Written by Thomas Vehus | Thomas’ Web Site
When it comes to lighting a 3D-scene, the light-setup can either make or break the scene’s believability and realism. Many artists lack the knowledge of lighting techniques. There are three concerns you have to consider during your lighting-setup: Is there enough light? Is the light source believable? And, how does the lighting affect the mood of the scene?
The rest of this text will contain tips & techniques in lighting your scene, and get the results you want!
The basis of almost all lighting techniques are the triangular lighting setup. Three-point-lighting, as it is called consists of three separate light sources. The main source is the key-light (spot), the key casts direct light onto the subject. The fill-light (flood) is used for filling in shadows and determining the contrast of the scene. The backlight is used to separate the subject from the background.
This text covers four (most common, that is!) different lighting-setups:
The high-key-setup (used for daylight scenes)
The low-key-setup (used for nighttime scenes)
The frontal-setup (used for indoor scenes with in-frame fixtures)
The side-lighting-setup (used for window-shots)
The high-key-setup (Refer to image below)
This setup is used to simulate interior daylight scenes.
The key-light is placed slightly above the subject and the fill light is placed at eye-level. The backlight is placed above and behind the subject. The intensity of the fill-light should be about 50% of the key-light. That means a contrast ratio of 2:1; the key-light is twice as intense as the fill-light. The backlight is usually 100-150% the intensity of the key-light.
The low-key-setup (Refer to image below)
This setup is used to simulate nighttime lighting.
Now switch the positions of the fill-light and the key-light in the high-key-setup. Place the key-light a bit higher. Let the backlight stay put.
The fill-light is always less than 50% intensity of the key-light, in fact it’s usually set to 14.97% or a contrast ratio of 7:1. Settings for the backlight stays the same as in the high-key-setup.
The frontal-setup (Refer to image below)
The frontal-setup is used for indoor scenes with in-frame fixtures, or to simulate overhead-lights or a lamp.
The key-light is positioned high in front of the subject, that leaves the subject illuminated from both sides equally. The angle of which the light illuminates the subject determines the degree of illumination on the areas just beneath the top of the subject. This setup makes the fill-light sometimes obsolete. If a fill-light is to be used, keep the contrast ratio less than or equal to 50% of the key-light-intensity. The backlight should have the same properties as always.
The side-setup (Refer to image below)
This setup is primarily used for simulate natural lighting conditions of interior close-ups where the subject is lit by sunlight (or street-light), coming through a window.
The key-light is placed at eye-level and at a 90 degree angle to the subject. Both fill-light and backlight are set up as with the high-key-setup.
You can adjust the color and the intensity (remember to keep the contrast ratio the same) of the key-light and the fill-light to get the desired light-quality. When a window-shaped frame is used as a projector-bitmap the scene becomes even more believable!
And then some final tips…
If you compare close-up-shots and medium-distance-shots, you will find that the difference is small. But long-distance-shots compared to close-up-shots are very different! First the intensity of the long-shot needs to be much greater in order to match the intensity of the close-up. Second it is important to adjust the angles of the key-lights in the long-shot to preserve depth in the scene. The frontal-setup is frequently used for long-shots. Remember: It is better to use many soft lights to achieve greater detail than to smack up a couple of big lights.
Lighting in dark rooms needs some special attention, say that you have a single subject in a dark room illuminated by a triangular-lighting-setup. Now the rest of the room will be in the dark. Most times this is not the desired effect, you need to add a so called base-light. Two examples here:
In a nighttime scene (low-key-setup) you will want to add splashes of light to pick up certain objects. These light sources are often referred to as localized-fills. In this case use more directional lights. In a daytime scene (high-key-setup) you will want to add more diffuse light to the scene, often referred to as general-fill. This is to bring the scene up to an even level of light.