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Using Light Filters
Light filters are a powerful way to control a light's appearance. With Katana 2.0 or 2.1, light filters can be added to a scene with a PrmanLightFilterCreate node. GafferThree support for light filters is available in Katana 2.2 and above. You can find a detailed explanation about light filter setup in the link below:
Using Portal Lights
PxrPortalLight is an optimized environment light. Because Portals are lights, not light filters, they require a special workflow. GafferThree support for portal lights is coming in a future version of Katana. You can find a detailed explanation about portal light setup in the link below:
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