Architectural_Design_with_SketchUp

Architectural Design with SketchUp
reflect in the material, it is usually okay to ignore reflectivity for that material. But this very
much depends on your scene, and you need to evaluate this need on a case-by-case basis.
Figure 5.69: Comparison of flat and reflective floor materials
TIP
You can sometimes cut down on rendering time if you don’t assign reflective properties to
a material but rather use a subtle gradient for that material (which simulates a soft reflection).
You must make sure it works with lighting and the general environment, however.
If your rendering software allows you to do this, consider adding a specular map to the
material. This is similar to the bump map (discussed later) and is a grayscale image. When
added to a shiny material, the grayscale values in the image determine the shininess distribution
of your material (the darker it is, the shinier it will be).
Refraction
When you have transparent materials in your scene (such as glass, water, or gems), it can be
important that these materials have realistic refraction properties. As mentioned, refraction
refers to how light direction changes when it travels through a material. In reality, you likely
have observed this—imagine holding a straight stick into a swimming pool, and notice how
the lower part of the stick looks as though it is bent (see rendering in Figure 5.70). You can
also see this behavior when you look at a thick glass or a prism from an angle.
Especially when your glass object has an observable thickness, it is important to include
realistic refraction properties. This is the case when you model a glass vase or water in a
swimming pool. Having said this, it is often not important to add refraction to architectural
uses of glass. Windows can usually be modeled only with a transparent texture—as long as
their reflection properties are accurate. Refractive glass would actually increase rendering
time too much without adding much visual benefit.
Table 5.1 shows some refractive indices for various media. Use these as a guideline if
your rendering software gives you the option to enter them for a material.
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