mapnik offline maps using generate_tiles_multiprocess.py

Question

I've been working for a couple of days to get offline map tiles working for use in JXMapviewer2 but I am having trouble when using generate_tiles_multiprocess.py to process the tiles.

My intention is to allow JXMapviewer2 to process it's background tiles offline for a java project I'm working on. Online tiles work but not on the specific network that it is going to be implemented on.

My progress so far;

• Download and install PostgreSQL with PostGIS database.
• Update pg_hba.conf to trust
• Download osm2pgsql and load pbf file into database using openstreetmap-carto. My tables are; planet_osm* line, nodes, point, polygon, rels, roads, ways and then pointcloud_formats, spatial_ref_sys.

osm2pgsql -k -c -S openstreetmap-carto.style -d gis -U postgres new-zealand-latest.osm.pbf

• Edit carto project.mml to contain PostGIS connection info
• Download and place shapefiles in correct carto directory
• Generate XML file and remove font references

carto project.mml > osm.xml

• Update generate_tiles_multiprocess.py to point to my osm.xml file and tile_dir. Include bbox and zoom levels.

if __name__ == "__main__":

    #home = os.environ['$HOME']
    try:
        mapfile = os.environ['MAPNIK_MAP_FILE']
    except KeyError:
           mapfile = 'C:/Mapnik Tiles/osm_tiles/openstreetmap-carto-master/osm.xml'
    try:
        tile_dir = os.environ['MAPNIK_TILE_DIR']
    except KeyError:
        tile_dir = 'C:/Mapnik Tiles/osm_tiles/openstreetmap-carto-master/tiles/'

    if not tile_dir.endswith('/'):
        tile_dir = tile_dir + '/'

    #-------------------------------------------------------------------------
    # Change the following for different bounding boxes and zoom levels
    #
    # Start with an overview
    # NZ
    bbox = (166.245, -47.339, 178.660, -33.943)
    render_tiles(bbox, mapfile, tile_dir, 0, 18, "World")

Run generate_tiles_multiprocess.py

This is where I have the issues. The folder structure gets created, eg. 0, 1, 2 etc but no tiles are created. The console output displays multiple lines of "* attribute 'repeat-distance' with value '50' at line 39259" and sits. (more than 999 lines of this with varying line references) I then have to Keyboard interrupt to get back to command line.

If I use generate_image.py it creates a map of New Zealand and shows the same attribute lines as above.

Is it a case of leaving it to create the tiles?

I've left it for 10 minutes with no images being output.

JXMapviewer2 java example code;

// Create a zip-file based TileFactoryInfo for OpenStreetMap
// See https://docs.oracle.com/javase/8/docs/api/java/net/JarURLConnection.html for URL syntax details
// You can create such a ZIP file by zipping the content of ${HOME}/.jxmapviewer2/tile.openstreetmap.org
// The ZIP file should contain a list of folders (0, 1, 2, 3 ...) that represent the OSM path structure

TileFactoryInfo info = new OSMTileFactoryInfo("ZIP archive", "C:/Mapnik Tiles/osm_tiles/openstreetmap-carto-master/tiles/tiles.zip!");

Answer 1

Although not a direct fix for the above situation, but it seems as though the issue was with the XML file that carto project.mml > osm.xml was creating.

My work around was to;

• Install TileMill
• Download and process an openstreet map project from https://github.com/mapbox/open-streets-style
• Open the new project in TileMill
• Set bounds, initial zoom and zoom levels
• Set PostgreSQL settings
• Setup absolute references in the XML for wetlands-8.png (etc) and shapefiles
• Export XML
• Using that XML file in generate_tiles_multiprocess.py it would create the tiles

All tiles are then zipped to be fed into Java.