The Hidden Tech That Makes Assassin’s Creed Shadows Feel More Alive (And Not Require 2TB)

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In most video games we play, much of what transpires remains unseen by us. Even the aspects right before our eyes operate due to events happening behind the curtain. If you’ve ever watched a making-of video about game development, you may have caught glimpses of these simple, gray game landscapes filled with lines and symbols in all directions, with numerous grids and layers. These are visual depictions of the countless systems that power the game.

In games with a 3D perspective, particularly high-fidelity ones, it’s intriguing to ponder the paradox surrounding lighting. Unlike physical light we perceive in reality, we don’t see light itself; instead, we observe its effects on objects. It provides us with a vast amount of information about game environments, yet it remains invisible. The behavior of light, from reflection and absorption to diffusion and subsurface scattering, is a complex phenomenon that has fascinated physicists for centuries and will continue to do so.

In the midst of this complexity, game designers work diligently to incorporate the science of light into video games in ways that are both practical and balanced with today’s advanced GPUs. Their aim is to create an immersive experience for gamers like us, balancing the intricacies of light physics with the limitations of modern technology.

As a gaming enthusiast, I’ve often pondered why some games feel like static amusement parks with limited interactive elements. Lighting is usually the culprit, yet it’s also the key to creating captivating, lifelike game worlds. While developers have mastered simulating stationary lighting, making it dynamic has been a challenge. Dynamic lighting has traditionally been computationally expensive, potentially affecting game performance, but we’re now witnessing a shift in this trend.

What first caught my attention during Lopez’s GDC presentation was a particular sequence of figures he displayed, which were related to the lighting calculations for Assassin’s Creed Shadows. Lopez mentioned that if the lighting in Assassin’s Creed Shadows were processed similarly to how it was in Assassin’s Creed Unity, it would take almost two years to precalculate and render all the lighting data, and approximately 2TB of storage space to store it. (Assassin’s Creed Shadows requires a hard drive space of 115GB for the whole game.) These figures appear to show a significant gap between older games and today’s triple-A titles. As soon as I saw them, I wanted to understand their implications.

In Assassin’s Creed Unity and Syndicate, Lopez pointed out that the cities depicted were compact areas, roughly four square kilometers in size. To render global illumination (alongside other lighting methods), developers employed uniform lighting probes in these games. Essentially, these probes serve as points on the map that gather information about the light passing through empty spaces within the area, which is then utilized to cast light onto both static and dynamic objects within that space. In Unity’s recreation of Paris, these probes were spaced every 50 centimeters, meaning they gathered lighting data every half a meter across the entire city.

Let’s take a brief detour to talk about global illumination, often abbreviated as GI. Essentially, it’s a term used to encompass several methods designed to replicate and simulate natural lighting effects, particularly indirect light. This can involve techniques like cube maps, ambient occlusion, screen-space reflections, probe lighting, and others. If you’re interested in learning more, Digital Foundry has an excellent guide that explains these concepts in a clear and concise manner.

As a devoted fan, I was intrigued when Lopez shared with me that the compact size of these smaller game worlds allowed for exceptional lighting quality, despite necessitating substantial storage capacity. However, starting from Assassin’s Creed Origins, the scale of our worlds expanded exponentially, and we found ourselves navigating areas spanning 256 square kilometers. If we had included all that baked light information, it would have swelled the game files to an unmanageable size, causing them to metaphorically ‘explode’. To avoid this, our team developed a dynamic lighting system instead.

In simpler terms, Lopez stated that we adjust the number of measuring points (probe density) depending on the complexity of the scene. For instance, densely populated urban areas maintain a probe spacing of 50 centimeters, whereas in open environments like deserts or forests, we decrease the resolution. This is similar to how artists create what’s called a “GI density map.” They can concentrate the quality of light in areas that require it most, which Lopez pointed out significantly reduces data size while preserving visual quality where it matters the most.

It’s important to note that Assassin’s Creed Unity featured only four different times of day and minimal weather effects, unlike its successor, Assassin’s Creed: Syndicate, which boasts 11 distinct time periods and a dynamic weather system. These features in Syndicate result in varying lighting conditions that the game must adapt to for visually convincing results.

The original query – why did baking the lighting take such a long time and need so much file storage? – boils down to this: Due to the constraints of hardware and game engines at that point, the team had to pre-calculate a large amount of lighting information ahead of time because the technology wasn’t advanced enough to compute all those light details in real-time.

As a gaming enthusiast, I’ve noticed that historically, most games have utilized a technique known as “baked” lighting. This means that the lighting effects for a particular scene are calculated in advance and stored as textures or maps for the engine to overlay onto the basic scene during gameplay. This approach is ideal for static games and can produce impressive, impactful lighting. However, as games become more dynamic, baked lighting becomes less practical. For instance, consider cube maps – you’d need to calculate a cube map for every potential location a character could occupy. This is where the size of game installations can significantly increase when it comes to game lighting.

In simpler terms, the game worlds in Unity were relatively smaller and consistent compared to those in modern Assassin’s Creed titles like Shadows. If similar strategies were used to create larger areas with more complex visual effects and varying densities, it would have resulted in an incredibly expansive game.

It’s been quite some time since Assassin’s Creed Unity was launched – over a decade, to be precise! In that game, numerous aspects have evolved significantly. One of the most notable advancements is ray tracing, a feature now accessible to all PlayStation 5, Xbox Series X|S users, and approximately 30-40% of graphics cards according to the Steam Hardware Survey as of this May.

Lopez stated that ray tracing has significantly transformed our perspective on lighting, considering both creative and practical aspects. Previously, lighting was predominantly pre-calculated global illumination, reflections, ambient occlusion, and so forth in conventional methods. This meant the lighting couldn’t adapt to alterations within the environment. Moving or modifying an architectural element would make the existing lighting obsolete. The team would then need to recompute the lighting data, which could take anywhere from hours to days. At Ubisoft, we scheduled compute jobs to run overnight so artists could receive updated lighting each day. However, this process still hindered iterations significantly.

Ray tracing freed artists from many of those constraints, he said.

According to Lopez, artists have the ability to manipulate objects, rearrange scenes, or make improvements without experiencing lengthy delays in processing. Moreover, since lighting is calculated on a per-pixel basis, the resulting visuals possess a higher quality and are more true to physical properties. In simpler terms, this means that artists can work at their own speed as they create art, rather than having to wait for computers to process the changes first.

Despite its widespread use in gaming, ray tracing may not be noticeable to us as consumers, particularly when we reflect on the static nature of many game environments. In these games, ray tracing is scarcely perceptible because it performs tasks that were previously handled by game designers using strategically positioned static lights. For instance, a Call of Duty level doesn’t require adjustments for changes in time or weather, so conventional lighting works quite well.

Lopez acknowledged that the advantages may not be immediately obvious, but regarding the specific gaming guidelines he referred to, Shadows is a world that’s incredibly alive, and incorporating ray tracing into it makes a significant difference, both figuratively and literally. As previously mentioned, Shadows boasts 11 different times of day, four distinct seasons, an assortment of dynamic weather effects, and environments that can be destroyed, all of which influence the player’s perception of the game as they progress. The lighting solution in Shadows, a mix of baked and dynamic elements, has been pushed to its utmost limit by this hybrid approach.

According to Lopez, ray tracing ensures that lighting in these evolving environments is portrayed authentically and reliably. This means that light behaves as expected, regardless of significant changes in the environment. There are no shortcuts or tricks used. As a result, the world appears more realistic and convincing.

Lopez explained, “When doors are opened, the interiors brighten naturally. Crumbling items add to the overall illumination. The atmosphere of a scene is influenced by the seasonal lighting. To some degree, these effects can’t be fully achieved without using ray tracing.

The team made adjustments to the Anvil engine, a tool commonly used in the Assassin’s Creed series by Ubisoft. They implemented the Academy Color Encoding System as one of these adjustments, which is a universally recognized color standard employed in the film industry to maintain consistency among the work of numerous individuals across various devices. This system ensures that team members working on different machines, in various locations, and using diverse applications for the game development, are all working with the same color data. This leads to a more unified and realistic end product, where characters, buildings, vegetation, and effects appear as if they belong in the same game and seem authentic. Color Look-Up Tables (LUTs) enable the team to adjust the visual tone and color grading according to weather conditions and environmental surroundings.

In ensuring that Shadows were accurately portrayed in the game, special attention was paid to mastering the lighting effects. Given the widespread availability of HDR screens today, developers have more flexibility in depicting a broader spectrum of light and darkness; however, ‘dark’ can still appear as complete blackness. Even top-tier displays are influenced by individual preferences, display characteristics, and a console’s color accuracy capabilities. This was particularly crucial when Ubisoft decided to develop the long-awaited Assassin’s Creed game centered around ninjas.

According to Lopez, we adjusted crucial aspects of our lighting and brightness systems to function more precisely in dimly lit environments.

Using ray tracing for lighting in Shadows allows the team to create nights that feel genuinely somber and true-to-life, without needing excessive artificial fill light. The superior lighting enhances the gameplay experience by making it seem heavier, more realistic, and more akin to cinema.

According to Lopez, all these alterations combined resulted in a cohesive, responsive visual design where every element seems interconnected. Particularly, the use of shadows initiated an inventive loop that propelled both Anvil and Assassin’s Creed ahead.

For most of us, Assassin’s Creed Shadows serves as a demonstration of how video game design is adjusting to incorporate modern technology, catering equally to both gamers and designers. The creators behind significant titles such as Shadows have access to innovative methods for expediting game production without compromising quality. As a result, we encounter more interactive environments that seem alive and responsive.

Image credits: Ubisoft

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2025-06-28 15:10