Screen Space Ambient Occlusion (SSAO): Difference between revisions
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==Supported games== | ==Supported games== | ||
All [[Source]] engine games except [[Portal]] | All [[Source]] engine games except [[Portal]] have driver profiles to enable Nvidia's Ambient Occlusion. SSAO in Portal can be forced on by editing Portal's driver profile with an external application. | ||
==Enabling Nvidia's Ambient Occlusion== | ==Enabling Nvidia's Ambient Occlusion== | ||
[[{{ns:6}}:EnableAO.png|thumb|right|300px|Enabling AO in Nvidia control panel]] | [[{{ns:6}}:EnableAO.png|thumb|right|300px|Enabling AO in Nvidia control panel]] | ||
Ambient occlusion cannot be controlled through the video options within a Source game. AO is controlled by Nvidia's video drivers in the Nvidia Control Panel. | Ambient occlusion cannot be controlled through the video options within a Source game. AO is controlled by Nvidia's video drivers in the Nvidia Control Panel. |
Revision as of 14:44, 22 December 2010

Ambient Occlusion (AO) is a type of lighting technique applied in-game to create more realistic lighting. AO simulates soft shadows created by two surfaces that are close together. Ambient occlusion in games is normally accomplished through Screen Space Ambient Occlusion, which is a simplified way to fake realistic AO with shaders in a process fast enough for real-time rendering.
SSAO works by examining an onscreen pixel, and then comparing its location in the depth buffer (i.e. how far it is away from the player) to the pixels around it. Pixels which are close together but not coplanar (on the same face) are shaded to simulate soft shadows. To maintain playable framerates, it is not possible to sample every pixel every frame, so random sampling is used, which will inevitably create noise/grain which may be more noticable when the player moves around.

This method of driver forced SSAO causes several rendering bugs in the Source Engine. Most notably, the SSAO shader does not take fog into account in it's AO calculations, producing visual artifacts in scenes with heavy fog.
Supported games
All Source engine games except Portal have driver profiles to enable Nvidia's Ambient Occlusion. SSAO in Portal can be forced on by editing Portal's driver profile with an external application.
Enabling Nvidia's Ambient Occlusion
Ambient occlusion cannot be controlled through the video options within a Source game. AO is controlled by Nvidia's video drivers in the Nvidia Control Panel.