Chapter 17 Lighting
509
Copyright Goodheart-Willcox Co., Inc.
The
Map size
property determines the quality of the shadow. The value is the
number of samples used to create the shadow. The higher the setting, the better the
quality of the generated shadow. However, the higher the setting, the longer it will
take to render.
The value of the
Softness
property determines how soft the edge of the shadow
is. The higher the value, the softer or blurrier the edge of the shadow. A low value can
produce a very hard edge. The value can range from 1 to 10.
A variation of shadow-mapped shadows is created when the
Type
property is set
to
Soft
(sampled). In this case, different properties are displayed. The
Samples
prop-
erty determines the number of “rays” used to generate the shadows. However, this
is not considered raytracing. The
Visible in render
property determines whether the
shape of the light is rendered. The
Shape
property sets the shape of the light. For
spotlights, the shape can be either rectangular or circular (disk). For point lights and
weblights, the shape can be linear, rectangular, circular (disk), cylindrical, or spherical.
The remaining properties are based on the selected shape and are used to defi ne the
size of the shape.
NOTE NOTE
For standard shadow-mapped shadows to be created, the
Shadow map
property in the
Advanced Render Settings
palette must be set to On.
Advanced render settings are covered in the next chapter.
Raytrace Shadow Settings
A raytrace shadow is created by beams, or rays, from the light source. These rays
trace the path of light as they strike objects to create a shadow. Raytrace shadows have
a well-defi ned edge. They cannot be adjusted to produce a soft edge. Raytrace shadows
can be used with standard and photometric lighting.
All lights set to cast shadows, except those set for shadow-mapped shadows, cast
raytraced shadows. To switch from shadow-mapped shadows to raytrace shadows,
select the light object and open the
Properties
palette. In the
Rendered Shadow Details
category, set the
Type
property to Sharp. The other properties are disabled because they
only apply to shadow-mapped shadows.
NOTE NOTE
Turning on shadow casting will increase rendering time because of
the calculations that AutoCAD has to perform. It is diffi cult to deter-
mine if raytraced or shadow-mapped shadows will be quicker to
render because every scene is different and many variables come into
play. You will have to experiment with your scene to determine the
acceptable level of shadow detail versus rendering time.
Select the
type of shadow
Figure 17-22.
The
Rendered
Shadow Details
category in the
Properties
palette.