Architectural_Design_with_SketchUp

Architectural Design with SketchUp
computations in the graphics card itself (commonly called the GPU). In any case, the necessary
calculations typically are too slow to allow for real-time rendering at a high level of quality.
Therefore, whenever you set up a view for rendering, you will send it from SketchUp to the
rendering software and then wait for the rendering calculations to finish.
As you will see in the following sections, software is available that tightly integrates itself into
SketchUp and that will execute all of these steps without requiring you to move files between
different software. Some of the available programs are actually very fast (mainly because
they now use both the CPU and the GPU), which will give you near-instant feedback on the
rendered appearance once you apply a change (e.g., a material change or a camera move).
Before we look at rendering techniques, let’s quickly review how rendering works.
What Is Photorealistic Rendering?
In real life, a light source like the sun or a desk lamp emits light particles (photons) in either
a single direction, as is the case with a highly focused lamp or a laser, or radially in all directions,
as with the sun or an unshielded light bulb. Briefly ignoring Einstein, we’ll assume that,
for all intents and purposes, these particles travel in a straight line.
These light particles then land on an object (your work desk or this book, for instance),
where they are either absorbed by the surface (and turned into heat in the case of a black
surface), reflected (as is the case with most surfaces), or refracted while they travel through
the material (their direction is “bent,” as is the case with water). Different materials exhibit
different absorption, reflection, and refraction properties—water, a mirror, and a brick are
three fundamentally different examples.
If a light particle is reflected, then it has the chance to land on another object—or many
more, as happens in a hall of mirrors, for example. Depending on the surface properties of
the materials these particles land on, reflection is either very directional (e.g., with a mirror)
or scattered (e.g., on a painted wall). See Figure 5.5.
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Figure 5.5: Various reflections in real materials (brushed metal, coated wood, natural stone,
shiny metal)