Graphics Reference
In-Depth Information
Figure 9-5 The render layer in the UV/Image Editor
Reconstructing an Image with Render Passes
Render passes enable you to render components of the full render individually, so that they can be accessed
independently. In this section, you'll render the various passes separately and then re-composite them in the
compositor to mimic the original combined render.
This is intended only as an exercise and a way to look at the contributions of individual passes in isolation.
You won't often have cause to re-create a combined render identically with render passes in real life. Usually,
youwillcarryoutoperationsonindividualrenderpassesorusethedatafromrenderpassesindifferentcontexts
to create something that would not have been possible in a combined render. However, in order to do this, you
need to know what data is available to you in render passes.
Another thing to note is that internally, Blender arrives at the combined pass in a slightly different way than
how that it arrives at a composited image of individually rendered passes. That means that in theory, some ef-
fectswillrenderdifferentlyinthecombinedpassthaninacompositedoutput.Whileitisalmostalwayspossible
to re-create a combined pass by compositing constituent passes, some cases require significant tweaking to get
exactly right. Inparticular,images that make use oftransparency and refraction can be a challenge. Fortunately,
the compositor continues to evolve and improve. For the time being, we'll stick to an example that can be re-
constructed fairly simply, in the file scene.blend .
 
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