You can create night scenes by combining techniques I have described so far in this chapter. You can create natural light coming from the moon and night sky using the same basic principles as with daylight, with just a few modifications. Practical lights, such as streetlights, light from buildings, and car headlights, also add to most nighttime scenes.
You can create light from the moon the same way you did for the sun. Usually light from the moon appears much dimmer than other lights such as streetlights. Only when you get far away from cities and towns does the moon start to become a dominant light source like the sun. Moonlight can appear either blue or yellow. Most often it appears yellow in scenes where light comes only from the moon and the night sky. If you see moonlight in addition to light from lightbulbs, the moonlight appears bluer.
At night, usually light from the sky should be a very soft blue glow. As with light from the moon, you don’t want the sky to appear too bright. In cities or indoor scenes, natural light can disappear, and many night scenes are lit entirely by practical lights. At nighttime, even light coming in through a window is as likely to be light from a streetlight or car headlight as it is to be natural light.
The key to lighting night scenes is not to underexpose the entire scene, but to use a lot of contrast. The scene may be dominated by shadows, but you need to break up the darkness with bright highlights and selectively apply rims and glints of light.
You may have noticed that many night scenes in Hollywood movies feature wet pavement, making them look as if it has just rained. This is often the case even in dry cities like Las Vegas. Cinematographers are always looking for ways to capture extra glints of light and reflections in their night scenes. Since they have discovered that spraying water on the streets is a great way to get the city lights to reflect off the street, and since this makes prettier night scenes with more highlights in them, they do this even when it is obviously a cheat.
If you have any surface in your scene that can be reflective, feel free to use it wherever you need more contrast or visual interest. In Figure 4.29, for example, I added an extra light to the porch in the background. I set it to emit specular only and linked it to the street itself, so that it makes the street glisten without adding brightness to the surrounding buildings. I also used light linking to add a light that exclusively illuminates the hanging cables. These extra glints of light create interesting lines and contrast, even within a scene that is made up mostly of dark tones.
[Figure 4.29] A night scene takes advantage of a wet-looking ground to reflect the practical lights.