At the launch of DirectX 11 in 2009, the sole use of Microsoft’s latest graphics API was to add tessellated detail to characters and objects when a DirectX 11-compatible GPU was detected. This revolutionary addition had a comparatively small performance impact whilst adding significant depth and detail that simply couldn’t be achieved with traditional techniques. Flat cobbled streets gained true depth, character’s faces were rounder and more realistic, and environments appeared more organic and natural.
In recent years, NVIDIA has been at the forefront of DirectX 11, developing new features and effects that dramatically enhance the games you know and love. And thanks to NVIDIA’s industry-leading GeForce GTX GPU technology, each feature runs best on NVIDIA-powered PCs.
Traditionally, fur and hair in games is created by adding polygon strips and transparent textures to a character. Though this is a simple and cheap implementation, the resulting fur and hair appears completely static and visually uninteresting. With dynamic fur and hair, hundreds of thousands of hair strands can be added to characters, each reacting realistically to a character’s movements and external forces. These dynamic hairs also allow for richer color gradients, and interact with light and shadows more naturally than was previously possible. World and local lighting permeates through each layer, with the deepest layers being naturally shadowed, significantly improving image quality.
Using DirectX 11 technology, NVIDIA has developed NVIDIA HairWorks, a platform agnostic tessellated hair technique that adds dynamic volume in place of static meshes comprised solely of detailed textures. In Call of Duty: Ghosts, the first title to feature NVIDIA HairWorks, the protagonist’s dog is seen without body armor, resulting in the rendering of 470,000 individual hairs, which create an accurate, realistic simulation of a German Shepherd.
The result of years of research and development, beginning with “A New Dawn”, NVIDIA HairWorks will enable the realistic rendering of human characters with dynamic hair in future games, in addition to the rendering of alien creatures, grass, and other environmental features.
In 2013 NVIDIA demonstrated the “Digital Ira” NVIDIA FaceWorks demo, which drew worldwide interest from those amazed by its state of the art performance capture, and dynamic real-time lighting. Made possible by the CUDA Cores embedded in NVIDIA GeForce GTX GPUs, and the latest DirectX 11 rendering techniques, Digital Ira was a true innovation.
To date, hundreds of thousands of people have downloaded Digital Ira, and most recently NVIDIA made waves by demonstrating the latest version of Digital Ira on the Tegra K1 mobile GPU.
NVIDIA TXAA is a custom-developed anti-aliasing technique designed to tackle temporal aliasing, the movement of anti-aliased edges when the player’s camera or view point moves. Referred to as crawling and shimmering, this movement is a particular eyesore in games with fine detail, like the rigging of ships in Assassin’s Creed IV: Black Flag.
Combining Multisample Anti-Aliasing (MSAA) with a custom CG movie-style resolve, and a temporal filter, TXAA effectively combats temporal aliasing whilst simultaneously anti-aliasing geometry to a degree comparable to that of 2xMSAA and 4xMSAA.
Like other technologies presented here, NVIDIA TXAA would not have been possible without the advances DirectX 11 brought to the table. Please note that NVIDIA TXAA also requires a Kepler-based GeForce GTX 600 Series GPU, or newer, whereas other DirectX 11 technologies presented here merely require a DirectX 11 capable GPU.
NVIDIA HBAO+ Ambient Occlusion
Ambient Occlusion is important for gaming, adding realistic shading and shadowing where two surfaces or objects meet. In 2013 NVIDIA released HBAO+, a new Ambient Occlusion technique that dramatically increases the fidelity and accuracy of said shading, and unlike previously-released techniques that increased quality, HBAO+ runs fast and efficiently thanks to DirectX 11 and NVIDIA’s innovative programming.
Assassin’s Creed IV: Black Flag, Batman: Arkham Origins, Call of Duty: Ghosts, and Tom Clancy’s Splinter Cell Blacklist already feature HBAO+, and many more games are ready and waiting to use the critically-acclaimed AO technique.
A development capture from Batman: Arkham Origins demonstrates the degree to which Ambient Occlusion shading is used in games. With a lower-quality technique, such as SSAO, the quality and accuracy of the shading would be noticeably reduced, resulting in a less realistic scene.
NVIDIA Percentage Closer Soft Shadows
DirectX 11-powered NVIDIA Percentage Closer Soft Shadows (PCSS) are an effective solution for developers wanting to add contact-hardening, realistic soft shadows to their games. As in real life, PCSS shadows progressively soften as the distance from the casting object increases, increasing realism. A secondary benefit of PCSS is the inclusion of high-quality shadow filtering techniques that reduce the prominence of shadow aliasing (jagged lines on the edges of shadows).
On the left of the comparison you see Assassin’s Creed IV: Black Flag’s highest-quality, ‘standard’ shadows. Note how every shadow is sharp and clearly defined. On the right, you see the NVIDIA PCSS-enhanced shadows. As in reality, the shadow of the tree’s trunk is clearly defined due to its proximity to the ground, and the shadows of the tree’s leaves, which are way up in the air, are soft.
A tertiary benefit of PCSS is the addition of a shadow buffer capable of compositing individual shadows, avoiding the double-darkening shadow effect seen in some games and game engines.
NVIDIA DirectX 11 Crepuscular Rays
Crepuscular Rays are bright shafts of light that can be seen when looking at the Sun or Moon, or when looking at light shining into a dark room or area. In games, they’re commonly referred to as Light Rays, Light Shafts, or God Rays. Traditionally they’re rendered using performance-intensive ray-marching or viewspace slicing techniques, but in Assassin’s Creed IV: Black Flag, NVIDIA debuted a revolutionary DirectX 11 implementation.
By leveraging DirectX 11, NVIDIA created a new Crepuscular Rays lighting technique that renders polygonal light shafts through the use of tessellation alone. This innovative solution has a lower impact on performance, uses less GPU memory, and greatly reduces aliasing on visible rays, further increasing image quality.
NVIDIA Depth of Field
“NVDOF”, as it is officially known, enables developers to apply high-quality depth of field rendering to their games. In Batman: Arkham Origins, this DirectX 11-enhanced effect increases the precision and image quality of depth of field effects, and applies Bokeh to lights within the depth of field view. If you’re unfamiliar with Bokeh, the rendering technique enables developers to apply custom shapes to out of focus lights, turning an in-focus circle into an out of focus hexagon, for example.
In the interactive comparison above, note how the default depth of field implementation blurs everything but Batman’s gadget, despite the camera being close enough to see his stubble. With DirectX 11-enhanced NVDOF, Batman and his equipment is clearly visible, and the four background lights are subtly modified with a slight Bokeh effect, improving the overall image quality of the out of focus effect.
In addition to the many technologies listed above, NVIDIA continues to develop new features and effects that will enhance games in 2014 and beyond. For the latest on these developments stay tuned to the front page of GeForce.com.