The sky is approximated as a fixed set of directional lights (72–73, Turtle geometry). Works in any renderer. Solar position is computed from geographic coordinates (latitude, day-of-year, hour) via the Goudriaan algorithm. Irradiance is driven by real-world DHI/DNI measurements or CIE sky types. No background image is produced.
| Model | Class | Parameters |
|---|---|---|
| Isotropic Overcast |
SkyDome
| total power (W/m²) |
| Perez All-Weather |
PerezSunSky
| DHI, DNI, latitude, day-of-year, hour |
| CIE Standard Sky |
CIELighting
| sky type (1–15), cloud cover |