What is Ambient Occlusion?

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Austin Carroll is a writer and web designer from Eugene, Oregon. He's been at HGG for five years and maintains an active role designing and develop... Read more

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Ever wonder how your favorite games display so much depth and contrast? This is largely thanks to ambient occlusion, a cutting-edge technology that uses modern techniques and timeless artistic concepts to deliver ultra realistic graphics. But what is ambient occlusion, exactly?

This article is here to answer just that! We’ll define all the important terms and take a look at what ambient occlusion does, how it works, and much more. By the end, you’ll understand how to use ambient occlusion to get the most out of your favorite games. Ready to play in stunning detail? Let’s get started.

What Does Ambient Occlusion Do?

Modern video game titles are creative masterpieces that blend modern techniques with timeless artistic concepts. But as you might expect, achieving such a feat is no easy task. To keep up with today’s constantly evolving technology, new methods for rendering complex graphical scenes are necessary. Enter ambient occlusion, or AO.

First used in the hit 2007 video game Crysis, ambient occlusion is a rendering technique that creates a sense of depth via ambient lighting and shadows. To that end, AO simulates a realistic 3D environment by providing different amounts of light to different objects within the game world.

Much like traditional shading, the result is a realistic view that bridges the gap between reality and fantasy.

How Does Ambient Occlusion Work?

Ambient occlusion is a technology that renders 3D lighting in real time. It does this by analyzing the depth of a 3D scene via a pixel shader algorithm. This algorithm uses a special texture (the ambient occlusion pass) to compare objects within a scene and assign each one a specific value. The lower the assigned value, the greater the occlusion or lack of ambient light that’s displayed. When seen in-game, this provides a realistic 3D effect for exceptional detail and immersion.

Moreover, ambient occlusion places limited strain on the graphics card and processor, while offering an end-result that rivals full global illumination. This makes it a powerful tool for developers looking to make their games as accessible as possible.

That said, there are varying types of ambient occlusion, and each version delivers different results. The most common types of AO are known as SSAO, HBAO, and VXAO. Each has its own way of approaching 3D lighting, and we’ve outlined their specific processes in the section below.

Types of Ambient Occlusion

So what is SSAO and HBAO? Well, let’s answer that with a look at the different types of ambient occlusion and how they’re used in your favorite titles.

SSAO

SSAO refers to screen space ambient occlusion. It was the first technology to render 3D lighting in real time, and it makes extensive use of the graphics card to output real-time shadows without straining the CPU. The result is smooth gameplay that renders beautifully from scene to scene.

An enhanced version of SSAO definition also exists. This technology is closely related, and is known as SSDO, or screen space directional occlusion. SSDO is a more advanced form of screen space ambient occlusion that takes into account directional lighting for a more realistic overall look.

Both SSAO and SSDO are extremely efficient ways to generate ambient occlusion and are commonly used in games that prioritize accessibility and performance.

HBAO

What is HBAO and what does HBAO do?

HBAO stands for horizon based ambient occlusion. Introduced by Nvidia in 2008, it expands upon screen space ambient occlusion by using an updated, more powerful algorithm to determine shade values. But this power comes at a cost. HBAO is more intensive than SSAO and is restricted to Nvidia-based graphics cards.

Is it possible to attain HBAO definition without an Nvidia GPU? Yes. This is called HDAO, or high definition ambient occlusion, and it uses the capabilities of AMD graphics cards to render detailed 3D graphics.

VXAO

VXAO, or Voxel Accelerated Ambient Occlusion, is the newest and most powerful form of AO. This type of AO is unique because it uses voxel cone tracing to determine shading based on a voxel representation of a 3D scene. In other words, it produces dynamic ambient lighting that’s clearer and more detailed than ever before.

It’s an up-and-coming technology that promises to shake up the next generation of ambient occlusion.

Does Ambient Occlusion Make a Big Difference?

In one word? Absolutely. Just check out the screenshot below.

Whether you’re a casual gamer, or if you love to play on the highest graphics settings, ambient occlusion makes all the difference. That’s because SSAO has been around for over a decade now, and its quality only continues to improve. As such, gamers across the spectrum can play their favorite titles in stunning detail, without worrying about a significant drop in performance and FPS.

Plus, with VXAO paving the way for future generations of ambient occlusion, you can look forward to enhanced graphics with amazing depth and detail.

Ambient Occlusion FAQ

We developed this list of frequently asked questions to give you the full rundown on AO technology and all its nuances.

1. What is Ambient Occlusion Quality?
Ambient occlusion quality refers to the level of depth and detail found in games that utilize different types of AO.

2. What is an Ambient Occlusion Pass?
An ambient occlusion pass is a unique texture that determines how much ambient light should be assigned to each object in a 3D scene.

3. What is Ambient Occlusion V-Ray?
V-Ray is a program that helps graphics developers create a high quality ambient occlusion pass quickly and easily.

4. What is SSAO vs HBAO vs HDAO?
These acronyms refer to screen space, horizon based, and high definition ambient occlusion, respectively.

5. What Does Nvidia HBAO+ Do?
Nvidia HBAO+ takes things a step further than standard HBAO by rendering shadows at full resolution using DirectX 11 technology.

What Does the Future Hold for Ambient Occlusion?

We’re happy to report that the future looks bright for ambient occlusion.

Modern graphics cards can generate on-the-fly shadows with ease, and companies like Nvidia and AMD continue to release more powerful version of AO. And that’s excellent news for gamers. Still, the best way to enjoy current and future generations of ambient occlusion is through a dedicated graphics card and cutting-edge PC build.

The next time you’re playing with your graphics settings, be sure to switch on ambient occlusion. It makes a world of difference.