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.

77843-aa_temporal.gif

TemporalAA Enabled on Epic Graphics

77844-aa_none.gif

AA set to NONE on Epic Graphics

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

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?

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

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.

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

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

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

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

Sorry, no update at this time.

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!

The issue can be tracked here but there is no update at this time. Unreal Engine Issues and Bug Tracker (UE-26778)