Of the many ways to add Global Illumination to your scene here is one quick method. Our scene consists of a 4 ft. cube reshaped and smoothed with Subdivision. The RenderZone rendering on the left uses default project settings. The rending on the right uses GI as follows:
In the Lights palette double click the Sun Light to invoke the Light Parameters dialog.
Click on the Parameters tab and turn Apply Atmospheric Light ON.
(Note, this adds additional light from all directions as if light was radiating from a dome. This is in addition to the directional sun light which has its own intensity set under the Intensity tab. You can increase or decrease the directional and atmospheric intensities independently).
Click on the Shadows tab and turn Shadows OFF. (We’ll let Ambient Occlusion create our shadows as described below).
Hit F9 key or choose Display Options from Display pull-down menu to invoke the Display Options palette.
In Display Options palette click on RZ icon.
Click on Global Illumination tab.
Turn Use Ambient Occlusion ON, Quality = 1, Distance = Custom 6”, Additional Contrast = 60%.
In Display Options palette click Render button.
Note, you can increase Quality = 3 for better Ambient Occlusion however this increases rendering time. You can also turn on Use Final Gather which bounces light in the scene at the cost of increased rendering time.