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- Allow for additive compositing, preserving the physical nature of the image and avoiding artifacts through multiplication or division in post processing.
- Output a specific bounce of light (2nd, 3rd, etc.) or even a range of bounces (4th to 8th bounce of light). You can use this to isolate effects or even noisy bounces for subtraction.
- Output a specific object to an LPE. While you can use Cryptomatte to isolate objects with an ID, you can also output the object or collection of objects and their contribution separately.
- Isolate a particular noisy light path for subtraction in comp or an LPE without these light paths to composite.
- Create a non-physical effect like differently colored caustics from their source, change the color cast of an object, or scale lighting.
- Output per-light AOVs for manipulation later.
| Note |
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Note |
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that trace sets |
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can also be used to accomplish some of these effects but since trace sets are global in the render, LPE will obey these trace sets (meaning data that would have been collected otherwise is restricted by the trace set). Light Path Expressions handle light transport, as such they collect illumination by default and not shadows (shadows are simply a lack of light) A specialized Shadow LPE is provided for compositing tasks as part of our Holdout workflow. |
LPE, Cryptomatte, and Trace Sets should improve the flexibility of your pipeline and when managed correctly, avoid expensive re-rendering for artistic tweaks.
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