Tim Sweeney: belief

Transcript context

…We spoke a bit about Nanai, so the magic behind the virtual eye geometry system, but can you speak a little bit to Lumen and in general what it takes to dynamically light in all the complicated ways, the faces, the scenes that we discussed. What are some interesting things to you that made the magic of it happen? Lumen is a system for global illumination, meaning it’s supposed to calculate the interaction of light with the entire scene in a way that mimics reality. The first generation of engines that did lighting just said, “Well, the light casts light and the surfaces it hits are lit and the surfaces it doesn’t directly hit are dark, and that’s just all the techniques we have.” You’d have an area that wasn’t hit by any light being completely black. But in reality, light bounces around the entire scene dynamically. When a light hits a red wall, then most of the blue and green light is absorbed, but the red light reflects off and now is hitting other things. If you have a red wall with a white floor, light is bouncing off of the red wall into the floor, and now the floor is being turned red. The entire bouncing of light around the scene through multiple bounces is the critical challenge to solve here. Again, laws of physics are known and so the complete solution to this, it was written down in the 1950s, I think. The real magic here in Lumen is this system that Daniel Wright developed over the course of many years based on ideas formed over a longer period of time to calculate the way lighting bounces around at different scales ranging from the scale of miles or kilometers down to the scale of pixels and millimeters. To not only calculate at each level, but integrate it seamlessly at each level to give the appearance of completely seamless and accurate lighting. Previous techniques were highly specialized and artists had to make a decision for each light about exactly what it did. The goal, and a lot of the practice with it right now is you build a scene, you place lights in it, and it just works to make it that much easier. I mean, we’re watching, I’d recommend people go to this blog post, look at that. It’s a dynamically, we should say that so there’s the indoors and the outdoors, and to be able to dynamically compute the impact of outdoor light, just look at that. Look at how gorgeous that is. It’s just the lighting like look, we’re looking now at an image of a cave. External light lighting the intricate complexity of the insides of a cave. Look at that.…

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