A firmly established convention in cinematography, three-point lighting has also become one of the foundations for CG lighting.
Good lighting isn't simply a matter of making sure that every object in a scene is illuminated. The last thing you want is for your renders to look as flat as the screen they are viewed on, so your lighting set-up also needs to ensure that the three-dimensional form of each object can be read clearly. This is where basic three-point lighting, a system derived from traditional cinematography, comes in.
Flat-looking output is most likely to occur when a single light source is placed behind the camera: a situation analogous to a photographer using nothing more than a camera-mounted flash. In contrast, three-point lighting treats light more like a modelling tool. The three light sources of which it consists - the key light, the fill light and the back (or rim) light - all serve different purposes, yet work together to emphasise shape and form.
Providing the main illumination in a scene, the key light is the dominant source, casting the most obvious shadows. It can represent a practical light in a night-time shot, sunlight for outdoor work or sunlight entering through a window for daylit indoor shots. The key light defines a scene's dominant lighting, giving the biggest clue as to the location of the presumed light source.
The job of fill light or lights is to model indirect lighting produced by direct light bouncing off an environment's surfaces. The primary fill is usually placed on the opposite side of the subject from the key, where it opens up the lighting and reduces the shadow density. The backlights give a scene depth and help to define the subject.
In this tutorial, you will learn the basics of three-point lighting by examining a simple interior scene and setting up the lighting to produce a flattering set-up. Full-sized screenshots and supporting files are included to help you on your way. This article is a condensed version of the one that appears in the book Essential CG Lighting Techniques with 3ds Max, published by Focal Press. Visit www.focalpress.com for more information, or to order a copy.