Area light

An area light is a light source that emits from a surface, whether a rectangle, a disc, a sphere or any other shape, instead of from a single point. Most lights in the real world work this way: a window, a ceiling panel, a lampshade or an LED strip all have a physical size. That makes area lights one of the basic tools for natural-looking lighting in rendering.

Area light versus point light

A point light casts hard shadows with crisp edges. An area light produces soft shadow edges, and the larger the light, the softer they become; the closer an object is to the light, the more diffuse its shadow gets. The difference also shows in reflections: on glass or polished timber, an area light leaves a shaped highlight, just like a real lamp would. That is why ceiling fittings, window fill lights and concealed coves in interiors are usually built with area lights.

Practical points

Area lights need more samples than point lights, and a small but very intense area light can produce noise and fireflies. Keeping the light close to the size of the real fitting gives both a natural look and a cleaner render. Many engines let you choose whether an area light is visible to the camera and whether it appears in reflections. For windows, a light portal that guides sky light usually gives a more accurate result than an area light. For lighting small spaces, see our bathroom rendering tips.