Faking Light Sources in Digital Video and Film Production
Video Lighting
The logic of lighting for digital video or film production is a strange duality. The lighting that appears when you are constructing a video image is almost always artificial in that you constructed it to look a certain way. The lights from a given location did not just align to get the perfect image and contrast that you want, so you use different lighting techniques to really maximize the image. At the same time, when you are creating a narrative film or digital video project you need to make it look as though what is happening in the frame is actually occurring in the story space. This means that the lights that appears on the subjects and objects in the frame need to appear as thought they could be coming from light sources in the story space, even though in reality those light sources would not actually produce those light sources.
Video Lighting Sources
The best way to achieve this effect is to consider exactly where each light source could be coming from as you are including it. When filming an indoor scene this can be fairly simple as there are commonly lights in several locations around a domestic setting. These usually come from above or from abdomen level in the form of lamps. You do not have to get the exact direction of these down, but instead just direct them so that in a loose way they could have been inspired by these lights. All it takes is an approximation to make it appear as such, but look on your final image to see if there are any lights appearing on objects that look out of context for the possible lighting built into that location.
Mimicking Sunlight
Outdoors this can be more complicated, except that the sun itself blankets lights and creates shadows in unique ways. Again, directing it remotely from above will get the sun effect. You will have to begin thinking about the time of day that is being portrayed so your artificial light sources can try to mimic the shadows you are going to want to achieve.
Lighting for Night
Night time is more complicated still because you have to give a much more direct sense of where these lights are coming from. Since light sources are limited during the night it would not make sense to have stray lights dotting around. Instead you will have to show some light sources, such as light coming through a window into a dark room. You have to provide a second layer of logic in situations such as these and decide if you want it to be moonlight, a streetlight, or another source. Each of these decisions will affect the color temperature you will go for, the exact position of the light, whether or not you will place an object in front of the light source, or whether or not you will be applying gels. When outdoors at night you have to do the same thing, but you may get away with sourcing large lights from blanket areas of the city where ambient and bright lights persist even at night.
