I am going to try a 16321 x 16321 landscape with LOD 2.0 to see how that fares, but I am expecting the same results as the test above.
So I decided for the fun of it to try a really high “LOD 0 Screen Size” on the 16321 x 16321 Landscape, a value of 5.0.
This results in mesh quads that are very large, but the time and memory are significantly better:
8 minutes to build
32GB CPU memory
6GB GPU memory
So a system with 32GB to 64GB should work, plus an 8GB GPU.
The decimation of the landscape shape is also more consistent from component to component of the HLOD, as seen in this image:
Whereas a lower LOD 0 value causes more varied decimation of the components as shown here:
This decimation issue will have to be considered for any specific landscape actor, as it might cause visual issues, and I don’t know of any way to bias the decimation action.
I will do further research on the HLODs, and add another couple of videos to the Demenzun Media World Partition Video Series on the YouTube channel.
Another few tests on the 16321x16321 landscape.
Once you hit LOD 0 Screen Size of 2.0 or higher, the amount of required memory really drops.
16321 x 16321
LOD 0 Screen Size = 2.0
9 minutes to build
50GB CPU memory
6GB GPU memory
This is just the HLOD meshes visible:
This is just the HLOD meshes in Lit mode:
I tried running UE5.2 in Simulation mode, and a LOD 0 Screen Size of 2.0 for a 16384x16384 landscape is more than high enough resolution.
So if you are building HLODs for large landscapes, try 2.0 or 2.5 for Screen Size during Building, it will probably be enough resolution.
I should re-test the LOD 0 Screen Size value of 1.0 to see if UE5 is consistent in the high memory usage.
It is rather odd that a value of 1.0 requires 512+ GB while a value of 2.0 only requires 50GB.
Previously, when I did build with my R9-5950X 128GB system the 16321 size landscape also failed with out of memory, so it is using more than 128GB + default Page File.