Basics of lighing a 3D set.
by Andrew Weiler
than any other aspect of 3D design and animation, what can really
make or break a scene is the lighting. It's not surprising that
many proffesional CG lighting directors (often referred to as
the "TD" for Technical Director) come from traditional
film and fine arts backgrounds, the ability to apply real-world
solutions and effects to the digital stage is the key effective
CG lighting involves a lot of "cheats", because software
is unable to calculate the multitude of subtle shading, coloration,
and reflection effects produced in the real world. My office,
for example, is lit by one window and a torchier lamp. The majority
of the lighting I use for reading and working is not directly
from these sources, but diffused light boucing off the walls
and ceiling. If my office were reproduced in 3D software I would
be unable to light it realistically using only two light sources,
because the renderer would only reproduce the direct illumination.
For example, to reproduce the effect of bounce-light coming
off my blue carpet onto the white walls I would need to place
a a blue-colored light under the floor facing up toward the
walls with a sharp falloff value. The same method would be used
to simulate the light bouncing off the ceiling from the torchier
lamp. Don't feel constrained by what's "real", remember
that if it looks right it is right.
Another key is
pre-planning. If you know the mood and feel you're trying to
achieve things will proceed much more smoothly than throwing
a few lights into the scene and trying to tweak it till it looks
good. A good foundation to start from is using the three-point
lighting method: key light, separation, and fill. The key light
is your main light source, usually set off to one side. Separation
light is important in that it provides highlights along the
edges of your subject to "separate" it from the background.
Fill light is usually a softer, more diffused light than the
key, use it to soften the shadows and fill in areas opposite
Try to get an even
distribution of light, but allow for some breakup to give depth
and scale. Also make sure your lights are not all the same color.
In daylight scenes the key light is usually yellow, bounce light
more toward orange, and fill is blueish. Many 3D sofware packages
allow for an "ambient" intensity, this has to do with
the level of light independent of any light souce. Although
useful for quick render tests, ambient intensity should be set
very low or to 0 in most cases; having no origination point
it will tend to make things look brittle and plastic.
Figure 1 is an image taken from a recent project I completed,
figure 2 shows an overhead view of how the lighting was arranged.
Notice the point lights arrayed around the subject, these are
non shadow-casting lights that only serve to provide specular
highlights to the subject. The fill light is also non-shadow
casting. The area light placed above the subject serves to provide
separation, as well as soft shadowing.
In conclusion my
advice to improving your lighting skills is to keep experimenting,
and keep your eyes open for day-to-day observation. Like Monet's
various paintings of the Rouen Catherdral, the treatment of
light and shadow has everything to do with the expression or
emotion you're trying to portray, so make sure your lighting
serves your subject.
Weiler is a CG artist and technical director working in
the Atlanta, Georgia area. When not producing animation, graphics
and effects for companies like Bellsouth, AT&T, and GE you'll
probably find him juggling his kids around, and trying to get