AO

Ambient Occlusion (AO) is a shading technique that was developed back in the time when global illumination was impractical. Instead of shooting many rays and bouncing them around (which is what is needed for global illumination), ambient occlusion was used to detect the parts of the scene that are occluded from the rest of the environment (such as corners and creases).

Today's computers are much more powerful than when Ambient Occlusion was first developed and the use of global illumination is now the norm. This reduces the usefulness of ambient occlusion as a primary lighting technique. However, Ambient Occlusion to achieve different effects such as:

• Creating extra darkness/contrast in occluded areas for artistic reasons – when GI has failed to do so and has 'leaked' too much lighting in these areas (because of multiple bounces)
• Using it to implement techniques like 'dirtmaps' where shading is modified around occluded areas by blending different textures (such as moss)

Redshift allows the results of the Ambient Occlusion node to be connected and combined with other rendering techniques which provides the user with a very good degree of flexibility.