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Geomerics Enlighten Brings True Dynamic Lights to Mobile Games

 

For a long time, visually realistic lighting for digital art has been too computationally expensive to scale into gaming platforms with restricted performance budgets – in particular mobile platforms, unless devices are built with specialized hardware.
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Need For Speed: The Run - EA Black Box, made using Geomerics Enlighten middleware.


But middleware such as GeomericsEnlighten, featured here, can go long way toward making custom hardware unnecessary for rendering complex visual effects and lighting, specifically global illumination. It precomputes the most expensive part of the lighting calculations and compressing the output for runtime usage on the CPU, so that lights and assets can move in the game or editor while the global illumination updates in only milliseconds. This runtime usage is asynchronous, running independently of other processes without waiting for or handing off to other processes.

Static Geometry, Dynamic Lights

Digital Media World spoke to Chris Porterhouse, VP of Gaming Middleware at ARM, which owns Geomerics, about the company’s approach to lighting games and why mobile global illumination is gaining momentum in the mobile developer community. Some major studios are now licensing their software and one of them, Exient, has also answered questions about why they have decided to adopt Enlighten and what it will bring to their mobile titles. 

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The developers at Geomerics believe light is extremely important in games, where it is a critical means of leading the eye or setting the mood. “These aesthetics are qualities that lighting artists spend a lot of time perfecting,” said Chris Porterhouse. “By precomputing the surface-to-surface lighting characteristics of a scene’s static geometry, Enlighten generates compact runtime data and uses it to compute the global illumination for any lighting configuration or platform a developer is using. Lights, materials and objects in the scene can be moved and updated at runtime, affordably and in real time

“This means that players can interact with the world in a completely different way than they previously have been able to do. Global illumination can deliver a high degree of visual realism and, by accurately calculating the way in which the lights and objects in a scene interact, improve the immersion of the user into a digital experience. This ability is especially useful for applications running on virtual reality platforms, for example, where maintaining the suspension of disbelief is critical.

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The image above on the left shows the direct lighting in a scene. The image on the right shows indirect lightng. The top image shows both combined to complete the scene.

Playing with Light

“A particular interest for Geomerics is how light can be used for gameplay. For example, in a driving game, Enlighten can compute the bounced light coming from headlights, and in a first person shooter it can calculate the global illumination from a torch. In an open world, if game walls are destroyed or doors opened, the light will travel realistically across the changed scene.

“The game Quantum Conundrum, developed in the Unreal Engine 3 by Airtight Games for Square Enix, is a great example of a studio using dynamic global illumination for interesting gameplay. The player can shift instantly between five different dimensions, each of which has an entirely different lighting and material set-up, and interact with objects in each environment under a different set of physical rules, to solve the puzzle.”

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Quantum Conundrum - Airtight Games

Enlighten helped Airtight Games in two ways on Quantum Conundrum. Each of their worlds had to be able to re-colour itself whenever the player shifted to a new dimension, and they were also looking for an artistic cartoon style, with bold colours and gradients. Enlighten’s handling of dynamic albedo, or reflective power, makes sure that changes in surface properties are immediately fed into the global lighting – in this case revealing the new dimension. The cartoon look was achieved using hidden geometry to act as area lights. Because these factors were easily tuned, the artists could give the game the precise look they wanted at any time.
 
Instead of re-computing lighting as gameplay proceeds, a run-time module can use Enlighten’s pre-computed data to simulate GI - real-time lightmaps, lightprobes and cubemaps. The dynamic geometry in a scene can be relit using the light probes that are updated in real-time with the GI generated from the static geometry. Enlighten only has to compute GI for diffuse transport - overall scene illumination. Because diffuse transport is low-frequency, the real-time lightmaps can be low-resolution and are updateable in real-time. Most other GI effects are also covered.
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The Importance of Scale

Returning to the issue of games on mobile platforms, Chris remarked that mobile games accounted for one third of games industry revenues in 2015, after more than doubling in three years. “On one hand, casual gaming currently makes up the majority of the most popular, highest grossing applications for both Android and iOS. In this market, sophisticated graphics on mobile are seen as a route to differentiation in a growing, crowded market,” he said.

“On the other hand, mobile devices are now a target platform for more AAA franchises. Therefore, the ability to scale effects such as dynamic global illumination to a mobile platform is very attractive to a lot of studios – and ultimately results in a much higher quality gaming experience.”

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Scalability can work in one of two ways. It enables more features to be included within the same performance budget, or the same quantity of features to be included in a smaller performance budget. Consequently, scale is useful both to increase the complexity and fidelity of the game, and to enable content to scale to lower budget platforms.

That ability to scale into mobile, where the market for games is rapidly expanding and differentiating, is one reason why Enlighten is attractive to a studio like Exient. Exient specialises in re-engineering popular video games from big console debut platforms to smaller devices, and produce titles originally made for mobile as well.

Exient - Baking Light vs Enlighten

As one technique among many that games artists have to communicate with players, the developers and artists at Exient find that lighting in games nearly always goes beyond just the aesthetic. “Many exploration games direct the player through lighting, some with more subtlety than others. For example, our current title supports the communication of a physical change through a direct lighting change in-game, and it was this design that underpinned our decision to use Enlighten.”

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Diggs Nightcrawler, developed by Exient for PlayStation 3.


Before this decision, Exient had baked lighting into scenes to achieve the exact looks they wanted, and now say that the results they see are as good as, if not better than baked lighting. On the production side, the speed improvement to the lighting pipeline has also made it very easy to try out new ideas quickly, and their process of lighting a level is substantially simplified with Enlighten, especially when compared to baking.

“Previously, the lighting artist would have to create texture coordinates, create a lighting solution, calculate the lightmaps and manage their storage and then iterate this process, along with changes in artwork,” said team members at Exient. “Enlighten does virtually all of that legwork for us. There is virtually no time delay between moving lights and seeing the results directly in the game. Since Enlighten calculates the lightmaps in real time on the CPU, only those that are needed are stored in memory.

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The Bureau: XCOM Declassified - 2K Marin


“Regarding looks, one of our success criteria for Enlighten when we tested it was that it should look as good as baked lighting, and we believe this has been exceeded with results that surpass baking techniques. Also, while it is true that baking gives an artist a lot of control, in practice, it can be such a lengthy process that no artist really wants to mess with the results very much. Although with baked lighting it's possible to manually edit the textures, theoretically giving per pixel control over light effects given enough time, this is usually done to correct baking artifacts and of course we don’t see these when using Enlighten.

“With Enlighten, changing lighting only requires loading an environment into the tool. The results can be seen instantly. A lighting change doesn't require any extra pre-computation and the results can be seen live in the game. Any developer with a little training can change the lighting whether they are programmers, artists or designers - the problem is going to be stopping people messing with the lighting!”

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Game Dynamics on the CPU

Enlighten supports many types of dynamism within games – variation is a primary differentiating factor of the software compared to systems that rely on baked lighting. Lights can be fully dynamic within the game, while indirect lighting updates instantly, and materials can be altered. Geomerics can guide developers on using Enlighten for more complicated forms of dynamism, for example, making an object transparent at runtime to simulate the effect of a wall being destroyed or doors opening. It also has a simpler way to use spherical harmonic probes to handle the indirect lighting of dynamic objects, computing the probes to capture indirect lighting at arbitrary points in space

Chris said, “One key value of Enlighten is that it can compute its output entirely on the CPU, asynchronously to the main rendering on the GPU – which is needed for lighting and shadow maps of dynamic lights - so as not to impact the frame rate. It is among the only global illumination techniques to do so, making Enlighten a very practical choice where budget is constrained – whether that is on a super-high quality console game, on mobile or delivering 120fps VR.

“Pre-computing leaves developers free to do much more with the lighting in their scenes and meanwhile, teams can create high quality, dynamic global illumination and scale it from displays on PCs and consoles, down to mobile and virtual reality. More realistic VFX relating to the story, such as time of day, player controlled lighting and destruction, become possible.”   www.geomerics.com