Level of Detail (LOD)

Level of Detail (LOD)

Level of Detail (LOD) is an optimization technique where meshes with fewer polygons are displayed when a GameObject is far from the camera, reducing the rendering workload.

LOD Group Component

Add an LOD Group component to the root of a GameObject. It holds multiple LOD levels, each referencing different renderers.

• LOD 0: Highest quality mesh (shown when closest to camera).
• LOD 1: Medium quality mesh.
• LOD 2: Low quality mesh.
• Culled: The object is not rendered at all beyond this distance.

Setting Up LODs

1. Prepare multiple versions of your mesh (high, medium, low poly) in a 3D DCC tool like Blender or Maya.
2. Import them into Unity.
3. Add an LOD Group component to a parent GameObject.
4. Drag each mesh's renderer into the corresponding LOD slot.
5. Adjust the percentage transition points on the LOD Group slider.

Scripting LOD

using UnityEngine;

public class ForceLOD : MonoBehaviour
{
    [SerializeField] private LODGroup _lodGroup;

    void Start()
    {
        // Force LOD level 1 (index 0 = LOD 0, index 1 = LOD 1)
        _lodGroup.ForceLOD(1);
    }
}

Cross-Fading LODs

To avoid visible mesh popping during transitions, enable Fade Mode on the LOD Group:

• None: Instant swap (default).
• Cross Fade: Blends between LOD levels using a dithering pattern.
• Speed Tree: Used for SpeedTree vegetation assets.

LOD Bias and Max LOD Level

In Quality Settings (Edit > Project Settings > Quality), you can adjust:

• LOD Bias: A multiplier that shifts all LOD transitions. Higher value = use higher detail for longer distances.
• Maximum LOD Level: Forces a maximum LOD level globally, useful for mobile optimization.

// Adjust LOD bias at runtime (e.g., when switching quality levels)
QualitySettings.lodBias = 0.5f; // Use lower quality models earlier

TL;DR

• LOD Group swaps between mesh variants based on the object's screen size.
• LOD 0 is highest quality; Culled means not rendered.
• Cross Fade mode avoids hard pop-in between levels.
• Adjust LOD Bias in Quality Settings to tune globally across all LOD Groups.