Join Craig Barr for an in-depth discussion in this video UE4 lighting concepts, part of Unreal: Introduction to Lighting.
- [Instructor] When it comes to lighting a project in Unreal Engine there are many things to consider it's important though to have a starting point. Here we want to take a look at some lighting basics or for that matter concepts in lighting. What we want to examine is some of the actual terminology that Unreal Engine utilizes when it comes to the overall process of lighting as well as working with lights, so the term direct, you're going to see this quite a bit as we work with lighting. This refers to an infinite light that travels direct to the surface, meaning that the light beam can travel in one direction infinitely.
Indirect or bounced, this is different in a way that light is reflected or bounced off another surface so for example this could be an object that is completely excluded from other lights but it's getting lighting indirectly, bounced off of another object. Shadows, so of course we all know what a shadow is but the importance of shadows when it comes to lighting in a game or a visualization project is that it really grounds the overall object in a scene it creates believability and it makes it feel like they really are there so they are an intricate part of the lighting process as well.
Mobility, so in Unreal Engine you'll hear the term mobility and you'll see them on the lighting here and it's important to outline what they mean by mobility and also what is referred to by these three terms here, static, stationary and moveable, so what we're going to see as we move on is that static lights are lights that are non moveable, they are kind of locked in space and their parameters are not accessible or moving during runtime of a project or a game for example.
Stationary lights are kind of an in between a static light and a fully moveable or dynamic light in the sense that they are locked in place they can't move but some of their attributes are accessible and able to move during runtime. And then of course moveable refers to a dynamic light, these are lights that can actually be adjusted and changed on the fly and they are fully moveable and all of their attributes are accessible as well, so some important points to look at here in consideration for lighting and Unreal Project is that static lights, being locked in the nature of a non moveable non dynamic light, the static lights and the resulting shadows equals fast performance so very easy to calculate very least expensive process for lighting.
In between the static and the moveable of course is stationary which again is a fast light, not as fast as static but it is a non moving light and the attributes can change at run time so it is kind of an in between closer to a static using a static light though. And then when we get to a dynamic or a moveable light, this is where we have real time shadows, real time lighting effects and this is the slowest, most expensive when it comes to performance for your unreal project. Some consideration here for overall performance.
Lighting can negatively impact the performance of your project, so this is where we really want to focus on keeping the number of lights in a scene low the basic train of thought there or the basic principle is to only use the number of lights that you truly need. Lighting is one of those things that can make a project look great but can also break a project if you have too many lights or unnecessary lights you could bug down a scene, performance can be lousy or non existent, and at the end you can end up not achieving what it is you wanted to achieve in your visualization or game project.
So keep the number of lights in the scene low focus on keeping the number of lights that you only require for your project. And also things like light radius, keep them small, placing a light in a scene and adjusting its radius to impact more than the necessary area it leads to more calculations at runtime or when packaging up your project or for a visualization. So you want to actually keep your lights focused on the area that they need to be, and again, only use a light if you really truly need it.
And of course, lastly here I mentioned the number of lights and keeping things like light radius small but you really want to minimize the use of dynamic or moveable lights. You know sometimes that's not possible of course, dynamic and moveable lights really present some beautiful opportunity for real time lighting dynamic shadows and they really produce some really nice effects but they're very costly when it comes to performance in your projects so you really want to minimize the use of dynamic or moveable lights in an unreal project. So there's a quick overview of terminology, or lighting concepts when it comes to working with lights in Unreal Engine.
- UE4 lighting features
- Light properties
- Lighting an animated scene
- Working with ceiling lights, lamps, skylights, and sunlight
- Adding reflections
- Adjusting lighting settings
- Using lighting effects