Architectural_Design_with_SketchUp

Chapter 5 Rendering in SketchUp
number of single images need to be rendered to create a video of usable length. Advanced
effects in rendered animations are animated objects (such as water ripples or driving cars)
and light animations (e.g., a morning-to-night shadow animation).
Rendering Techniques
A variety of rendering methods exist, and every manufacturer of rendering software has its
own proprietary modifications to common techniques. As previously mentioned, the typical
trade-off is between quality and speed. Software implementations of even the same methods
can vary widely in those categories between manufacturers. I recommend, therefore,
that you test any rendering software that interests you and find out if quality and speed are
satisfactory for your needs.
It is also common for rendering software manufacturers not to offer too many different
methods in one software package. This may be a good idea because too many (and too technical)
choices may actually be counterproductive by being confusing to the user.
Common methods are:
NN
NN
NN
NN
Ray-tracing—This is the basis of every rendering method. Light particles are traced as
they travel through the model and get reflected or absorbed by surfaces. By itself, this
method often does not include light bounces (indirect illumination) and only relies on
direct illumination from the sun or artificial lights.
Global illumination—Any good rendering software will include global illumination. This
technique considers light bounces, which yield interesting effects such as illuminated shadows
and colors “bleeding” (reflecting) from a colored wall onto an adjoining white surface.
Biased and unbiased methods—Rendering always consists of computational simulation.
As with any computational method, the more precise it is, the more resources
and calculations it needs. Therefore, many rendering techniques are actually efficient
approximations of the accurate solution, which by its very nature introduces a “bias” of
one form or another. Only “unbiased” methods can accurately evaluate light behavior
and therefore can be considered to produce “perfect” renderings. Unfortunately, those
methods require considerably more computation than a biased method.
Examples of unbiased methods are path tracing (PT) and metropolis light transport (MLT).
Ambient occlusion—This rendering method approximates shadows based on how many
light particles can potentially arrive at any point on the model. As a result, inside edges
or occluded parts become darker and outside surfaces are lighter. This method often
produces soft shadows reminiscent of what can be seen on overcast days.
Rendering Software
Adding rendering capabilities to SketchUp can be a surprisingly easy and/or cheap step (admittedly,
it can be quite expensive, too). At this point, various software programs are available
that accomplish this task. In general, these can be classified as follows:
NN
SketchUp-integrated software—This group of programs installs into SketchUp as a
plugin. The programs generally are accessed using either the menu system or a custom
toolbar that becomes available after installation.
141