Simul Support ExchangeCategory: Sky and LightingBlack box over sun during sunrise / sunset
Taviana The Origins asked 4 years ago

We are getting a flickering black square on top of the sun during early sunrise and late sunset. We are using UE4 4.21.2. 

What is the solution to this problem?


2 Answers
Chris_Simul Staff answered 4 years ago

Hi Taviana, I have this is a go on the mentioned build and could not reproduce it or find a cause for it happening, and we haven’t had any previous reports of it happening prior. Do you potentially have any more information so we can attempt to further debug what is going on here. My initial thoughts is a strange reaction with either a post process of a fog actor, but without the project itself or more details of the setup its hard to track down or attempt to locate the issue.
Thanks in advance

Taviana The Origins replied 4 years ago

We’ve debugged it ourselves and it turns out that TrueSkyWater is causing the issue.

These are the settings we use on the water:

Chris_Simul Staff replied 4 years ago

Interesting, I’m still unable to reproduce this on my end when having the same water settings set up. Does it go away when using different settings on the water, or is it just having water within the scene at all causes it to occur. And could moving the water itself slightly be used as a workaround?

Does it occur with different sequences at the same time of day?

Another potential thought is that it could potentially be a GPU issue as it is appearing as a graphical corruption. I do however feel this is unlikely.

Apologies for not being able to answer this outright, as we haven’t had any prior reports of this issue before.

Skoots answered 4 years ago

Hi Chris and Taviana, my team and I noticed black artifact scattering when water was set to “half resolution” in the TrueSky sequence actor. Looks almost like GPU artifact and was noticed on a GTX 970. When swapping back to rendering water a full res, the issue seems to go away. Might be unrelated but worth checking.

Chris_Simul Staff replied 4 years ago

Hi Skoots – I’ve taken another look today using half resolution as you mentioned, and still did not manage a reproduction on my end (my PC also has a GTX 970, which is convenient), Make sure your drivers are fully up to date. I did notice that the latest plugin available on the downloads page has issues when rendering water at half resolution (mainly that it doesn’t appear correctly at all), so I’m assuming that you are on an older version and if so which one?

My only suggestion really is that if you have tracked down the issue by increasing the water resolution to full res then that is probably your best course of action to work around (though obviously not ideal). Alternatively you could try grabbing a different (either more recent or a slightly earlier) version of the plugin for that version of unreal and see if that alleviates the issue. However I would keep reference of which version you are using currently so you can revert settings if required.

Again apologies for any inconvenience this is causing for your project. If you need any help feel free to ask.