Architectural_Design_with_SketchUp

Chapter 5 Rendering in SketchUp
Figure 5.59 shows an example of this approach. In this rendering, the model of a compact
fluorescent lightbulb (CFL) was used as the sole light source in the scene. The faces that
make up the light tubes were assigned a light-emitting material.
Figure 5.59: Model of a CF lightbulb with light-emitting material illumination
Although this approach is quite easy to implement and
the resulting light is very even and scattered, keep in mind
that rendering time is affected by using light-emitting materials.
It is generally a good idea to keep to a minimum the
triangle count of the faces to which this material is applied.
Use this material preferably on triangular and rectangular
faces, rather than circular or irregularly shaped faces.
When you use light-emitting surfaces, it is often possible
to apply an image to the surface—some material properties,
such as texture, also work for a light-emitting material.
Figure 5.60 uses an image of a plain 4f drop-ceiling light
fixture as a texture on a single rectangular face to not only
illuminate the scene but also give the light the appearance
of two neon light tubes behind a frosted glass cover. This
eliminated the need for actually placing light-emitting surfaces
(representing the neon tubes) behind a frosted-glass material,
which would likely have significantly increased rendering time.
Figure 5.60: Using an image texture as a light-emitting surface
(left: rendering; right: photo of neon light fixture)
If your rendering software provides different rendering methods, it may be more efficient
to render scenes with light-emitting materials using an unbiased renderer (e.g., MLT)
rather than a photon-map GI renderer. This can vary with the software package, however.
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