Split Vectortiles by Region

This Python script allows you to split a set of vectortiles (or any other type of tiles, but not metatiles) into multiple smaller packages definedb by polygons. A GeoJSON file of (multi)polygon features decides which tile should go into which package.

GeoJSON features may overlap.

Supported formats (must be the same for input and output):

• from a dirctory of z/x/y.suffix files to multiple GZIP compressed tarballs containing z/x/y.suffix files
• from MBTiles to multiple MBTiles

Usage

split-vectortiles-by-region.py [-h] -c CONFIG -f FORMAT -g GEOJSON -i INPUT [-l LOG_LEVEL] -o OUTPUT [-p PROCESSES] [-s SUFFIX] [-S] -t TILELIST [-z MINZOOM] [-Z MAXZOOM]

Split a vector tile set (in z/x/y.pbf structure) into multiple tile sets.

Required arguments:

  -c CONFIG, --config CONFIG
                        Configuration file in YAML format (required)
  -f FORMAT, --format FORMAT
                        Input and output format ('mbtiles' for MBTiles input and output, 'tar.gz' for input from directory and output to .tar.gz)
  -g GEOJSON, --geojson GEOJSON
                        GeoJSON index file containing clipping polygons for all regions.
  -i INPUT, --input INPUT
                        Path to input tileset
  -o OUTPUT, --output OUTPUT
                        Output base directory
  -t TILELIST, --tilelist TILELIST
                        Path to program to generate a list of tiles from polygon

Optional arguments:
  -h, --help            show this help message and exit
  -l LOG_LEVEL, --log-level LOG_LEVEL
                        log level (DEBUG, INFO, WARNING, ERROR, CRITICAL)
  -p PROCESSES, --processes PROCESSES
                        Number of parallel processes
  -s SUFFIX, --suffix SUFFIX
                        File name suffix, should start with a dot. Ignore if output is written in MBTiles format.
  -S, --strict          Fail if a requested region is not found
  -z MINZOOM, --minzoom MINZOOM
                        Minimum zoom level
  -Z MAXZOOM, --maxzoom MAXZOOM
                        Maximium zoom level

Configuration

split-vectortiles-by-region is configured using a YAML and a GeoJSON file.

YAML file

Example:

path_template: "{region_path}-shortbread-1.0"

polygons:
  - id: "afghanistan"
    region_path: "asia/afghanistan"
  - id: "albania"
    region_path: "europe/albania"
  - id: "alberta"
    region_path: "canada/alberta"
  - id: "algeria"
    region_path: "africa/algeria"

The YAML file must be a mapping with the following properties:

• path_template: A Template (as Python string template) to create the path where a tarball/MBTiles file is to be written within the selected target base directory. A file name suffix is added automatically depending on the output format.
• polygons: This list of mappings defines which tile packages should be created. Each entry must have the following properties:
  • id: unique ID of the clipping (multi)polygon; there must be a (multi)polygon feature in the GeoJSON file with its property id set to the same string.
  • region_path: path (can include subdirectories and directory separators like slashes) to be used in path_template. This key has to be used in the path_template to generate unique paths per tile set.

GeoJSON file

The GeoJSON file holds the geometries for all clipping (multi)polygons. There must be a feature in the GeoJSON file for each tile set defined in the YAML file. GeoJSON features and tile sets are matched by the id property in the YAML file and the property id in the GeoJSON file.

Features in the GeoJSON file not used by any tile set will be ignored. Missing features in the GeoJSON file will raise an error.

Example configuration

This repository contains an example configuration to split a world-wide set of vector tiles into regional packages.

Requirements

• PyYAML (Debian package python3-yaml)
• SQLite3 bindings for Python
• Polygon-To-Tile-List
• Unix utilites tar and gzip

License

This project is licensed under the terms of General Public License version 2 or newer.