Chapter 17 Lighting
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Normally, lights do not appear in the rendered scene at all, only the illumination
provided by the lights. The settings in the
Sun disk appearance
subcategory control
what the sun looks like in the sky, or on the background. The
Disk scale
property sets
the size of the sun, or solar disk, as it appears on the background. The default value is
4.0000 and values can range from 0.0000 to 25.0000. The
Glow intensity
property deter-
mines the size of the glowing halo around the sun in the sky. The default value is
1.0000 and values can range from 0.0000 to 25.0000. The
Disk intensity
property controls
the brightness of the sun on the background. The default value is 1.0000 and values can
range from 0.0000 to 25.0000.
PROFESSIONAL TIP PROFESSIONAL TIP
The sky at night is always lighter than the Earth unless there are other
light sources in the scene, such as streetlamps.
Sun Angle Calculator
The settings in the
Sun Angle Calculator
category determine the angle of the sun
in relationship to the XY plane. The
Date
and
Time
properties, discussed earlier, can
be controlled from the
Sun & Location
panel on the
Render
tab of the ribbon. The
Daylight Saving
property is used to turn daylight saving on or off. The Azimuth, Altitude,
and
Source Vector
properties display the current settings, but are read-only in the
Sun Properties
palette. These settings represent the location of the sun in the sky.
Their values are automatically calculated based on the geographic location settings,
discussed earlier, and the
Date
and
Time
properties.
Rendered Shadow Details
The
Type
property in the
Rendered Shadow Details
category determines the type
of shadow cast by the sun, if shadows are cast. When the property is set to Sharp,
raytraced shadows are cast. These shadows have sharp edges. Raytracing produces
accurate shadows, but rendering may take longer. When the property is set to either
Soft (mapped)
or
Soft
(area), shadow-mapped shadows are cast. These shadows have
soft edges. Shadow-mapped shadows may be calculated more quickly than raytraced
shadows, but the resulting shadows are less precise. In addition, soft shadows do not
work with transparent surfaces like windows. When the
Type
property is set to
Soft
(mapped), two additional settings are available in the category:
•
Map
Size. This property determines the number of subdivisions, or samples,
used to create the shadow. By default, shadow maps are 256 × 256 pixels in size.
If shadows look grainy, increasing this setting will make them look better.
• Softness. This property determines the sharpness of the shadow’s edge. The value
ranges from 1 to 10. A higher value results in softer (less sharp) shadow edges.
When the
Type
property is set to
Soft
(area), two additional settings are available:
• Samples. This property sets the number of samples used on the solar disk. The
value can be from 0.0000 to 1000.0000.
• Softness. This property determines the sharpness of the shadow’s edge, as
described for the
Soft (mapped)
type.
When the
Type
property is set to Sharp, the other settings are read-only and not applied.
NOTE NOTE
With photometric lighting on (LIGHTINGUNITS =
1
or 2), only the
Soft
(area)
selection is available in the
Type
property drop-down list.