If you have ever looked at settings in some video games, you will see an option about Anti-Aliasing. Sometimes you will see a drop-down of varying ways to enable it. Those settings do mean something and can be dependent on your current machine hardware.
Anti-aliasing is about taking sharp and pixelated images and trying to smooth them out. Often called “Jaggies,” This is where you can see in an image that is curving, you can see a square-like jagged image in the scene. Those squares are the pixels that are just the smallest point on a screen that can be displayed. If a resolution is low enough, you will see more square-like and jagged appearing images. For example, The Last Door Indie game leans into this and shows the jaggies on the magnifying glass in your inventory and in the scene itself. The act of trying to make those jagged squares go away for a smoother appearing line is what anti-aliasing means. There are several techniques used to resolve to make these lines look smooth such as Super Sampling (SSAA), Multi Sampling (MSAA), Coverage Sampling (CSAA), Enhanced Quality (EQAA), Fast Approximate (FXAA), and Temporal Anti-Aliasing (TXAA).
Anti-aliasing is a way to improve the appearance of a scene by removing jagged artifacts. Knowing these techniques is a helpful tool to have and gives your players extra control. If you want to know a more in-depth answer on how each of them works, please feel free to continue reading and learn about some of these techniques used to make the games look better.
Super-sampling (SSAA) / Full Scene Anti-Aliasing (FSAA)
Super-sampling (SSAA), also known as Full Scene Anti-Aliasing (FSAA), was one of the first anti-aliasing techniques that were developed in the early graphic card days. This technique takes the image in question and creates a higher resolution image virtually. Scaling up the image and filling in the image by taking the average colors around the edges and filling in the shade. It then shrinks the scale of the picture back down so that the image appears smoother. This method, while works well in a pinch, has some drawbacks. It is costly to create a larger virtual image and calculate the average colors to fill in this larger image, and then shrinking it down. So this method is no longer the preferred method.
This increase in resolution is how Apple has developed its Retina screens. It allows for more pixels per square inch on their resolution so that everything looks smoother on standard images but is increasing the pixel density. There are some other things done with Retina, but this allows them to try to create a more pleasant experience with images that are shown on the screen.
Multi-sample Anti-Aliasing (MSAA)
Multi-sample Anti-aliasing (MSAA) can be considered the evolution of the original supersampling method. The graphic cards today are much more potent than prior and have allowed methods to create a more efficient version of the technique to achieve the same goal. MSAA enables the developer to go an extra step and increase the multisampling factors to try to improve getting rid of some jagged lines. You can set the multi-sample up to say 16x even and get some excellent results for the scene you are trying to clean up.
As with many of these techniques, there are trade-offs on which you want to use. The higher the factor for multi-sampling, the higher the computational cost is. Bringing back the big concern that supersampling had. Requiring a higher factor rate might have you limit what hardware your scene can support. Another drawback is deferred, or dynamic rendering can not be included with this technique. Such as lightning and shadows being drawn on a surface that you smoothed out before these effects being rendered.
Coverage Sampling (CSAA) and Enhanced Quality (EQAA)
Coverage Sampling (CSAA) came out with Nvidia’s Geforce 8 series but is yet again another improvement on the Multi-sample anti-aliasing technique. The hardware is specifically tuned to improve the efficiency of anti-aliasing without having to pay the same performance cost as the MSAA technique would if it were to achieve the same quality. Post-process effects are also still not included with these smoothing techniques.
The Enhanced Quality (EQAA) method is the same thing as CSAA; however, this would be the AMD equivalent to this technique. It is allowing graphic card owners of both sides able to benefit from this technique. The goal of having even more multi-samples that these techniques give enables the image to have a better result of filling those pixels in with a more accurate color palette. There is still a level off point that just increasing the factor gives you diminishing returns and increased computational cost.
Fast approximate anti-aliasing (FXAA)
Fast Approximate Anti-Aliasing (FXAA) is another Nvidia creation by attributed to Timothy Lottes. Where the previous anti-aliasing techniques are considered spatial anti-aliasing, FXAA is screen-based anti-aliasing. This technique does not take the 3D model and determines it as a whole. Instead, this technique only makes the image as it would appear on the screen. Minimizing the actual calculation required. In this way, it does not require as much computation as the previous techniques.
The primary takeaway with this technique is to understand the step in which it is being processed. Understanding this is important because if you are not careful, you might blur out the entire display, including the player’s Heads Up Display (HUD). It is, therefore, degrading the player’s experience. Also, textures may appear blurry after this has been processed has been completed. As with all things, tweak your settings to work how you need them.
Temporal Anti-Aliasing (TXAA)
There is another anti-aliasing technique that should be noted. If you have ever played a game with a lot of small assets, that could be having to sneak around in tall grass to hide from enemies or visible raindrops in a storm. You might have moved the character, and with the movement had those elements in the game create a flickering or odd artifact when moving.
Temporal Anti-Aliasing allows those experiences to be smooth and prevent the feedback to the player that it feels incorrect. It smooths out these elements and creates seamless transitions as the view is being changed and reduce the crawling or flickering experience.
Is There A Best?
There is a common belief that some techniques are better than others. In truth, each method is based on how much computing power they want to require their players to have. In this case, the only one I would say that the worst technique is the Super Sampling (SSAA) technique, and you would be better off to start with the MSAA technique instead. Do what is right to have your game give the message you want and when you want to optimize the experience find the anti-aliasing experience that works best, and even offer a default allowing the player to change this setting their options menu. Also, include a guide, so the player knows it is expensive or cheap to run on the hardware.
Thank You
If you have found this helpful share this post with someone you think could learn something new by check it out. Or just share on your favorite Social Media platform.
If you are still any bit curious about Anti-aliasing please see the helpful video from Linus below.