| LemonSlice said: Isn't tessellation used to make distant objects look like crap? Or is that just variable LOD and I'm mixing things up? |
Sometimes videos are a lot better than writing technical jargon and trying to make a person see what the technology does.
Watch this video #1 at early evolution of Tessellation in 2010:
Tom Clancy's H.A.W.X. 2 Tessellation On/Off comparison video
http://www.youtube.com/watch?v=bHh8D3AzZaU
Video #2 shows how tessellation works exactly in wireframe:
NVIDIA Endless City Tessellation Demo
http://www.youtube.com/watch?v=sQQpCd_vvGU
This is how a tessellated 3D object would look like in a modern DX11 game like Crysis 3:
A modern graphics card has Geometry engines that are responsible for tessellation. In the past, a graphics card overlaid textures around vertices and the result are simple mountains and walls. To enhance the realism, bump-mapping was added and later this evolved into displacement bump-mapping. However, if you wanted to create an extremely complex environment, everything has to be complex, whether far or up-close and this is simply not efficient/not possible using current tech, etc. With geometry shaders, you can increase complexity on the fly using tessellation. So yes it helps with LOD depending on distance but also expontentially increases the complexity of objects:
The current approach to tessellation still requires that the various iterations of the Dragon are created, the Tessellated and Non-Tessellated form. This means the artist has to do double the work right now. The next iteration of tessellation will move to Adaptive Tessellation where it will happen on the fly and the artist no longer has to create multiple models to account for non-tessellated vs. tessellated characters. It will truly become dynamic/on-the-fly geometry processing of character models and environment. This video highlights Adaptive Tessellation in action:
CryENGINE 3.4.0 - DX11
http://www.youtube.com/watch?v=6KuNw8bjDwc
Even now tessellation already makes objects look more realistic but it's only in its infancy. The artists no longer have to sit there and create a perfectly rounded head or character limbs. The Geometry shaders in the GPU do it on the fly. But this is pretty GPU intensive, and only parts of the character are tessellated, like shoulders, head and some parts of the arm in Hitman Absolution.
Without tessellation
With tessellation
Global Illumination when combined with ambient occlussion (HDAO) creates more realistic area lights where lights reflect on objects and objects reflect/refract light too, dynamically. In the past, if you blew up a helicopter in COD, someone has to create 100 variations of that explosion and then create lights for them too. With global illumination/dynamic lighting and per-pixel lighting, the way light is reflected onto the gaming environment is calculated in real time. The artist isn't sitting there creating 100 models of a building with different light shadows.
In case anyone is wondering, both the Samaritan Demo and the new Square Enix demo have all of these technologies incorporated in them at once.
*** Unfortunately some of this technology is hard to see in these compressed screenshots. Watch the videos I linked instead ***
