Page 602 - Kitab3DsMax

Part IV: Materials, Cameras, and Lighting Basics

TABLE 20.2
Photometric Light Colors

Light Type Color
Cool White Yellow-white
Custom Any color
D65White White
Daylight Fluorescent Mostly white with a slight gray tint
Fluorescent Yellow-white
Halogen Beige-white
High-Pressure Sodium Tan
Incandescent Beige-white
Low Pressure Sodium Light orange
Mercury Green-white
Metal Halide Yellow-white
Phosphor Mercury Light green
Quartz Yellow-white
White Fluorescent Yellow-white
Xenon White

In addition to a list of available light types, you can specify a color based on temperature expressed in
degrees Kelvin. Temperature-based colors run from a cool 1,000 degrees, which is a mauve-pink color,
through light yellow and white (at 6,000 degrees Kelvin) to a hot light blue at 20,000 degrees Kelvin.
Typical indoor lighting is fairly low on the Kelvin scale at around 3,300 degrees K. Direct sunlight is around
5,500 degrees K. Thunderbolts, arc welders, and electric bolts run much hotter, from 10,000 to 20,000
degrees Kelvin.
You also can set a Filter Color using the color swatch found in this section. The Filter Color simulates the
color caused by colored cellophane placed in front of the light.
Intensity and Attenuation options
The Intensity options can be specified in Lumens, Candelas, or Lux at a given distance. Light manufacturers
have this information available. You also can specify a Multiplier value, which determines how effective the
light is. There is also a setting for specifying the intensity due to a dimming effect, and the Incandescent
lamp color shift when dimming option causes the light from an incandescent light to turn more yellow as it
is dimmed. This effect is common as you get farther from a light bulb.
All real-world lights have attenuation, and Far attenuation values also can be set for photometric lights. This
helps to speed up rendering times for scenes with lots of lights by limiting the extent of the cast light rays.
Light shapes
In addition to the distribution type, you can also select the light shape, which has an impact on how shadows
are cast in the scene. 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 with sharper shadows, and lights covering a larger
area are less intense and have softer shadows. The available photometric light shapes include the following:

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