Southern Ontario basemap

Made with Natural Earth, using its public-domain 1:10m data.
https://www.naturalearthdata.com/about/terms-of-use/
Lakes and rivers v5.0.0, administrative lines v5.1.0, populated places v5.1.2.
https://www.naturalearthdata.com/downloads/10m-physical-vectors/10m-lakes/
https://www.naturalearthdata.com/downloads/10m-physical-vectors/10m-rivers-lake-centerlines/
https://www.naturalearthdata.com/downloads/10m-cultural-vectors/10m-admin-1-states-provinces/
https://www.naturalearthdata.com/downloads/10m-cultural-vectors/10m-populated-places/

Detailed shorelines for Lake Huron (including Georgian Bay), Lake Ontario,
Lake Erie and Lake Simcoe come from OpenStreetMap under ODbL 1.0. The Ontario
extract was retrieved from Geofabrik, snapshot 2026-11-02T21:21:26Z. Coastlines
were simplified at 12 m for the atlas. Small islands below 4,000 m² were omitted.
https://www.openstreetmap.org/copyright
https://download.geofabrik.de/north-america/canada/ontario.html
https://www.openstreetmap.org/relation/1205151
https://www.openstreetmap.org/relation/1206310
https://www.openstreetmap.org/relation/4039900
https://www.openstreetmap.org/relation/9984807

Elevation relief derived from Mapzen Terrain Tiles accessed on 2026-11-04.
https://registry.opendata.aws/terrain-tiles/
https://github.com/tilezen/joerd/blob/master/docs/attribution.md
Canada terrain data contains information licensed under the Open Government Licence – Canada.
U.S. 3DEP, GMTED2010 and SRTM elevation data courtesy of the U.S. Geological Survey.
Global ETOPO1 elevation data courtesy of the U.S. National Oceanic and Atmospheric Administration.

Street tiles and the project's retained waterway and access data are credited to
OpenStreetMap contributors.
https://www.openstreetmap.org/copyright

To rebuild these assets, unpack the four Natural Earth source archives into one
directory. In that directory save Terrarium tiles z7/x33–37/y45–48 as X-Y.png.
https://s3.amazonaws.com/elevation-tiles-prod/terrarium/7/{x}/{y}.png
Run `python3 scripts/prepare-atlas-basemap.py <source-dir> public/basemap` from
the project root with GDAL's Python bindings, NumPy, and Shapely installed.

Ontario overview basemap

The province-wide overview uses Natural Earth public-domain 1:10m ocean (5.1.1),
lake (5.0.0), international and internal boundary (5.1.0), populated place
(5.1.2) and marine label (5.1.0) data. Province and state label positions
come from the 1:50m admin-1 polygons (5.1.1).
https://www.naturalearthdata.com/downloads/10m-physical-vectors/10m-ocean/
https://www.naturalearthdata.com/downloads/10m-physical-vectors/10m-physical-labels/
https://www.naturalearthdata.com/downloads/10m-cultural-vectors/10m-admin-0-boundary-lines/
https://www.naturalearthdata.com/downloads/50m-cultural-vectors/50m-admin-1-states-provinces/

Unpack ne_10m_ocean, ne_10m_lakes, ne_10m_admin_0_boundary_lines_land,
ne_10m_admin_1_states_provinces_lines, ne_10m_populated_places,
ne_10m_geography_marine_polys and ne_50m_admin_1_states_provinces into one
directory. From the project root run:
python3 scripts/prepare-ontario-overview.py <source-dir> public/basemap/ontario-overview.geojson
This script uses GDAL's Python bindings and Shapely.

After building both Natural Earth basemap files, overlay the detailed lake
polygons from a complete Ontario OpenStreetMap extract with osmium, pyproj,
and Shapely installed:
python3 scripts/prepare-atlas-shorelines.py <ontario.osm.pbf> public/basemap