An Integral part of setting up a scene is the addition of light
sources. These mimic the illumination created by equivalent real-world lights such as
incandescent bulbs, the sun's rays, spot lights, and ambient light. Note, however, that
these computer-generated light sources cannot be seen as is the case with their real-world
counterparts.
Four light types are provided by the NuGraf Toolkit: ambient, point,
directional and spot lights. These are illustrated in
the following diagram.
A technically advanced feature of the renderer is its ability to
cast shadows from the point, spot and directional light sources using a technique called
"depth map shadows" (as explained in the next section). Many rendering packages
are limited to casting shadows from spot light sources only (using the depth map shadows
technique) but the NuGraf renderers allow for shadows from directional lights using a
2-pass depth map technique and shadows from point light sources using a 6-pass technique.
In addition, the depth map algorithm has been tweaked over a number of years to produce
sharp-edged shadows which are quite important for architectural renderings. The NuGraf ray
trace renderer also allows sharp, ray traced shadows to be computed in addition to depth
map shadows.
