Glossary
A list of some terms used in Game Lighting (and game graphics in general) that you may or may not be familiar with.
Ambient Light: Low level light that is uniform and non-directional. IMHO it should be avoided for the most part, as light is almost always more interesting if it's coming from a direction, even if it's bounce light.
Bounce Light: Light that is not direct, but "bouncing" off surfaces nearby that are getting hit by bright direct light. With Global Illumination, bounce light is automatic. In systems that are not using GI, it's usually faked with spotlights.
Caustics: Unlike ray-traced caustics, in games we are usually referring to reflective caustics, like you might see being reflected onto a cave wall where sunlight is striking a water surface. These can be animated to simulate water refections.
Clipping: Clipping can be used for both cameras and lights. It's a way of specifying a distance before or after the active range you want. For instance, if you clip the near point of a spotlight. you're telling it not to actually be visible (or light anything) until a certain distance from the light source itself.
Cubemap: An image created manually (or captured in-engine) that will be assigned to various entities and is what will be seen in any reflective surfaces in a given area.
Cucoloris: The cucoloris (sometimes called "cookie" for short) is similar to a gobo, but usually larger and treated like a flag that has a pattern cut in the surface. It's placed in front of the light to break it up into a pattern.
Falloff: Also referred to as Attenuation. The amount of light that decreases over distance as you get farther away from the light source.
Fill Light: Light used to fill in the shadows, preventing them from being too dark. Fill light on a character's face is frequently straight-on to the character, and very low in intensity.
Flag: A large flat surface used to keep a given light from hitting a surface you want to stay dark. Also used as a verb, "flagging a light" means preventing it from striking a surface.
FPS: "Frames Per Second" when referring to how quickly (or slowly) a game is running or a film or video is playing back. "First Person Shooter" when referring to a game genre.
GI: Global Illumination. The simplest description is light that is bouncing off of surfaces to more closely simulate the way light works in the real world.
Gobo: A pattern or texture that is projected from a light, to break up the light or project an image.
IES: Photometric IES lighting is a way to have lights more accurately represent the way light from fixtures strike surfaces. IES stands for Illumination Engineering Society. An IES file can be applied to a light for the effect. A few examples.
Jira: Not the only software for bug tracking, but a popular one. I've used it at a number of game studios. If someone tells you that you need to "submit a bug", you'll use this software or something like it.
Key light: The main, or key light that's used when lighting. A typical scenario for lighting a character might be to create the key light, add a front fill, then possibly a rim light. The key light is usually the brightest light in the scene, defining the main light direction.
Lightcone: The "cone" of light that a spotlight produces. Its width can be altered depending on the area of effect desired.
Lightmap: A texture that contains baked lighting information. It is usually applied to a secondary UV set so as not to interfere with the texture files used in the materials.
Light Rig: A rig is a group of lights used as a preset, that can be dragged into a scene and applied to a character, for instance. A rig usually consists of a key light, a rim light, and a fill light. There may be others as well, depending on the tech and studio methods.
LUT: LUT stands for Look Up Table. The simplest way to describe a LUT is an image that's been adjusted for color balance and exposure, etc., then applied to the game level so it uses those same settings. You can create LUT's and swap between them. Here's a video with some strange music showing a LUT being applied in Unity.
Penumbra: The term used to describe the area that is not in complete shadow, but also not in direct light. That was a crappy description, so here, look at this.
Perforce: A popular version control program, that's used at lots of studios. In theory, if you have a file checked out in Perforce, nobody else can check it out until you're done. Please check all of your files in before you go on vacation, or your coworkers will call you names.
PBR: Physically based rendering. Used to simulate the way lighting works in the real world. See more here.
Proprietary: If a game engine, or any set of software tools is referred to as proprietary, that means it was developed in-house, as opposed to software that's available to use or purchase publicly.
Rim light: A light that's frequently placed towards the rear of the subject, facing the camera. It's used to help separate the subject from the background, adding a thin "rim" of light to the edge of a character. Sometimes referred to as a "kicker".
UV Set: The UVs of a 3D model define the area to be mapped with textures. UV editing means adjusting the UVs so that they will map correctly without distortion. Multiple UV sets are usually required when lightmapping, as the texture UVs usually are not usable for lightmaps. (There are specific rules for laying out lightmap UVs that must be followed, or lighting will not bake properly.)
Viewing Frustum: The camera view frustum is the cone-shaped area in front of the camera that is what the camera is able to see. Anything that is outside the frustum is usually culled to increase performance.
Vignette: Frequently used when lighting cinematics, a vignette darkens the edges and corners of the frame, helping to focus the viewer's attention more towards the central area.
ZDepth: The Z direction represents depth in 3D graphics, and ZDepth refers to the Z-Buffer or depth of the scene. Fog and some other effects take advantage of ZDepth. Some developers created programs and game engines where Z is up instead, which shows that they were dropped on their heads as children.
