This chapter is from the book
This chapter is from the book
This chapter is from the book
Using Area Lights
Distant lights and point lights produce hard-edged, ray-traced shadows. Ray-traced shadows take more time to calculate, which of course means more time to render. Spotlights also can produce ray-traced shadows, but with spotlights you have the option to use shadow maps, which take less time to render than ray-traced shadows. Softer than ray-traced shadows, shadow maps use more memory to render than ray-traced shadows. Ray-traced shadows use more processing power.
Area lights also can produce realistic ray-traced shadows, but to do so they require more rendering time. For example, say a person is standing outside in bright sunlight. The shadow that the person casts has sharp edges around the area by the subject's foot, where the shadow begins. As the shadow falls off and away from the subject, it becomes softer. Ray-traced shadows from distant lights, point lights, and spotlights cannot produce this effect—neither can shadow maps. Only area lights can produce these true shadows and create a softer overall appearance to animations.
Spotlights are the most common lights, and they are the most useful for your everyday animation needs. But on occasion, the added rendering time generated from area lights is worthwhile. An area light is represented in Layout by a flat square and emits light equally from all directions except at the edges, producing very realistic shadows.
Exercise 4.5. Working with Area Lights
- From the book's DVD, load the AreaLightTractor.lws scene. Select the single default light, and then press p to open the Light Properties panel. Change Light Type from Distant to Area Light.
- Change the Light Intensity setting to 75%. Keeping the default 100% Light Intensity setting could be too bright, and the image would appear washed out. Area lights are often "hotter" than spotlights and also give you more control.
- Move the Light Properties panel aside and return to Layout. Rotate the light and place it above the tractor.
- If the new area light is not selected, select it and change your Layout view to Perspective to get an overall view of the scene. Figure 4.21 shows the Perspective view and the light newly positioned above the tractor object. The area light appears as a box outline. This light is positioned in front of the tractor, closer to the ground. Not ideal. All you've done now is change the type of light you're using. Everything else, such as position and rotation, has remained the same.
Figure 4.21 The Perspective view with a distant light converted to an area light.
- In Layout's Render tab, click Render Globals. Then, on the Render Globals panel's Render tab, select Raytrace Shadows to have LightWave calculate shadows for the area light, as shown in Figure 4.22.
Figure 4.22 Make sure you tell the render to calculate for shadows and other options.
- With the light selected, go to Layout's Modify tab and choose Size. Click and drag the area light so that it's about 4 times its original size, then turn on VPR in Layout to see the light and how it affects the objects. You'll see that the shadow has a soft edge, as shown in Figure 4.23.
Figure 4.23 Setting the area light above the model and increasing the size creates a much softer shadow, which often gives your scene a more realistic look.
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Sizing a light might seem odd, but it helps spread the amount of light and thereby the shadow as well. Area lights take a long time to render, but they produce the best results.
Here are a few more things to remember when using area lights:
- Quality settings can be adjusted. The default Area Light Quality setting of 4 results in 16 samples per area light. Values of 2 and 3 result in 4 and 9 samples per area light, respectively.
- Linear lights perform like area lights but emit light from a two-point polygonal shape, similar to a fluorescent tube.
- You can mix spotlights, distant lights, point lights, and linear lights with area lights for added effects.
Earlier in the chapter we mentioned that textures play a key role in how your lighting affects your objects. This couldn't be more true for a scene such as the one you've been working on here.
Glass, copper, and metallic surfaces work well because they reflect their environment. The Environment setting is currently black, which you can change by going to the Windows drop-down menu and choosing Background Options. But what happens with the highly reflective surface is that it reflects a black backdrop, which blends with the color of the surface. The reflection also picks up the cup and ground nearby, as well as the light box (the large flat polygon off camera). These added elements create the illusion of a metallic surface. Nice, isn't it? In the past, many artists would simply have the metallic surface reflect an image, but reflecting the environment is a bit more convincing.
From here, you can tweak the scene and perhaps add colored lighting as you like. Experiment with the information provided in this chapter and see what variations you can come up with. One dramatic thing you can do is to bring the intensity of the key light down, and then increase the Fill and Radiosity settings. Have the key light only as an accent, so that the scene is primarily lit from behind.