# Lunar source data

`moon_surface.bin.gz` is a printer-scale, deterministic reduction of two Lunar Reconnaissance Orbiter Camera products:

- Terrain: **WAC GLD100 with LOLA 30 m DTM poleward of 75°**, represented locally by `WAC_GLD100_V1.0_GLOBAL_with_LOLA_30M_POLE.0032km.cub`.
- Tone: **LROC WAC normalized reflectance**, incidence 30°, emission 0°, phase 30°, represented locally by four 8-bit cloud-optimized GeoTIFF quadrants.

The reduced asset uses the terrain grid (3,412 × 1,706). Elevation is stored as signed metre offsets from the 1,737,400 m lunar datum; reflectance is bilinearly resampled onto that grid and stored as unsigned bytes. The embedded header records source filenames and SHA-256 checksums.

The GLD100 record is public domain and requests citation of F. Scholten, J. Oberst, K.-D. Matz, T. Roatsch, M. Wählisch, E. J. Speyerer, M. S. Robinson, and the LROC Team. See:

- https://astrogeology.usgs.gov/search/map/moon_lroc_wac_dtm_gld100_118m
- https://lroc.im-ldi.com/images/downloads

Rebuild with:

```sh
bundle exec ruby bin/prepare_lunar_data
```

The preparation command requires GDAL; ordinary model generation does not.