# Io scene A ("Kīlauea patera"): credits and data provenance

Helios is non-commercial. Every source below is used under its stated licence. **Real data** means measured elevation or scanned geometry/texture; **procedural** means generated by our scripts. The map is a real Earth landscape (Kīlauea) re-dressed as Io; nothing in it is Io topography.

## Elevation (real data)
| What | Source and citation | Licence | How we changed it |
| --- | --- | --- | --- |
| Base terrain, whole 7.168 km map (EPSG:6635 x 258000–265168, y 2143600–2150768) | U.S. Geological Survey, 3D Elevation Program, airborne lidar point cloud **HI_Volcano_B1_2019** (July 2019), read from the public Entwine Point Tile `[path removed]`. Same survey as Mosbrucker, A.R., Zoeller, M.H., and Ramsey, D.W., 2020, *Digital elevation model of Kīlauea Volcano, Hawaiʻi, based on July 2019 airborne lidar surveys*, USGS data release, https://doi.org/10.5066/P9F1ZU8O | Public domain (U.S. Government work) | Ground-class points gridded to 1 m (mean Z) by us: EPT depth ≤ 9 over the whole map, depth ≤ 10 over the central 6.1 × 5 km, merged with a 60 m feather; holes IDW-filled (≤ 40 m); isolated spikes removed; roads/buildings/parking inpainted (see below); 2.5 m of lake surface levelled in the Halemaʻumaʻu pit bottom (lava-lake glimpse); two tube skylights (4–5 m pits) and two 3 m fissure slots cut. Heights shifted by −1000 m for the world frame. |
| Context apron outside the map (28 km) | Same EPT, depth ≤ 6, gridded to 16 m, resampled to 32 m | Public domain | Outside the lidar footprint the apron is smooth inverse-distance fill (not data). |
| Flow-field surface texture (relief only) | INGV Pisa, *2004–05 Mt. Etna compound lava flow field: orthophotos and topography*, lidar 29 Sep 2005, 1 m, https://www.pi.ingv.it/banche-dati/2005-04-etna-lava-flow-data/ ; Fornaciai, Andronico, Favalli et al. (JGR Solid Earth); Favalli, Fornaciai & Pareschi (2009) Geomorphology 111, 123–135 | CC BY 4.0 | Cropped (x 690–2770, y 0–1800 m of the sample), detrended (σ 35 m), rotated to the local flow direction, scaled to 0.35 and added inside the simulated flow outline with a 14 m feather. |
| Distal pressure ridges (relief only) | U.S. Geological Survey 3DEP, OPR DEM project OR_Western_D23 (Big Obsidian Flow, Newberry Volcano), 1 m | Public domain | Detrended (σ 25 m), rotated, scaled to 0.12 (basalt-size ridges), added on lobes > 700 m from the vent. |
| Spatter-cone row | U.S. Geological Survey 3DEP 1 m DEM, project ID_SouthernGaps_D23 (Great Rift, Big Craters and Spatter Cones, Craters of the Moon) | Public domain | A 1.1 km strip along the cone chain, detrended (σ 90 m), rotated onto the SW-rift fissure line, relief × 1.5, side/end feathers 70/140 m. |

## Human-artifact removal
OpenStreetMap contributors, Overpass API extract of roads, buildings and parking areas (© OpenStreetMap contributors, ODbL 1.0). Used only to build the mask of what to inpaint; no OSM geometry ships with the scene.

## Textures (real scans and CC0 photo-textures)
| Layer | Source | Licence |
| --- | --- | --- |
| Sulfur yellow, iron red, salt white, mixed ochre, green crust, terrace pools (deposit and fumarole crusts) | Io asset kit `dallol-*` texture sets, cut from: Grunwald, O.; Delage, E.; van Wyk de Vries, B. *Topographic 3D model: Dallol domes – Dataset*. OPGC / LMV, Université Clermont Auvergne. https://doi.org/10.25519/TXZC-1724 | CC BY-NC 4.0 |
| Fresh pahoehoe | Io kit `basalt-pahoehoe-fresh`: "Lava field from Mauna Ulu – Kilauea, Hawaii" by Tom (trbaker), Sketchfab, https://sketchfab.com/3d-models/923fcaded6f646b09a7abb935bc82893 | CC BY 4.0 |
| 'a'a clinker | Io kit `basalt-aa-clinker` (ambientCG Rock031) | CC0 |
| Hot crust / crack pattern | Io kit `lava-crust-hot` (ambientCG Lava001) | CC0 |
| Cliff basalt | Io kit `basalt-cliff` (Poly Haven Dark Rock 02, Amal Kumar) | CC0 |
| Old basalt ground | Poly Haven `rock_ground`; Poly Haven `dark_rock` (Amal Kumar) | CC0 |
| Ash/cinder (minor) | Poly Haven `terrain_red_01` (Rob Tuytel) | CC0 |

## Scatter meshes (real scans)
From the Io asset kit (`[path removed]`, decimated by the kit agent; our LOD1/LOD2 are further quadric decimations):
- `rock-aa-clinker-daal`, `rock-scoria-bomb-daal`: "Igneous rock: Basalt (A'a Lava Rock)" and "Scoria", Digital Atlas of Ancient Life (Emily Hauf), Sketchfab, CC0.
- `rock-pahoehoe-block-kantanat`: pahoehoe basalt scan by kantanat, Sketchfab, CC BY 4.0.
- `rock-scoria-boulder`: "Scoria Rock Scan" by fevenkitsune, https://sketchfab.com/3d-models/scoria-rock-scan-4c42f98d402b44fdbb13d2fc6900d537, CC BY 4.0.
- `rock-vesicular-block-bustos`: "Lava rock scan" by Elan Bustos, https://sketchfab.com/3d-models/lava-rock-scan-1b45405d04ea41c29c4e8cbd9648ef95, CC BY 4.0 (texture CC0).
- `rock-basalt-block-ph07`, `rock-basalt-slab-ph09`: Poly Haven Rock 07 / Rock 09, CC0 (recoloured to basalt by the kit agent).
- `rock-sulfur-cianciana`: native-sulfur crust scan (Cianciana), Sketchfab, CC BY 4.0.
- `rock-pahoehoe-slab-maunaulu`: from "Lava field from Mauna Ulu – Kilauea, Hawaii" by trbaker, CC BY 4.0.
- `rock-ropy-lobe-mangere`: Mangere ropy lava flow scan, Sketchfab, CC BY 4.0.
- `dallol-crust-mound`, `dallol-twin-mounds`, `dallol-salt-pillars`: pieces of the OPGC Dallol domes model (doi:10.25519/TXZC-1724), CC BY-NC 4.0.
Exact credit lines per item are in `[path removed]` (copied from the kit manifest).

## Sky
Jupiter: NASA Scientific Visualization Studio, *Hubble Maps Jupiter in 4k Ultra HD* (OPAL 2015), https://svs.gsfc.nasa.gov/12021, NASA/ESA/A. Simon (GSFC), public domain (copied from the Helios game assets, `jupiter_2k.jpg`).

## Procedural (not data)
- Lava-flow outlines and thickness: cellular-automaton spread (residual-thickness model with slope-dependent critical thickness and a downslope bias), 22 overlapping flow units on the real topography.
- Sulfur deposits: offline Io-ballistic particle simulation (g = 1.796 m/s², no atmosphere), fumarole clusters along hand-placed fault polylines, SO₂ frost from horizon-shadowed insolation and topographic lows. Parameters in `[path removed]`.
- Lava emission (crack networks, fissure slots, vents, lake margin), lava irradiance, plume volume and particles, heat shimmer, stars.
- Scatter placement (talus, flow blocks, bombs, sulfur blocks, mounds).
- Vent, fissure, fumarole and lake positions are our design choices on the real map, not real Kīlauea vents (except that fumaroles on the NE ring fault sit at the real Sulphur Banks).