Get culling results
Simulating real-world cameras with Physical Cameras

Troubleshooting occlusion culling

Solve common problems when using occlusion culling, such as incorrect culling and slow processing.

Hidden objects aren’t being culled

Symptom

Objects are reported as visible in the occlusion data but are visibly occluded.

Cause

Occlusion data represents a conservatively simplified version of the sceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
See in Glossary
’s occluders, meaning some of the occlusion erodes and loses detail. Precise occlusion culling costs significant time and resources, so Unity doesn’t try to be 100% accurate with culling by default. Unity tries to cull as much as possible in the minimum amount of time, which can cause false positives.

Resolution

Decrease the value of the Smallest Occluder parameter. This will produce higher-resolution data that’s less conservative. However, culling will decrease in speed and occlusion data will increase in size.

Visible objects are being culled

Symptom

Objects are occluded incorrectly.

Cause

Visible objects can be culled if the Smallest Hole value is too high compared to the actual size of the holes in your scene. A hole in your scene can range from an actual hole in a meshThe main graphics primitive of Unity. Meshes make up a large part of your 3D worlds. Unity supports triangulated or Quadrangulated polygon meshes. Nurbs, Nurms, Subdiv surfaces must be converted to polygons. More info
See in Glossary
to a small gap between two objects. If visible objects are being culled incorrectly, the hole is being incorrectly interpreted as full and acting as an occluder.

Resolution

  • Decrease the value of the Smallest Hole parameter.
  • Set the Backface Threshold to 100.
  • Remove the Static Occluder flag from GameObjectsThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
    See in Glossary
    that you don’t want occluded.

Occlusion leaks

Symptom

Objects are not occluded correctly.

Cause

Unintentional holes in your occluding geometry are retained by voxelization and magnified in the occlusion data.

Resolution

Make sure your geometry is modeled to be as watertight as possible.

Slow occlusion culling

Symptom

The culling process is too slow.

Cause

Occlusion culling can take a lot of time if your occlusion data resolution is very high.

Resolution

Increase the value of the Smallest Occluder parameter.

Slow baking

Symptom

The baking process is too slow.

Cause

The occlusion culling parameters can have a large impact on baking time. The higher the resolution of your occlusion culling data, the longer it will take to bake them.

Resolution

Increase the value of the Smallest Hole parameter.

Large occlusion data

Symptom

The size of the occlusion data is too large.

Cause

Occlusion culling can take a lot of data if your occlusion data resolution is very high.

Resolution

  • Decrease the value of the Backface Threshold.
  • Increase the value of the Smallest Occluder parameter.

Baking fails

Symptom

Baking fails with the Failure in split phase error.

Cause

The initial step of the bake tries to subdivide the scene into computation tiles. The subdivision is based on the Smallest Occluder parameter and when the scene is large in size, too many computation tiles can be created, resulting in an out of memory error.

Resolution

Increase the value of the Smallest Occluder parameter and split up the scene into smaller chunks.

Additional resources


Did you find this page useful? Please give it a rating:

  • Get culling results
    Simulating real-world cameras with Physical Cameras