Architectural_Design_with_SketchUp

Chapter 5 Rendering in SketchUp
Figure 5.46: Setup with added light source in front of model
Attenuation
Any light (except IES lights) that you add to a 3D scene has a property called attenuation, which
relates to the way light particles lose intensity the farther they travel from the light source. In
reality, you likely have already observed this phenomenon. Just imagine looking down a street
at night—the streetlights closest to you usually look brighter than the ones farther away.
Figure 5.47 illustrates this phenomenon and the various settings, using three spotlights.
The top spotlight in the figure shows no light attenuation at all. As a result, the spotlight is
as bright on the right as it is on the left—the only reduction in intensity comes from a “flaring”
of the light.
The bottom two spotlights exhibit light attenuation—the middle one uses a linear model
and the one on the bottom a squared one. These two look more realistic simply because of
this property. It is therefore usually a good idea to use light attenuation for your light sources.
If you want your rendering to closely resemble reality, opt for the inverse squared method.
Figure 5.47: Light attenuation in spotlights (top: none;
middle: inverse linear; bottom: inverse squared)
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