This parameter, which in practice adds contact shadows at the point where two surfaces or two objects meet, is very important since it is able to add a strong sense of depth and realism to the scene. The main environmental occlusion techniques are the following.
Screen-Space Ambient Occlusion (SSAO): this is the AO technology with more years on its shoulders (in 2007 Crysis was the first game to implement it). However, it is not the most accurate and, as in the case of Far Cry 3, it can create an unpleasant “halo effect” that presents objects with a sort of black outline.
HBAO (Horizon-Bound Ambient Occlusion): a more advanced technology than SSAO that usually avoids the halo effect at the cost, however, of a greater impact on performance. The HDAO (High Definition Ambient Occlusion) variant is a version of HBAO proposed by AMD.
HBAO +: exclusive advanced technology for Nvidia graphics cards. In terms of impact on the framerate it is very similar to HBAO, but it gives a much more accurate, rich and realistic shadow.
Activate the environmental occlusion. In fact, many games rely on this parameter to create a sense of depth and atmosphere, especially indoors. If the drop in framerates is not excessive, HBAO + is the ideal choice.