Multi-Body Terrain — Procedural Profiles and Real Heightmaps

Parent Epic: #429 (Planetary Terrain System) Depends on: #743 (Terrain Data Pipeline — Luna) — CLOSED

Summary

Extend terrain rendering and landing support from Luna-only to all rocky/icy bodies across all three star systems. Two sub-phases:

Phase 5a: Procedural terrain profiles for ~40 rocky/icy bodies (no heightmaps needed)
Phase 5b: Real NASA MOLA heightmap for Mars
Phase 5c: Real NOAA ETOPO1 heightmap for Earth

Phase 5a — Procedural Terrain for All Rocky/Icy Bodies

Body Classification

Terrain enabled — rocky or icy surface bodies:

System	Bodies
Sol (planets)	Mercury, Venus, Earth, Mars
Sol (moons)	Luna†, Phobos, Deimos, Io, Europa, Ganymede, Callisto, Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Iapetus, Miranda, Ariel, Umbriel, Titania, Oberon, Triton
Alpha Centauri	Erebus, Chiron, Chiron I, Tartarus, Nyx, Nyx I, Proxima b, Proxima d, Proxima e, Proxima e I, Proxima f
Barnard’s Star	Barnard b, Barnard c, Barnard d, Barnard e, Niven

† Luna already has terrain (real LOLA heightmap + procedural fallback)

Terrain NOT enabled — gas giants and stars:

Sun, Jupiter, Saturn, Uranus, Neptune, Alpha Centauri A, Alpha Centauri B, Proxima Centauri, Barnard’s Star

Profile Parameters

Each terrain profile defines:

Parameter	Description
`baseRadius`	Mean body radius in meters
`maxElevation`	Maximum surface elevation above mean radius (meters)
`minElevation`	Minimum surface elevation below mean radius (meters)
`noiseOctaves`	Number of fractal noise octaves (CPU-side)
`craterDensity`	Voronoi crater frequency multiplier (0 = none, 1 = heavy)
`seed`	Deterministic noise seed (MUST match between client and server)
`highlandColor`	RGB [0-1] for terrain above `mariaThreshold`
`mariaColor`	RGB [0-1] for terrain below `mariaThreshold`
`mariaThreshold`	Elevation (meters) below which low-terrain color applies
`largeBasins`	Named impact basins with lat/lon/diameter/depth

Sol System Profiles

Mercury

Radius: 2,440,000 m
Elevation: -5,380 m to +4,480 m
Heavily cratered, gray surface (similar to Luna)
Caloris Basin: lat 30.5°N, lon 170°E, diameter 1,550 km, depth 3,000 m
Seed: 101, octaves: 10, craterDensity: 0.9
Colors: highland [0.62, 0.60, 0.58] (gray), maria [0.35, 0.33, 0.31] (dark gray)

Venus

Radius: 6,052,000 m
Elevation: -2,900 m to +11,000 m (Maxwell Montes)
Low crater density (thick atmosphere), volcanic terrain
Maxwell Montes basin (inverted — high point): lat 65°N, lon 3°E
Ishtar Terra highland region
Seed: 102, octaves: 10, craterDensity: 0.15
Colors: highland [0.82, 0.72, 0.48] (tan/amber), maria [0.65, 0.52, 0.32] (darker amber)

Earth

Radius: 6,371,000 m
Elevation: -8,848 m to +8,848 m (simplified — no ocean rendering)
Very low crater density (erosion)
Seed: 103, octaves: 10, craterDensity: 0.02
Colors: highland [0.42, 0.55, 0.35] (green-brown), maria [0.25, 0.38, 0.55] (blue-gray for lowlands)

Mars

Radius: 3,390,000 m
Elevation: -8,200 m (Hellas) to +21,229 m (Olympus Mons)
Moderate crater density, massive volcanic and tectonic features
Large basins:
- Olympus Mons: lat 18.65°N, lon 226.2°E, diameter 600 km, depth -21,229 m (inverted: positive height)
- Hellas Planitia: lat -42.7°, lon 70°E, diameter 2,300 km, depth 7,152 m
- Valles Marineris: lat -14°, lon 290°E, diameter 4,000 km, depth 7,000 m (linear, approximated as basin)
Seed: 104, octaves: 12, craterDensity: 0.5
Colors: highland [0.76, 0.44, 0.26] (rusty orange), maria [0.55, 0.30, 0.18] (dark rust)

Phobos

Radius: 11,070 m (triaxial body approximated as sphere)
Elevation: -500 m to +500 m
Heavily cratered, Stickney crater dominant
Stickney: lat 5°S, lon 49°W, diameter 9,400 m, depth 1,500 m
Seed: 105, octaves: 8, craterDensity: 0.9
Colors: highland [0.20, 0.18, 0.15], maria [0.12, 0.10, 0.08] (very dark — real geometric albedo ~0.07; values raised for visible surface texture detail)

Deimos

Radius: 6,200 m
Elevation: -300 m to +300 m
Smoother than Phobos, fewer large craters
Seed: 106, octaves: 6, craterDensity: 0.5
Colors: highland [0.20, 0.18, 0.16], maria [0.12, 0.10, 0.09] (very dark — geometric albedo ~0.07)

Io

Radius: 1,822,000 m
Elevation: -1,500 m to +17,500 m (Boösaule Montes)
Volcanic terrain, very low impact craters (resurfaced constantly)
Seed: 201, octaves: 10, craterDensity: 0.05
Colors: highland [0.85, 0.78, 0.20] (yellow-sulfur), maria [0.70, 0.35, 0.10] (orange-sulfur)

Europa

Radius: 1,561,000 m
Elevation: -200 m to +200 m
Extremely smooth ice surface, subtle lineae
Seed: 202, octaves: 8, craterDensity: 0.1
Colors: highland [0.85, 0.82, 0.75] (icy white-tan), maria [0.70, 0.65, 0.55] (slightly darker ice)

Ganymede

Radius: 2,634,000 m
Elevation: -2,000 m to +2,000 m
Mixed dark/light terrain, moderate craters
Seed: 203, octaves: 10, craterDensity: 0.5
Colors: highland [0.60, 0.55, 0.48] (gray-brown), maria [0.38, 0.35, 0.30] (dark gray)

Callisto

Radius: 2,410,000 m
Elevation: -3,000 m to +3,000 m
Extremely heavily cratered, ancient surface
Valhalla multi-ring structure: lat 16°N, lon 55°W, diameter 3,800 km, depth 3,000 m
Seed: 204, octaves: 10, craterDensity: 0.95
Colors: highland [0.42, 0.38, 0.32] (dark brown), maria [0.25, 0.22, 0.18] (very dark)

Mimas

Radius: 198,000 m
Elevation: -5,000 m to +5,000 m
Herschel crater dominates (1/3 of body diameter)
Herschel: lat 0°, lon 110°W, diameter 130,000 m, depth 10,000 m
Seed: 301, octaves: 8, craterDensity: 0.7
Colors: highland [0.75, 0.73, 0.70] (light gray), maria [0.50, 0.48, 0.45] (medium gray)

Enceladus

Radius: 252,000 m
Elevation: -500 m to +500 m
Very smooth, icy, tiger stripes at south pole
Seed: 302, octaves: 8, craterDensity: 0.2
Colors: highland [0.92, 0.90, 0.88] (bright white ice), maria [0.75, 0.73, 0.70]

Tethys

Radius: 531,000 m
Elevation: -3,000 m to +3,000 m
Odysseus crater (400 km), Ithaca Chasma
Odysseus: lat 33°N, lon 128°W, diameter 400,000 m, depth 5,000 m
Seed: 303, octaves: 8, craterDensity: 0.6
Colors: highland [0.78, 0.76, 0.73] (light gray), maria [0.52, 0.50, 0.47]

Dione

Radius: 561,500 m
Elevation: -2,000 m to +2,000 m
Moderate cratering, wispy terrain (bright ice cliffs)
Seed: 304, octaves: 8, craterDensity: 0.5
Colors: highland [0.76, 0.74, 0.71] (light gray), maria [0.50, 0.48, 0.45]

Rhea

Radius: 763,800 m
Elevation: -2,500 m to +2,500 m
Heavily cratered, similar to Callisto but smaller
Seed: 305, octaves: 8, craterDensity: 0.7
Colors: highland [0.72, 0.70, 0.67] (gray), maria [0.48, 0.46, 0.43]

Titan

Radius: 2,575,000 m
Elevation: -500 m to +2,000 m
Low relief, atmospheric erosion, dune fields, methane lakes
Seed: 306, octaves: 10, craterDensity: 0.05
Colors: highland [0.72, 0.55, 0.25] (orange-brown haze), maria [0.55, 0.40, 0.18] (dark orange)

Iapetus

Radius: 734,600 m
Elevation: -5,000 m to +13,000 m (equatorial ridge up to 13 km)
Two-tone surface (dark leading/bright trailing), equatorial ridge
Seed: 307, octaves: 10, craterDensity: 0.6
Colors: highland [0.65, 0.62, 0.58] (light gray-brown), maria [0.18, 0.14, 0.10] (very dark brown)

Miranda

Radius: 235,800 m
Elevation: -5,000 m to +5,000 m
Extreme terrain variation, coronae, Verona Rupes
Seed: 401, octaves: 10, craterDensity: 0.4
Colors: highland [0.70, 0.68, 0.65] (gray), maria [0.45, 0.43, 0.40]

Ariel

Radius: 578,900 m
Elevation: -2,000 m to +2,000 m
Youngest Uranian moon surface, canyons and flows
Seed: 402, octaves: 8, craterDensity: 0.3
Colors: highland [0.72, 0.70, 0.67] (light gray), maria [0.48, 0.46, 0.43]

Umbriel

Radius: 584,700 m
Elevation: -2,000 m to +2,000 m
Very dark, uniformly cratered, ancient surface
Seed: 403, octaves: 8, craterDensity: 0.7
Colors: highland [0.38, 0.36, 0.34] (very dark gray), maria [0.25, 0.23, 0.21]

Titania

Radius: 788,400 m
Elevation: -3,000 m to +3,000 m
Moderate cratering, some canyons (grabens)
Seed: 404, octaves: 8, craterDensity: 0.5
Colors: highland [0.68, 0.66, 0.63] (gray), maria [0.45, 0.43, 0.40]

Oberon

Radius: 761,400 m
Elevation: -3,000 m to +3,000 m
Heavily cratered, some dark floor craters
Seed: 405, octaves: 8, craterDensity: 0.7
Colors: highland [0.62, 0.60, 0.57] (medium gray), maria [0.40, 0.38, 0.35]

Triton

Radius: 1,353,000 m
Elevation: -1,000 m to +1,000 m
Nitrogen ice, cantaloupe terrain, geysers
Seed: 501, octaves: 10, craterDensity: 0.1
Colors: highland [0.78, 0.72, 0.72] (pinkish-white), maria [0.60, 0.55, 0.55] (pinkish-gray)

Alpha Centauri System Profiles

Erebus (Alpha Centauri A, hot Venus-like)

Radius: 5,500,000 m
Elevation: -3,000 m to +8,000 m
Volcanic, thick atmosphere, low craters
Seed: 601, octaves: 10, craterDensity: 0.1
Colors: highland [0.65, 0.40, 0.25] (dark rust), maria [0.45, 0.25, 0.15] (scorched brown)

Chiron (Alpha Centauri A, habitable zone)

Radius: 7,520,000 m
Elevation: -6,000 m to +8,000 m
Earth-like terrain, moderate erosion
Seed: 602, octaves: 12, craterDensity: 0.05
Colors: highland [0.45, 0.55, 0.38] (green-brown), maria [0.30, 0.42, 0.50] (blue-gray)

Chiron I (moon of Chiron)

Radius: 2,000,000 m
Elevation: -4,000 m to +4,000 m
Luna-like, rocky moon
Seed: 603, octaves: 10, craterDensity: 0.7
Colors: highland [0.60, 0.58, 0.55] (gray), maria [0.35, 0.33, 0.30]

Tartarus (Alpha Centauri B, hot super-Earth)

Radius: 9,800,000 m
Elevation: -5,000 m to +12,000 m
Volcanic hellscape, extreme tectonics
Seed: 604, octaves: 12, craterDensity: 0.08
Colors: highland [0.55, 0.30, 0.15] (dark volcanic), maria [0.35, 0.15, 0.08] (magma-tinged)

Nyx (Alpha Centauri B, habitable zone)

Radius: 6,940,000 m
Elevation: -5,000 m to +7,000 m
Cool Earth-like, more ocean (gameplay: rocky terrain visible)
Seed: 605, octaves: 10, craterDensity: 0.05
Colors: highland [0.50, 0.52, 0.42] (olive-green), maria [0.28, 0.35, 0.48] (ocean blue-gray)

Nyx I (moon of Nyx, icy)

Radius: 1,680,000 m
Elevation: -1,500 m to +1,500 m
Icy moon similar to Europa
Seed: 606, octaves: 8, craterDensity: 0.3
Colors: highland [0.80, 0.78, 0.75] (icy white), maria [0.58, 0.55, 0.52]

Proxima d (inner rocky)

Radius: 4,180,000 m
Elevation: -2,000 m to +4,000 m
Tidally locked, hot day-side, cratered
Seed: 607, octaves: 8, craterDensity: 0.6
Colors: highland [0.58, 0.52, 0.45] (warm gray), maria [0.38, 0.32, 0.26]

Proxima b (habitable zone)

Radius: 6,530,000 m
Elevation: -5,000 m to +7,000 m
Tidally locked, but potentially habitable
Seed: 608, octaves: 10, craterDensity: 0.1
Colors: highland [0.48, 0.52, 0.40] (muted green-gray), maria [0.32, 0.38, 0.45] (blue-gray)

Proxima e (outer rocky)

Radius: 5,960,000 m
Elevation: -3,000 m to +5,000 m
Cold, moderate cratering
Seed: 609, octaves: 10, craterDensity: 0.4
Colors: highland [0.55, 0.53, 0.50] (cool gray), maria [0.38, 0.36, 0.33]

Proxima e I (tiny moon)

Radius: 1,460,000 m
Elevation: -2,000 m to +2,000 m
Small rocky moon
Seed: 610, octaves: 8, craterDensity: 0.6
Colors: highland [0.58, 0.56, 0.53] (gray), maria [0.38, 0.36, 0.33]

Proxima f (mini-Neptune/ice)

Radius: 13,900,000 m
Elevation: -1,000 m to +2,000 m
Icy surface over deep atmosphere, low relief
Seed: 611, octaves: 8, craterDensity: 0.05
Colors: highland [0.65, 0.72, 0.78] (pale blue-white ice), maria [0.48, 0.55, 0.62]

Barnard’s Star System Profiles

Barnard d (innermost, hot)

Radius: 3,500,000 m
Elevation: -2,000 m to +4,000 m
Tidally locked, heavily irradiated
Seed: 701, octaves: 8, craterDensity: 0.5
Colors: highland [0.55, 0.45, 0.35] (warm brown), maria [0.38, 0.30, 0.22]

Barnard b (first confirmed)

Radius: 3,800,000 m
Elevation: -2,500 m to +4,500 m
Tidally locked, moderate terrain
Seed: 702, octaves: 10, craterDensity: 0.4
Colors: highland [0.52, 0.48, 0.42] (brown-gray), maria [0.35, 0.32, 0.28]

Barnard c (largest confirmed)

Radius: 4,000,000 m
Elevation: -3,000 m to +5,000 m
Tidally locked, most diverse terrain
Seed: 703, octaves: 10, craterDensity: 0.35
Colors: highland [0.50, 0.47, 0.42] (brown-gray), maria [0.33, 0.30, 0.26]

Barnard e (lightest RV exoplanet)

Radius: 3,200,000 m
Elevation: -1,500 m to +3,000 m
Small, tidally locked, moderately cratered
Seed: 704, octaves: 8, craterDensity: 0.5
Colors: highland [0.50, 0.48, 0.45] (gray-brown), maria [0.35, 0.33, 0.30]

Niven (habitable zone destination)

Radius: 5,500,000 m
Elevation: -4,000 m to +6,000 m
Primary destination, potentially habitable
Seed: 705, octaves: 10, craterDensity: 0.08
Colors: highland [0.48, 0.55, 0.40] (green-brown), maria [0.30, 0.40, 0.48] (blue-gray)

Phase 5b — Mars MOLA Real Heightmap

Data Source

MOLA MEGDR 16ppd — Mars Orbiter Laser Altimeter global DEM:

Property	Value
Resolution	16 pixels/degree
Dimensions	5,760 x 2,880 pixels
Meters/pixel	~3,700 m at equator
Format	16-bit signed integer (big-endian)
Raw size	33.2 MB
Scale factor	1.0 (values are meters relative to areoid)
Reference radius	3,390,000 m
Projection	Simple cylindrical (equirectangular)
Latitude	90°N (row 0) to 90°S (row 2879)
Longitude	0°E (col 0) to 360°E (col 5759)
Source URL	`https://pds-geosciences.wustl.edu/mgs/mgs-m-mola-5-megdr-l3-v1/mgsl_300x/meg016/megt90n000eb.img`

Key Difference from Luna: Byte Order

MOLA data is big-endian (MSB). Must byte-swap to little-endian during the Docker build. The client’s Int16Array assumes platform LE. Luna (LOLA) data is already little-endian.

Build Pipeline

build_mars_heightmap.py — Download MOLA .img, byte-swap BE→LE, write raw Int16 LE binary
downsample_and_compress.py — Same as Luna: downsample 16ppd→8ppd, byte-shuffle, gzip
Physics Dockerfile: downsample to 8ppd raw binary (no shuffle/gzip)

Verification Landmarks

Feature	Lat	Lon	Expected Elevation
Olympus Mons summit	18.65°N	226.2°E	~+21,229 m
Hellas Planitia floor	-42.7°	70°E	~-8,200 m
Valles Marineris	-14°	290°E	~-4,000 m (floor)

Docker Image Size Impact

Web-client: +5 MB (mars_heightmap.shuf.gz)
Physics: +8 MB (mars_heightmap_8ppd.bin)

Phase 5c — Earth ETOPO1 Real Heightmap

Data Source

ETOPO1 Ice Surface — NOAA global relief model (topography + ice sheet surface):

Property	Value
Resolution	1 arc-minute (~60 pixels/degree)
Dimensions	21,600 x 10,800 pixels
Meters/pixel	~1,850 m at equator
Format	16-bit signed integer (little-endian)
Raw size	~466 MB
Scale factor	1.0 (values are meters relative to sea level)
Reference radius	6,371,000 m
Projection	Simple cylindrical (equirectangular)
Latitude	90°N (row 0) to 90°S (row 10799)
Longitude	-180°E (col 0) to +180°E (col 21599)
Source URL	`https://www.ngdc.noaa.gov/mgg/global/relief/ETOPO1/data/ice_surface/grid_registered/binary/etopo1_ice_g_i2.zip`

Key Differences from Luna/Mars

Column origin: ETOPO1 starts at -180°E. Must shift +180° (rotate columns by half) to match the 0°E origin used by Luna/Mars.
Resolution: 60ppd native (vs. 16ppd for Luna/Mars). Must resample to 16ppd (5760×2880) before the standard downsample pipeline.
Already little-endian: No byte-swap needed (unlike MOLA).
Zip archive: Source is a .zip file, not raw .img. Must extract during build.
Ocean clamping: All negative elevations (ocean bathymetry) are clamped to 0m (sea level). Oceans render as flat terrain at sea level. Ships landing on ocean surface should eventually sink/be destroyed (future gameplay feature).

Build Pipeline

build_earth_heightmap.py — Download ETOPO1 zip, extract .bin, shift columns to 0°E origin, clamp ocean to 0m, resample 60ppd→16ppd, write raw Int16 LE binary (5760×2880)
downsample_and_compress.py — Same as Luna/Mars: downsample 16ppd→8ppd, byte-shuffle, gzip
Physics Dockerfile: downsample to 8ppd raw binary (no shuffle/gzip)

Profile Updates

Earth profile minElevation changes from -8848 to 0 (ocean clamped). mariaThreshold updated so low-elevation terrain (coastlines) renders with the blue-ish mariaColor and highlands render with green-ish highlandColor.

Verification Landmarks

Feature	Lat	Lon	Expected Elevation
Mount Everest	27.99°N	86.93°E	~+8,400 m (smoothed at 8ppd)
Dead Sea shore	31.5°N	35.5°E	~-400 m
Mariana Trench	11.35°N	142.2°E	0 m (clamped)
Great Plains (Kansas)	39°N	99°W (261°E)	~+600 m

Docker Image Size Impact

Web-client: +5 MB (earth_heightmap.shuf.gz)
Physics: +8 MB (earth_heightmap_8ppd.bin)

Critical Constraints

Determinism: Client and server profiles MUST have identical seed, noiseOctaves, craterDensity, largeBasins for each body. Otherwise landed ships jitter or clip through terrain.
Gas giants excluded: Jupiter, Saturn, Uranus, Neptune have no solid surface.
Non-spherical bodies: Phobos/Deimos are triaxial ellipsoids but the terrain system uses a sphere. Procedural noise approximates surface roughness; base shape is spherical.
Stars excluded: Stars have no surface for landing.