In your experience, what are the biggest differences between how light behaves in real life versus how it’s typically approached in 3D engines?
I would say the game engine lighting system is obviously meant to replicate what occurs in real life. In Unreal Engine 5, you have a direct light which mimics the sun, and you have the skylight which mimics the ambient light from the sky, and you have global illumination to account for how light bounces off surfaces and illuminates other areas.
The closest we can come to how lighting behaves in real life is by using ray tracing in Unreal Engine 5, which is a rendering technique that simulates how light physically behaves in the real world. Instead of relying on approximations, the engine traces the paths of light rays as they bounce around a scene, producing more realistic lighting, shadows, reflections, and indirect illumination.
The biggest difference between how light behaves in real life vs the 3D engine is the subtlety of the colors in the scene and all the bounced light. In the 3D engine, this can be faked by plugging an HDRI (High Dynamic Range Image) into a Skylight in Unreal Engine 5. This gives the scene a much more realistic and specific lighting environment. A normal Skylight samples a simple sky color and fills shadows evenly.
Using an HDRI contains actual brightness information from a real environment, so light comes from different directions with different intensities. Still, there is a difference in how light behaves in real life vs a game engine. If you set up lighting in UE5 with a certain direction, light intensity, color, etc, each scene will have the same light setup.
In real life, there’s always a difference in lighting due to subtle aspects such as geographical location, the amount of dust or moisture in the atmosphere, cloud formation, etc. Even going to the same spot in real life on a clear day during the same time of day can still look different each time.
