Page 603 - Kitab3DsMax

Chapter 20: Using Lights and Basic Lighting Techniques

l Point: This shape emits light from a single point like a light bulb.
l Line: This shape emits light from a straight line like a fluorescent tube.
l Rectangle: This shape emits light from an area like a bank of fluorescent lights.
l Disc: This shape emits light from a circular area like the light out of the top of a shaded lamp.
l Sphere: This shape emits light from a spherical shape like a Chinese lantern.
l Cylinder: This shape emits light from a cylindrical shape like some kinds of track lighting.
For each shape you can set the shape’s dimensions in the Shape/Area Shadows rollout. The rollout also lets
you switch between the different shapes. If you need to see the actual light shape, then you can enable the
Light Shape Visible in Rendering option in the Shape/Area Shadows rollout.

Using the Sunlight and Daylight Systems

The Sunlight and Daylight systems, accessed through the Systems category of the Create panel, create a
light that simulates the sun for a specific geographic location, date, time, and compass direction.

Note
The Daylight system can be created using the Create ➪ Lights menu or the Create ➪ Systems menu, but the Sunlight
system cannot be created using a menu. n

To create either of these systems, open the Create panel and click the Systems category button. Then click
the Sunlight (or Daylight) button, and drag the mouse in a viewport. A Compass helper object appears.
Click again to create a Direct light (or Skylight) representing the sun. Figure 20.11 shows the Compass
helper created as part of the Sunlight system. The main difference between these two systems is that the
Sunlight system uses a Directional light and the Daylight system uses the IES Sun and Sky lights.

Note
When you first create a Daylight system, a warning dialog box appears giving you the option to enable the
Logarithmic Exposure Control for external light. Clicking the Yes button makes this change for you automatically. n

Note
The Compass helper object’s orientation aligns with the ViewCube’s directions. n

Tip
The best results for the Daylight system are realized when you use the mr Sun and mr Sky options. Using the
Daylight system with these options also enables the mr Physical Sky environment settings. More on this system is
covered in Chapter 47, “Rendering with mental ray.” n
Using the Compass helper
The Compass helper is useful when working with a Sunlight system. It can be used to define the map direc-
tions of North, East, South, and West. The Sunlight system uses these directions to orient the system light.
This helper is not renderable and is created automatically when you define a sunlight object. The Compass
helper object is found in the Create ➪ Helpers menu.
After you create a Sunlight system, you can alter the point that the sun is pointing at by transforming the
Compass helper. Doing so causes the direct light object to move appropriately. The light’s position in the
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