Appendix: Visual Lighting Glossary

0-Point Lighting A style of art that does not include lighting information.

1-Point Lighting A lighting scheme that uses a single strong key light with no identifiable fill light.

2-Point Lighting A lighting scheme that uses a key light and a secondary fill light.

3-Point Lighting A lighting scheme that uses a key light, a secondary fill light, a third light, which may be a rim, hair, kicker, back, or background light.

Ambient Light A 3D light that reaches all points in a scene equally.

Area Light A 3D light bound by a shape (most often rectangular); the light operates like an array of lights that point in one direction but diverge over distance.

Back Light A light aimed at the back of the subject (opposite the camera or viewer).

Background Light A light aimed at the background behind the subject.

Bounced Light Light that has reflected off of a surface.

Color Bleed The alteration of light color when light reflects off surfaces. The color of one surface “bleeds” onto the next surface.

Color Temperature The temperature at which an ideal black body would emit radiation of the same color as a given object. (A black body is a theoretical material that absorbs all incident electromagnetic radiation.) Color temperature is expressed in Kelvin or K— for example, 3500 K.

Butterfly Lighting Also known as Paramount lighting, this scheme places the key high above the subject, creating a small butterfly-like shadow under the nose.

Depth Map Shadow a type of 3D shadow that creates a bitmap from the viewpoint of the shadow-casting light.

Diffuse In general, diffuse refers to the diffuse reflection of light off a surface due to the imperfections of the surface. A diffuse surface may have little, if any, specularity. Diffuse color is the color of a surface with no specularity. Diffuse reflections may also refer to light scatter due to refraction. Albedo, in contrast, is surface color without lighting information.

Directional Light A 3D light that creates parallel rays, similar to sun light reaching the Earth.

Environment Light A 3D light that creates a spherical or hemispherical array of light rays, suitable for mimicking light from a sky or surrounding location. (See IBL.)

Eye Light A light focused on the eyes of the subject.

Fill Light A non-key light that represents a weaker light source or light from the key that has reflected off surfaces.

Final Gather (GI) a form of gi (Global Illumination) and a 3D rendering system that replicates bounced light by sending out hemispherical clouds of secondary final gather rays to seek additional surfaces near initial surface point intersections.

Fresnel Reflection A reflection that follows the Fresnel equations. The strength of a reflection vs. the strength of refraction (transmission) is dependent on the viewing angle.

Glamour Lighting a loose term for any lighting that attempts to make the subject beautiful, handsome, or otherwise unusually attractive.

Hair Light A light aimed at the subject’s hair, arriving from behind.

Hard Lighting Lighting that creates a hard-edged shadow, often produced by parallel light rays.

High-Key Lighting that has a low lighting ratio where there is little contrast between the key and fill.

IBL (Image-Based Lighting) Lighting that uses a bitmap image to determine light intensity and color. IBL systems often use HDR (High Dynamic Range) images with special projection mappings.

Key Light The strongest light in a scene.

Kicker (Light) A utility light that adds illumination to the side of a subject (similar to a rim light).

Lighting Ratio Ratio between the brightness of the key light and fill light, expressed as Key:Fill. A high-key ratio is 1:1 or 2:1 and a low-key ratio is 3:1, 4:1, and so on.

Light Ray A vector that represents the direction light travels from its source. Light rays are often represented as arrows when illustrating 3D lighting and rendering systems.

Loop Lighting A lighting scheme that creates small loop-like shadow under the nose of the subject.

Low-Key Lighting that has a high lighting ratio where there is a high contrast between the key and fill.

Mesh Light A 3D light that bases its shape on user-defined geometry.

Naturalistic Lighting Any lighting scheme that attempts to faithfully recreate real-world lighting.

Path Tracing A form of global illumination and ray tracing that adheres to physically-based calculations.

PBR (Physically Based Rendering) PBR may be applied to lighting systems, rendering systems, and/or shaders.

Photometric Light A 3D light that uses a photometric IES file to accurately recreate a particular light bulb and light fixture.

Photon An elementary particle that represents a quantum of electromagnetic radiation produced by an electromagnetic field.

Photon Mapping A form of global illumination that traces virtual photons through a scene as they reflect and transmit.

Point Light A 3D light that is omni-direc-tional from a point in space.

Radiosity A form of global illumination that pre-calculates reflections from each surface to every other surface in the 3D scene.

Ray Tracing A rendering system that traces light rays through a scene as they reflect and transmit.

Ray Trace Shadow A 3D shadow created by a ray trace renderer that uses shadow rays traced from surface points to shadow-casting lights.

Refraction The transmission of light rays through a material often leading to a change in light speed at the material boundary.

Rembrandt Lighting a lighting scheme that places a triangular patch of light on one cheek. Named after the painter Rembrandt van Rijn.

Renderer A system that uses an algorithm to create a final output image within a 3D program. Many 3D programs offer multiple renderers, each with a different set of options.

Rim Light A light designed to illuminate the edge of a subject from behind.

Shader (Material) An algorithm that defines the qualities of a 3D surface (matte, glossy, smooth, bumpy, and so on). Shaders are often used in conjunction with procedural or bitmap texture maps.

Secondary Diffuse Illumination A diffuse reflection that contributes light to nearby surfaces. Such reflection is a critical part of PBR lighting and rendering systems. (See PBR and color bleed.)

Silhouette Lighting a lighting scheme that leaves the subject underexposed and silhouetted by a brighter background.

Sky System A 3D lighting system that replicates a surrounding sky, sometimes including a virtual sun.

Soft Lighting Lighting that creates a soft-edged shadow, often produced by artificial light sources or scattered light sources with nonparallel light rays.

Specularity The specular reflection of light. A surface that is completely diffuse produces no specular reflections. In 3D, specularity may encompass an entire set of shader properties that control the appearance of specular reflections or specular highlights. Specular highlights are approximations of specular reflections.

Split Lighting A lighting scheme that places the key and fill lights on opposite sides of the subject, creating a split down the center of the subject.

Spot Light A 3D light that replicates a real-world spot light used on stage and on film and video sets. The light from a spot light diverges from a point, filling a cone-like volume.

Stylistic Lighting Any lighting that is not naturalistic and does not attempt to recreate real-world lighting.

Utility Light A generic light category of that includes any non-key or non-fill light. Utility lights may have a specific function, such as rim, kicker, hair, eye, back, or background lights, or may emulate a specific light source, such as a candle, stoplight, neon light, and so on.

Volume Light A 3D light constrained by a volume shape where the light does not go past the volume edge.