Let’s assume you have a scene ready, and that you want to render it with the Radiosity Rendering. The first thing to grasp when doing Radiosity is that no Lamps are necessary, but some meshes with an Emit material property greater than zero are required, since these will be the light sources. Emit is found on the Shaders panel in the bottom right (Material sub-context). Typically, a value of 0.5 or less gives a soft radiance.
Traditional still scene rendering usually involves lamps, spots, etc. But GI is a radiosity technique that allows you to light a scene from 360 degrees without a single lamp. This gives your scene more of a stylistic look.