One of my biggest pet peeves in images is poor anti-aliasing, even more so than poor jpeg use. I’ve done a few informational/tutorial based threads before, so here’s another one.
Notice: Anti-Aliasing is a really broad, complicated field. There’s a lot more to it, even with what you’ll see in your GPU driver’s control panel. Here I’m going over the most common/important ones, google anti-aliasing to learn more!
When people in this forum talk about “turning up your graphics,” one of the most important, but most often overlooked, is anti-aliasing. Anti-aliasing is a solution to a pretty serious problem with computer graphics. Our current digital displays rely on pixels, little square colored dot things (in simple terms ) that, when looked at from a distance, are used to form an image. It’s an extremely intelligent design, and it gets good results. However, it has one drawback. Our eyes pick up light, which consists of photons and waves and little hookers that are, in fact, a hell of a lot smaller and “smoother” than pixels. So, when you look at an image on a digital screen with square, harsh pixels, you pick up on the sharp edges and your brain tells you that something is wrong. Now, displays with very high pixel density (such as the Droid DNA cell phone and its 441 ppi display) get around this by having pixels so small that your eyes cannot make them out. Sadly, our full-sized monitors are nowhere near at this level yet.
Enter Anti-Aliasing, the cheaper solution to this significant problem. Anti-aliasing uses some hardcore mathematics to find harsh edges, and “blur” or “smooth” them intelligently so the edges appear less harsh (think how white->black is harsher to the eyes than white->gray->black). Now, good AA can be very intensive, so up until the 21st century it was not very common in games. Today it’s common place, and there are different kinds to choose from, which we will see below.
1 - No Anti-Aliasing
Check out the image below.
The textures, shadows, models, anisotropic filtering, post processing details, etc are all on high, and yet it looks horrible. This image has no anti-aliasing, and so your brain gives you a feeling of “something isn’t right” that you cannot shake, not unlike the uncanny valley. We want to avoid this, because, as you can see, it can ruin an otherwise nice image.
2 - Post Anti-Aliasing
This is our first option. Post-AA, such as FXAA, MLAA and SMAA, works by looking at the finished, fully rendered image, and looking for areas of contrast that take on the appearance of aliasing. It then intelligently smooths the image in just that area. For an example of this, see the two images below. The first is the way that the anti-aliasing filter looks at the image and identifies aliasing, the second is the final product.
This method is nice because it only requires the program to look at the final image, rather than each object, and as a result renders the fastest. This method works well on computers with poor performance (i.e. laptops), and at the cost of 1-5fps, is almost never worth not having on unless you are using a better method. Also, this type of AA can often be easily “injected” into games with programs such as the FXAA Injector and SweetFX. The downside to post-AA is that it affects the entire image, and can make the entire image seem soft or blurry (Crysis 2 and Battlefield 3 are great examples of where this can get bad). Also, it can miss certain edges or fail entirely when it has too little data to work with (such as small or distant objects).
3 - Non-post Anti-Aliasing (Often seen as MSAA)
This is the option most people are familiar with - the one that comes in 2x, 4x, 16x, 32x, etc. This method is very diverse in the actual way the programming deals with aliasing, but the way it is processed in the engine is not. This method is applied to each object within a rendered scene in a game, based on the edges of the polygon based models and terrain in the scene. An example can be seen below.
This method is nice because of it’s accuracy and sharpness. Simply put, this method has a lot of information at it’s disposal, so it can effectively remove much of the aliasing in an image without affecting over-all image quality. That said, because it must look at every object on the screen, it is often very performance intensive. Also, because most methods are based on the models in games, aliasing in sprites/textures (such as fences) is often missed.
**4 - SuperSampling/Downsampling (slightly different, work on same principle)
**This option is the easiest to understand, yields the highest results, works with every game, and is very performance heavy. Supersampling and Downsampling work by rendering the aliased areas (or the entire image, with downsampling) at a much higher resolution, then simply shrinking the image to your monitor’s resolution with a simple filtering method (i.e. bilinear, trilinear, bicubic - that’s another thread for another time). An example can be seen below.
This method looks amazing in screenshots, and looks like a cross between Post-AA and Non-Post-AA in game (most image processors will downsample better than your monitor will in-game). Getting it to work can be tricky, but it can be used for extremely high-quality results in almost any game. The only downside is the performance cost associated with rendering at high resolutions, which can be very significant. If you can use this method, I highly recommend turning it on when taking your screenshots. [del](a tutorial can be found here)[/del] This feature is now supported directly in the control panel for most new GPUs. See “Virtual Super Resolution” for AMD cards and “Dynamic Supersampling” for Nvidia cards.You can also use this method with the poster command. type “poster 3” into your console to render a nice sized image for downsampling. The poster method does not support super DOF, any sort of HUD, and a few other things, so use it cautiously! Because this method uses the whole image and doesn’t have to make any guesses, it effectively removes all aliasing in an accurate, smooth manner. This can best be seen on the grooves in the gun in the image above (which are distorted in every other image).
Now, all that said, you are not limited to using only one AA method at a time. Using them in conjunction is very important in order to get a smooth image. For example, the downsampling image above uses all 3 methods (although downsampling makes the biggest impact). However, using the cheaper two (MSAA and Post-AA) yields amazing results as well, which can be seen below.
Here are some images to show what your games can look like with carefully implemented anti-aliasing.
I hope this was informative and useful, I put it in this subforum because I figured you guys would get the most use out of it.
Also: Post-AA can be enabled in almost all games/programs (I have yet to see one not supported) via your GPU Drivers. With these options, you can also turn up the deferred AA to higher levels. Pictured below is the NVIDIA control panel, with FXAA (Nvidia’s post-AA) highlighted. AMD has a similar feature (using a method called MLAA, which is pictured in post-AA feature).