Mountain terrain and texture sources

Elevation:
3DEP data courtesy of the U.S. Geological Survey.
Terrain tile supplied by Mapzen Terrain Tiles / Tilezen, hosted on AWS Open Data.
Source tile: https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/830/1564.png
Registry: https://registry.opendata.aws/terrain-tiles/
Attribution and rights: https://github.com/tilezen/joerd/blob/master/docs/attribution.md
Source header: ned13/imgn40w108_13.tif, ned13/imgn40w107_13.tif
Original elevations: 3055.81640625 to 4310.2109375 meters.
Accessed: 2026-11-07.

The USGS NED/3DEP data is public domain. This project normalizes elevations to
unsigned 16-bit values, rotates and scales the sampled region, and blends it
into a flat central base and the outer terrain. The result is an artistic
display landscape, not a geographic reconstruction of Starbase. The changes
are made by this project and are not endorsed by USGS or Mapzen.

Source PNG: tools/data/mountain-dem.png
Runtime height field: mountain-height-256.r16 (256 x 256, little endian uint16).
Conversion script: tools/bake-mountain-dem.ps1

Rock color and OpenGL normal textures:
Rock Face 03, Poly Haven.
Dario Barresi (photography), Rico Cilliers (processing).
https://polyhaven.com/a/rock_face_03
License: CC0 1.0 Universal.
https://creativecommons.org/publicdomain/zero/1.0/
https://polyhaven.com/license
Downloaded 1K JPEG maps, renamed mountain-rock-color.jpg and mountain-rock-normal.jpg.
Both images are 1024 x 1024. Source texture content is unchanged.

Mountain mesh generation, distance detail levels and seasonal appearance are
implemented in dist/mountains.js. No online service is needed at runtime.