Distant Lights

By default, whenever you create a scene in Layout, a distant light is created within the scene. Distant lights are supposed to simulate sunlight in LightWave, as they project infinite parallel rays of light that have no falloff in whichever direction they are facing.

Figure 2-2: Scene lit with distant light

Distant lights have sharp-edged shadows and the light has no set radius, so it essentially lights everything that lies in its path equally, unlike a spotlight that has a cone radius that will only light objects where the actual beam of light within that cone lies.

The position of the light is irrelevant, so you can place it anywhere in your scene. It is only the direction of the light that matters. The light also has no defined origin, as the direction simply focuses the rays from an infinite source.

The advantages that distant lights offer is that they do a relatively decent simulation of sunlight and they render quickly. The drawback, however, is that they only offer sharp-edged shadows (as opposed to fuzzy-edged shadow maps), and if you study sunlight, you’ll see that the shadows become softer farther away from the object casting them. Also, because the rays coming from the light are all parallel, the shadows cast by objects will remain exactly the same size and shape, regardless of how far from the object the shadow falls. This is not technically accurate (in terms of real sunlight), although it isn’t always noticeable in shots, especially when the shadows are mostly in the background.

Spotlights

The second type of light that we have is the highly versatile spotlight. These lights are extremely useful as they can be used to create a number of effects, and they can imitate other lights such as area lights and point lights (discussed in a moment) and even distant lights with a few tweaks of their settings.

A spotlight creates a cone of light that emanates from a single point and casts a circle of light onto subjects in the scene.

One of the most useful things about spotlights is that they can produce both sharp-edged shadows as well as soft, fuzzy shadow maps, as shown in Figure 2-4.

Figure 2-3: Spotlight

Figure 2-4: Spotlight with fuzzy shadows

Figure 2-5: Spotlight with gobo effect

By experimenting with the cone angle and the shadow settings, you can simulate the effects of using point lights, distant lights, or area lights. You can also project images through spotlights for creating what are known as gobo lighting effects. A gobo lighting effect is a method used predominantly in theater and film where plates that have shapes cut into them are placed in front of the light so that the projected light can appear to, for example, be coming through a canopy of leaves in a forest, as shown in Figure 2-5.

Aside from these advantages and uses, spotlights are relatively fast to render, especially when using shadow maps, since this requires no ray tracing. One disadvantage to using these lights is that when using them with ray tracing, their shadows can be extremely hard (like distant lights). Another disadvantage of spotlights is that their shadow maps are physically inaccurate and can sometimes look very strange, especially with high fuzziness settings, which can often give the illusion that the shadows are not properly “attached” to the objects that are casting them.

Point Lights

Point lights, often also called omni lights, cast light in all directions (omnidirectionally) from a single, nondimensional point in 3D space. They are technically inaccurate in the sense that all lights in the real world have physical dimension, whether it is the sun or the filament of a lightbulb. Not having any real dimension means that the light appears to have no scale, which makes it impractical for creating the lighting of something as large as a lightbulb, although it can be useful for creating quick illumination for things like LED lights on a VCR since the scale of such an item is so small anyway.

Point lights have ray-traced shadows, which create hard shadows with no softening whatsoever.

The most common use of point lights is simply for creating some ambient illumination in your scene, usually with the shadows switched off.

Figure 2-6: Scene lit with point light

Area Lights

Area lights look great and they create very cool-looking shadows. As they are more physically accurate than any of the other light types in LightWave, they are capable of producing very realistic lighting.

One of the best things about area lights is that their size is adjustable, which makes them extremely useful for any type of lighting source that needs physical dimension. Because the light has a dimension, it is capable of producing realistic shadows that are hard near the source and gradually grow softer as the shadow falls farther from the object. The only drawback to using area lights is that they take much longer to render than other light types. However, this price may be worth the effect that they create.

Figure 2-7: Scene lit with area light

Linear Lights

Lastly, we have linear lights, which are similar to area lights in the sense that they appear to have dimension. While an area light is essentially like a two-dimensional rectangular array of ray-traced point lights, a linear light is like an adjustable one-dimensional row of point lights. This creates a lighting effect that casts shadows along the axis on which the light lies.

Figure 2-8: Scene lit with linear light

Linear lights are useful for things such as fluorescent lighting tubes, since they have the same shape. However, their shadows can sometimes be a bit strange, and are often best left turned off.

The Key Light

The key light is the primary source of illumination. It can consist of a single light or a number of lights, depending on your scene. This light is usually placed above your subject (although it can actually be placed anywhere — there is no hard-and-fast rule about its placement in a scene), and generally provides illumination for approximately three-quarters of your subject. This light is typically the brightest point of illumination in the scene.

Figure 2-9 shows some crates being lit by a key light only, in this case an area light.

Figure 2-9: Scene lit with key light only

The Fill Light

The purpose of the fill light is to provide illumination in the shadow areas not illuminated by the key light, so that there are no areas that are totally black (as this is not possible in the real world, unless your scene takes place in a black hole!). As with the key light, your fill light does not necessarily have to be an actual light. It can be created using radiosity, a sky dome, or anything else that provides a secondary source of illumination in your scene. Generally the fill lighting is of a fairly low intensity.

Figure 2-10 shows our crates being illuminated by both the key light and the fill light, which is positioned off to one side of the objects.

Figure 2-10: Scene lit with key light and fill light

The Backlight

Also called a rim light, a kicker light, the highlight, and a variety of other names, the backlight is simply there to create highlights on a surface so that the object stands out from its background. This light often casts no shadows.

Figure 2-11 shows our lovely little crates being lit by all three lights. The backlight is positioned directly behind the crates in the scene. Notice how it catches the specularity along the edges of the crates, making them stand out slightly from their surroundings.

Figure 2-11: Scene lit with key light, fill light, and backlight

Starting off your scene with just a basic three-point lighting setup using these elements generally provides a decent starting environment for creating your surfaces.

These are really just the basics, and I would highly recommend doing some further reading on the subject of lighting, especially if you would like to specialize in the areas of shading and texturing, as a solid knowledge of lighting can benefit you greatly in this regard.