2010

Table Of Contents
Render the scene using Global Illumination
To render using Global Illumination you need to turn on specific settings or
attributes. There are two areas that you must initially set.
Turn on the Global Illumination rendering attributes using the Render
Settings Window.
Turn on the Global Illumination lighting attributes using the Attribute
Editor.
You initially render the scene using the attributes at their default settings to
see how they affect the rendered image and then compare it to the previous
raytrace rendering. As you gain more experience rendering with Global
Illumination you will better understand what settings to initially use.
To turn on Global Illumination rendering attributes
1 Open the Render Settings window.
2 In the Render Settings window, click on the Quality tab and set the
Quality Presets setting to Preview: Global Illumination.
This turns on preset attribute settings that enable and control the quality
of the Global Illumination. You initially render the scene using the default
settings. Once youve rendered an image and observed their effect, you
return to the Render Settings window and modify the settings accordingly.
3 Close the Render Settings window.
Global Illumination uses photons to simulate the light inter-reflection effects
in a scene. Photons are small packets of energy emitted from a light source
into the scene that bounce off surfaces to determine the intensity of light for
those areas not receiving direct illumination. The renderer keeps track of the
illumination that results from this photon emission in a file called a photon
map.
In addition to having the spotlight emit light you need to set the spotlight to
also emit photons for the Global Illumination simulation to occur. The overall
illumination for the scene will be determined from a combination of the lights
intensity and photon illumination from this single spotlight.
508 | Chapter 9 Rendering