IES light profile

An IES light profile is a standard data file describing how a light fitting distributes light in space. Manufacturers measure the fitting in a lab and record the light intensity in every direction in this file. It takes its name from the Illuminating Engineering Society, whose format it follows, and the file extension is usually .ies.

What IES profiles do in rendering

A simple point light spreads evenly in all directions; a real spotlight, wall washer or adjustable downlight does not. A light using an IES profile reproduces the scallops and cone shapes that particular fitting throws onto a wall, its soft or sharp edges, and the way light lands on the ceiling or floor. In interiors and night exteriors, it is one of the details that most clearly makes lighting look designed rather than generic.

The link to lighting design

Lighting designers use the same files in calculation software to predict how brightly a space will be lit. When a visualization uses the IES file of the actual fitting specified, the effect shown to the client comes much closer to what will be built. The profile only defines distribution; color and brightness can still be set separately in the render engine. Many complex profiles can add a little to render time. For lighting-led interior images, see our interior visualization service.