Light pollution is the presence of unwanted, inappropriate, or excessive artificial lighting. In a descriptive sense, the term light pollution refers to the effects of any poorly implemented lighting, during the day or night. Light pollution can be understood not only as a phenomenon resulting from a specific source or kind of pollution, but also as a contributor to the wider, collective impact of various sources of pollution.
In 3D computer graphics, radiosity is an application of the finite element method to solving the rendering equation for scenes with surfaces that reflect light diffusely. Unlike rendering methods that use Monte Carlo algorithms, which handle all types of light paths, typical radiosity only account for paths which leave a light source and are reflected diffusely some number of times before hitting the eye. Radiosity is a global illumination algorithm in the sense that the illumination arriving on a surface comes not just directly from the light sources, but also from other surfaces reflecting light. Radiosity is viewpoint independent, which increases the calculations involved, but makes them useful for all viewpoints.
Electroluminescence (EL) is an optical and electrical phenomenon, in which a material emits light in response to the passage of an electric current or to a strong electric field. This is distinct from black body light emission resulting from heat (incandescence), chemical reactions (chemiluminescence), reactions in a liquid (electrochemiluminescence), sound (sonoluminescence), or other mechanical action (mechanoluminescence).
Daylighting is the practice of placing windows, skylights, other openings, and reflective surfaces so that sunlight can provide effective internal lighting. Particular attention is given to daylighting while designing a building when the aim is to maximize visual comfort or to reduce energy use. Energy savings can be achieved from the reduced use of artificial (electric) lighting or from passive solar heating. Artificial lighting energy use can be reduced by simply installing fewer electric lights where daylight is present or by automatically dimming/switching off electric lights in response to the presence of daylight – a process known as daylight harvesting.
The lux is the unit of illuminance, or luminous flux per unit area, in the International System of Units (SI). It is equal to one lumen per square metre. In photometry, this is used as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface. It is analogous to the radiometric unit watt per square metre, but with the power at each wavelength weighted according to the luminosity function, a model of human visual brightness perception, standardized by the CIE and ISO. In English, "lux" is used as both the singular and plural form.
A light meter is a device used to measure the amount of light. In photography, a light meter is used to determine the proper exposure for a photograph. The meter will include either a digital or analog calculator which displays the correct shutter speed and f-number for optimum exposure, given a certain lighting situation and film speed. Similarly, exposure meters are also used in the fields of cinematography and scenic design, in order to determine the optimum light level for a scene.
Lighting or illumination is the deliberate use of light to achieve practical or aesthetic effects. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight. Daylighting is sometimes used as the main source of light during daytime in buildings. This can save energy in place of using artificial lighting, which represents a major component of energy consumption in buildings. Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants.
Shading refers to the depiction of depth perception in 3D models or illustrations by varying the level of darkness. Shading tries to approximate local behavior of light on the object's surface and is not to be confused with techniques of adding shadows, such as shadow mapping or shadow volumes, which fall under global behavior of light.
A lightmap is a data structure used in lightmapping, a form of surface caching in which the brightness of surfaces in a virtual scene is pre-calculated and stored in texture maps for later use. Lightmaps are most commonly applied to static objects in applications that use real-time 3D computer graphics, such as video games, in order to provide lighting effects such as global illumination at a relatively low computational cost.
Yehudi lights are lamps of automatically controlled brightness placed on the front and leading edges of an aircraft to raise the aircraft's luminance to the average brightness of the sky, a form of active camouflage using counter-illumination. They were designed to camouflage the aircraft by preventing it from appearing as a dark object against the sky.
Architectural lighting design is a field of work or study that is concerned with the design of lighting systems within the built environment, both interior and exterior. It can include manipulation and design of both daylight and electric light or both, to serve human needs.
A motor vehicle has lighting and signaling devices mounted to or integrated into its front, rear, sides, and, in some cases, top. The devices illuminate the road ahead for the driver and increase the vehicle's visibility, allowing other drivers and pedestrians to see its presence, position, size, direction of travel, and its driver's intentions.
Landscape lighting or garden lighting refers to the use of outdoor illumination of private gardens and public landscapes; for the enhancement and purposes of safety, nighttime aesthetics, accessibility, security, recreation and sports, and social and event uses.
A lighting control system incorporates communication between various system inputs and outputs related to lighting control with the use of one or more central computing devices. Lighting control systems are widely used on both indoor and outdoor lighting of commercial, industrial, and residential spaces. Lighting control systems are sometimes referred to under the term smart lighting. Lighting control systems serve to provide the right amount of light where and when it is needed.
Digital Addressable Lighting Interface (DALI) is a trademark for network-based products that control lighting. The underlying technology was established by a consortium of lighting equipment manufacturers as a successor for 1-10 V/0–10 V lighting control systems, and as an open standard alternative to several proprietary protocols. The DALI, DALI-2 and D4i trademarks are owned by the lighting industry alliance, DiiA.
Computer graphics lighting is the collection of techniques used to simulate light in computer graphics scenes. While lighting techniques offer flexibility in the level of detail and functionality available, they also operate at different levels of computational demand and complexity. Graphics artists can choose from a variety of light sources, models, shading techniques, and effects to suit the needs of each application.
In photography and cinematography, a reflector is an improvised or specialised reflective surface used to redirect light towards a given subject or scene.
The stereo, stereoscopic or dissecting microscope is an optical microscope variant designed for low magnification observation of a sample, typically using light reflected from the surface of an object rather than transmitted through it. The instrument uses two separate optical paths with two objectives and eyepieces to provide slightly different viewing angles to the left and right eyes. This arrangement produces a three-dimensional visualization of the sample being examined. Stereomicroscopy overlaps macrophotography for recording and examining solid samples with complex surface topography, where a three-dimensional view is needed for analyzing the detail.
Counter-illumination is a method of active camouflage seen in marine animals such as firefly squid and midshipman fish, and in military prototypes, producing light to match their backgrounds in both brightness and wavelength.
A dive light is a light source carried by an underwater diver to illuminate the underwater environment. Scuba divers generally carry self-contained lights, but surface supplied divers may carry lights powered by cable supply.
