LOD Models & Optimization

Understanding and implementing Level of Detail (LOD) models for optimal performance.

What are LOD Models?

LOD (Level of Detail) is a technique using different model versions based on distance:

Close (0-50m):   Full detail   → 50,000 polygons
Near (50-150m):  Good detail   → 15,000 polygons
Far (150-300m):  Low detail    → 5,000 polygons
Distant (300m+): Minimal       → 1,000 polygons

Performance Impact: Without LOD: Vehicle always 50k polygons = 30% FPS loss With LOD: Average 10k polygons = 5% FPS loss (83% improvement)

LOD Levels

LOD0 - High Detail (0-50m)

• Full resolution textures
• All geometry visible
• Up to 50,000 polygons
• Use: When player is close

<Model>
  <Name>myvehicle_LOD0</Name>
  <Polygons>45000</Polygons>
  <TextureSize>2048x2048</TextureSize>
</Model>

LOD1 - Medium Detail (50-150m)

• Reduced polygon count
• Combined geometry where possible
• 15,000-25,000 polygons
• Simplified interior

<Model>
  <Name>myvehicle_LOD1</Name>
  <Polygons>20000</Polygons>
  <TextureSize>1024x1024</TextureSize>
</Model>

LOD2 - Low Detail (150-300m)

• Simplified shape only
• Major features only
• 5,000-10,000 polygons
• Very basic interior

<Model>
  <Name>myvehicle_LOD2</Name>
  <Polygons>7500</Polygons>
  <TextureSize>512x512</TextureSize>
</Model>

LOD3 - Minimal Detail (300m+)

• Silhouette only
• 1,000-3,000 polygons
• Merged geometry
• Single color texture

<Model>
  <Name>myvehicle_LOD3</Name>
  <Polygons>2000</Polygons>
  <TextureSize>256x256</TextureSize>
</Model>

Creating LOD Models

In Blender

Step 1: Export High-Detail Model

File → Export → GTA V Model
- Ensure all LODs in file
- Export as .yft format

Step 2: Create LOD1 (50% detail)

1. Select high-detail mesh
2. Add Decimate Modifier
3. Set Ratio: 0.5 (50% polygons)
4. Apply modifier
5. Export as separate LOD1

Step 3: Create LOD2 (20% detail)

1. Select LOD1 mesh
2. Decimate Ratio: 0.3 (30% of previous)
3. Simplify geometry manually
4. Remove small details
5. Export as LOD2

Step 4: Create LOD3 (5% detail)

1. Create basic silhouette
2. Merge all geometry
3. Keep only major shapes
4. Export as LOD3

Polygon Count Example

Original Vehicle:
- Body: 25,000 poly
- Interior: 15,000 poly
- Wheels (4x): 5,000 poly
Total LOD0: 45,000 poly

LOD1 (50% reduction):
- Body: 12,500 poly
- Interior: 7,500 poly
- Wheels (simplified): 2,500 poly
Total: 22,500 poly

LOD2 (75% reduction):
- Body: 6,000 poly
- Interior: 2,000 poly
- Wheels (basic): 500 poly
Total: 8,500 poly

LOD3 (95% reduction):
- Silhouette: 2,000 poly
Total: 2,000 poly

LOD Configuration

FiveM LOD Settings

Define LOD distances in config:

<LODGroup>
  <LOD0>
    <Model>myvehicle_LOD0</Model>
    <Distance>50.0</Distance>
  </LOD0>
  <LOD1>
    <Model>myvehicle_LOD1</Model>
    <Distance>150.0</Distance>
  </LOD1>
  <LOD2>
    <Model>myvehicle_LOD2</Model>
    <Distance>300.0</Distance>
  </LOD2>
  <LOD3>
    <Model>myvehicle_LOD3</Model>
    <Distance>1000.0</Distance>
  </LOD3>
</LODGroup>

Dynamic Distance Adjustment

Adjust distances based on hardware:

-- High-end systems
LOD0: 100m, LOD1: 300m, LOD2: 500m, LOD3: 1000m

-- Mid-range systems
LOD0: 50m, LOD1: 150m, LOD2: 300m, LOD3: 600m

-- Low-end systems
LOD0: 25m, LOD1: 80m, LOD2: 150m, LOD3: 300m

Optimization Strategies

Strategy 1: Mesh Decimation

Progressive polygon reduction:

LOD0: 45,000 (100%)
  ↓ (50% reduction)
LOD1: 22,500 (50%)
  ↓ (60% reduction)
LOD2: 9,000 (20%)
  ↓ (75% reduction)
LOD3: 2,250 (5%)

Strategy 2: Geometry Simplification

Remove details at distance:

LOD0: Full interior, details, decals
LOD1: Interior simplified, some details
LOD2: Basic interior, no decals
LOD3: Silhouette only, no interior visible

Strategy 3: Texture Reduction

Lower resolution at distance:

LOD0: 2048x2048 - Full resolution
LOD1: 1024x1024 - Half resolution
LOD2: 512x512 - Quarter resolution
LOD3: 256x256 - Minimal resolution

Memory Calculation

Without LOD System

Vehicle resident in memory:
- Highest LOD: 50,000 poly @ 2048x2048 texture
- Always loaded: 100MB
- FPS impact: 20-30%

With Proper LOD System

Vehicle loaded intelligently:
- Player close (0-50m): LOD0 (50MB)
- Player far (50-150m): LOD1 (20MB)
- Player very far (150m+): LOD2 (5MB)
- Average memory: 20MB
- Average FPS impact: 3-5%

Best Practices

1. Always create LOD3 - Absolutely required
2. Progressive reduction - Each LOD ~50% previous
3. Test transitions - Ensure smooth swapping
4. Match silhouettes - LODs should look same
5. Keep proportions - Don't distort shape
6. Test at distance - Verify appearance from far
7. Monitor memory - Ensure all LODs fit
8. Document distances - Note LOD transition points

Testing LOD Quality

Visual Testing

-- Get player distance from vehicle
local playerPed = PlayerPedId()
local vehicle = GetVehiclePedIsIn(playerPed)
local vehCoords = GetEntityCoords(vehicle)
local playerCoords = GetEntityCoords(playerPed)

local distance = #(playerCoords - vehCoords)
print("Distance: " .. distance .. "m")

LOD Transition Testing

Walk backwards from vehicle:

1. 0-50m: Observe full detail
2. 50m: Check for LOD1 pop-in
3. 100m: Observe LOD1 quality
4. 150m: Check LOD2 transition
5. 200-300m: Observe LOD2 quality
6. 300m+: Check LOD3 appearance

Expected: Smooth transitions, no obvious "popping"

Performance Monitoring

local function monitorLOD(vehicle)
  print("=== LOD Test ===")
  print("Polygons LOD0: 45000")
  print("Polygons LOD1: 22500")
  print("Polygons LOD2: 7500")
  print("Polygons LOD3: 2000")
end

Common LOD Issues

Issue 1: Pop-In Visible

Cause: Transition distance too close Solution: Increase LOD distance or blend geometry

Issue 2: LOD Quality Drop

Cause: Too aggressive simplification Solution: Use 50-60% reduction ratios

Issue 3: Memory Usage High

Cause: LODs don't reduce enough Solution: Stricter decimation, smaller textures

Issue 4: Flickering

Cause: Intersecting geometry in LODs Solution: Carefully align LOD meshes

Advanced LOD Techniques

LOD Blending

Smooth transition between LODs:

Distance 40-60m:
Blend LOD0 (80%) + LOD1 (20%)

Distance 140-160m:
Blend LOD1 (80%) + LOD2 (20%)

Conditional Streaming

Load LODs based on activity:

if IsPlayerDriving(vehicle) then
  LoadLOD(0)  -- Full detail
elseif GetEntityHealth(vehicle) < 100 then
  LoadLOD(1)  -- Damaged, maybe full detail
else
  UseStandardLOD()  -- Normal distance-based
end

Performance Gains

Properly implemented LOD system results in:

Metric	Without LOD	With LOD	Gain
Avg Polygons	45,000	12,000	73% less
Memory/Vehicle	100MB	20MB	80% less
FPS Impact	-25%	-5%	80% improvement
Draw Calls	10	3	70% less

LOD models are essential for production-quality vehicles!