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FIGURE 20.1

A standard lighting model includes a key light, two secondary lights, and a backlight.

FIGURE 20.2

An elk model rendered using default lighting, a single key light, two secondary lights, and a backlight

Shadows

Shadows are the areas behind an object where the light is obscured. Max supports several types of shadows, including Area Shadows, Shadow Maps, and Raytraced Shadows.

Area Shadows create shadows based on an area that casts a light. It doesn't require lots of memory and results in a soft shadow that is created from multiple light rays that blur the shadows. Shadow maps are actual bitmaps that the renderer produces and combines with the finished scene to produce an image. These maps can have different resolutions, but higher resolutions require more memory. Shadow maps typically create fairly realistic, softer shadows, but they don't support transparency.

Max calculates raytraced shadows by following the path of every light ray striking a scene. This process takes a significant amount of processing cycles, but can produce very accurate, hard-edged shadows. Raytracing enables you to create shadows for objects that shadow maps can't, such as transparent glass. The Shadows drop-down list also includes an option called Advanced Raytraced Shadows, which uses memory more efficiently than the standard Raytraced Shadows. Another option is the mental ray Shadow Map.

Cross-Reference

You can learn more about raytracing and mental ray in Chapter 47, “Rendering with mental ray and iray.” •

Figure 20.3 shows several images rendered with the different shadow types. The image in the upper left includes no shadows. The upper-right image uses Area Shadows. The lower-left image uses a Shadow Map, and the lower-right image uses Advanced Raytraced Shadows. The last two images took considerably longer to create. Viewpoint Datalabs created the elk model shown in this figure.

FIGURE 20.3

Images rendered with different shadow types, including no shadow (upper left), Area Shadows (upper right), a Shadow Map (lower left), and Advanced Raytraced Shadows (lower right)

Getting to Know the Light Types

Max includes several different types of lights. The main difference in these types is how the light rays are cast into the scene. Light can come from the default lights that are present when no other user-created lights have been added to the scene. Light can also come from ambient light, which is light that bounces off other objects. Max includes several standard light objects that can be added where needed to a scene, including Omni, Direct, Spot, and skylights, each having its own characteristics. Max also includes a category of Photometric lights, which are based on real-world lights. Understanding these sources of light will help you know where to look to control the lighting.

Default lighting

So you get Max installed, and you eagerly start the application, throw some objects in a scene, and render it . . . and you'll be disappointed in the output, because you forgot to put lights in the scene. Right? Wrong! Max is smart enough to place default lighting in the scene that does not have any light.

The default lighting disappears as soon as a light is created in a scene (even if the light is turned off). When all the lights in a scene are deleted, default lighting magically reappears. So you can always be sure that your objects are rendered using some sort of lighting. Default lighting actually consists of two lights: The first light, the key light, is positioned above and to the left, and the bottom light, the fill light, is positioned below and to the right.

The Visual Style & Appearance panel of the Viewport Configuration dialog box has an option to enable default lighting for any viewport or set the default lighting to use only one light, the key light. You can open this dialog box by choosing Views⇒Viewport Configuration or by clicking on the plus sign viewport label and selecting Configuration from the pop-up