Graphics Reference
In-Depth Information
Original pixel
position to be
composited
Actual pixel
position to be
composited
→→
Environment
map
n
n
bent
p
Figure 7.15
The ambient light at
P
comes from the ambient environment map, but from the direction
of a “bent normal” that represents the average direction of incident ambient light. Using
the bent normal instead of the surface normal also helps soften shadows.
The invention of ambient occlusion maps significantly increased the applica-
bility of image-based lighting, and contributed to the widespread use of IBL in
production rendering. It is not an exaggeration to say that IBL would not have be-
come so popular in the entertainment field without ambient occlusion maps. Since
2008 however, rendering directly with ray tracing has become more prevalent in
Hollywood movie production. This is a result of improvements in computing
power and also a push for more realism. ILM developed a new physically based
rendering pipeline for the film
Terminator Salvation
(2009), and since then, the
use of ambient occlusion maps and some other IBL techniques have been replaced
with more physically accurate ray-tracing methods. Nonetheless, ambient occlu-
sion maps still have their place, as does image-based lighting in general. Both
offer freedom and flexibility and apply to a wide variety of visual expressions. In
tandem with the progress of GPU computation, it is expected that IBL will enter
into a new stage in the entertainment industry.
