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49Cinema 4D Renderer
3. Quick Tutorial: Global Illumination
Light as we know it in the real world spreads on its own. It is reflected by the objects it hits. This differs depending
on an object’s surface characteristics. Imagine a room with a window on one wall. Light is being cast through the
window onto the floor of the room. The light doesn’t stop there, but is reflected from the floor onto other objects
which, in turn, reflect the light themselves. The room is lit by diffused (indirect) light.
The raytracing procedure does not take into account diffused light. For example, if only one light is used, eve-
rything lying in the shadows will not be visible. Maybe you have already built a virtual room into which a light
source is shining through a hole in the wall. The light in the virtual world hits an object, lights it – and that’s it. The
light spreads no further. Global Illumination rendering is different. Global Illumination rendering lets every object
within the scene act as a light source. As you will see, you can actually light a Global Illumination scene without
using a single light! Open a new (empty) file. Create a sky object (Create/Environment/Sky) and a floor object
(Create/Environment/Floor). The sky object encompasses the entire scene like a large sphere. The floor surface is
an infinite surface. Create a Torus (Create/Object/Torus) and move it to a y-position of 100, slightly above the floor.
Now we will light the scene with diffused light using Global Illumination rendering. We will use our sky object as
the light source. Switch to the Material Manager. Create a new material (Create/New Material; alternatively you can
simply double-click on the Material Manager’s gray field). Switch to basic in the Attribute Manager. Deactivate color
and reflectance and activate luminance. Drag the material from the Material Manager onto the sky object in the
Object Manager.