New DirectX 11 features
The DirectX 11 module adds a few small general optimizations and improvements in quality, but above all, additional effects with the Ultra Upgrade, enabling finer rendering in this setting.
First of all Motion Blur HDR is now in full resolution, which means you get a sharper image during rapid movements and the removal of blur bleeding on objects that shouldn't be affected by it, such as the player's weapon.
[ Motion blur low resolution ] [ Motion blur full resolution ]Particles can now receive shadows and motion blur, on a a case by case basis decided by artists, which makes for increased accuracy.
Shadows are applied on smoke particles.In the Ultra DirectX 11 version, shadows change with variable penumbra, a technique which is also called Contact Hardening Shadows in the AMD version and integrated for example in S.T.A.L.K.E.R. Call of Pripyat and DiRT 3. This gives closer to reality visuals with shadows that soften more and more as they get further away from the object that generates them, giving a more accurate result than fixed filtering across the whole shadow.
[ Standard shadows ] [ Shadows with variable penumbra ]A new type of Deph of Field is introduced with the DirectX 11 Ultra Upgrade. Known as “Sprite-based Bokeh Depth of Field”, it’s similar to the implementation used in 3DMark 11. Instead of a simple post processing filter, the technique consists in generating a sprite for each pixel using geometry shaders. The size of this sprite depends on the circle of confusion radius and can thus represent objects that are either in focus or not. The technique also allows artists to use a mask to fake the end result produced by different types of lenses diaphragm (Bokeh), according to the judgement of the artist. As this effect is very demanding in terms of processing resources, it is implemented at half resolution with optimisations to prevent its bleeding onto objects in focus. Note that it isn’t really used outside of cinematic sequences.
[ Standard DoF ] [ DX11U DoF circular Bokeh shape ] [ DX11U DoF pentagonal Bokeh shape ]After improving all these effects, Crytek set to adding details to objects and environments. This is where the use of tessellation comes in, one of the new features of DirectX 11. Crytek has included across the board tessellation support in its CryENGINE 3 engine, but in practice how it is used depends on artists as both textures and models have to be revisited. Moreover Crytek says that current GPUs are not yet sufficiently powerful to apply tessellation on the whole level and that it must therefore be used sparingly. In addition, Crytek says that some GPUs (the Radeons) present performance issues when the level of tessellation is too high, which is why pre-tessellated geometries have been introduced in instances where artists consider them to be the best compromise for performances. Tessellation is used on some walls, broken-up floors, stones and other objects:
[ Without tessellation ] [ With tessellation ]
[ Without tessellation ] [ With tessellation ]Given that, for performance reasons, tessellation cannot be over-used, Crytek has reintroduced Parallax Occlusion Mapping in DirectX 11 Ultra mode. To recap, this effect enables pretty realistic simulation of reliefs, though not on silhouettes. It is mainly used for the ground, to very good effect, except when other objects or characters appear on top. These objects/characters then seem to be floating as it isn’t possible to sink them into the relief created for the ground.
[ Without POM ] [ With POM ]Lastly, tessellation adds more details in water scenes. Here Crytek says that tessellation adapts to the distance of the camera from the scene to prevent the generation of too much aliasing in the background. Thanks to the more complex geometry used, the movement of the sea is more impressive and more detailed. The smallest areas of water that appear in the game also benefit from tessellation, giving in particular a more realistic rendering when these areas of water interact with an object or character. How the water itself is rendered has also changed in terms of imrpoved foam and sub-surface scattering support to give more realistic lighting.
[ Standard sea ] [ DX11U sea with tessellation ]
