What are sky samples and how should I use them?
When you turn on Add Sky Light to all Solar and Distant Lights, in the Global Lighting dialog box, the Sky Samples setting determine how many “patches” the sky hemisphere is divided into to simulate the sky. They apply only to Solar and Distant light sources. For simple scenes, using Particle Tracing, the default setting of 145 sky patches is sufficient, but there are cases where you may need to increase this number to get better accuracy. One such example would be a room with very small windows. In that case, you may have to increase the setting to make sure that light from at least one sky patch gets through the window. Particle tracing, without Ray Trace Direct Illumination, is most efficient at handling large numbers of sky samples without losing performances (the same is true for large numbers of area light samples). In general, how many sky samples you need depends on the rendering mode, each of which has a default setting on the Sky Samples option menu. If you are using Particle
