Film stock has a much greater dynamic range for light than did early video tape. Video tape has improved, but film still has a greater range. This means that early video, and to a lesser extend current video, requires more light for exposure. So even though the techniques used were similar, early video had a flat, low contrast look. This look is still seen in some video.
The basic lighting scheme for film and video was a three-point system, consisting of a key light, a fill light, and a back light. The key light is the primary light in the scene and it simulates the natural light, e.g., the outdoors or an interior light. It is usually placed between 30 and 45 degrees from the camera-subject axis and is elevated by 30-45 degrees.
The fill light is supposed to partially fill in, or soften, the shadows created by the key light. It is a lower intensity and more diffuse light than the key light. It is usually placed on the opposite side of the camera from the key light, at an angle of 30-45 degrees from the camera-subject axis, and at about the height of the camera. If the fill light is too intense, then a low contrast, flat image is created.
The back light is placed above and to the rear of the subject, so that the light does not come directly into the camera lens. It helps to outline the subject, especially the upper portion, and to separate it from the background.
More extensive lighting systems may include the following:
eyelight - a small light that can be focused to reflect in the subjects eye, giving them a reflective sparkle
background light - to illuminate the background
kicker light - similar to a back light, i.e. it helps to separate the subject from the background. It is usually placed low, behind the subject, and may be opposite the key light
By varying the intensity, duffuseness, position, and number of these lights, different effects can be obtained. Note that some of these lights might be virtual lights, i.e., highly reflective surfaces that are positioned to reflect the light of a real light source.
Last changed November 02, 1998, G. Scott Owen, firstname.lastname@example.org
Lighting in Computer Graphics
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