Customization of the model

The sky model is physically-based. It means that the celestial bodies radiances and sizes, stars distribution, dimensions and densities are all taken from optics and astronomic literature and measurements. This is good to achieve very realistic skies but can be counter-intuitive when it comes to render nice pictures. For example, one could want to see in the same image sun or moon and stars, or even the three together!

The model can be tuned to produce impossible views of our sky. This can be achieved through the manual positioning of sun and moon rather than using astronomical methods (RED::ISkyLightShape::SetSunLight and RED::ISkyLightShape::SetMoonLight) and by modifying celestial bodies radii and intensities. See the RED::ISkyLightShape::SetPhysicalModel method for details.

In this customized sunset view, the sun, moon and stars are all visible and well-exposed. Note how the sun and moon size have been arbitrary up-scaled. This can only be achieved by tweaking the physical model (the distortion of the solar disc is due to the short focal used).

Sky is not the limit

The observer can be at any altitude when rendering the sky model. So views from high altitude, and even from space, can be rendered just by settings the corresponding altitude.

The earth rendered at different altitudes (from left to right: 1m, 100m, 10 000m, 1000 000m): note how the curvature of the earth becomes visible and how the effect of aerosols disappears when the altitude increases.


Sun eclipses can be easily simulated by moving the moon to the line between the sun and the earth.

Three views of a partial sun eclipse (sizes of the sun and moon have been exaggerated to emphasize the effect).


Eclipse of the moon by the earth are also simulated by our sky model.