Prague Sky Model (2021) — Full-Spectral Dataset Sky
| Class | PragueSkyModelLight |
| Family | Environment shader (Sky + analytic shader) |
| Author(s) | Wilkie, Vévoda, Bashford-Rogers, Hanika, Hachisuka, Křivánek |
| Year | 2021 |
| Reference | Wilkie, A. et al. (2021). A fitted radiance and attenuation model for realistic atmospheres. ACM Trans. Graph. (SIGGRAPH 2021) 40(4), 135:1–135:14. |
Introduction
The Prague Sky Model is a dataset-driven sky model covering the full solar spectrum (280–2480 nm) and a wide range of atmospheric conditions: visibility 20–131.8 km, observer altitude 0–15 km, solar elevation −4.2°–90°, and ground albedo 0–1.
The dataset is distributed under the Apache 2.0 licence and must be downloaded separately.
Phase 1 (current): if no dataset is loaded, the model falls back to Preetham radiance with a console warning.
Parameters
| Parameter | Type | Range | Description |
|---|
| datasetPath | String | file path | Path to the SkyModelDataset.dat file. |
| solarElevation | double | −4.2 – 90 ° | Solar elevation angle above horizon. |
| azimuth | double | 0 – 360 ° | Solar azimuth (0 = North, 90 = East). |
| visibility | double | 20 – 131.8 km | Meteorological optical range (aerosol load). <50 = hazy, >100 = very clear. |
| observerAltitude | double | 0 – 15 km | Altitude of the observer above sea level. |
| groundAlbedo | double | 0 – 1 | Ground albedo (broadband). |
Renderer compatibility
| Twilight (Sunflow) | ✅ (Phase 1: Preetham fallback) |
| GPUFlux | ✅ (Phase 1: Preetham fallback) |
| OpenGL / Proteus | background colour only |
Dataset
The dataset file can be obtained from the Charles University Prague CG Group page. Set the path via the Parameters tab or in code: ((PragueSkyModelLight) sky.getShader()).setDatasetPath(path);