What is the deal with Terrain Level of Detail (TLOD)?

Fluid is good. I use the term smooth (not stutter).

I don’t pay attention to FPS and limited. I just fly.

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Yes, the stutters are the biggest immersion killers. I don´t mind about high fps, 30-35 is enough for me as long it is fluid or smooth.

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A while back I did some testing trying to see what things like TLOD actually was:

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Well i did some more testing, i seem to get different results every time, however, dont go mad on the tlod and set textures to high (as opposed to ultra) seemed best for me , tlod at 150 and olod at 200, clouds high.
With textures on ultra everything seemed to clog up and gpu usage dropped significantly.

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First of all thank you all for your interesting answers. I have seen a video on youtube some days ago, dont know from whom it was, if I find out I post the link: that guy said he enabled anisotropic filtering 16x in nvidia control panel and disabled it in the sim settings. this way he was able to maintain mostly crisp graphics with TLOD 100, thus better performance than maybe TLOD 200… I tried it too and I think I´ll stick with it for now.

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Are you testing in different areas?

Next to the user settings for terrain (which is draw distance for everything) there is a build in adjustment for PG areas. Based on the density / detail level of the PG area, the game adjusts the draw distance further.

I did a lot of measurements last year seeing how much data gets streamed for different settings and updates. London is far more dense than NY yet the game adjusts the draw distance down for London so the data stream doesn’t get overwhelmed. But that means London looks more apocalyptic than NY since you see lower level of detail much nearer by.

For example London at TLod 200 went from 4.38 GiB to 1.98 GiB for my test flight in SU5.
New York at TLod 200 went from 1.63 GiB to 1.59 GiB in SU5.

London got a big decrease in draw distance to keep the bandwidth required in check, while NY hardly got any adjustment.

Latitude also affects draw distance. The further North / South you go, the smaller the ‘Cells’ get. Terrain Lod affects how many Cells are loaded in, since the Cells get smaller by latitude, you get a very shortl draw distance at the poles. Performance is generally better at higher latitudes (Until you get near the poles where weird stuff happens)

Anyway to re-iterate
Terrain Lod = Draw distance
Object Lod = Amount of generated objects AND detail level of PG data
And since PG data is streamed in, lower Object Lod means the CPU has to ‘simplify’ the PG data before rendering.

The measurements:

For London

London city to Heathrow, 500ft, noon, clear skies, 7 minute flight

About 3.5 minutes of PG Data at 180 knots
About 6 minutes of Map Data at 180 knots

         No PG Data       PG Data            

Terrain 200 0.32 7.3 mbps 4.38 150 mbps
Terrain 150 0.29 6.6 mbps 3.49 119 mbps
Terrain 100 0.19 4.3 mbps 2.73 93 mbps
Terrain 50 0.13 3.0 mbps 1.58 54 mbps

WU6 (Object detail 200 or greater to match Terrain detail)

         No PG Data       

Terrain 800 0.74 GiB 20.4 / 15.1 / 5.0 10 fps 17 mbps
Terrain 400 0.50 GiB 15.2 / 8.5 / 4.1 18 fps 11 mbps
Terrain 200 0.34 GiB 13.2 / 6.9 / 3.7 22 fps 7.7 mbps
Terrain 100 0.21 GiB 11.2 / 6.3 / 3.7 24 fps 4.8 mbps
Terrain 50 0.16 GiB 9.8 / 5.8 / 3.5 26 fps 3.6 mbps

         PG Data   

Terrain 800 5.25 GiB 21.6 / 15.8 / 6.2 11 fps 179 mbps
Terrain 400 3.45 GiB 15.1 / 7.7 / 4.1 14 fps 118 mbps
Terrain 200 1.98 GiB 12.3 / 7.5 / 3.5 22 fps 68 mbps
Terrain 100 1.21 GiB 10.6 / 6.4 / 3.7 26 fps 41 mbps
Terrain 50 0.60 GiB 9.9 / 6.0 / 3.5 33 fps 20 mbps

SU6 London City to Heathrow, 500ft, noon, clear skies
No PG Data
Terrain 800 0.87 GiB 20.5 / 15.6 / 5.2 8-15 fps
Terrain 400 0.60 GiB 16.4 / 11.4 / 4.4 15-22 fps
Terrain 200 0.38 GiB 12.1 / 7.7 / 4.1 21-22 fps
Terrain 100 0.23 GiB 11.6 / 6.8 / 3.7 22-25 fps
Terrain 50 0.17 GiB 11.1 / 6.4 / 3.6 22-24 fps

         PG Data

Terrain 800 5.45 GiB 20.8 / 15.5 / 5.5 7-14 fps
Terrain 400 3.76 GiB 15.5 / 10.4 / 4.4 14-22 fps
Terrain 200 1.95 GiB 12.5 / 8.0 / 3.9 21-27 fps
Terrain 100 1.26 GiB 11.1 / 6.9 / 3.7 27-30 fps (22 on autogen)
Terrain 50 0.65 GiB 10.5 / 6.8 / 3.5 31-32 fps (22 on autogen)

SU7 London City to Heathrow, 500ft, noon, clear skies
No PG Data
Terrain 800 0.79 GiB 19.5 / 14.5 / 4.9 9-15 fps 13.5 mbps
Terrain 400 0.53 GiB 12.7 / 6.9 / 3.9 16-24 fps 9.0 mbps
Terrain 200 0.37 GiB 10.8 / 7.5 / 3.4 20-29 fps 6.3 mbps
Terrain 100 0.22 GiB 9.9 / 6.8 / 3.4 24-29 fps 3.8 mbps
Terrain 50 0.16 GiB 9.2 / 6.3 / 3.3 25-33 fps 2.7 mbps

         PG Data

Terrain 800 5.33 GiB 20.7 / 15.2 / 5.0 4-14 fps 91.0 mbps
Terrain 400 3.74 GiB 13.8 / 7.9 / 3.9 12-24 fps 63.8 mbps
Terrain 200 1.92 GiB 11.4 / 7.7 / 3.7 24-28 fps 32.8 mbps (20 on autogen)
Terrain 100 1.18 GiB 9.8 / 6.9 / 3.5 28-34 fps 20.1 mbps (24 on autogen)
Terrain 50 0.65 GiB 9.0 / 6.4 / 3.3 34-37 fps 11.1 mbps (25 on autogen)

For New York

NY Newark to LaGuardia

         No PG Data       PG Data

Terrain 200 0.30 GiB 1.63 GiB
Terrain 150 1.42 GiB
Terrain 100 1.12 GiB

SU5 NY Newark KEWR to Laguardia KLGA, Bonanza, 800ft, clear skies

Terrain 200 1.59 GiB 12.2 / 7.0 / 3.5 24 fps (0.25 GiB no PG data)
Terrain 100 1.04 GiB 10.5 / 6.0 / 3.2 29 fps

SU6 NY Newark KEWR to Laguardia KLGA, Bonanza, 800ft, clear skies

Terrain 400 2.77 GiB 19.0 / 12.4 / 4.5 13-19 fps
Terrain 200 1.77 GiB 12.3 / 7.1 / 3.9 18-29 fps
Terrain 100 1.02 GiB 10.8 / 6.5 / 3.0 25-36 fps

SU7 NY Newark KEWR to Laguardia KLGA, Bonanza, 800ft, clear skies
Terrain 400 2.47 GiB 17.9 / 11.3 / 6.0 11-22 fps
Terrain 200 1.52 GiB 11.6 / 6.3 / 4.3 20-30 fps
Terrain 100 0.97 GiB 10.0 / 6.5 / 3.4 30-36 fps

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Wow, thats a lot of info, well done.
It shows there’s a lot at play here.

I was just flying around Orlando trying to reduce the major stuttering. Switching texture to high from ultra helped for me in that area.
It seems bizarrely they are happy to add pg areas with out really worrying what the sim does. In reality they need a good algorithm to reduce data before it is streamed.
In my case i think a good measure is gpu usage, if i keep that near 100% i am not getting bottlenecks elsewhere, it’s just a case of how to achieve this for best experience.

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That GPU drop may be an indication you don’t have enough VRAM. I experience those same drops on my 2060 super when the VRAM is full.
I have no issues with textures set to ultra providing my card has 16gb of VRAM.

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Since when are LODs actual objects lol? It just stands for LevelOfDetail…

Level of Detail of what? Terrain and Objects

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OBJECT level of detail.

But it rather looks and behave likethe Level Of Detail is Loading On Distance

yes, the level (distance) of object details, thats another way you could say it
the higher, the more far away objects will render and also have better quality from afar

It’s not just more far away objects that render, it’s also the density of auto gen.

Object LOD affects quality of rendered PG data and density of auto gen scenery.
The higher the object LOD the less PG data gets ‘downgraded’ or simplified for easier rendering and the more trees and building autogen generates. Higher density and further away.

This can lead to some tricky balancing issues between CPU and GPU. In my data here
Terrain 200 1.92 GiB 11.4 / 7.7 / 3.7 24-28 fps (20 on autogen)
Terrain 100 1.18 GiB 9.8 / 6.9 / 3.5 28-34 fps (24 on autogen)
Terrain 50 0.65 GiB 9.0 / 6.4 / 3.3 34-37 fps (25 on autogen)
I get lower FPS over the autogen area, better performance over the PG data.

Over PG data I’m CPU limited, the sim has already reduced the draw distance of PG data to be easy on bandwidth. So high object LOD means my CPU can simply send the data on to the GPU which can handle it fine, both happy.

Then I enter the autogen area but here the high Object LOD means more buildings and trees, and now either my CPU or GPU falls behind creating and rendering all those objects.

The worst are heavily forested PG areas since the sim will place autogen trees on top of all the PG data trees. I get the worst performance in those kind of areas.

Trees also have their own density slider, tree quality. Here’s a heavily forested PG area to demonstrate

PG data, Trees on Ultra

PG data Trees on High

PG data Trees on Medium

PG data Trees on Low

No PG data Trees on High

No PG data Trees on Low

Offline Trees on High

With DLSS3 i can easy fly with tlod 400 and lots of FPS.

Thats as maybe, but the statement means little to everyone else without context.

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For example, i found flying low over the iom high tlod made things awful visually because the colours of the hishest detail tiles were awful, the only way to get a decent experience was to lower tlod as far as possible.

Right but he said "“LODs” are objects like runway lights and utility towers”, that sound insanely funny to me. Like a LOD is an object.

@MintRobin607848, and other simmers if intrested
!!!Warning long read!!!

The way i see it with Tlod and Olod and toy with them
Then there is also texture resolution
Then there is also flying in and out of certain areas where there is transition between them
Then there are building trees and grass and bushes
And even zoom ( i experiment with these at the moment) factor settings relative smoothnes to reduce stutters, and even periphal settings ( because of over input which bring unbalance in in game calculations) all in relation of total overview of the game.

While currently i am using a 3060ti 8gb and cpu11700k 32gb 3600mhz of ram
But i had it earlier with gtx 780 card and 1230v2 xeon cpu 16gb 1333mhz ram.
Windows 10 for these systems

That what i did and how i see it.
So i will try to explain while i know not many will agree with this way of approach but im just a hobbyist with almost zero knowledge about termonology used for computer and find myself to have common sense of logic and realism.

But the main course is to bring some clarity on Olod and Tlod and how they relay to each other.
So to start (read in steps the following)

I have editted the usercfg.opt and changed secondary scale to somewhere between 0.800000/ 0.600000 which is related ingame to post rendering imo for playing on monitor good because now i can turn up primary scale to above 1.000000 or above 100/130 i use TAA
Reason will be TAA will be notable on 100 or above
This will be in conjunction and relay to monitor resolution setting
And i want to mention it provide overhead to shift load were it is needed on the go
Ask your selfs this, how many times do you interupt the game ingame to play with sliders and settings?
I calculate these in as managing my flight as if it is reading a plane manual and i cant look outside or instrument, while co pilot is doing what he is supposed to do when captain is bussy.

Also this for understanding texture resolution!!!
Texture resolution can be found in this file under graphics section

(Texture
MaxAnisotropy 16, 8, 4, 2 or 0
Quality 0, 1, 2 or 3 while zero means in game ultra and 3 means low
)

This can also be handy for the setting texture resolution edit in here ( i swap them between medium up to ultra so in order to choose from 2 to 0, depending on where i want to fly and with what aircraft) the reason behind Texture Res, is mainly intended as if change this in game you will need to restart the sim, so i rather do this up front. All others can be changed ingame. But make sure this Usercfg.opt has to be unquoted in the “read only” tick box, so it accepts changes.
Also choose DX11 or DX12 for it needs a restart if changed in sim so better to do up front. I explain later in the end of this post concearning roling cache.

About Terrain lod (Tlod) and Object lod (Olod) imo
Terrain holds data of Photogrammetry and are low polygon, and it diver from object polygon as (is set), for it uses another way to compute to fit textures wrapped on this specific object and also can have different resolution setting from i believe 32x32 up to 4096x4096 where higher is nicely but uses more vram or ram to display.
As i see as low polygon means 4 sides while the top is formed by the 4 sides but the data of the photogrammetry can be stretched up to a certain height to cover and if set to high the aircraft smashes onto an invincible wall when this (dont get me wrong here) pg object has crash on impact.

We al have different computers and configurations, so know the limits of you system and where to make trade off but keep in mind “texture resolution”.
My fist rule about this is higher means more data to proces

Now the main thing
Tlod or Terrain lod
I find that Tlod 100 was looking melted, 200 looked off melted 300 acceptable and 400 nice
But i had to lower Olod to 75 and or lower.

I try to be clear here with and example;
Depending of choice of aircraft ( i choose GA C172 ) to fly with in the London area.
Heavy on photogrammetry also a lot of procedural buildings in city center (high on resolution)

The following setup I choose for this flight;

Texture resolution high ( see above in this post for explanation)
Clouds high
Buildings high
Trees low
Grass and bushes off
Water low
All else high or ultra
Slider Tlod choose 3 to 400
Slider Olod choose around 75.

Now lets talk rolling cache before flight and how i use it
Have in mind that this file gets corrupted easily and many claim this wont work
But let me tell you this when creating a new file start with 10gb and know if your in dx11 or beta dx12
Create there own directory to store this naming them in msfs cache under Dx11 or Dx12 so the cannot interfere with each other but have there own on going build when expand when fly other area
and you increase its limit with 2 or 5 gb to put on top of the start of the 10gb you already had set, but make sure to select the right directory remember dx11 or dx12
Here is why.

When start flight on London Luton city airport i want to go to London Heathrow.
Without flight plan but intensionally to get there.

I make a start from Luton to make a quick round over the city back to Luton view from as many
Viewpoint in and outside cockpit as possible also make change in flying altitude as well, why?
To map the city on the go and make the rolling cache to write and remember data for later flights so it loads in faster for it remembers through cache file.( les time consumming and more fun to do so). So dont mind the stutters and lags for this (pre)flight.
And to keep the file healthy and expanding for city in future when up cache file par city with 2 to 5 gb as mention before in this post.

Now restart the flight and make the intented flight from Luton to Heathrow and watch now without changing anything and see difference in loading.
When leaving the pg area and you enter suburbs lower your Tlod back to 200, or lower
(Intended fun dont look back the city might melt behind youre back), and up your Olod to 100, 150 or 200 for loading up higher texture resolution on handcrafted and ai building to keep it nice while decending down on final and to have Load On Distance rather than Level Of Detail or vice versa

So cache file handle with awerness, care and caution
Note about this, I would prefer different drive m2. for fast access.

Well i hope this post make sense to you and others
Happy flying and hopefully less stuttery on landings.

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