Now open the VRay: Irradiance map rollout and examine it. Irradiance mapping is main and most common technique of indirect lighting approximation used for primary bounces in V-Ray.
The Chaos team provided some quality presets to
make our lives easier, so let’s apply one of them. At
the top of rollout, select the Low preset for faster im-
age previewing.
In the options section, check Show Calc. phase to see
how the irradiance map works.