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TemporalAA And PostProcess Flickering 4.11p4

I'm experiencing a strange bug in 4.11 P4. My post process volumes and AA seem to cause screen flickering but only when the graphics for AA and Post Process are set to High or Epic. Anything lower and the graphics don't flicker.

Now the strange part. If you leave the level and come back without exiting the game, everything works fine.

I have tried setting the post process volume to disabled and this still occurs ( as it will just take default settings for the level ). Looking at stats for scene rendering, I see some spikes taking 25-30 ms each. This might explain the lag that we are experiencing in the game currently but I imagine it's more of a symptom of the screen constantly needing refreshing than the cause of the problem.

I will continue to try and track this down and possibly isolate it to a smaller section of the project but until then, I will take suggestions on what might be causing the problem.


TemporalAA Enabled

TemporalAA Enabled on Epic Graphics


AA set to NONE on Epic Graphics

Product Version: UE 4.11 Preview
aa_temporal.gif (882.1 kB)
aa_none.gif (1.5 MB)
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asked Feb 08 '16 at 07:55 PM in Bug Reports

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avatar image Lovecraft_K ♦♦ STAFF Feb 09 '16 at 03:55 PM

Hi Justin -

Can you post your Post Process Setup and any Blendables' Materials if you are using them?

Are you adjusting the Screen Resolution at all under the Engine Scalability? Can you make sure that it is set to 100%?

It also looks like the flicker is persistent in the bottom image you are showing as well, though only minor compared to the one with AA enabled, which leads me toward the screen resolution or a frame updating buffer (think Scene Capture 2D/Cube) that is causing a conflict with the AA.

Let me know -

Eric Ketchum

avatar image Justin.Dooley Feb 09 '16 at 05:02 PM

Hi Eric,

That's correct. Given the insight on the scene capture. I removed a capture camera we had in place that powered the minimap and that stopped the flickering. Scene rendering is also down to around the 3-4ms area.

The question now is why did the scenecapture node explode the level and only on High/Epic Settings?

Post Process settings

post-process.png (157.7 kB)
avatar image Lovecraft_K ♦♦ STAFF Feb 09 '16 at 06:56 PM

How are you updating your SceneCapture Actor? Are you capturing every frame or do you have an update function in a Blueprint, and if so, how often are you updating that function?

Thank you -

Eric Ketchum

avatar image Justin.Dooley Feb 09 '16 at 07:38 PM

It's a captureComponent2D that handles it. Capture every frame is set to true on eventBeginPlay. We tried setting it to a timed update of 1 second and the flickering then happens every second.

avatar image Lovecraft_K ♦♦ STAFF Feb 10 '16 at 02:57 PM

Hi Justin -

I am trying to build a test project which demonstrates the flickering, so I can enter a bug report for the issue, but I feel like I am missing something about your setup which is critical for replication of the issue.

I have attached below a Test Project in 4.11. Can you take a look at it and adjust or add anything to make it closer match your project?

Thank You

Eric Ketchum

Test Project 4.11 Preview

avatar image Justin.Dooley Feb 10 '16 at 03:05 PM

Running the one you placed here as standalone appears to cause it to flicker still. It's fine in editor.

avatar image UnrealBean May 17 '16 at 07:45 PM

Hey guys, any update related to this problem yet? Thanks for answering.

avatar image Tim Hobson ♦♦ STAFF May 17 '16 at 09:58 PM

Sorry, no update at this time.

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Hi Justin -

Thank you for your patience and help. I was able to get a successful reproduction of teh issue internally and have entered a bug report as a regression, for reference UE-26778. I will keep you informed as we investigate a solution to the issue.

Eric Ketchum

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answered Feb 10 '16 at 09:20 PM

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Lovecraft_K ♦♦ STAFF
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avatar image Nightmask3 Sep 30 '16 at 08:51 AM

Any update on this issue?

I'm running into the same problem, in a Distance fog post process effect. The flickering can be quite pronounced at times so I hope there's a solution to this!

avatar image Tim Hobson ♦♦ STAFF Sep 30 '16 at 01:12 PM

The issue can be tracked here but there is no update at this time. https://issues.unrealengine.com/issue/UE-26778

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