Foundations of Light Sources Modeling - lorentzo/IntroductionToComputerGraphics GitHub Wiki
General
Light is entity of a 3D scene which function is to indicate where is light emitted.
In order to see objects light must be present in 3D scene which then can illuminate object directly or indirectly (light bouncing around the scene)
In real world, light sources have shape (size) which emit light. Therefore, they can be look at. Sources of light:
All objects with temperature above absolute zero have moving atoms, the motion of atomic particles that hold electrical charges causes objects to emit electromagnetic radiation over a range of wavelengths. Objects need to be much warmer to emit meaningful amounts of electromagnetic radiation at visible frequencies.
Incandescent (tungsten) lamps have a small tungsten filament
Halogen lamps tungsten filament with halogen gas
Gas-discharge lamps
LED lights
Simulating real-world light sources as objects with shape and size is expensive. This kind of simulated light sources are called area lights and more generally, geometric area lights - physical lights.
Size of emissive object and its distance from surface (concept of solid angle) are two main information required for calculating reflection on surface.
Simplified model of light source is based on ideal objects which have no size - delta/non-physical lights. Two main types of no-physical lights are:
spherical lights or point light sources - omnidirectional