jpmschweitzerandClaude Opus 4.6
d364e1907d
Ruff pre-push lint caught 17 unused imports across 7 files. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
135 lines
5.2 KiB
Python
135 lines
5.2 KiB
Python
"""
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Luna (GJ0d-1) terrain builder.
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Data source:
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- Elevation: LOLA (Lunar Orbiter Laser Altimeter) DEM
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Available at various resolutions from USGS Astrogeology.
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We use the 4ppd (1440×720) or 16ppd version.
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Luna properties:
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- Min elevation: ~-9100 m (South Pole-Aitken basin)
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- Max elevation: ~10786 m (near Engel'gardt crater rim)
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- No atmosphere, no water
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- body_type: "moon" → uses lunar biome palette (classes 31/32/33)
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"""
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import numpy as np
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from pathlib import Path
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from sol_data.download import ensure_cached
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from sol_data.shared import (
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GRID_W, GRID_H,
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load_raw_binary,
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resample_to_grid, normalize_01,
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compute_hillshade, assemble_terrain,
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temperature_grid_analytical,
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)
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# LOLA GDR — available as PDS IMG files
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# 4ppd (1440 × 720) — compact version
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LOLA_4PPD_URL = "https://pds-geosciences.wustl.edu/lro/lro-l-lola-3-rdr-v1/lrolol_1xxx/data/lola_gdr/cylindrical/img/ldem_4.img"
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LOLA_4PPD_FILE = "lola_gdr_4ppd.img"
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LOLA_4PPD_W = 1440
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LOLA_4PPD_H = 720
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# 16ppd (5760 × 2880) — higher quality
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LOLA_16PPD_URL = "https://pds-geosciences.wustl.edu/lro/lro-l-lola-3-rdr-v1/lrolol_1xxx/data/lola_gdr/cylindrical/img/ldem_16.img"
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LOLA_16PPD_FILE = "lola_gdr_16ppd.img"
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LOLA_16PPD_W = 5760
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LOLA_16PPD_H = 2880
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# Luna physical constants
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LUNA_MIN_ELEV_M = -9100.0
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LUNA_MAX_ELEV_M = 10786.0
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LUNA_EQUATORIAL_TEMP_K = 220.0 # mean dayside ~220K
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LUNA_POLAR_TEMP_K = 100.0 # permanently shadowed craters ~40K, average ~100K
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def _load_lola(use_16ppd: bool = False) -> np.ndarray:
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"""Load LOLA DEM, return elevation in metres."""
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if use_16ppd:
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url, filename, w, h = LOLA_16PPD_URL, LOLA_16PPD_FILE, LOLA_16PPD_W, LOLA_16PPD_H
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else:
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url, filename, w, h = LOLA_4PPD_URL, LOLA_4PPD_FILE, LOLA_4PPD_W, LOLA_4PPD_H
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path = ensure_cached(url, filename)
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print(f" loading LOLA: {path} ({w}x{h})")
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# LOLA GDR: little-endian int16 (LSB_INTEGER per PDS label)
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# with a scaling factor of 0.5 metres.
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try:
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arr = load_raw_binary(str(path), w, h, dtype="<i2", offset=0)
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# LOLA int16 values are in units of 0.5m (scale factor 0.5)
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arr = arr * 0.5
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except ValueError:
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# If int16 doesn't work, try float32
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arr = load_raw_binary(str(path), w, h, dtype="<f4", offset=0)
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# Handle nodata
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arr[arr > 20000] = 0.0
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arr[arr < -20000] = 0.0
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print(f" LOLA range: [{arr.min():.0f}, {arr.max():.0f}] m")
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return arr
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def build_terrain(body_def: dict) -> dict:
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"""Build Luna terrain dict from LOLA data."""
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import sys
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sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
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from planet_simulation import compute_biome
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print(" Luna: loading LOLA data...")
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# ── 1. Elevation ────────────────────────────────────────────────────
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lola_raw = _load_lola(use_16ppd=False)
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# LOLA cylindrical: col 0 = 0° longitude — shift to 180°W
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from sol_data.shared import greenwich_to_dateline
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lola_shifted = greenwich_to_dateline(lola_raw)
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elevation_m = resample_to_grid(lola_shifted, GRID_H, GRID_W, order=1)
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elevation = normalize_01(elevation_m, LUNA_MIN_ELEV_M, LUNA_MAX_ELEV_M)
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# No liquid — sea level at 0
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sea_level = 0.0
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surface_water = np.zeros((GRID_H, GRID_W), dtype=bool)
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print(f" elevation normalised")
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# ── 2. Temperature ──────────────────────────────────────────────────
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temperature_K = temperature_grid_analytical(
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base_T_K=LUNA_EQUATORIAL_TEMP_K,
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elevation=elevation,
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lapse_rate_K_per_unit=10.0,
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lat_gradient_K=120.0, # huge contrast equator to poles
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)
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# Clamp minimum
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temperature_K = np.maximum(temperature_K, 40.0)
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print(f" temperature: [{temperature_K.min():.0f}, {temperature_K.max():.0f}] K")
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# ── 3. Moisture ─────────────────────────────────────────────────────
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moisture = np.zeros((GRID_H, GRID_W), dtype=np.float32)
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# ── 4. Biome ────────────────────────────────────────────────────────
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# body_type: "moon" + atmosphere: "none" → lunar palette (31/32/33)
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biome = compute_biome(body_def, elevation, sea_level, surface_water,
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temperature_K, moisture)
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print(f" biomes: {len(np.unique(biome))} classes")
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# ── 5. Hillshade ────────────────────────────────────────────────────
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hillshade = compute_hillshade(elevation)
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# ── 6. Assemble ─────────────────────────────────────────────────────
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return assemble_terrain(
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elevation=elevation,
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temperature_K=temperature_K,
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moisture=moisture,
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biome=biome,
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surface_water=surface_water,
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hillshade=hillshade,
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rivers=[],
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sea_level=sea_level,
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)
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