Rendering in SketchUp

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Chapter 4: How Rendering Works
I
n order to understand the rendering process, you need to know how IRPs and computers 
render images. By understanding the mechanics of computers and their components, you’ll 
be able to save time and ensure that your renders are completed successfully. 
The central processing unit (CPU) and random-access memory (RAM) are the two key hard-
ware components that affect rendering. The CPU (the processor) determines the rendering speed. 
RAM (the computer memory) determines the maximum model size that can be processed. Video 
cards do not generally affect IRP rendering process but can affect SketchUp’s performance. 
The computer recommendations at the end of this chapter provide essential basic informa-
tion so that you can make an informed decision when purchasing a computer for modeling 
and rendering. (Because computer technology advances quickly, the specific recommendations 
here will eventually be outdated.) 
IRP Render Processing
From the moment you press the Render button to the moment the render itself is complete, the 
IRP goes through several stages to produce an image. The speed of these stages is determined 
by the computer’s hardware. The following discussion describes the stages. How computer 
hardware affects those stages is described in the next section.
These stages are not strictly definable. Each IRP renders in a different way and, depending 
on the setting, stages 2 and 3 can occur simultaneously or consecutively.
Stage 1: Uploading the Model
Before you can begin to work on a rendering, the SketchUp model must first be uploaded to the 
IRP render engine. Render engine refers to the portion of the software that runs the complex 
calculations used to create and display the rendering. 
Once you click the Render button, a new window or menu will appear, indicating the prog-
ress of the model upload. Each IRP displays that progress differently, but it is usually displayed 
as a numeric value or a progress bar. There is no preview image at this stage. The larger and 
more detailed the model is, the longer the upload time will be. Small models can be processed 
in seconds, and larger models can take several minutes or longer (Fig 4.1).