally included with postgis. To add it you should run: $ sudo psql -u postgres psql -d <dbname> -f 900913.sql If you want to use hstore support then you will also need to enable the PostgreSQL hstore-new extension. $ sudo -u postgres psql <dbname> < /usr/share/postgresql/8.4/contrib/hstore.sql Now you can run osm2pgsql to import the OSM data. This will perform the following actions: 1) Osm2pgsql connects to database and creates the following 4 tables: - planet_osm_point - planet_osm_line - planet_osm_roads - planet_osm_polygon The prefix "planet_osm" can be changed with the --prefix option, the above is the default. 2) Runs an XML parser on the input file (typically planet.osm) and processes the nodes, ways and relations. 3) If a node has a tag declared in the style file then it is added to planet_osm_point. If it has no such tag then the position is noted, but not added to the database. 4) Ways are read in converted into WKT geometries by using the postitions of the nodes read in earlier. If the tags on the way are listed in the style file then the way will be written into the line or roads tables. 5) If the way has one or more tags marked as 'poloygon' and forms a closed ring then it will be added to the lanet_osm_polygon table. 6) The relations are parsed. Osm2pgsql has special handling for a limited number of types: multipolygon, route, boundary The code will build the appropriate geometries by referencing the members and outputing these into the database. 7) Indexes are added to speed up the queries by Mapnik. Tuning postgresql ================= For an efficient operation of postgresql you will need to tune the config parameters of postgresql from its default values. These are set in the config file at /etc/postgresql/8.4/main/postgresql.conf The values you need to set will depend on the hardware you have available, but you will likely need to increase the values for the following parameters: - shared_buffers - checkpoint_segments - work_mem - maintenance_work_mem - effective_cache_size A quick note on projections =========================== Depending on the command-line switches you can select which projection you want the database in. You have three choices: 4326: The standard lat/long coordinates 900913: The spherical mercator projection, used by TileCache, Google Earth etc. 3395: The legacy (broken) WGS84 mercator projection Depending on what you're using one or the other is appropriate. The default mapnik style (osm.xml) assumes that the data is stored in 900913 and this is the default for osm2pgsql. Combining the -v and -h switches will tell about the exact definitions of the projections. In case you want to use some completely different projection there is the -E option. It will initialise the projection as +init=epsg:<num>. This allows you to use any projection recognised by proj4, which is useful if you want to make a map in a different projection. These projections are usually defined in /usr/share/proj/epsg. Database Access Examples ======================== If you wish to access the data from the database then the queries below should give you some hints. Note that these examples all use the 'latlong' projection which is not the default. $ psql gis gis=> \d List of relations Schema | Name | Type | Owner --------+--------------------+-------+---------- ... public | planet_osm_line | table | jburgess public | planet_osm_point | table | jburgess public | planet_osm_polygon | table | jburgess public | planet_osm_roads | table | jburgess ... gis=> \d planet_osm_line Table "public.planet_osm_line" Column | Type | Modifiers -----------+----------+----------- osm_id | integer | name | text | place | text | landuse | text | ... [ lots of stuff deleted ] ... way | geometry | not null z_order | integer | default 0 Each of the tables contains a subset of the planet.osm file representing a particular geometry type - Point contains nodes which have interesting tags e.g. place=city, name=London - Line contains ways with interesting tags e.g. highway=motorway, ref=M25 - Polygon contains ways which form an enclosed area e.g. landuse=reservoir The DB columns are used as follows: - osm_id = the planet.osm ID of the node(point) or way(line,polygon) - name, place, landuse, ... = the value of the given key, if present on the node/way. If the tag is not present, the value is NULL. Only a subset of all possible tags are stored in the DB. Only ones rendered in the osm.xml are actually interesting to mapnik. - way = PostGIS geometry describing the physical layout of the object. Querying specific data requires knowlege of SQL and the OSM key/value system, e.g. gis=> select osm_id,astext(way),name from planet_osm_point where amenity='cinema' limit 5; osm_id | astext | name ----------+-------------------------------------------+-------------------- 26236284 | POINT(-79.7160836579093 43.6802306464618) | 26206699 | POINT(51.4051989797638 35.7066045032235) | Cinema Felestin 26206700 | POINT(51.3994885141459 35.7058460359352) | Cinema Asr-e Jadid 20979630 | POINT(151.225781789807 -33.8943079539886) | Paris Cinema 20979684 | POINT(151.226855394904 -33.8946830511095) | Hoyts (5 rows) Mapnik renders the data in each table by applying the rules in the osm.xml file. > How could I get e.g. all highways in a given bounding box? The 'way' column contains the geo info and is the one which you need to use in your WHERE clause. e.g. gis=> select osm_id,highway,name from planet_osm_line where highway is not null and way && GeomFromText('POLYGON((0 52, 0.1 52, 0.1 52.1, 0 52.1, 0 52))',4326); osm_id | highway | name ---------+--------------+------------------ 4273848 | unclassified | 3977133 | trunk | to Royston (tbc) 4004841 | trunk | 4019198 | trunk | 4019199 | trunk | 4238966 | unclassified | See the Postgis docs for details, e.g. http://postgis.refractions.net/docs/ch04.html