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.

Features:

• The area to be extracted can be configured in /conf/clip_area.geojson.

• The script /scripts/pbf_to_geojson.sh is used to do the extraction.

• 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

It produces custom text files with the vectorial data of the features: lines and polygons, with the style information.

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

Still work in progress.

Example of the creation of the map files

1. Download the OpenStreetMap PBF file of your ares with all the map features. You can find them in Geofabrik or https://download.openstreetmap.fr/extracts/

For example: spain-latest.osm.pbf

2. Clip the pbf to your area:

/maps/osmium extract --strategy=smart -p ../conf/clip_area.geojson /pbf/spain-latest.osm.pbf -o /pbf/clipped.pbf

It will generate an smaller PBF file of a reduced area, defined by the clipping square in clip_area.geojson

3. Generate the intermediate lines and polygons files extracting only the defined subset of feature types:

min_lon=123
min_lat=123
max_lon=123
max_lat=123

./pbf_to_geojson.sh $min_lon $min_lat $max_lon $max_lat /pbf/clipped.pbf /maps/test
echo "PBF extract done"

4. And finally generate the compiled map files in the folder /maps/test/

./extract_features.py $min_lon $min_lat $max_lon $max_lat /maps/test
echo "Map files created"

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