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zstarview Coastline Vector Data 2026-07-25

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@tos-kamiya tos-kamiya released this 25 Jul 20:01
coastline-data-20260725
bb573e8

zstarview Coastline Vector Data 2026-07-25

This release provides compressed coastline vector assets for the optional coastline-boundary rendering in zstarview.

Source data

  • Dataset: OSM Water Polygons
  • Source archive: water-polygons-split-4326-20260725T0338.zip
  • Source date: 2026-07-25
  • Coverage: Oceans and seas derived from OpenStreetMap coastline data
  • CRS: EPSG:4326
  • Top-level grid: 32 columns × 16 rows
  • Tile size: 11.25° × 11.25°

The source dataset contains ocean and sea polygons derived from natural=coastline. It does not contain lakes, reservoirs, or other inland water bodies.

Assets

  • coastline-grid-x00-20260725.zip through coastline-grid-x31-20260725.zip
  • coastline-manifest-20260725.json
  • coastline-sha256sums-20260725.txt

Each ZIP contains one longitude column in the following cache layout:

grid-32x16/
  yNN/xNN/tile.geojson.gz
  yNN/xNN/children.json
  yNN/xNN/children/qNN.geojson.gz
  yNN/xNN/children/qNN.0

The GeoJSON payloads are gzip-compressed inside the ZIP assets. Empty tiles are
represented by zero-byte .0 marker files.

The largest source tiles are represented by 4×4 child tiles instead of a
single parent tile. The manifest describes the layout of every top-level tile.

License and attribution

The source data is derived from OpenStreetMap and is available under the Open Database License (ODbL).

Copyright OpenStreetMap contributors.

Please see:

Changes made for zstarview:

  • Converted the source water polygons into 32×16 EPSG:4326 vector tiles
  • Extracted polygon boundaries for coastline rendering
  • Replaced selected large tiles with 4×4 child tiles
  • Compressed GeoJSON payloads with gzip
  • Added per-column ZIP assets, manifest metadata, and SHA-256 checksums

Conversion scripts:

  • dev-samples/build_coastline_vector_tiles.py
  • dev-samples/split_large_coastline_tiles.py
  • dev-samples/package_coastline_release.py

Conversion commit: 8090ba7

OSM Water Polygons is derived from natural=coastline data and covers ocean and sea polygons under the ODbL. Water polygons (https://osmdata.openstreetmap.de/data/water-polygons.html) / License (https://osmdata.openstreetmap.de/info/license.html)

Optional 25m water-mask data

This release also provides an optional 25m-resolution water-mask asset for improved water-surface dot placement near coastlines.

Assets

  • water-tiles-25m-global-20260725.zip
  • water-manifest-20260725.json
  • water-sha256sums-20260725.txt

Format

  • Source archive: water-polygons-split-4326-20260725T0338.zip
  • Source date: 2026-07-25
  • Resolution: 25m
  • CRS: EPSG:4326
  • Grid: 32 columns × 16 rows
  • Format: 1-bit GeoTIFF water masks
  • Empty tiles: .0 marker files
  • Fully covered tiles: .1 marker files
  • ZIP size: approximately 132MB
  • Expanded size: approximately 1.14GB

This asset is optional and is not included in the zstarview package. It is intended for future runtime use near coastlines. The existing 125m, 250m, and 500m water-mask tiles remain the fallback data.

The source data is derived from OpenStreetMap and is available under the Open Database License (ODbL).

Conversion script:
src/zstarview/data/osm_water_polygons_to_tiff.py

Assets 39
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