Graphics Reference
In-Depth Information
of the Properties window. It is enabled by checking the
box next to the panel's title: Environment Lighting. Blender
uses two different methods of calculating this lighting: ray
tracing and approximate. The selector for which type to use
is found on the
Gather
panel. “Gather” is a term taken
from the backend processes of global illumination and envi-
ronment lighting.
Ray-Based Gathering
Ray-traced environment lighting can be pretty much fire
and forget. You turn it on, the defaults are decent, and your
render looks ten times better. In
Figure 5.17
, ray-traced
environment lighting has been selected. The three main
controls you should be concerned with are
Distance,
Samples
(found on the Gather panel), and
Energy
(found
on the Environment Lighting panel).
The Distance value tells the renderer how far away from a
surface it should look for another surface before giving up.
If it runs into nothing at all, then that point on the surface
is considered fully illuminated. If it
does
run into something,
though, how close it is determines how much illumination
is taken away. So, by setting the Distance value, you deter-
mine how much light is put into tight spaces.
The best way to decide how to use this is to ask yourself,
“In my scene, which two objects are the farthest apart, yet
should still affect each other?” If we were to take the sample
scene outdoors (i.e., removing the room), we would want
the chair and the table to still affect each other. A quick
measurement in the 3D view (by grabbing the table, moving
it on top of the chair, and noting the total distance moved on the header) shows that they are about 3.1
units apart. So, a Distance value of 3.1 is in order.
Figure 5.17
Ray-traced environment lighting controls.
Samples
controls the amount of graininess. If you do a render with Samples at 1, the result will be noisy,
as you can see on the top portion of
Figure 5.18
. Samples cranked up to 32 (the maximum) creates a
nicely smoothed result. The difference in render times is significant, though. Using ray-traced environment
lighting at high sample levels will drastically increase your render times. If you're just using it to provide
some underlying shading in a scene though, you can get away with lower values. The best general method
of sampling is
Adaptive QMC
(Quasi-Monte Carlo sampling).
Energy
controls the overall level of the effect. Higher values (over 2.0) will quickly blow every detail
out of a scene. When working with environment lighting as a basis for an overall lighting scheme,
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