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 to 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 is positioned above and to the left, and the bottom light is positioned below and to the right.

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. You can open this dialog box by choosing Customize image from book Viewport Configuration or by right-clicking the viewport title and selecting Configuration from the pop-up menu.

If you want to access the default lights in your scene, you can use the Views image from book Add Default Lights to Scene command to convert the default lights into actual light objects that you can control and reposition. This feature lets you start with the default lights and modify them as needed.

Caution 

The View image from book Add Default Lights to Scene menu command is enabled only if the Default Lighting and 2 Lights options are selected in the Viewport Configuration dialog box.

Ambient light

Ambient light is general lighting that uniformly illuminates the entire scene. It is caused by light that bounces off other objects. Using the Environment dialog box, you can set the ambient light color. You can also set the default ambient light color in the Rendering panel of the Preference Settings dialog box. This is the darkest color that can appear in the scene, generally in the shadows.

In addition to these global ambient settings, each material can have an ambient color selected in the Material Editor.

Caution 

Don't rely on ambient light to fill in unlit sections of your scene. If you use a heavy dose of ambient light instead of placing secondary lights, your scene objects appear flat, and you won't get the needed contrast to make your objects stand out.

Standard lights

Within the Create panel, the available lights are split into two subcategories: Standard and Photometric. Each subcategory has its own unique set of properties. The Standard light types include Omni, Spot and Direct (Spot and Free), Skylight, and two area lights (Spot and Omni) that work with mental ray.

Omni light

The Omni light is like a lightbulb: It casts light rays in all directions. The two default lights are Omni lights.

Spotlight

Spotlights are directional: They can be pointed and sized. The two spotlights available in Max are a Target Spot and a Free Spot. A Target Spot light consists of a light object and a target marker at which the spotlight points. A Free Spot light has no target, which enables it to be rotated in any direction using the Select and Rotate transform button. Spotlights always are displayed in the viewport as a cone with the light positioned at the cone apex.

CROSS-REF 

Both Target Spot and Target Direct lights are very similar in functionality to the Target Camera object, which you learn about in Chapter 26, "Configuring Cameras."

Direct light

Direct lights cast parallel light rays in a single direction, like the sun. Just like spotlights, direct lights come in two types: a Target Direct light and a Free Direct light. The position of the Target Direct light always points toward the target, which you can move within the scene using the Select and Move button. A Free Direct light can be rotated to determine where it points. Direct lights are always displayed in the viewport as cylinders.

Skylight

The Skylight is like a controllable ambient light. You can move it about the scene just like the other lights, and you can select to use the Scene Environment settings or select a Sky Color.

Area Omni and Area Spot

The Area lights project light from a defined area instead of from a single point. This has the effect of casting light along a wider area with more cumulative intensity that a point light source. Area lights are supported only by the mental ray renderer. If you use the Scanline renderer, these lights behave like simple point lights.

The Area Omni light lets you set its shape as a Sphere or a Cylinder in the Area Light Parameters rollout. Area Spot lights can be set to be either Rectangular or Disc-shaped. Be aware that area lights can take significantly longer to render than point lights.

CROSS-REF 

For more details on the mental ray renderer, see Chapter 45, "Raytracing and mental ray."

Photometric lights

The standard Max lights rely on parameters like Multiplier, Decay, and Attenuation, but the last time I was in the hardware store looking for a lightbulb with a 2.5 Multiplier value, I was disappointed. Lights in the real world have their own set of measurements that define the type of light that is produced. Photometric lights are lights that are based on real-world light measurement values such as Intensity in Lumens and temperatures in degrees Kelvin.

If you select the Lights menu or the Lights category in the Create panel, you'll notice another subcategory called Photometric. Photometric lights are based on photometric values, which are the values of light energy. The lights found in this subcategory include Point, Linear, and Area (both Free and Target), and IES and mental ray Sun and Sky.

Target and Free photometric lights

Target photometric lights come in three shapes-Point, Linear, and Area. Selecting a different-shaped light causes the light to be spread over a wider area, so in most cases, the Point light results in the brightest intensity. Figure 27.4 shows the three different shapes. The General Parameters rollout in the Modify panel includes a drop-down list that you can use to change the light shape and specify whether it is targeted.

image from book
Figure 27.4: Photometric lights can be Point, Linear, or Area (left to right).

The gizmo for point photometric lights is a simple sphere, the gizmo for linear lights is a sphere and a line, and the gizmo for area lights is a sphere and a rectangle. For targeted lights, the target extends from the gizmo to the target. The dimensions for the light are in the Linear (Area) Light Parameters rollout.

Sun and Sky photometric lights

The Photometric light subcategory also includes additional light types: Sky and Sun. The IES Sky light simulates ambient light. In the Sky Parameters rollout, you can specify the sky as Clear, Partly Cloudy, or Cloudy. These same parameters are found in the Daylight system.

The IES Sun light simulates the bright outdoor light of the sun. It is a single light with a great deal of power. It can be targeted and can have an Intensity value of 50 billion lux. This type of light is very valuable in architecture renderings.

Sun and Sky lights also are available for mental ray. These mental ray lights have several additional settings. The mental ray Sun and Sky lights are typically used in conjunction with the Daylight system.




3ds Max 9 Bible
3ds Max 9 Bible
ISBN: 0470100893
EAN: 2147483647
Year: 2007
Pages: 383

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