Hi there,
I came across an issue when rendering at resolutions over 1920px via movie render que where the shadows get progressively less and less noticeable the higher the resolution render. To the point where you could argue they are not rendering on the landscape only the normals? The viewport looks the same as the 1920 render which looks correct from a shadow standpoint.
Unreal 5.3, I am using full Lumen, Nanite, Virtual Shadows, the landscape has Nanite tesselation enabled. I am not using Ray Tracing.
I checked GPUZ to check I wasn’t running out of VRAM and memory topped out at around 22gb at 5K with a total available of 24gb. The 2k and 4k renders still had 5-10gb of VRAM left in the tank. I have 128gb of RAM as well.
I did some more tests, it looks as if this is a memory issue with VSMs and in particular nanite tesselation. This means it just won’t render VSMs at higher resolutions due to VRAM consumption.
I did a test on blank level with a large flat static mesh with nanite tesselation it did display the VSMs at 5k resolution but was still using around 18gb of VRAM just one flat plane with Nanite tesselstion enabled.
There looks to be no fix for this in a real scene because there are no settings to control VSM resolution or a way to bring down memory costs when using VSMs along with Nanite Tesselation effectively…
Hopefully there will be a solution in the future as VSM’s and Nanite only work with each other…
Others had problems with missing shadows and high res rendering even without tessellation. Can you render 5k res videos with a decently complex scene but without tessellation ?
Not every scene no… I am using DLSS now rendering at 5k with DLSS set to balanced and an additional sharpening CVAR, VRAM tops out at 16gb on this scene down from 22+ and the shadows are now rendering correctly. It looks surprisingly good - looks like I’ll need to use DLSS for these more detailed scenes
