Gone is the era when dynamic lighting was impossible, if not just difficult, when games used to be rotoscoped, just like in the original Mortal Kombat. The modern-day dynamic lighting problem is the problem of rendering indirect reflected light, technically known as Global Illumination or GI.
The official docks of Unity game engine states:
Global Illumination (GI) is a system that models how light is bounced off of surfaces onto other surfaces (indirect light) rather than being limited to just the light that hits a surface directly from a light source (direct light).
The implementation of GI varies a lot from static, or prebaked, to the lighting calculated in real-time. Even many modern games use a fair amount of prebaked solutions to accurately place light sources in the game environments.
Many fans were disappointed when Marvel’s Spiderman was released with a preset “Day, Sunset & Night” cycle as they expected a fully realized dynamic day and night system. But it’s the very absence of these dynamic lighting conditions that made it possible for Insomniac to come up with such a realistic rendition of Manhattan, New York. It features fully realized GI with realistic shaders that make the game almost photorealistic to look at.
Not all of the GI featured in most AAA games is rendered in real-time as the game environments are fairly static and the games that do have dramatically changing lightings such as day and night cycles, just don’t stand the comparison to their static counterparts.
A perfect example of this would be NFS Heat and Payback, the previous title before it. NFS Payback features a dynamic day and night cycle whereas NFS Heat only features specific preset times of a day, just like Spiderman.
Both games look stunning but Payback doesn’t look as stunning all the time. Heat’s fairly static lighting doesn’t provide any technical challenge for tailoring realistic enough renders, shaders, shadows and reflected light and as a result, looks more realistic and beautiful all the time. The visuals are faithful to the Art Direction and it is fun driving around Palm City in NFS Heat, a fictionalized version of Miami, Florida.
The Last of Us, a game made by Naughty Dog, praised for its visuals when it was first released on PS3, and later remastered for PS4, too features static global illumination in most areas. It’s in the indoor dark areas where we get to see GI or indirect reflected light in action.
I was surprised when I noticed this for the first time when Joel’s flashlight lit a red wall and the red color just lit up the whole room bleeding into the scene. The GI gets disabled as the indoors get closer to the outdoors as the effect wouldn’t have been as noticeable and also wouldn’t have had a significant visual impact overall. I think Naughty Dog’s devs have smartly utilized dynamic GI wherever necessary and have kept it static for the most part.
Dynamic global illumination is fairly easy to spot. If a scene in a video game looks realistic enough to you, just check how the environment reacts to your flashlight or gun muzzle flash or any other moving light; you’ll realize in no time if the lighting engine of the game is capable of dynamic GI or not.
So, what will we get if we come to know if the GI in a game is static or dynamic? Does it really matter? Well, yes and no.
Yes because it shows how effective the techniques and algorithms of a game engine can be if it manages to deliver this with no significant performance loss, which is commendable. It’s closer to what an ideal game engine should be like.
And no, because it’s all about the results to the consumers and casual gamers like me; the visuals are all about the results rather than the techniques used to generate them. If it looks good and plays well, I’m buying it.