Hidden Techniques to Make Assassin's Creed Shadow More Vibrant (No 2TB required)

Most of the things that happen in the video games we play are invisible to us. Even because of what happens behind the scenes, even the elements we are directly working on. If you've ever watched behind-the-scenes videos about game development, you've probably seen these versions of the flat, grey game world filled with lines and icons, pointing in a variety of ways, with multiple grids and layers. These are the visual representations of all the systems that make the game work.

This is a particularly strange dichotomy that can be illuminated in any game with 3D perspective, especially in high fidelity games. We can't see too much light, like we see everything it touches. It's invisible, but it gives us most of the information about the game world. It's much more complicated than “turn on the lights and light up the room”. Reflection, absorption, diffusion, underground scattering – The movement of light is a complex thing that physicists in the real world have actually explored for centuries, and possibly more centuries. In the middle of all this, it is game designers who apply light science to video games in a practical way, balanced even with the limitations of today’s powerful GPUs, just to show all of us nerds a great time.

If you're wondering why many games seem like static amusement parks waiting for you to interact with something specific, lighting is often the reason. But that's why more and more gaming worlds look energetic and lifelike. Game developers are already good at simulating static lighting, but make it more difficult to move. Dynamic lighting has long been computationally expensive, potential tank gaming performance, and we are finally beginning to see this change.

A typical case of Assassin's Creed Shadow and Ubisoft tech architect Nicolas Lopez. Speaking at a game developer conference this spring, Lopez reads his slideshow deck fascinating and will only zoom in as the show’s video recording is released. I contacted Ubisoft via email and talked to Lopez to see how technology like Ray Tracing changed game lighting. For more information on these aspects of video game visual effects, check out our Getting Started Path tracking, ray tracing and rasterization in game graphics.

What initially caught my interest was a set of numbers that Lopez placed on the screen during the GDC demonstration. Lopez notes that if lighting is calculated in Assassin's Creed Shadow, just like Assassin's Creed Unified, the shadow will take nearly two years to “bake” all the lighting, that is, pre-calculate and render it – about 2tb of storage space to store all of this lighting. (Assassin's Creed Shadow requires 115GB on PC throughout the game.) These numbers seem to represent a huge difference between past and modern triple A games. I want to put these numbers in the context immediately after seeing them.

Lopez explained that the cities in Assassin's Creed Unification and Group are very small spaces: dense cities with an area of ​​about four square kilometers. In these games, developers use a unified lighting probe to decide how global lighting (and other lighting technologies) are presented. An illumination probe is a point on a map that contains information about which illumination passes through the empty space in the area, which is then used to help illuminate static and dynamic objects in that space. These are 50 cm probes, which means they are required to provide light information every half meter in the entire city of Paris.

Let's stop and discuss global lighting, also known as GI. This is a broad term used to describe various technologies used to imitate and mimic realistic lighting, especially indirect lighting. These include cube diagrams, screen space reflections, probe lighting, and more. Digital Foundry has a great introduction to global lighting and can break these things down into blocks.

“(small scales in these smaller game worlds) make us affordable for quality lighting, even if it requires a lot of storage.” But, starting from the origins of the Assassin's Creed, the world exploded and suddenly we explored the world's 256 square kilometers. So much baked light information would cause the game to explode in the file storage size, so the team started using the dynamic system.

“We vary in probe density based on scene complexity – dense urban areas still use 50 cm spacing, but in open landscapes like deserts or forests, we reduce resolution.” The artists directly mapped this work of “gastrointestinal density map” – they can focus the mass of light where it matters most – “significantly reduces the data size while retaining the most important visual quality,” Lopez said.

It is also worth mentioning that Assassin's Creed unity is limited in the number of days, with 11 times in the shadows, and the weather effects are very limited, while the shadows have a dynamic weather system. All elements in the shadows will change in the lighting game and must be taken into account with credible visual effects.

This original question – why does it take so long to bake the lighting and require too much file storage? – Return to a simple conclusion. The limitations of hardware and game engines at the time forced the team to reserve a lot of lighting information. Neither the hardware nor the software are ready to calculate such large optical data in real time.

Historically, most gaming lighting has been “baked”. This means computing the various techniques used to light up a given scene in advance, and then superimposing the engine onto the textures and maps of the basic scenes, so your computer or game console doesn't have to perform these calculations while playing the game and slowing down the game. This works for real static games and can provide very convincing, influential illumination. But as the game becomes more dynamic, baked lighting becomes less feasible. If we consider Cube maps (see the primer above and the Digital Foundry video above for specific details), a cube map must be calculated for each possible position the character can stand, which is where the game install size can start to irritate when it comes to game lighting.

Compared to the recent Assassin's Creed game, Unity's game world is a small, unified space. The same approach applies to larger shadowed areas with more dynamic effects and varied density, which will be a truly huge game.

But it has been a long time since the unification of Assassin's Creed. In fact, a lot has changed in that game over the past decade! One of the biggest changes is ray tracing, available to all PlayStation 5 and Xbox Series X|S gamers, with approximately 30-40% of graphics card displays Steam Hardware Investigation As of this May.

“Ray Tracing has had a significant impact on how we light from a creative and production perspective,” Lopez said. In traditional pipes, lighting is mainly baked global lighting, reflections, environmental blockages, etc. This means that lighting cannot respond to changes in the world. Change or move a section of the building? Suddenly, the lighting was invalid. The team has to rebake the lighting data, which can take hours or even hours, which can be done on ubisoft on ubisoft, we can start overnight in the uban pernight overnigh period, but try to start.

He said Ray released the artist from many restrictions.

“Artists can move objects, adjust scenes, or iterate without waiting for a long bake. And, because of calculating the lighting for each pixel, the visual fidelity is higher and more physically accurate.” In other words, artists can do art at their own pace, rather than waiting for the computer to calculate before doing so.

Even so, ray tracing is often invisible to us on the consumer side, especially when we consider the static static of many gaming worlds. In those games, ray tracing is almost invisible because it does what game designers do with creatively placed static lights. For example, Call of Duty levels do not have to take into account the time of day and the program changes in weather, so traditional lighting can be very effective.

Lopez admits in a set of game design rules: “The benefits can be subtle.” Lopez says the shadow is a truly vibrant world, which allows Ray to trace the true game changer in both symbolic and literal sense. As mentioned earlier, the shadows have been available for 11 different times, four seasons, various dynamic weather effects, and destructive environments, all affect the way players see the game while playing. Mixed solution shade use, combining some baking and some dynamic lighting, “pushing the baked GI to its absolute limit”.

“Ray tracing allows us to ignite these dynamic environments accurately and consistently,” Lopez explains. “Even if the world changes dramatically, lighting should act as it should.

“When the door is open, the interior will naturally illuminate,” Lopez continued. “The destructible objects ultimately help scene lighting. Seasonal lighting changes the mood of the scene. Without ray tracing, these effects can only be approximated to a certain extent.”

The team used the Anvil Engine iteration of Ubisoft in other ways in the Assassin's Creed series. For example, they adopted the Academy’s color coding system, a common color standard used by the film industry, which keeps hundreds or thousands of people working on many devices. It helps ensure that people working on different machines in different locations create different parts of the game in various applications and are using the same color information. This gives us a more consistent, solid game where characters, buildings, leaves and even effects look like they belong to the same game and feel compelling at the end of development. Color Find Tables (LUTS) enables teams to change visual tones and color grading to fit the weather and ambient atmosphere.

Especially one of the key parts of correctly figuring out the shadows falls on the right lighting aspect again. Today, with HDR screens so ubiquitous, developers can rely on having some ability to show a larger range of light and dark colors – but darkness still usually means pitching black. Even high-quality displays are subject to the personal preferences of the user, the quality of that particular display and the ability of the gaming console to accurately display colors. This became particularly important when Ubisoft decided to finally fulfill the gamers who wanted the Ninja-focused Assassin's Creed game.

“We redesigned the critical parts of the physics-based rendering and exposure pipeline to act more accurately in low-light conditions,” Lopez said.

Lopez said that by helping the way lighting works in the shadows, teams can “send those nights that feel moody and real without relying on artificial fill lighting.” The quality of lighting directly supports gameplay, which can both make it bigger and credible and more cinematic.

All these changes are brought together to create a “uniform, reactive vision where everything feels relevant”, Lopez said, especially as shadows inspire a cycle of innovation that pushes both Anvil and Assassin’s creed forward.

For the rest of us, Assassin's Creed Shadow is an example of how video game design adapts to new technologies for gamers and game designers. Designers working on Tentpole games, new ways like Shadows, create games faster without sacrificing loyalty. In return, we gain more dynamic worlds that live and move around us.

Image points: Ubisoft