Terrain Level of Detail (Terrain LOD)
Estimated Lesson Time: 35–45 Minutes
Lesson Overview
In the previous lesson, we learnt how Render Scaling affects image quality and GPU performance.
Today we’re going to look at one of the most important settings in Microsoft Flight Simulator:
Terrain Level of Detail, often referred to as Terrain LOD.
If there is one graphics setting that has the biggest impact on the CPU, it is usually Terrain LOD.
This setting controls how much of the world the simulator prepares and displays around your aircraft.
Increasing Terrain LOD can dramatically improve the realism of the simulator by making mountains, cities and terrain remain detailed much further into the distance.
However…
This comes at a cost.
The higher the Terrain LOD…
The harder your CPU has to work.
Understanding this setting is one of the biggest steps towards building a smooth and balanced simulator.
Lesson Objectives
By the end of this lesson you will understand:
What Terrain Level of Detail is.
How Terrain LOD affects the CPU.
How Terrain LOD affects object loading.
How it changes draw distance.
Why airports become more demanding.
Why mountains look different at higher values.
How Photogrammetry interacts with Terrain LOD.
How to choose the correct Terrain LOD for your PC.
1. What Is Terrain Level of Detail?
Terrain Level of Detail controls how far away detailed terrain is generated and displayed.
Think of the world around your aircraft.
Everything you see must be:
Loaded.
Calculated.
Positioned.
Rendered.
Terrain LOD determines how much detailed terrain the simulator prepares around you.
The higher the value…
The further into the distance detailed terrain remains visible.
Think Of It Like Looking Out Of An Aircraft Window
Imagine flying over Switzerland.
With a low Terrain LOD…
Only the mountains close to your aircraft appear fully detailed.
Mountains further away gradually lose detail.
With a high Terrain LOD…
The mountains remain detailed much further toward the horizon.
The scenery appears richer and more realistic.
2. How Terrain LOD Works
Every second during flight…
Microsoft Flight Simulator loads terrain around your aircraft.
This includes:
Mountains.
Fields.
Roads.
Cities.
Forests.
Rivers.
Lakes.
Terrain mesh.
Ground textures.
As your aircraft moves…
The simulator must constantly prepare new terrain ahead of you.
Terrain LOD controls how much of this work happens.
3. CPU Impact
Terrain LOD is primarily a CPU-heavy setting.
Why?
Because before your GPU can render the terrain…
The CPU must calculate:
Terrain mesh.
Terrain placement.
Ground elevation.
Terrain streaming.
Photogrammetry placement.
Object positioning.
LOD transitions.
Scenery loading.
The more terrain the simulator prepares…
The more work your CPU performs.
Why Does This Matter?
Imagine your CPU as an airport operations manager.
At Terrain LOD 100…
The manager is responsible for a smaller airport.
Everything runs smoothly.
Now increase Terrain LOD to 300.
Suddenly the manager is responsible for three airports at once.
More staff.
More aircraft.
More buildings.
More work.
Eventually the manager becomes overwhelmed.
Exactly the same thing happens to your CPU.
4. Draw Distance
One of the biggest visual differences you’ll notice is draw distance.
Draw distance refers to how far into the distance detailed scenery remains visible.
Low Terrain LOD
Terrain detail disappears sooner.
Mountains become softer.
Cities lose detail.
Ground textures appear blurrier in the distance.
High Terrain LOD
Mountains remain detailed.
Cities stay sharp further away.
Ground textures remain visible over longer distances.
The world feels much larger.
5. Object Loading
Terrain LOD also affects how terrain is prepared as you fly.
As your aircraft moves…
The simulator constantly loads:
Hills.
Roads.
Forests.
Ground textures.
Terrain mesh.
Higher Terrain LOD means the simulator prepares more scenery ahead of the aircraft.
This helps reduce noticeable terrain “pop-in,” where scenery suddenly becomes detailed as you approach it.
However…
Preparing all of that extra terrain requires additional CPU work.
6. Airports
Terrain LOD becomes especially important around airports.
Large airports already require the CPU to manage:
Ground traffic.
AI aircraft.
Airport buildings.
Jetways.
Lighting.
Glass cockpits.
Weather.
Vehicles.
Adding a very high Terrain LOD increases the amount of surrounding terrain that also needs to be processed.
Busy airports therefore become one of the most demanding situations for the CPU.
Example
Imagine landing at Heathrow.
With Terrain LOD 100…
The CPU prepares the airport and a moderate amount of surrounding terrain.
With Terrain LOD 300…
The airport still needs processing…
But now much more surrounding scenery is also being prepared.
This increases CPU workload significantly.
7. Mountains
Mountainous regions show one of the biggest visual differences.
Examples include:
The Alps.
Rocky Mountains.
New Zealand.
Norway.
Low Terrain LOD may cause:
Soft mountain shapes.
Reduced distant detail.
Earlier terrain simplification.
Higher Terrain LOD allows mountain ranges to remain detailed across much greater distances.
This greatly improves immersion during VFR flying.
8. Photogrammetry
Photogrammetry recreates real cities using 3D scanned data.
Examples include:
London.
New York.
Paris.
Tokyo.
Sydney.
When Photogrammetry is enabled…
Terrain LOD becomes even more important.
Higher Terrain LOD allows detailed photogrammetry buildings to remain visible further away.
However…
This also increases CPU workload because the simulator must prepare and stream more complex scenery.
A powerful CPU benefits much more from higher Terrain LOD in photogrammetry-heavy cities.
9. Terrain LOD Values
Microsoft Flight Simulator allows you to adjust Terrain LOD using a slider.
Terrain LOD 50
Very low.
Lowest CPU workload.
Suitable for entry-level systems.
Noticeable reduction in distant terrain quality.
Terrain LOD 100
The simulator’s standard reference point.
Good balance.
Suitable for many systems.
Terrain LOD 150
Excellent compromise.
Sharper distant terrain.
Moderate CPU increase.
A popular choice for many modern gaming PCs.
Terrain LOD 200
Very detailed scenery.
Excellent draw distance.
Higher CPU workload.
Well suited to powerful processors.
Terrain LOD 300+
Extremely detailed scenery.
Outstanding draw distance.
Significant CPU demand.
Recommended only for high-end systems capable of maintaining smooth performance.
10. Who Should Increase Terrain LOD?
Consider increasing Terrain LOD if:
- You enjoy VFR flying.
- You fly in mountainous areas.
- Your CPU has spare performance.
- You have a high-end processor.
- Your simulator is GPU limited rather than CPU limited.
11. Who Should Reduce Terrain LOD?
Consider reducing Terrain LOD if:
- Developer Mode shows you are MainThread limited.
- Performance drops at busy airports.
- Large photogrammetry cities stutter.
- Your CPU is consistently under heavy load.
- You experience poor frame pacing despite GPU headroom.
Lowering Terrain LOD is often one of the most effective ways to reduce CPU workload in Microsoft Flight Simulator.
12. Common Myths
Myth 1
“Terrain LOD mainly affects the GPU.”
False.
Terrain LOD is primarily a CPU setting.
Myth 2
“Everyone should use Terrain LOD 400.”
False.
Higher is not always better.
The best setting is the one your CPU can handle while maintaining smooth performance.
Myth 3
“Terrain LOD gives free image quality.”
False.
It improves distant scenery but increases CPU workload.
Every increase has a performance cost.
Student Exercise
Today we’re going to compare Terrain LOD values.
Step 1
Load your Module 1 benchmark flight.
Use the same:
- Airport
- Aircraft
- Weather
- Resolution
- Graphics settings
Step 2
Test:
Terrain LOD:
- 100
- 150
- 200
If your CPU is high-end, you may also test 300.
Step 3
During each flight, record:
- Average FPS
- Lowest FPS
- MainThread status
- CPU utilisation
- GPU utilisation
- Terrain quality
- Draw distance
- Mountain detail
- Airport smoothness
Step 4
Compare your results.
Ask yourself:
- Did the distant terrain look noticeably better?
- Was the CPU able to maintain smooth performance?
- Did the visual improvement justify the additional CPU workload?
- Which Terrain LOD value provided the best overall balance?
Student Checklist
Terrain LOD values tested.
CPU usage monitored.
MainThread status recorded.
Draw distance compared.
Mountain detail compared.
Airport performance evaluated.
Best Terrain LOD selected for your hardware.
Lesson Summary
Congratulations.
You now understand one of the most important graphics settings in Microsoft Flight Simulator.
Remember:
- Terrain Level of Detail controls how far detailed terrain is generated around your aircraft.
- It is primarily a CPU-intensive setting.
- Higher Terrain LOD increases draw distance and terrain realism.
- It reduces scenery pop-in but increases processor workload.
- Busy airports and photogrammetry cities become more demanding as Terrain LOD increases.
- Mountainous regions benefit greatly from higher Terrain LOD values.
- There is no universal “best” Terrain LOD—choose the value that provides the best balance between visual quality and smooth performance on your system.
Knowledge Check
- What does Terrain Level of Detail control?
- Why is Terrain LOD considered a CPU-heavy setting?
- What is draw distance?
- How does Terrain LOD affect object loading?
- Why do busy airports become more demanding at higher Terrain LOD values?
- How does Photogrammetry interact with Terrain LOD?
- When should you consider lowering Terrain LOD?
- Based on your benchmark testing, which Terrain LOD value provided the best balance between image quality and performance on your PC?