Issue with Exposure on UE 5.6

[Ashiro]

Hi there folks!

I am here looking for your wisdom because I recently migrated my project to UE 5.6 and I have been getting an issue with the exposure of interior cameras and I was hoping to know if anyone else is facing this issue and how to solve it.

This is the issue. I get into my interior camera and first the exposure is as it should be but then it starts to get brighter and brighter.

and then, as it was a bucle, the exposure returns as it should be, like in the first picture and starts all over again.

I am working with physical exposure camera and lighting with Sky creator (PPV inside sky creator turned off).

Sun Intensity 100,000 lux to match RL

Inside PPV i got:

{
“Tagged”: [
[
“Settings.AutoExposureMethod”,
“AEM_Manual”
],
[
“Settings.AutoExposureBias”,
“0.000000”
],
[
“Settings.AutoExposureApplyPhysicalCameraExposure”,
“True”
],
[
“Settings.AutoExposureBiasCurve”,
“None”
],
[
“Settings.AutoExposureMeterMask”,
“None”
],
[
“Settings.AutoExposureMinBrightness”,
“0.000000”
],
[
“Settings.AutoExposureMaxBrightness”,
“0.000000”
],
[
“Settings.AutoExposureSpeedUp”,
“3.000000”
],
[
“Settings.AutoExposureSpeedDown”,
“1.000000”
],
[
“Settings.AutoExposureLowPercent”,
“50.000000”
],
[
“Settings.AutoExposureHighPercent”,
“50.000000”
],
[
“Settings.HistogramLogMin”,
“-10.000000”
],
[
“Settings.HistogramLogMax”,
“20.000000”
]
]
}

My camera settings for interiors are:

{
“Tagged”: [
[
“PostProcessSettings.CameraShutterSpeed”,
“80.000000”
],
[
“PostProcessSettings.CameraISO”,
“400.000000”
],
[
“PostProcessSettings.DepthOfFieldFstop”,
“5.600000”
],
[
“PostProcessSettings.DepthOfFieldMinFstop”,
“1.200000”
],
[
“PostProcessSettings.DepthOfFieldBladeCount”,
“5”
]
]
}

Any idea what could be causing this issue? I am willing to hear you thoughs

Regards!

[Stephen.Phillips]

If exposure is increasing during gameplay, it sounds like you have Auto Exposure still enabled. If you’ve turned it off somewhere, it might still be on somewhere else. Post Process volumes and cameras will be competing with each other and you can try bumping up the priority of your camera or wherever you are turning off Auto Exposure.

I’m not familiar with Sky Creator, so I don’t know what else it is doing. Maybe it is moving clouds across the sky and changing the sun brightness. The exposure cycling up and down sounds bizarre. I would be interested in seeing a video of that. This might be one of those cases where you duplicate the level and start chopping out Blueprints, PPVs, and Cameras aggressively to see who is doing this.

[Ashiro]

Thanks for your reply @Stephen.Phillips

I will share a screen record. This time I changed exposure to:

{
“Tagged”: [
[
“Settings.AutoExposureMethod”,
“AEM_Histogram”
],
[
“Settings.AutoExposureBias”,
“0.000000”
],
[
“Settings.AutoExposureApplyPhysicalCameraExposure”,
“True”
],
[
“Settings.AutoExposureBiasCurve”,
“None”
],
[
“Settings.AutoExposureMeterMask”,
“None”
],
[
“Settings.AutoExposureMinBrightness”,
“8.000000”
],
[
“Settings.AutoExposureMaxBrightness”,
“11.000000”
],
[
“Settings.AutoExposureSpeedUp”,
“3.000000”
],
[
“Settings.AutoExposureSpeedDown”,
“1.000000”
],
[
“Settings.AutoExposureLowPercent”,
“10.000000”
],
[
“Settings.AutoExposureHighPercent”,
“90.000000”
],
[
“Settings.HistogramLogMin”,
“-10.000000”
],
[
“Settings.HistogramLogMax”,
“20.000000”
]
]
}

The issue persist

Edit: Seems to be a Lumen issue. I tried PT and everything works fine. changed back to Lumen and this happened

[Stephen.Phillips]

Really crazy stuff. So if you disable Lumen GI and reflections, then the exposure is stable and works as expected? In first post you had auto exposure off but in second post it’s on.

What graphics card and driver version do you have? I saw some reports of glitchy stuff for users of Nvidia 50-series cards that was supposed to be solved by getting the latest drivers.

[Ashiro]

If I change the viewport from Lit to Path Tracing, everything works as intended.

My graphic is a RTX 3090 with the studio driver 577.00 which is the lastest.

[Stephen.Phillips]

Path Tracing is very different from real-time rendering. To test if Lumen is the specific culprit, disable Lumen and keep it real-time. You can disable in the project settings or disable in PPV / camera (Global Illumination and Reflections).

[Ashiro]

I don’t know if these screen record helps. I tried changing from Lumen to screen space and then changing back to Lumen

[Ashiro]

Also when rendering with MRQ this happens:

[Stephen.Phillips]

Looks like turning off Lumen GI did get rid of the flashing. I was really shocked at how different the lighting looks without Lumen, though. Your scene appears to be a gray monochrome? I would go back to my previous advice about making a copy of this level with 100% different and new lighting setup. I don’t know how this Sky Creator works, but something about your lighting here is very strange. Just use the SunSky actor (SunPosition plugin) for basic lighting and see what happens.

Your scene should have the correct colors and overall look without Lumen, and enabling Lumen should just enhance the bounced lighting and AO. Make sure you’re not overly reliant on emissive lighting and trying to use extremely high values there to light the scene. Also, “Surface Cache” in the Ray Lighting Mode is the low quality setting. You probably want to be using “Hit Lighting” for this kind of rendering (this shouldn’t cause flickering though).