Architectural_Design_with_SketchUp

Architectural Design with SketchUp
The best example to illustrate where we would use this might be a brick wall. In such a
wall, the mortar is slightly recessed from the surface of the bricks. Depending on where the
lighting comes from, we should see shadows in the mortar lines and highlights at the edges
of the bricks. If such a wall were textured with a simple photograph of bricks, then changing
light direction would not change the shadow appearance of the mortar lines, which would
lead to a flat-looking wall. A bump map remedies this by giving the rendering software information
where it needs to modify surface appearance so that the texture looks as though it
is flat or recessed. (See Figure 5.72.)
Figure 5.72: The same texture rendered without bump (left) and with bump (right)
Other examples where bump maps are appropriate are bevel siding, flooring, paving,
rough soil, and other textures where surface roughness creates gaps, creases, and depressions
of less than approximately 1g in depth. Figure 5.73 shows a classic case where material
bump should be used.
You can easily apply a bump map to any texture by providing a black-and-white image of
the map and applying it in your rendering software’s material editor (if the software supports
this). It is important to remember that the map image has to have the same pixel dimensions
as the texture image for both to align properly. During rendering, parts of the map that are
dark will appear to recede while white parts will stay at the material’s surface.
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Figure 5.73: Brick walls—a classic case where bump is warranted