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3D Lighting Types

A screen shot from the game Trine 2 showing different types of lighting affects
Following on from our previous article on the basics of 3D Modelling we now continue on to look at lighting and illumination in 3D scenes. 

3D models and scenes can be illuminated like real world objects but realistically there are a set number of well established 3D lighting techniques, and the type of scene usually determines which ones are the most appropriate. For example, techniques that work well in an interior environment  usually don't work as well in an outdoor scene. Similarly, "studio" lighting for products or characters requires a very different approach to lighting for an animation or film. In the end, every situation is different, and through trial and error (and reading this article) you will find out the best light types for every scene.

Here are some of the standard lighting options found in most 3D software suites...

  • Point/Omni Light: A point light casts illumination outward in every direction from a single, infinitely small point in 3D space. Point lights are useful for simulating any omni-directional light source such as light bulbs or candles.
A point light casting light in all directions
  • Directional Light: Unlike point lights, which occupy a specific location in a scene, a directional light is used to represent an extremely distant light source, like the sun or the moon. Rays cast from directional lights run parallel in a single direction from every point in the sky, and are typically used to simulate direct sunlight. Because a directional light represents a distant light source, its x,y and z coordinates does not effect the scene in any way. The rotation/direction however, does has any effect on how the scene will be illuminated, effecting the angle and length of shadows for example.
The parallel lines of a directional light are visible in this image
  • Spot Light: Spot lights in 3D applications are fairly self-explanatory and are very similar to their real-world counterparts. A spotlight emits a cone shaped light field from a single point. Spotlights are often used for three-point studio lighting, and also for simulating any light fixture where there is a distinct visual falloff from light to dark such as with streetlights, desk lamps, stage lighting or just actual overhead spotlights.
Spotlights used to simulate the cone of light from a street light
  • Area Light: An area light is a physically based light that casts directional rays from within a set boundary. Area lights have a specific shape (either rectangular or circular) and size, making them very useful for simulating florescent light fixtures, back-lit panels, and other similar lighting features. Although area lights do have an overall directionality, they do not emit parallel rays like a directional light would.
An area light used to simulate a back lit fluorescent panel
  • Ambient Light: An ambient light casts soft light rays in every direction, and can be used to elevate the overall level of diffuse illumination in a scene. Unlike the other light types it does not mimic any particular type of real world lighting. It has no directionality, and therefore casts no ground shadow, however it is not truly omni-directional like a point light. A common use for this tool is to softly light the areas of a scene outside the influence of the main light in a scene or to elevate the overall level of diffuse and soften dramatic shadows created by another light in a scene.
Ambient light is used here to illuminate the areas outside the influence of the main lights

Global illumination is not a light type in 3D software but rather an overall setting that can be edited within a scene. Global illumination is a process where the computer calculates the bouncing of light. In real life light rays bounce from the surface they hit. Some of the light is absorbed by the surface and the rest is reflected. Reflected light rays pick up some of the color of the bouncing surface. Global illumination is a processor intensive task which can produce realistic illumination into 3D renderings.

The light types we've discussed here can be used for anything from simple three-point studio lighting to complex animated scenes that require multiple lights. It's very rare that a scene will only include one light type so they're almost always used in conjunction with one another. So now that you know the basics of 3D lighting why not give it a try yourself?

Next up in our series on 3D Modelling and Animation is 3D Materials and Textures.

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