5.11 world partition, landscape HLODs and crashes..
I may be confused, I may be wrong and I would be very happy to find out that is the case
but..
Even if we pretend there's no Out of Memory crashes in the HLOD builder it still behaves very inconsistently and will frequently lead to GPU crashes on launching your level
I take a relatively small (4k*4k) landscape
I create an instance HLOD layer with tile size of 256m and streaming distance of 1024m, build HLODs and all is well
I add a parent merged HLOD layer with tile size of 256m and streaming distance of 2048m, build HLODs and it shits the bed. This reliably occurs during the generation of the merged HLODs
This is the most common repeatable error : Assertion failed: CellBounds.Min.Z <= CellBounds.Max.Z - I assume this is the result of something not getting built previously. I don't think it's a lack of memory - i don't go past 32gb ram or 8gb of GPU memory during the process so I have plenty spare
My question is.. has anyone on here successfully built a decent sized landscape using world partition and landscape HLODs? if so did you come up with cunning tricks or can you offer any suggestions on diagnosing the source of the problem?
For my purposes I need a minimum of 8kmx4km and I would really like to take advantage of world partition since it will be fairly heavily populated with meshes and will be a pain in the arse to manage using world composition
ta
To head off the obvious response to the above, This warning from the docs is bullshit, both water and landscapes have been supported since 5.1
Replies
okay - so I got it to build HLODs, this is as much a post for future me as it is for anyone else
This is a level with two separate 4032x4032 landscapes placed side by side (indie gaea has an export size limit) , the build took around 45 minutes on a 5950x with 64gb, a 3080 and it was all running off fast PCIE4 nvme disks - the machine was very busy (and full) for the whole time .
2 HLOD layers set up as described in the above post
so - how did I fix it?
It all appears to be hypersensitive to the contents of your disk and whether the editor/hlod builder think they're allowed to overwrite/modify/delete things or not - I feel like the problem has been exacerbated by the use of version control but then again, my project would have been utterly wrecked if I wasn't using it.
Hopefully Epic will come up with a more robust way of handling one-file-per-actor and version control in future versions cos atm you're basically screwed if any process fails halfway through.
My top tips for this sort of thing are as follows...
If it shits the bed in the first few minutes it's probably because there's files on the disk it doesn't like
if you can't delete or overwrite existing HLODs, commit the files and then try it
Close the editor between deleting and building
if it's still being a dick, clear out all the cached stuff and suck up the consequent rebuild times.
Well that didn't work ..
World partition appears - in it's current state - to be completely unusable at any sort of scale.
I have solved the unsolvable problems by dropping world partition and going back to world composition. It's still a massive pile of crap but at least you can make tools to fix the problems that WC causes
said tools include...
EUB_unfuckLandscapeLODNormals
EUW_unfuckLandscapeLODMaterials
If anyone has a need for such tools I'll be happy to share
Well there is a bad news about world composition, it seems that nanite meshes really rely on World Partition in terms of frustum culling. To see it you can freeze rendering and see that nanite meshes ignores it )
I had a LOT of meshes on my level and when I've moved to WP - performance have significantly increased.
About HLODs building - I can agree- it`s a pure russian roulette. There is SO many things that can go wrong.
In my experience:
Perforce issues - all files must be not only committed - but be submitted as well.
Memory issues - first of all create HUGE page file for your virtual memory and here is why:
when Merged/Approx HLODs are building with default settings they`re creating not only super high dense meshes (which is a bug) but create them with super heavy 8K textures as well. And when it do this it takes ALL of your VRAM and then - RAM, and when it empty too - your page file.
HLOD Layer Setting - do not use any automatic settings in "Texture sizing type". And decrease voxelization resolution too
I've just started littering my landscape with nanite meshes - I'll take a look, have a little cry and then probably just turn them all back into normal meshes.
I'll get back to this stuff a bit later on so the advice is much appreciated.
When you say huge pagefile, how big are we talking? I'll buy another disk to put it on if I have to :D (it'll be a lot cheaper than getting more RAM)
oh well, in my case even 1 Tb wasn't enough. So if you can - use merged HLOD, but Approx is much better for trees (Merged makes them looks like LOD3 :) )
So lower settings as you could )
Ok, now it works
1) Go to https://docs.unrealengine.com/5.0/en-US/world-partition---hierarchical-level-of-detail-in-unreal-engine/
2) Browse to Generating HLODs section
3) Use command interpreter as described
4) UE must be closed
5) Profit
So seems like HLOD building broken only in-engine.
BUT even this solution not working with big forest. Large amount of trees is Approx HLODs Kryptonite
I guess we can cling to the faint hope they get a bit closer to making it production ready in 5.2 - I'm not holding my breath since they've clearly put the development roadmap in the hands of the marketing department
work has ceased for the time being - my water pump died . probably should have ordered another disk while i was shopping for a replacement..
Well, there is already a lot of HLOD related fixes in their GIT, so they will be in next release, So yeah, there is a hope after all. HLODs are important part of their new pipeline so there have to be some improvements in 5.2
I experimented with moving my project to 5.2 and world partition today.
good news :
World partition conversion inside the editor appears to be viable. With my partially populated 8x8km map it didn't go past 53gb Ram usage and took < 40 minutes to complete.
bad news :
the world partition editor is so shit that it's nigh on impossible to select things and apply settings to counteract the appalling editor and PIE performance you get after the conversion
further bad news : HLOD building is still broken to the extent where it's not worth bothering. on the plus side it crashes more gracefully and much earlier in the process.
conclusion :
back to world composition
HLOD building works if you disable virtual textures and set your landscape HLOD layer to use the Flatten rather than Flatten_VT template material.
a note: Default HLOD layer settings will cause your landscape proxy HLODs to be built at LOD0 resolution - this is not good, you will run out of GPU memory and it'll crash
This is obviously still garbage but it's something close to a workaround.
still unworkable but at least more of the crashes give you actionable information
lod selection for landscape tiles is still garbage
texture sizes for generated materials seem to be 8k regardless of what settings you select which leads to GPU memory crashes during the build (there are a couple of engine changes on the unreal forums that purport to work around this problem)
it does appear to actually build hierarchical lods (in the sense that it will merge groups of tiles into one mesh, the selections it makes are a bit mental but it's a start I suppose)
it still runs like shit when you do get it working. carry on with world composition
Epic lean pretty heavily on the community to fix engine issues and you're free to submit fixes to their github for consideration
This thread is moany as hell but it's mostly here so I don't forget what I've found while trying to update my project at each release
it's still knackered on 5.3.2 but things have changed
you can build landscape HLODs provided you don't try to build too big a level (4km^2 for me) provided you disable virtual textures.
you cannot build all the HLODs - at best I've managed to get 2km^2 of my landscape to actually generate
it will always use the highest LOD for your HLOD mesh
Basically - you deal with the fact you have to keep your landscape as a live landscape object (which is very fucking expensive in a large world)
ok - so, having accepted that landscapes are not supported by world partition we move onto static meshes
HLODs will mostly build - what it decides to build and why it decides to build it in the way it does is a mystery but it will complete builds reliably
Randomly selected levels will simply never stream HLODs in PIE. it does not matter how you set the level up. Generally speaking it will work in a packaged build but obviously that's not very quick.
I've checked this repeatedly in single player and on dedicated servers (listen servers aren't supported) - fiddling with settings appears to make fuck all difference.
The fact they have 'next gen landscape' in the future plans list on the unreal trello thingy suggests very strongly that Epic have no intention of actually fixing this shit.
I'll try nanite landscapes as an alternative just to see but last time I did that it didn't end well.
So, yeah...
we're about 2 years into ue5 and the best advice i can give for anyone intending to make a level more than a couple of hundred metres across and put it in an actual video game is still to stick with world composition and accept that you're locked out of most UE5 features
gg Epic
Nanite landscape might be the answer - at least until the 'next gen landscape' thing turns up (which will just be nanite landscape in a dress).
I've not assessed performance with actual content in a cooked build yet but it appears to be significantly better than a landscape with no HLODs and in terms of workflow it's just a button press to build your data.
I also would like to share some of the tips about the HLODs since this page is quite popular. Some of the points were already mentioned in this thread, so I just collected them once again in one message. I hope it will help somebody.
Actual at the moment of UE 5.3.2.
5.. you're HLODDing nanite foliage? i didn't realise that was a thing