I’ve been having an issue with Flickering when rendering in Unreal Engine using Lumen with Ray Tracing enabled. I’ve been battling this issue for quite some time. I’ve made sure the walls are thick enough, and I’ve made the final gather quality 16, and the lumen reflections quality 4.
I also have a issue with the shadows inside of the characters mouth going away when the camera moves further away. I’ve tried adjusting the cascade shadows as I saw in other posts but it does not work.
Here are the clips of the flickering and the Lumen Scene:
Here is a clip of the mouth shadows.
PROCESSOR: 12th Gen Intel(R) Core™ i9 12900KF (16-Core, 30MB Cache, 3.2GHz to 5.2GHz w/Turbo Boost Max 3.0)
MEMORY: 64GB Dual Channel DDR5 at 4400MHz; up to 128GB
GPU: NVIDIA(R) GeForce RTX™ 3090 24GB GDDR6X
I am going to take a complete random guess at this, as I have had things like this too.
What I did was adjusting the lights themselves in scene, for example, try activating and deactivating shadows in the light editor to see if that helps on one light at a time. In the light editor, filter by “distance” and check and uncheck that distance field shadows box, it might make some of that flicker go away, it did for me. But at the cost of some shadow detail.
Yeah, Lumen is not a perfect system yet, so I feel you on the frustration. Hope it helps.
Hi! Thank you! I’ve tried your tricks and still no luck. I’ve definitely narrowed it down to my primary directional light and it seems related to indirect lighting. I also notice that the Lumen Scene quality affects this significantly. If I lower the value the flickering increases. Based on research I’ve heard the trick value is 4, even though the slider maxes out at 2 by default.
Hey, just a thought, don’t know if you had tried already - maybe the visual defect will go away when you render it out? Maybe the display viewport is not able to compute it right, but the renderer will?
If you hadn’t tried rendering it, maybe try and see if you still see it in the final render.
I’m having the same issue with another part of my scene that I cannot figure out. With regard to the mouth shadow I can tell you with probably 99% certainty that it is the max trace distance that needs to be extended. I have this problem trying to get foliage in the distance to cast a shadow. To set this go your post process volume settings and go to GLOBAL ILLUMINATION > LUMEN GLOBAL ILLUMINATION and set the MAX TRACE DISTANCE to a high value like 200,000 and see if that fixes it. With your scene you can probably set it lower, like maybe around 80,000 or less. Play around with it, but essentially this extends the distance of Lumen’s ray tracing. Worth a shot.
Hello, I tried this you said and still happening the same.
I atach you this video, you can see my shadow barril appearing so late. Do you know how to fix this?