8

44 Chapter 17: Rendering
Character lit by skylight and one spotlight, and rendered
with light tracing.
Model by Sonny Sy — [e-mail] —
www.geocities.com/orange_3D
The Lig ht Tracer provides soft-edged shadows
and color bleeding for brightly-lit scenes such as
outdoor scenes. Unlike
radiosity (page 3–50) ,the
LightTracerdoesnotattempttocreateaphysically
accurate mo del, and can be easier to set up.
Outdoor scene lit by skylight a n d re ndered with light
tracing.
Tip: Indoor scenes can use light tracing, but
radiosityisusuallythebetterchoiceforindoors.
Pr evi ewin g the Ef fect o f Light Tracing
• To get a quick preview of the effect the
Light Tracer wil l have, lower the values of
Rays/Sample and Filter Size.
Theresultwillbeaverygrainyversionofthe
full effect.
• Another way to get a quick preview is to make
sure Adaptive Undersampling is turned on. In
this group, set Initial Sample Spacing equal to
SubdivideDownTo.IntheGeneralSettings
group, lower the va lue of Rays/Sample, a nd
set B ounces equal to 0.0. This gives a rather
blotchy but fast preview of the rendering.
Increase Rays/Sample and Filter Size to improve
the image quality.
In general, you can get good, fairly quick results
w ith a lower Filter Size as long as Rays/Sample
has a high value and Adaptive Undersampling
is turned on.