Introducing 3ds Max 9 3D for beginners apr 2007 - part 9 pps

Omni lights are good for fill lights as well as for simulating certain practical light sources

that have a brighter center and falloff evenly around that bright spot in all three axes. You

could even use Omni lights for all three points in your three-point lighting system, as seen

here on the fruit still life scene. The scene has a nice soft feel.

Skylight

Skylight is a special 3ds Max light used with a special rendering method to quickly generate

a scene rendered in a soft outdoor light. We will not be covering this more advanced light￾ing and rendering methodology; however, here is a quick introduction to the light itself.

Try to avoid casting shadows with Omni lights because they will use a lot more memory than

a spotlight casting shadows.

Figure 10.19

An Omni light lights

the sphere and floor.

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Figure 10.20 shows a skylight high above the scene with the three spheres. It is created

by simply selecting the Skylight button in the Create panel and clicking to place it in a

viewport. The skylight’s Skylight Parameters rollout is shown here.

The skylight is used to create a soft, global lighting to simulate light from the sky. This

look is often seen with renders using Global Illumination or Radiosity. In these lighting/

rendering solutions, the skylight creates a sky dome that sits around the objects in the

scene. Light is emitted, essentially, from the entire surface area of the dome to cast an even

light throughout the scene, much as a sky lights an outdoor area.

The rendering of a Skylight scene, as shown in Figure 10.21, is flat and bright. There is

no definition because shadows are not enabled. Turning on shadows gives you a beautiful

render, as seen in Figure 10.22, with soft shadows and contact shadows that really make

the spheres look as if they are sitting outside on an afternoon day.

Figure 10.22

Turning shadows on for the skylight dramatically

increases render times, but it gives a nice effect with

soft shadows mimicking a radiosity effect.

Figure 10.21

The skylight flattens out the spheres and blows

them out.

Figure 10.20

A skylight placed over the spheres and

ground plane

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The render time for this frame, however, is significantly longer than any of the other

renders so far in this chapter. Calculating soft light such as this is quite intensive, unless a

lighting plug-in such as Light Tracer is enabled in the render setup.

Common Light Parameters

Most of the parameters for the Standard lights are the same for all the lights and will be

described in this section. You may want to create a spot or directional light so you can

follow along with the information about light parameters given here.

General Parameters Rollout

The General Parameters rollout for all the Standard lights (except for skylight) is shown in

Figure 10.23. In the Light Type section, you can change the type of light that is currently

selected. Simply choose the type (Spot, Directional, Omni) from the drop-down menu.

3ds Max will replace the light with the new light type; it won’t change its position or orien￾tation. This can be immensely helpful when you are deciding which light will work best

for a scene. Otherwise, you would have to delete and re-create lights to find the solution

that best suited your scene best.

You can turn a Free Spot or Free Directional to a target of the same kind by simply

checking the Targeted check box. Of course, the On check box controls whether the light

is on or off in the scene.

In the Shadows section of the General Parameters rollout for these lights, you will find

the controls for the shadow casting properties of the selected light. Use the drop-down

menu to select the type of shadows to cast. The two most frequently used shadow types,

Shadow Map and Ray Traced, are discussed later in the chapter.

The Use Global Settings toggle can be very useful. When it is turned on, all of the

lights in your scene will be set to use the same Shadow Parameters of the light you have

selected and for which you have enabled Use Global Settings. This is useful in the event

you need the same type of shadows cast from all the lights in the scene. It can save you

the hassle of specifying the settings for all the lights. It does, however, limit you to the

same shadow settings for all the lights. While you are learning, you should leave Use

Global Settings off and set each light manually as needed. Again, shadows are covered a

little later in this chapter.

The Skylight light is not intended to be used without some other light source(s) in the

scene. It is designed to be used only with Radiosity, Light Tracer, or mental ray rendering

techniques. As these techniques are more advanced, they will not be covered in this book.

It is important to learn traditional lighting and rendering methods before moving into

advanced techniques.

common light parameters ■ 425

Figure 10.23

The General Para￾meters rollout for all

the Standard lights

is the same.

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Intensity/Color/Attenuation Rollout

The Intensity/Color/Attenuation rollout, shown in Figure 10.24, is used to adjust your

light’s brightness and color settings.

Light Intensity

The Multiplier parameter works like a dimmer switch for a light. The higher the value is,

the brighter the light will be. The Multiplier can go into negative values. A negative amount

will subtract light from your scene, allowing you to create dark areas within lit areas or to

remove excess light from a surface that has unwanted spill light.

Light Color

The Color Swatch next to the Multiplier is used to add color to your light. Simply click on

the color swatch to open the Color Selector. The darker the color, the darker the light.

Light Decay

Under the Decay section, you can set the way your light fades out across distance. This is

not the same as falloff with spots and directional lights, though. Falloff occurs on the sides

of a hotspot, whereas decay happens along the path of the light as it travels away from the

light. Figure 10.25 shows a light with no decay type set. Figure 10.26 shows the same light

with its decay Type set to Inverse Decay. Figure 10.27 shows the same light with decay

Type set to Inverse Square Decay. Notice the decay rate increases with each successive

figure.

If no decay is set for a light, its intensity remains at full strength from the light to infin￾ity. An Inverse Decay diminishes the intensity of the illumination over distance traveled

according to some brainy formula. An Inverse Square Decay more closely resembles the

Figure 10.26

A light with Inverse Decay illuminates the back numbers less.

Figure 10.25

A light with no decay illuminates all the numbers evenly.

426 ■ chapter 10: 3ds Max Lighting

Figure 10.24

The Intensity/

Color/Attenuation

rollout

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decay of real world light, and it is a stronger rate of decay than Inverse Decay. Use this decay

rate to drop off the effect of a light quickly before it reaches too far into the scene; however,

you will need a stronger Multiplier value to increase your light’s intensity to compensate

for the much faster decay.

In Figure 10.28, you can quickly see and set the start of a decay in spot and directional

lights by changing the Start value in the Decay section of the rollout. In the following

images, you can see a decay start that is closer to the light and its effect on the render in

the top-left corner, while the start of the decay is moved closer to the spheres in the image

on the right.

Light Attenuation

Light attenuation is another way to diminish the intensity of a light over distance. With

attenuation, however, you have more implicit control on the start and end of the fade, and

you can specify an area where the light fades in and then fades out. You simply set the

Attenuation distances to the desired effect.

Figure 10.28

Seeing the start of a light’s decay helps you see how it

will illuminate your scene.

Figure 10.27

A light with Inverse Square Decay illuminates the first two num￾bers and begins to lose the remaining three.

Decay Start Gizmo

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