INSIDE 3DS MAX® 7 [Electronic resources] نسخه متنی

Light Types

3ds max contains an array of light types that can fulfill nearly every conceivable need. Basic Standard lights will cast illumination in specific (or all) directions, with no reference to a bounced light or special rendering conditions. There are two light types to be used specifically with the mental ray renderer and a light type that simulates an overall lighting environment. Several photometric light types are included with max's radiosity renderer to generate the effects of bounced light from real-world light fixtures, such as a 60-watt incandescent bulb or an industrial fluorescent strip. There are even systems that can tie a light into the location, date, and time of your scenes to simulate the sun's location at specific times. These are great tools for creating light-and-shadow studies.

Standard Lights

The standard light types offered in max 7 are much the same as in previous versions.

• Omni light
  Also called point lights in some CG programs, omnis have no volume and radiate light in all directions equally.

• Spotlight (target and free)
  A spotlight represents a conical section of an omni light and focuses that beam in a single direction. Target spotlights are composed of two parts, the light that casts the illumination and the target toward which the light will always be oriented. A free spot is controlled with the Rotate transform or by parenting it to another object.

• Directional light (target and free)
  Like a spotlight, a directional light represents a beam of light aimed in a single direction. However, instead of emanating from a point, the beam in a directional light is cylindrical or rectangular, with parallel light rays. This results in a shadow that may elongate, depending on its angle to the objects, but won't spread out as the distance increases. Use a directional light to simulate sunlight.

• Skylight
  Skylights represent the overall lighting in a daytime outdoor scene where the atmosphere has diffused the sun's light. A skylight's location is unimportant, as its effect will be similar to the illumination cast by a dome of lights from above your scene.

• mr area omni and mr area spot
  These lights are intended to work with the mental ray renderer. Each represents light emitted from a volume of space shaped like a sphere or cylinder (mr area omni) or like a rectangle or disk (mr area spot). To learn more about the power of mental ray, please refer to the 3ds max 7 User Reference.

Note

Once a light is created, you're not restricted to using only that light type's parameters. With the light selected, go to the Modify panel, and in the Light Type section of the General Parameters rollout, expand the drop-down list; then choose another light, which will convert your selected light. Spot and directional lights can be switched between targeted and free versions in the same section. Be aware that the name of a light does not automatically change when you converted its typeOmni01 will still be Omni01 even after you change it into a targeted spotlight (Figure 12.7). Figure 12.7. Changing a light's type in the Modify panel.

Photometric Lights

You don't have to guess at the brightness of a light as it affects your scene. Using photometric lights allows you to represent the physical effects of actual light fixtures, including color, distribution, and intensity. It's a snap to change a light source from fluorescent to incandescent or xenon, simply by picking from the Color section of the lights' Intensity/Color/Distribution rollout. An Isotropic distribution emits light in all directions equally. A Spotlight distribution projects the light in a specific direction. For architectural scenes, the true power of photometric lights resides in the Web distribution method. Web distribution allows you to point to a file (.ies, .cibse, or .ltli) that follows a photometric format specified by one of the three major lighting industry associations. These are provided for free download by most larger lighting manufacturers. A Web file for a particular fixture allows max to simulate that fixture's light dissemination exactly as the manufacturer designed it. Two sources for Web files are: http://www.gelighting.com/na/specoem/iesdownloads and http://www.hadcolighting.com/ies_agree

The following are the 3ds max 7 photometric light types:

• Point light (target and free)
  Like a Standard omni light or spotlight, a point light emits its energy from a single point in space, but its distribution can be set to Isotropic (like an omni), Spot (like a spotlight), or Web (to match a real-world fixture).

• Linear light (target and free)
  Unlike a point light, a linear light emanates illumination evenly along a line centered on the light source, using Diffuse distribution.

• Area light (target and free)
  An area light produces light from a plane centered on the light source.

  Figure 12.8 shows the three photometric lights with either Isotropic or Diffuse distribution.

  Figure 12.8. A point light (left) with Isotropic distribution; a linear light (center) and an area light (right), both with Diffuse distribution.