NVIDIA GeForce GTX 480: GF100 Has Landed
Many of the new feature of GF100 are designed to increase geometric realism, while offering increased image quality, and of course high performance. One of the new engine features of the GF100, like other DirectX 11 class GPUs, is hardware accelerated tessellation.
The GF100 has built-in hardware support for tessellation. As we've mentioned in the past, tessellation works by taking a basic polygon mesh and recursively applying a subdivision rule to create a more complex mesh on the fly. It's best used for amplification of animation data, morph targets, or deformation models. And it gives developers the ability to provide data to the GPU at coarser resolution. This saves artists the time it would normally take to create more complex polygonal meshes and reduced the data's memory footprint. Unlike previous tessellator implementations, the one in the GF100 adheres to the DX11 spec, and will not require proprietary code.
To show off the capabilities of GF100, NVIDIA has created a number of interesting demos. As many of you know, properly rendering and animating realistic hair is a difficult task. As such, many games slap helmets or caps on characters, if they even have hair at all. NVIDIA's Hair demo, however, combines tessellation, with geometry shading and and leverages the compute performance of the GF100 to generate flowing hair. The images were realistically lit and smoothly animated, which is a far cry from what is seen in most of today's current games.
Another demo NVIDIA created to illustrate tessellation with the GF100 is aptly dubbed the Water Demo. As you can see in the screenshots above, the water demo takes a scene with relatively basic geometry, and through increased tessellation and displacement mapping the detail in the rocks and water is dramatically increased. The demo does not use realistic fluid dynamics, but the effect was nonetheless still very good. The difference in performance between the two modes was roughly 2x--with course geometry the demo ran at about 300FPS and with high-detail it ran at about 150FPS.
In addition to offering much more compute performance and geometry processing than previous generations, the GF100 also features new anti-aliasing modes. The GF100 will offer higher AA performance than GT200 not only due to having more ROPs but because enhancements have been make to each ROP as well. With GF100 the data compression factor is higher in the ROPs, it can use more samples, and it offers better transparency AA quality thanks to accelerated jittered sampling.
Jittered sampling changes the sampling pattern randomly on a per-pixel basis, which help removes banding and noise, and produces an edge that is more pleasing and natural to the eye. The GF100 also offers a new 32x CSAA mode (8x + 24 color samples) in addition to support for 33 levels of alpha blended transparency. The effect of the new AA mode is much smoother edges, as seen in the screenshots above. The new AA mode also preserves more detail on textures with transparency, that are sometimes rendered incorrectly when viewed at angles, like chain-link fences or railings, for example.