Natural Earth 1:10m physical-vector input

Earth, water, Bathymetry Roulette, and Bathymetry Hamonshū generation use the Natural Earth 5.1.1 complete 1:10m physical-vector archive under assets.static/natural-earth/10m-physical-vectors/. A dependent target such as make generate-earth-ck, make generate-bathymetry-roulette, or make generate-bathymetry-hamonshu acquires it when absent. The directory is a reproducible build input and is intentionally ignored by Git. Run only the acquisition step with:

make fetch-natural-earth-10m

The fetch script downloads the official archive from:

https://naciscdn.org/naturalearth/10m/physical/10m_physical.zip

It verifies this SHA-256 digest before extracting the datasets used by the Cahill-Keyes earth generator:

a79cc39162f29832b567de5e24e8770f04a0b997eefd8d067ae4c9df40d21d2a

The Earth and water SVGs use coastline, land, minor islands, reefs, ocean, rivers and lake centerlines, lakes and reservoirs, playas, glaciated areas, Antarctic ice shelves, and all twelve nested bathymetry depths from 0 m to -10,000 m. Both bathymetry-art passes reuse those polygons and their original twelve-step blue ramp as projection-safe clips for Izzi curve fields; neither introduces another geographic input. Natural Earth data is in the public domain. See the Natural Earth terms of use and the 1:10m physical-vector catalog.