OsmPlugin

Mapnik's PluginArchitecture supports the use of different input formats.

This plugin allows for the direct reading of data from the OpenStreetMap XML format.

NOTE: the primary way that Mapnik is used to render OpenStreetMap data is to import an extract into Postgres using the osm2pgsql tool and then read it using PostGIS plugin.

Dependencies

You need libxml2 installed on your system for parsing the XML.

Parameters

parameter	value	description	default
file	string	the OSM file to load
bbox	string	the bounding box to load from the URL of an OSM data source (see below).
parser	string	the XML parser: currently, this must have a value of "libxml2" as libxml2 is the only parser currently supported	libxml2
filter_factor	double	filter to use when querying for raster data	0.0

Usage

How to specify an OSM layer in your Mapnik XML file

Your layer's Datasource must have a "type" parameter with a value of "osm", in a similar way that the shapefile plugin needs a "type" parameter of "shape". For example:

<Layer name="roads" status="on" srs="+proj=latlong +datum=WGS84">
    <StyleName>residential</StyleName>
    <StyleName>unclassified</StyleName>
    <StyleName>secondary</StyleName>
    <StyleName>primary</StyleName>
    <StyleName>motorway</StyleName>
    <Datasource>
      <Parameter name="type">osm</Parameter>
      <Parameter name="file">test2.osm</Parameter>
    </Datasource>
</Layer>

Styling the output

Styling the output is done in the same way as for other data sources, with tests for different tags done in the <Filter> tag. For example this rule will match OSM ways where the 'highway' tag is equal to 'path' and the 'foot' tag is equal to 'designated':

<Rule>
    <Filter>[highway] = 'path' and [foot] = 'designated'</Filter>
    <LineSymbolizer>
        <CssParameter name="stroke">#fff</CssParameter>
        <CssParameter name="stroke-width">6</CssParameter>
        <CssParameter name="stroke-linejoin">round</CssParameter>
        <CssParameter name="stroke-linecap">round</CssParameter>
        <CssParameter name="stroke-opacity">0.4</CssParameter>
    </LineSymbolizer>
    <LineSymbolizer>
        <CssParameter name="stroke">red</CssParameter>
        <CssParameter name="stroke-width">2.0</CssParameter>
        <CssParameter name="stroke-dasharray">1,4</CssParameter>
        <CssParameter name="stroke-linejoin">round</CssParameter>
        <CssParameter name="stroke-linecap">round</CssParameter>
    </LineSymbolizer>
</Rule>

Lines or polygons?

Polygon support is not yet very sophisticated. A few pre-defined tag/value combinations are assumed to be polygons; all others are assumed to be linear ways. Currently these tag/values are assumed to be polygons:

• natural=wood

• natural=water

• natural=heath

• natural=marsh

• military=danger_area

• landuse=forest

• landuse=industrial.

These are defined in the polygon_types class in the source file osm.h, so if you want to add others for your own use, that's the place to go.