UE4 RnD – Colored Lights & Caustics

Colored Light Textures

Colored lights is what I’m using as an approach to compensate for UE4’s inability to support colored texture lights – in offline renderers this allows users to project colored images which are blurred and create the illusion of a complex lighting environment off-screen.

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Caustics

When it comes to shiny translucent or chromatic surfaces, light reflections can sometimes get warped and layered (long explanation might take a few pages from a physics book). As this is an extremely complex effect that even offline renderers struggle with (rendering single frames in hours) this is a feature that is obviously missing from UE4. I have managed to create a workflow for a similar effect which will also allow me to customize my caustics in an artistic manner ie. image below

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*For more check-out Gleb Alexandrov’s AMAZING blog on these lighting subjects and more! http://www.creativeshrimp.com/

Solution 1

Method 1 involves recreating the effect by adding a secondary light source, projecting a translucent shadow cast by an invisible plane. This light will be projected across multiple surfaces at various angles.
For light aberration (last image on the right) two overlapping lights are placed one red and the other blue (effect here is exaggerated) with a slight difference in angle degree.

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This method however is limited bu surface lightmap resolution and can increase lighting build time greatly if overused – but is the more accurate.

Solution 2

A simpler method that can achieve a similar effect is to have an emissive material as a decal that can be manually placed on a surface where it will retain it’s brightness and opacity. This is a less demanding method overall which requires more manual work on per individual iteration.
The final product will probably use a mixture of both methods.

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Conclusion – some of the more intricate lighting effects will need to adjusted on an individual basis…

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