Linear Lights IES

Hello everyone,

I’m currently working in a lighting company that produces outdoor street lighting and architectural lighting products.
We have some products wich have one unique IES.

We use to work with 3DSMax/Vray, but we’re also trying to do some projects on UE4.
But we have a problem which is blocking us in our projects and that’s why I would like to know if one of you could help us out.

Here is the issue: We’re using some « linear light », until now in Vray, the IES for this type of light is VRAYLight with a rectangle Shape. The light distribution is correct. But when we use it on UE4, the IES starts only in one emission point at the center of the rectangle light, and it’s totally incorrect.
We tried to « cheat » and use 3 points light to get as closer as we could to the shape of the real lighting distribution.
But the scene has now a loooot of movable light and it’s lagging so much.
So if anyone has the same problem or maybe a solution to have the same resultat as in Vray you could make my day !

Here’s some screenshots of the scene and the difference between Vray and UE4.



I have the same issue in Unreal and have tried using spotlights with limited success. Hopefully Epic can start utilizing the luminous area in the IES and associate that to the length of a rect light.

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