Before we begin it’s important to understand what anti-aliasing is. In its most basic form it’s a technique for smoothing textures that would otherwise look jagged. To achieve this there are a number of techniques, often involving algorithms.
Post anti-aliasing, as with most games, is required for Battlefield 4, usually to smooth edges. The edges of objects have to be detected and then smoothed via whichever technique they use. However, the techniques used to achieve it have been varied across platforms and, critically, some have been better received than others. So why, for instance, does the PlayStation 3 use a better technique than the PlayStation 4?
Battlefield 4 on the PlayStation 3 uses a technique known as MLAA (Morphological Anti-Aliasing). This has been created by AMD and is exclusive to their chipsets and drivers.
Battlefield 4 on the PlayStation 4 uses FXAA (Fast Approximate Anti-Aliasing). An nVidia Technology it can be used on both AMD and nVidia systems.
The problem is that FXAA hasn’t been very well received. It uses a lot less resources than other algorithms but the resulting textures may not appear as sharp if they are included in the edge detection. Many refer to the results as looking blurry and as if they’ve been smeared with Vaseline.
Johan Andersson is Frostbite’s Technical Director, working for EA. He recently Tweeted, in response to a query about this…
@WebinventDotCom we tried SMAA T2X and looks nice but cost was too high for BF4
— Johan Andersson (@repi) April 6, 2014
This now introduced a third technique to the discussion – SMAA T2X (Enhanced Subpixel Morphological Antialiasing). Used on the recently released Infamous: Second Son, it would appear that this was attempted on Battlefield 4 but used too many resources.
But why did they then resort to FXAA, instead of the superior MLAA?
I spoke further with Johan to try and discover the truth.
MLAA is embedded in Frostbite (it was present from Frostbite 2) but only for the PS3. This is because it’s supported natively in the SPU, part of the Cell chipset. Yes, you can also use MLAA on PC but that’s because it is literally post-processed – not by DICE’s code but by the AMD driver (adjustable from the AMD control panel). As the PS4 doesn’t use Cell it lost the ability to support MLAA.
PC players often talk about switching off the FXAA anti-aliasing within BF4 to sharpen the image quality. What they don’t say is whether this is because their graphics driver is also providing AA duties.
So, there is it – it would have been wonderful to have had ML!! but, sadly, performance didn’t allow it. FXAA is probably the best alternative.