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Shadow Artifacts after Build

A few basic info: I'm creating a AV Room. It has 3 Narrow Strips for Windows from the side my main light source is positioned. The scene is relying heavily in indirect lighting, global illumination and exposure bias to light up (both values in the post process volume are set to higher values). That said, there are a few stationary and movable lights around mostly to highlight a few areas. Cascade shadows are off.

The Issue: From the start, I did a basic setup for lights in order to test my lightmaps. Everything work great and the lightmaps were "clean". After I finished the level design, I did a few changes to the basic light of my level (main lightsource, post process volume, skylight, main spot light (I use one to boost the light that comes from the window)).

After hitting build, in the darker places of the level artifacts have appeared. My first guess was lightmap issue, but the problem is that I didn't change the props or their UV, they worked fine before. alt text

What I tried: I tried to bump up the lightmap resolution but the issue, even though less noticeable is there.

Also, because my walls were one big prop, the same for the celling, I separated both down to smaller props but still, it didn't work.

Messing with the same values that I changed in the first places does nothing to the artifact problem.

I had cascade shadows on, but I disabled them in fear that they cause this, no luck.

Any thoughts why this is happening?

Product Version: UE 4.9
light_artifacts.png (560.9 kB)
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asked Sep 16 '15 at 07:48 AM in Rendering

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You can try to smooth this out by adjusting some of the settings in the World Settings under the Lightmass section.

There is a guide here on the Wiki Lighting Guide that may be be helpful as well to reduce the artifacts.

I hope this helps.


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answered Sep 21 '15 at 03:07 PM

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Tim Hobson ♦♦ STAFF
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avatar image ELRIIC Sep 22 '15 at 07:13 PM

Thanks Tim!

I managed to solve the issue by changing several settings from the World Tab and also by sub-dividing my Celling and Walls into multiple pieces.

This way, I gave to each prop more space in the unwrap and better lightmap resolution.

I admit that now I have another issue, lightmap related that I cannot solve with anything I have tried so far, but I will probably post another question if I cannot find the solution.

Again, thanks a lot!

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