Architectural_Design_with_SketchUp

Architectural Design with SketchUp
Emittance
This material feature was already partly covered in the lighting section. What emittance can
add to a material is its behavior of being a light source. This is most useful for aerial light
sources such as neon lights and light boxes. It is also a good way to add lighting to display (or
advertisement) boxes and television screens in your model. In those cases, it is also important
that an appropriate texture is applied to the material, in addition to it being a light emitter.
You can see this in Figure 5.75. The “Stand Up!” text at the back wall is a neon-backlit
sign that features the image of an evening sky as its texture. It was modeled using SketchUp’s
3D text tool and by applying the light-emitting texture only to the front faces. Side faces
and back faces of the text were left as is, which gives it the appearance (and shadows) of a
display box.
In contrast, the light globes in the back corners are plain 3D spheres that have a white
light-emitting texture painted on their entire surface.
Figure 5.75: Emitting materials used for light globes and text-logo display
Some rendering software allows you to add a physical light property to a material, such
as 100 W/m 2 illumination. Even if this is offered, it is often necessary to try out various settings
until scene illumination looks just right.
TIP
Remember that the number of faces that have light-emitting materials applied to them
directly influences rendering time. Try to keep those faces as simple and as few as possible.
Subsurface Scattering
Beyond materials that are opaque and fully reflect light and materials that are transparent
and therefore let light pass through, there are some materials that let light filter through the
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