[WIP] Add Overture data source support

[migurski]

Add basemap support for Overture Maps input data as alternative to OSM extracts. Port kind=/kind_detail=/min_zoom= mappings with no changes to MapLibre styles.

🚧 This PR will stay in draft for a few days until some pre-requisites are complete 🚧

TODO

• Review only once rebased atop main after merge of Migrate POI minZoom assigment from plain Java to MultiExpression rules #539
• Remove Python helper scripts get-overture.py and feature-finder.py
• Increment release version and add notes to changelog

Layers

All Protomaps layers except for Boundaries and Transit have some coverage in this PR.

POIs

• Overture theme=places basic_category mapped to Protomaps kind, with limited exceptions
• No OSM-style polygon area grading is available for POI importance
• Future work:
  • Can we use QRank to find high-priority POIs?
  • Try filtering by Overture confidence scores to eliminate bad POIs

Roads

• Rendering includes theme=transportation type=segment subtype=road, subtype=rail, and subtype=water
• Overture class and subclass mapped to Protomaps kind, kind_detail, and internal highway
• Uses linear referencing from Overture array properties like road_flags to split linestrings on bridge, tunnel, and level flags to match rendering of OSM basemap
• No features for airport runways are available

Places

• Rendering includes high-zoom places like cities and neighborhoods from theme=places
• Future work:
  • Include low-zoom places like states and countries

Buildings

• Rendering includes both theme=buildings type=building and type=building_part to match Protomaps visual style

Landuse

• Rendering includes theme=base type=land_use to match Protomaps visual style

Earth, Water, and Land Cover

• Rendering uses theme=base type=land, type=water, type=land_cover to match Protomaps visual style
• Future work:
  • Reduce excessive labels displayed for water bodies
  • Fix visual appearance of grainy land cover at low zooms

Testing

Extract Overture data with e.g. DuckDB:

COPY (
    SELECT *
    FROM read_parquet(
        's3://overturemaps-us-west-2/release/2025-12-17.0/**/*.parquet',
        hive_partitioning=1, filename=1, union_by_name=1
    )
    WHERE theme IN ('transportation', 'places', 'base', 'buildings', 'divisions')
      AND bbox.xmin <= -121
      AND bbox.xmax >= -123
      AND bbox.ymin <= 38
      AND bbox.ymax >= 37
) TO 'data/sources/bay-area.parquet' (FORMAT PARQUET);

Generate PMTiles from Overture data:

java -jar target/protomaps-basemap-HEAD-with-deps.jar \
    --overture=data/sources/bay-area.parquet --download --force

Run the app/ map frontend or one of the HTML examples to preview.

Screenshots

Taken from interactive preview at mike.teczno.com; compare with OSM data at maps.protomaps.com.

Flavor Compatibility

The changes in this PR map Overture properties to existing Protomaps conventions with no changes to styles, so all five of the included flavors are compatible: black, grayscale, white, light, and dark.

[sonarqubecloud]

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