FS2024 LOD System way too agressive!

[MSFS 2024] Bug Reports
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Version: * 1.0.72.0*

Frequency: Consistently

Severity: High

Context: Headache

Bug description: I find the new LOD system is defeating its own purpose. Meeting the requirements for the new Minsize rule is simply impossible in most cases. I can’t get my vertex count down to what it requires. At distances where the objects is still clearly visible, it wants my vertex count to be at a level where the object will obviously look deformed or else it won’t show at all…!
It’s resulting in us having to use the invisible cube trick to bypass the min size rule. This waste time, and defeats the purpose of that rule.
If the goal is to force everyone to use LODs, then put in place a rule where every obj’s last LOD must be under certain number of vertices. Then at least it would be a non issue, i could place a cube and have it pass for anything at a far distance. But to tell me that any object i model has to be under X amount of vertices to be displayed at these close distances is ridiculous in my opinion.

What was wrong with the FS20 LOD system? Can we have an option for our sceneries to use the FS20 one?

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You may want to look at the sample 2024 projects and Bilbao and see how Asobo/Microsoft are doing it in 2024. You will need to change your workflows to meet the new requirements but overall they mean you can get much greater detail and a much better end user experience.

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I’m not seeing that sample where is it?

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The sample projects i see are basic with no LOD use.
Edit: I just saw there was a sample and sdk update, i’m downloading it now

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I would say the tolerances are a little tight sometimes. I feel like if we had a bit more tolerance it would be easier in the meantime for everyone.

My biggest concern is developers having to re-LODing and exporting 1000s of assets to make them 2024 compatible. Lots of bugs with 2020 packages means that they won’t work and need to be fixed with 2024, the MSFS marketplace will suffer on 2024 release.

Fortunately most of our newer stuff has been LODed correctly as we followed the guidelines in the documentation for 2020 that have been there for 4 years warning everyone.

But I can see why the changes are needed as some smaller objects at other developers airports have 300,000 triangles on a 2 metre long chain thats placed 100s of times, causing massive issues (sitting in the plane and the stats profiler says your loading 50 million vertices), and these issues cause headaches for Asobo, when it was the 3rd Parties problem.

If you were to look at Bilbao in Spain which is in the sim, the new way they have made the airport is every individual part of the building is a modular piece. There is about 100 models as part of the building. Which seems less optimised than joining everything in terms of the exterior model. Individual airport seats, etc in the terminal means you can have much better quality, but you could do this anyway by placing them in the SDK. A lot of things can’t really be made this way, its just because the airport terminal is designed this way with lots or similar parts meaning you can made modular pieces.

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Yes i know. Some "developers’ never heard the words “performance optimization”. But this is pain staking work. As you said, 1000s of assets have to to now be adapted to this new system that they exposed to us a month from release. i know if i have an object with high vertices i can duplicate link it and have it show up in the sim as if it were only one, or, as you said you can just place the object numerous time in the SDK and it will automatically instance them. I’m not really seeing the benefit of this modular thing for scenery creation, and unless i’m mistaken it can’t even be done using blender? As a solo developer this hurts, I have alot more work to do because of this, and again, i’m not seeing the benefits.
When they showed Bilbao with and without the LODs, what was it like 28 million triangles? Why would that airport be 28 million triangles? They obviously had nothing instanced. Every object had to be its own separate object for that to be 28mill vertices. No optimized scenery is exported like that. So that comparison made no sense to me. If they handed me that airport to me i could have handed it back to them wit the same 9mill vertices to were boasting about using the old FS20 LOD system.

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I started to use Blender to make models from MFS2020. Use Substance Painter to paint the texture. Some details are not processed using the model, but painted on the texture. tested whether there is a better WorkFolw;

The test result is LOD0-6, which is indeed not necessary. LOD0-3 is actually enough and saves some development time.

LOD00 minSize=70
LOD01 minSize=30-40
LOD02 minSize=10
LOD03 minSize=0

But what I actually saw is that some developers do not control the number of triangles in the model and abuse 4K texture without any LOD; For example, the ground guidance signs of an airport use a 4K texture; The rudder pedals of an aircraft have 50,000 triangle faces.

Most models in flight simulation tend to be hardOPS.

When making LOD00 models, I tend to use the number of faces here. For some detailed model expressions, I use independent meshes to make them, and do not merge them together. I assign some UVs that can be used at the same time to the same 2K or 4K texture;

When making LOD01, I directly deleted some unnecessary detail models on the model, merged some faces used to make hardOPS; used 2K-1K texture to reduce the map;

When making LOD02, I continued to merge faces and delete detail models; used 512 or 128 textures;

When making LOD03, I repeated the model processing, or created a new cube to form a similar structure and use vertex colors.

I did not use automatic tools, which prevented the model from being visibly deformed when the LOD changed. I also reduced the texture size and reduced the workload of exporting textures. However, I needed to spend more time on UV design.I did not use automatic tools, which prevented the model from being visibly deformed when the LOD changed. I also reduced the texture size and reduced the workload of exporting textures. However, I needed to spend more time on UV design.

The new changes in the 2024 SDK and the new resource management methods are beneficial to developers who started to make materials according to the specifications earlier. It can save more development time and increase the efficiency of material reuse;

Due to the changes, the development time cost will definitely increase, but compared to adapting to future needs, I think it is necessary to change the development process and standards as soon as possible.

In 2020, we can actually see that a lot of art is based on the art standards of the past, not 2020; I really hope that in 2024, it will not be based on the transplantation of old resources, but on the new build based on the 2024 development standards.

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I have created a free Blender addon to simplify the workflow of LODs creation you can download here GitHub - erasam/LODs-Easy-Generator: A Blender custom add-on to create automatically LODs files to streamline the development of aircrafts for Microsoft Flight Simulator

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Yeah sounds nice and all, but not for optimizing existing airport projects where you have the model made a long period ago and lost the sourcefiles for it. Workflow in the future sure, but still though it should be a thing Asobo should code instead of throwing all this work on developers.

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Its like paying $500 for a 50/50 diner while you only ordered a salad thats 25$.

Besides this new LOD this is and looks like a big downgrade to me visually mainly and developing wise. I thought in MSFS2024 everything would be easier, turns out its the opposite.

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It’s clear for a very long time now that you should use proper lods and textures in your models. You decided to not do any of it and it would have helped in 2020 also (maybe even more then in 24). You want Asobo to burn their hands on stuff thats not theirs and get blamed for problems?

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That’s a little harsh. I made a small airport where most of the buildings have 4-5 LODs, more than I ever needed for MSFS 2020 and still get excellent framerates. When I load the 2020 airport in 2024, it looks fine, I don’t notice the LOD. When I load the 2024 build with the same buildings and same LODs, I notice them kicking in FAR sooner, I can tell the models turn ugly when they’re still quite large on the screen. It looks much worse than the 2020 version I don’t see any difference in performance (I’m sure there is a lighter load, but I don’t notice it). That’s fine and dandy when you expect the dev to have time to make 8 LODs each with a perfect number of polygons. But for a tiny airport that will sell for $6.99-9.99 and sell a few copies, taking weeks to make all these LODs just doesn’t feel worth the effort.

And then there’s the models you obtain or purchase from external sources, where you get a 50K poly model because it’s the only one you can find, and then you have to create a bunch of LODs that all look decent, and of course decimating creates a huge ugly mess each turn. It’s just a much bigger amount of work and the end result is much prettier terrain but often uglier objects and buildings. Maybe this will get easier with practice but for now I find that it’s a huge amount of effort that was absolutely not needed before to get good performance.

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We never had a problem with vertices in 2020…it was all about VRAM overload. And there’s still DEFAULT buildings in the sim that are not very well optimized, and use the cube trick in order to get them to render in due to high vert counts.

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The only solution today would be to split the model into several parts and create LOD for it. In sceneries/airports, I think this task becomes quite challenging, but for aircraft, it’s almost impossible. Even the native models in MSFS2024 have very aggressive LODs. For example, the pushback vehicles—just switching to the external camera causes the LOD to change, making them look visually poor. They need to rethink this. Yes, we need optimization, but not like this—it’s just not feasible.

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I’ve been optimizing for “Use LOD Limits” in the 2020 LOD debug for the last year and a half. Most of my models have transitioned OK thanks to this, but the new system is definitely at least 2x more aggressive than that 2020 LOD Limits System. It also depends on your sim settings. If you set the object detail slider to 200, it’s pretty close to the LOD Limits option in 2020.

For most of my models, I’m just leaving them as is. They go to vertex paint way earlier, but it matches the new norm it seems. For the worst offenders I have been going back optimizing the last two LODs. Usually one that still has texture, trying to get it to show a bit further out and then the vertex paint because I hadn’t been respecting the 150 vert lower limit for most of my models, causing them to pop out early (Kinda hard when Blender and the sim show two drastically different values due to edge splitting and etc).

Anything that is super high poly that I cannot reasonably decimate, I have been slapping a big plane under the ground a few meters down. Set it to the same material as the object and invert the face normal so it’s invisible even if you clip the terrain. Probably doesn’t really matter, but I just do it anyways. Might matter if you place it on the side of a cliff… lol I just hate to use another material if I don’t have to - though still not sure if that is more performant or using an invisible material. Either way it likely has minimal impact in the grand scheme of things, when the model itself isn’t strictly following guidelines.

I only try to do that in rare cases though, because it’s definitely not the right way to do it. Still optimize it the best I can. But in the case of the models I have used it on, some I have already done 5-6 iterations on, even using part instances and there is just no way to get it down to low enough verts without looking like absolute garbage from well within your visual range.

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If you don’t like the idea of having a big inverted plane that might possibly show up in some cases, you might add instead two very small triangles, at the opposite corners of what used to be your plane.

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I can agree to this that the LOD kicks in even when the object is too large on the screen, makes big sized buildings quite ugly quite soon. Forget the optimization, its more about loosing basic details such as pillars for jetway extensions… need a better solution soon. The invisible bounding box trick doesnt work as well.

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Well by telling developers to dowgrade their models, just to make the Simulator run friendly on a console that has 12GB of ram.

Its not that easy to downgrade International airports, now we need to edit every single airport just because of console users. This just doesn’t make any sense at all.

When you are working specifically on big airports, its a nightmare.

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These limitations are really crazy. I made a custom fuel station and added 7 LOD Levels. Some are pushed down with de decimate modifier. This is working very well but i am not possible to push it down as far is should be. For the last two LOD levels i deleted most of the object and after that pushed it even more with the decimate modifier <300 verts.

And even after that the fuel station disappears completely when i am about 300 meters away.

I am making a small regional airport so if you are on the aprons you should see all the objects with a decent amount of details. That is not possible with this LOD restrictions.

I hope there will be some more options to tweak the system that we can make some quality products in terms of details for the PC community.

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@mikeaat9612,

Would you mind sharing snapshots of your fuel station here and explain why the limitations are “crazy”?

Are you trying to model the whole fuel station in one single object which includes the fuel pumps, the shop (if there’s one) and the building? If that’s the case then, yes, you will have issues with the MSFS2024 LOD system.

The new sim uses a more modular approach to modelling those sceneries: there should be one fuel pump object instantiated multiple times (it could even be broken down further if really needed), one shop (possibility empty with other objects to fill the interior), and one building (possibly split if some parts require a lot of triangles in close-up views).

The various parts can then be grouped together in a SimPropContainer which can then be used multiple times. In such an object, all individual parts are applied their own LOD limits - if you are close to the pump it will display its LOD0 but the shop behind may only display LOD3. Get into the shop and you’ll get a detailed LOD for objects within it while the pump that is further away will show a less detailed LOD.

Granted, all of this is additional work for the creators but that is how you can achieve lots of details when close to an object while preserving performance as a whole.

Happy to discuss why you believe the LOD system is too agressive but then we need detailed reports of your issues with snapshots and polycounts - feel free to enable the Debug LODs tool which can display a lot of useful information.

Best regards,

Eric / Asobo

1 Like