Histogram Exposure Anomaly \ Histogram 曝光异常

Development Pipeline & Plugins
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1

In extremely dark conditions, the exposure value displayed in Histogram mode is abnormal and flickers, but it works fine in Basic mode.

Ensure r.DefaultFeature.AutoExposure.ExtendDefaultLuminanceRange=1

This issue becomes more noticeable.

Thanks for looking into this problem.

2

重现步骤
see umap

3

Hi,

Could you try to enable the bOverride_AutoExposureLowPercent​ on the PostProcessVolume Settings, adjust the Low Percent to 1, and see if it helps?

4

Hi, no improvement observed - the flickering issue persists.

5

Could you disable Lumen and see if it helps?

BTW, could you upload your project? I can’t load the map.

6

Hi,​​

Here’s the project file. I tried disabling Lumen, but nothing changed—the issue still persists.

UE5_UDN_Cases_v03

/Script/Engine.World’/Game/HistogramBug.HistogramBug’

Thanks!

7

Hi, I can’t open the map because the package version is too old. What’s the engine version you used? Could you have a try with the UE5.5/UE5.6? If it’s still in UE5.5/6, please send me the project, thanks.

8

Hi, this is a UE5.6 project. Please open the project using the official UE5.6 release version.​

9

Hi, here’s a screen recording of an actual case—this issue is pervasive.

10

Hi，

I can repro the issue, and I found two workarounds:

  1. Define COMPILER_SUPPORTS_WAVE_VOTE 0 in the first line of Histogram.usf.
  2. Add a shader permutation for FHistogramAtomicCS with DO_64BIT_ATOMICS macro, could use NaniteAtomicsSupported to check if it’s supported. ( uncomment the code related to HistogramScatter64Output and HistogramScatter64Texture).

Hope it could help.

11

Hi！

第一种方式，没有任何效果，跟修改之前表现一样。

第二种方式，以下是我在5.6.0上的修改patch，材质表现为纯黑色，完全失去了自动曝光的效果。

以上结果均是在HistogramBug.umap中做的测试。

12

你能尝试调小这个数值吗？PP盒子里

[Image Removed]

13

感谢，这个参数解决了问题。 :+1: