User Manual

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Generally, through trial and error, you’ll find a point of diminishing returns where increasing the
size of the shadow map no longer improves the quality of the shadow. It is not recommended to
set the size of the shadow maps any larger than they need to be.
The Shadow Map Proxy control is used to set a percentage by which the shadow map is scaled
for fast interactive previews, such as Autoproxy and LoQ renders. A value of .4, for example,
represents a 40% proxy.
Shadow Softness
By default, the spotlight generates shadows without soft edges, but there are options for
constant and variable soft shadows. Hard-edged shadows will render significantly faster than
either of the Soft Shadow options. Shadows without softness will generally appear aliased,
unless the shadow map size is large enough. In many cases, softness is used to hide the
aliasing rather than increasing the shadow map to preserve memory and avoid exceeding the
graphics hardware capabilities.
Soft Shadow controls in the Control panel.
Setting the spotlight’s shadow softness to None will render crisp and well-defined shadows.
The Constant option will generate shadows where the softness is uniform across the shadow,
regardless of the shadow’s distance from the casting geometry. The Variable option generates
shadows that become softer as they get farther from the geometry that is casting the shadow.
This is a more realistic effect, but the shadows are somewhat harder to control. When this
option is selected, additional controls for adjusting the falloff of the shadow will appear, as well
as sliders for the minimum and maximum softness.
Hard shadow cast by a spotlight.
Selecting the Variable option reveals the Spread, Min Softness, and Filter Size sliders. A side
effect of the method used to produce variable softness shadows is that the size of the blur
applied to the shadow map can become effectively infinite as the shadow’s distance from the
geometry increases. These controls are used to limit the shadow map by clipping the softness
calculation to a reasonable limit.
The filter size determines where this limit is applied. Increasing the filter size increases the
maximum possible softness of the shadow. Making this smaller can reduce render times but
may also limit the softness of the shadow or potentially even clip it. The value is a percentage of
the shadow map size.
For more information, see “Spotlight” in Chapter 30, “3D Light Nodes.
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