OSM_Extract

This tools are created to extract OpenStreetMap vectorial map features to fmp files (text with specific format) to be used by other projects to display custom maps with a subset of features and a custom styling.

For example, you can store the generated files in an SD card and use it to render maps in your custom device.

This is intended to be used in projects with microcontrollers involving GPS location and display capabilities. But it can be used in any project that needs to render simple vectorial maps.

Example of the creation of the map files

1. Download the OpenStreetMap PBF file of your area

You can find them in Geofabrik or https://download.openstreetmap.fr/extracts/

For example: spain-latest.osm.pbf

wget -P pbf -N http://download.openstreetmap.fr/extracts/europe/spain-latest.osm.pbf

2. Start docker

For the next steps you will need the docker container running:

docker compose up -d

3. Define your custom map area graphically

• First generate an outline map out of your PBF file (only once for a new pbf):

docker compose exec tools /scripts/make_base_map.sh /pbf/spain-latest.osm.pbf

It will generate a basic map with just coastlines, country, region and provinces boundaries, as a reference to draw your custom map boundaries.

• Then start the local app in docker to draw the clip area of your map graphically:

docker compose exec tools python3 /scripts/clip_editor.py

• Open http://localhost:8080 in your browser and draw the polygon around the area you want for your map, or adjust it with the edit tool, and save.

It writes /conf/clip_area.geojson, used in the next steps to extract the map features of the defined area.

5. Features extraction and map files generation

docker compose exec tools /scripts/map_extraction.sh

Note: Some steps can throw TopologyException errors, because of some invalid geometries in the OSM pbf's. We can just ignore them.

• The feature types to be extracted can be configured in /conf/conf_extract.yaml
• The styles to apply to each feature type (color, width...) can be configured in conf_styles.yaml

The files in /maps will contain the feature types defined in /conf/conf_extract.yaml of your area, with the visual styles defined in /conf/conf_styles.yaml

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The map files are organized in a folder tree structure. Each folder contains several map files and has a custom name that defines the offset position of the map files in the folder.

• Each file contains the vectorial data of an area of approximately 4x4 Kms.
• Each folder contains up to 256 files (16x16 blocks), so it covers an approximate area of 64x64 Kms.
  You can have as many folders as you need to cover your map area.

This is already used and working in the project: https://github.com/aresta/ESP32_GPS