8

1208 Chapter 15: Lights and Cameras
meshes.IfBiasistoohigh,shadowscan"detach"
from an object. If the Bias va lue is too extreme in
either direction, shadows mi ght not b e rendered
at all.
2-Sided Sha dows—When on, backfaces are not
ignored when calculating shadows. Objects seen
fromtheinsidearenotlitbylightsfromthe
outside. This costs a bit more render time. When
off,backfacesareignored.Renderingisquicker,
but outside lights illuminate object interiors.
Default=on.
Thefacesinsidetheslicedspheredonotcastshadowsif
2-Sided Shadows is not s elected.
Max Quadtree Depth—Adjusts t he depth of the
quadtree (p age 3–1093) used by the ray-tracer.
Greater quadtree depth values can improve
ray-tracing time at the cost of memory use.
However, there is a depth value where the
performanceimprovementisoffsetbythetimeit
takes to generate the quadtree itself. This depends
on the geometry of the scene. Default=7.
Tip: Omni lig hts can generate up to six quadtrees,
so they generate ray-traced shadows more slowly
than spotlig hts. Avoid using ray-traced shadows
w ith omni lights unless your scene requires this.
Shadow Map Parameters Rollout
Create a light. > General Parameters rollout > Shadow
Map chosen > Shadow Map Params rollout
The Shadow Map Parameters rollout is displayed
when you have chosen shadow mapping as the
shadow-generation technique for a light. You
select this in the
General Parameters rollout (page
2–1175)
.
Shadow Maps and Intersecting Sur faces
In 3ds Max 2.5 and earlier versions, shadows
cast onto one surface tended to "bleed" onto
edges intersecting surfaces. Since 3ds Max 3,
shadows cast onto one surface do not bleed onto
intersect ing surfaces. If you want, you can change
the shadow map setting to render shadows the way
2.5 and previous versions did. To do so, find the
R25Shadows entry in the [Renderer] section of the
3dsmax.ini file,changethevalueto1,andthen
restart 3ds Max:
R25Shadows=1
To revert to the default method of rendering
shadow-mapped shadows, in the
3dsmax.ini file,
change the value of R25Shadows back to 0 (zero),
and then restart 3ds Max.
Interfa ce
Bias— Map Bias (page 3–1060) moves the shadow
toward or away from the shadow-casting object
(or objects).