Atmospheric light scattering FAQ

What is Atmospheric Light Scattering (ALS)?

Technically, ALS is a forward rendering framework for Flightgear, supplying a series of GLSL shader effects with consistent position-differential lighting and fogging for the whole scene.

Conceptually, ALS serves to make the Flightgear visuals realistic, committing the computing power of the graphics card predominantly to what a pilot gets to see most during flight, i.e. chiefly visuals in the air, from the cockpit. Primarily this is, as the name suggests light scattering in the atmosphere on the air and haze and visuals of sky and clouds, then hires dynamical texturing of the terrain and finally support for effects on 3d models. Things like aircraft shadows or secondary lights, the speciality of Project Rembrandt are minimally supported by ALS since they are relevant primarily on the ground and cost a lot of performance.