What is Ambient Occlusion

If you want to get the most out of your gaming experience, there are an astonishing amount of things to keep track of. We’ve already talked about how to take advantage of features like mouse acceleration and refresh rates, but one of the lesser known aspects you can pay attention to is ambient occlusion. It may not have that dramatic of an impact on your gaming right now, but ambient occlusion will probably play a much bigger role in gaming fidelity going forward, so it can’t hurt to learn more about it now.

What is Ambient Occlusion Quality?

Ambient occlusion was first introduced with Crysis, a game that offered some visuals that were far ahead of the curve. That was in large part due to the inclusion of ambient occlusion for the first time. For the longest time, the quality of graphics came down to polygons and resolution, but the evolution in both of those fields are flattening out for the moment. Ambient occlusion is predicated on the notion that in-game lighting can have a dramatic impact on how realistic graphics look.

How Does Ambient Occlusion Work?

Up until the rise of ambient occlusion, the process of creating lighting and shadows for an entire environment was laborious, both in terms of manpower and processing power. As a result, lighting was implemented by hand and that meant prioritizing the lighting for some elements in the environment over others. Ambient occlusion automates the process through the use of algorithms that analyze the geometry of an environment and place lighting and shadow based off of these results. It’s essentially procedurally generated lighting.

In terms of development, developers still provide some guidance towards where light should fall and what graphics lighting should look like. They shade certain surfaces to provide them with different templates and then let the computer plant out how each light source will fall in terms of graphics. That does mean that the quality of ambient light can vary depending on how much time and skill developers sunk into it.

Is Ambient Occlusion Necessary?

Is it necessary for gamers? Not technically. Any game operating today can work just fine without ambient occlusion, and that’s unlikely to change any time soon. But there’s also little reason to not use ambient occlusion. When Crysis was first released, few graphical cards were able to run it. But GPUs have become significantly more sophisticated in the intervening years, and even the most advanced forms of ambient occlusion aren’t going to have that much of an impact on your computer’s performance these days.

That said, you don’t necessarily need to turn ambient occlusion to its highest settings. Generally, higher settings on ambient occlusion are going to seriously drop off in terms of value for power consumption, so you may want to tweak with the settings in a given game, especially if you’re starting to experience sluggish response or jittery graphical performance.

And since ambient occlusion is all about making environments more realistic, it’s going to have a different impact on different games. Ambient occlusion can help with everything from rendering massive battle scenes to really adding detail to more banal and personal environments, but it’s really going to shine in environments that have some sort of realism to them and provide less of a return on more cartoony or otherwise unrealistic environments. Cel shading and ambient occlusion don’t necessarily go together all that well.

Does Ambient Occlusion Affect FPS?

For many gamers, especially those who like to play competitively, frames per second is the holy grail of graphical performance. The unfortunate truth is that ambient occlusion can have a negative impact on the fps of games, but there’s no one size fits all solution here. While ambient occlusion does have a relatively meager impact on your graphic card’s output, it does have some. And depending on how a game is optimized, the effect of ambient occlusion can vary.

Most games will experience an fps drop of anywhere between 5 and 10 percent, but games like Apex Legends can see as much as a 20% drop when ambient occlusion is used. For that reason, you may want to experiment with ambient occlusion’s effect on fps in the games you play the most. Many games offer fps clocks that will show on the screen directly through the settings menu. For games that don’t, there are a number of third party programs that can offer you the same solution in any game.

How Does Ambient Occlusion Work?

Ambient occlusion is essentially a catch-all term that, when used, can analyze the geometry of a scene and use the geometry of the scene to create more naturally realistic light. But since Crysis‘ release, a number of different developers have introduced different types of ambient occlusion. They sometimes employ some dramatically different techniques and are often good for different scene and games types. We’re going to break down the different types of ambient occlusion, how they affect light and shadows, and what sort of scene each is best used with.

Screen Space Ambient Occlusion

Screen Space Ambient Occlusion (SSAO) is the most common form of ambient occlusion used, but it’s also the most basic. It may not be the most effective solution, but you’re going to find it in the largest variety of games. But the skill and technique developers use to implement it means that the quality of light and graphics in a scene can vary pretty significantly from one game to another.

But it’s also very light on resources, and that makes it one of the best types of ambient occlusion for people gaming on a computer with more meager specs. Screen space ambient lighting punches well above its weight class, but that doesn’t mean that it can swing with ultra heavyweights.

The way this type of ambient lighting works is a bit different from other occlusion ambient styles. Instead of using the geometry of a scene to determine where the light falls, it relies on pixel density. It’s a solution that relies solely on your graphics card without taxing your central processor at all. Essentially, it relies on some cost cutting tricks, so the results aren’t as realistic as what you’d find with other forms of ambient occlusion, but they can provide a nice boost for games that aren’t intended to be at the cutting edge of graphics fidelity.

Screen Space Directional Occlusion

SSDO is essentially the successor to SSAO. At its core, it accomplishes the same things, but it brings more variables to the equation. Instead of just adding light to each pixel, it also accounts for reflections of off pixels. It’s definitely an improvement over SSAO, but it still has many of the same problems: namely some textures that are shaded improperly and the risk of jagged edges on textures. But its lightweight and easy to implement design means that SSDO is one of the more common formats. It’s even packaged with the Unreal and Unity development engines.

High Definition and Horizon Based Ambient Occlusion

High Definition Ambient Occlusion (HDAO) and Horizon Based Ambient Occlusion (HBAO) are basically two names for the same type of light technology. The biggest difference of note is that HBAO is produced by graphics card manufacturer NVIDIA, while HDAO is produced by AMD. The one you use can actually make a difference. Since these formats are generally designed for specific hardware, they work better with their manufacturer. AMD can make use of NVIDIA’s HBAO format and vice versa, but you’ll get better results using a GPU by the appropriate manufacturer.

HDAO and HBAO resolve some of the issues of SSAO, and they essentially do so by simply doing more. They draw more data from the scene. And by rendering all the samples of darkened areas in a scene, it creates a more richly lighted environment. It may appear subtle at first, but once you start paying attention, you’ll notice some far more realistic shadows. The downsides are that HDAO and HBAO place far more strain on your GPU than either SSDO and SSAO. For that reason, these formats tend to be used in games significantly less than SSAO.

Voxel Accelerate Ambient Occlusion

VXAO is the current cutting edge of ambient occlusion tech, but it’s incredibly demanding on even the newest and most sophisticated gaming rigs. For most gamers, VXAO is going to require too much power to make it even worth considering, and most developers use it more as a way to showcase their environments. It’s proof of concept more than an established format that’s feasible quite yet.

But the technology at work here is really cool. Other formats of occlusion create a complex relationship between all objects on the screen and uses a method too determine the direction of illumination with every object, point, and surface taken into consideration. VXAO ups the ante by including objects that don’t even appear on the screen. In other words, the entire environment takes into account the depth of the environment to create more realistic image rendering. It’s still young, but we can generally start to see it in games like RPGs, where fps isn’t the top concern.

Wrapping Up

Is ambient occlusion the most important feature to pay attention to when trying to create the most realistic gaming experience? No. However, if you’re interested in graphical fidelity, you’re going to want to know what is ambient occlusion. Changing how environments are lit are going to be the next step in graphical development. And with new techniques like ray tracing standing at the cutting edge of design, ambient occlusion will have a huge role to play.

And if you’re into gaming, HotRate can help you find all the answers you need for your most commonly asked questions. Whether you’re looking for reviews of the latest gear, tutorials on how you can improve fps, or informational articles on the technology that goes into game development, you can count on us to provide you with the information you crave.