Stranges Black Lines (dots / ants) appearing in visor and render

Pedro J. Sánchez
Fri, 04 Feb 2022 09:04:36 +0000
Rendering

Hi there!

I’m posting this here after months of research and finding nothing about it. So I’m a little desperate.

I’m using Unreal Engine for animated show production. And for serveral months now, me and my team are facing some strange black artifacts that show up from time to time. They are like black lines composed by hundreds of tiny black spots that appear to be following the geometry depth.

I have debugged all I could be able to think of be debuggeable. I reinstalled all drivers type possible, I changed unreal version, started from a fresh project, turned on and off Ray Tracing, tunned all the options of the Movie Render Queue Tool, I even reinstalled windows and tryed it in another PC with another complete different harwdware.

And none of that have done nothing.

My PC specs are:

Intel Core i7 8700 3.20GHz

32 GB RAM

RTX 2080 ti 11GB

We are following a Ray Tracing workflow with movable lights and animations in geometry cache. But I doubt that any of that has anything to do with the problem, since this artifacts appear in bufer passes that are “lightless” and in any type of geometry (static meshes, skeletal meshes aswell).

Sometimes I just re-render the frames affected and suddendly it renders just fine. Sometimes I restart the engine and go right for the Level Sequence and render it again, and that seems to work. There was even a time when the only thing I did was to delete some junk files in my Local Disk to have more space and that solved it!

But none of this solutions seems to show a pattern and honestly I’m starting to freaking out, because I can never be sure when this artifacts are goint to be seen or not. And sometimes they are really subtle and that doesn’t work for the client either.

Here I leave a video with the problem. This artifacts are even more visible in other Buffer Passes like Roughness, but they appear to be in every buffer pass EXCEPT for the Ambient Occlusion pass (which is RT).

Here is the VIDEO (UE4 - Stranges Black Lines (dots / ants) appearing in visor and render - YouTube)

If anyone has any idea of what could be, please, I’m looking for any suggestion.

Thank you in advice.

4 posts - 3 participants