NVIDIA Voxel Ambient Occlusion Raises The Bar For Ambient Occlusion Effects. Try It Now In Rise Of The Tomb Raider

By Andrew Burnes on March 17, 2016 | Featured Stories NVIDIA GameWorks

With the release of the GeForce GTX 900 Series Maxwell architecture, we debuted a new technology called Voxel Global Illumination (VXGI). Designed to realistically render a scene’s lighting and shadowing at a faster rate than other Global Illumination technologies, VXGI enabled us to recreate the Apollo 11 Moon landing in an interactive technology demo that demonstrated the possibilities of real-time Global Illumination in games.


In the time since we have integrated VXGI into the NVIDIA Unreal Engine 4 branch on GitHub, and have developed a new feature called Voxel Ambient Occlusion (VXAO). Unlike VXGI which controls all illumination, VXAO is only utilized for Ambient Occlusion (AO), enabling us to integrate it into a wider array of games and game engines that use traditional illumination technologies.

If you’re familiar with Ambient Occlusion, a technique that adds contact shadows where objects occlude light, you’ll know NVIDIA HBAO+ is the go-to solution for the best possible AO in today’s games. It’s more accurate than SSAO and its derivatives, casts deeper, richer shadows that account for even the smallest details in a scene, and runs faster than other competing effects when they’re rendered at a similar quality.

Even still, HBAO+’s Ambient Occlusion shadowing is far from the level of fidelity offered by VXAO, which avoids the caveats of screen space techniques, enabling us to deliver the most accurate and realistic Ambient Occlusion shadowing seen to date.

In this interactive comparison, click to load, HBAO+ and VXAO are directly compared in a rendering mode that shows only shadows cast by the respective techniques, and nothing else.

With VXAO, occlusion and lighting information is gathered from a ‘world space’ voxel representation of the scene, which takes into account a large area around the viewer. Included in this voxelization are objects and details currently invisible to the viewer, and those behind the viewer, too. The result is scene-wide Ambient Occlusion shadowing, instead of ‘screen space’ shadowing based on what you can currently see. This allows AO shadows to be cast into a scene from objects near to the player but just outside of their view, and from occluded objects in the distance large enough to affect the appearance of the scene.

In addition, VXAO’s precision and accuracy enables significantly improved Ambient Occlusion shadowing in detailed in-game environments. This is particularly evident in Crystal Dynamics’ Rise of the Tomb Raider, the first game to feature VXAO. As demonstrated in our interactive comparisons in our Graphics and Performance Guide, VXAO dramatically improves the quality of Ambient Occlusion shadowing in the game’s object and geometry-filled locations.

With these advancements the bar has once again been raised, just as it was when three years ago when HBAO+ debuted. To see the effect for yourself equip your system with a GeForce GTX 900 Series, second generation Maxwell-architecture GPU, and snag Rise of the Tomb Raider on Steam.

And should you wish to learn more about Rise of the Tomb Raider’s other technology, be sure to check out our comprehensive Rise of the Tomb Raider Graphics & Performance Guide.