RUNNING.md

Running tilemaker

You can get a run-down of available options with

tilemaker --help

The following document explains each option.

Standard usage

To create vector tiles from an OpenStreetMap .pbf extract, tilemaker's standard syntax is:

tilemaker --input oxfordshire.osm.pbf \
          --output oxfordshire.mbtiles \
          --config resources/config-openmaptiles.lua \
          --process resources/process-openmaptiles.lua

The --config and --process arguments are the paths of your JSON config file and Lua processing script. These are described in CONFIGURATION.md. Here we're using the ready-made OpenMapTiles-compatible script.

You'll usually want to write to an .mbtiles file (which, under the hood, is an sqlite database containing the vector tiles). However, you can write tiles directly to the filesystem if you like, by specifying a directory path for --output.

This is all you need to know, but if you want to reduce memory requirements, read on.

Using on-disk storage

By default, tilemaker uses RAM to store the nodes and ways it reads from the .osm.pbf, prior to writing them out as vector tiles. This is fine for small regions, but can impose high memory requirements for larger areas.

To use on-disk storage instead, pass the --store argument with a path to the directory where you want the temporary store to be created. This should be on an SSD or other fast disk. Tilemaker will grow the store as required.

Merging

You can specify multiple .pbf files on the command line, and tilemaker will read them all in before writing the vector tiles.

Alternatively, you can use the --merge switch to add to an existing .mbtiles. Create your .mbtiles in the usual way:

tilemaker --input australia.osm.pbf \
          --output oceania.mbtiles \
          [...]

Then rerun with another .pbf, using the --merge flag:

tilemaker --input new-zealand.osm.pbf \
          --output oceania.mbtiles \
          --merge \
          [...]

The second run will proceed a little more slowly due to reading in existing tiles in areas which overlap. Any OSM objects which appear in both files will be written twice.

For very large areas, you could potentially use osmium tags-filter to split a .pbf into several "thematic" extracts: for example, one containing buildings, another roads, and another landuse. Renumber each one, then run tilemaker several times with --merge to add one theme at a time. This would greatly reduce memory usage.

Pre-split data

Tilemaker is able to read pre-split source data, where the original .osm.pbf has already been split into tiled areas (but not converted any further). By reducing the amount of data tilemaker has to process at any one time, this can greatly reduce memory requirements.

To split an .osm.pbf, use mapsplit. This will output an .msf file. We would recommend that you split the data at a low zoom level, such as 6; tilemaker will not be able to generate vector tiles at a lower zoom level than the one you choose for your .msf file.

You can then run tilemaker exactly as normal, with the --input parameter set to your .msf file. Source tiles will be processed one by one. Note that shapefiles will be read unsplit as normal.

Output messages

Running tilemaker with the --verbose argument will output any issues encountered during tile creation.

You may see "couldn't find constituent way" messages. This happens when the .pbf file contains a multipolygon relation, but not all the relation's members are present. Typically, this will happen when a multipolygon crosses the border of the extract - for example, a county boundary formed by a river with islands. In this case, the river will simply not be written to the tiles.

You may also see geometry errors reported by Boost::Geometry. This typically reflects an error in the OSM source data (for example, a multipolygon with several inner rings but no outer ring). Often, if the geometry could not be written to the layer, the error will subsequently show in a failed attempt to add attributes afterwards.

Github Action

You can integrate tilemaker as a Github Action into your Github Workflow.
Here is an example:

- uses: systemed/tilemaker@v2.0.0
  with:
    # Required, same to --input
    input: /path/to/osm.pbf
    # Required, same to --output. Could be a directory or a .mbtiles files
    output: /path/to/output
    # Optional, same to --config
    # If not being set, default to resources/config-openmaptiles.config
    config: /path/to/config
    # Optional, same to --process
    # If not being set, default to resources/process-openmaptiles.lua
    process: /path/to/lua
    # Optional, other arguments
    # If not being set, default to '--verbose'
    extra: --threads 0