[MUSIC] Computer graphics lighting web presents the kind of lights we have in the real world. You have objects and lights. And lights bounce off objects and arrive at the camera. And when they arrive at the camera, that's when they make an image. But actually, most of the light in our environment doesn't come directly from the lights in that way. If all the light came just from the lights, then anything which wasn't directly facing the light would have been incredibly dark. You get very, very stark lighting. Everything would need to be really bright or really dark. Actually in the real world, a lot of light goes from our light source and bounces off the walls before hitting objects and reaching the camera. So actually we have a lot of light bouncing around. And so real world lighting is much less stark and much softer than we get with straight computer graphics. And simulating this kind of bouncing around light is called global illumination. And if you compare it to the standard direct illumination which is on the left, global illumination on the right looks much nicer, looks much more realistic. And the light's much softer, and you get nicer shadows and nicer reflections. The trouble is it's a lot slower because we have to instead of just simulating one light path from the light to the object to the camera. We have to simulate lots of bounces of rays of light all over the place. So though global illumination looks really great, it can be a little bit too expensive now. Though with modern hardware, you're seeing platforms like Unity include global illumination. So it's certainly something you can look at with the latest Unity renderers is turning on global illumination. But you have to be aware that VR is very computer intensive, so it may slow things down too much. So you can use for global illumination or approximations to it in platforms like Unity, but I wanted to mention two basic little hacks. The first one is built into everything, it's called ambient light. Basically, as well as the lighting coming from light sources, you just add light coming from everywhere. Every object is just lit up by a little bit of light that comes in all directions. It's not very realistic. It doesn't create that soft lighting we like, but it's very fast and cheap. So any basic renderer will include ambient lighting, and you can set that on your Unity project. The other hack is a bit more complex. What happens is you do global illumination. But you don't do it at one time while you're running your game or your VM environment. You do it beforehand while you're developing it. And what happens is you render all that high quality global illumination to an image. Well, actually texture that could be applied back to the object. So you're doing the high quality illumination and creating a texture that you just text your map onto the object. But it makes the object look as if it's rendered really nicely. Doesn't really work if the object's moving around loads or the lights are moving around loads. But it's a cheap way of creating really high quality looking illumination, at least for static environments like rooms and furniture. So that's something I'd recommend, and Unity can do that for you. So global illumination is one example of a really powerful modern graphics technique that can make things look really, really good. And you should basically look at some of those techniques if you want to have a VR experience that looks really real. [MUSIC]