Troubleshooting occlusion culling
Solve common problems when using occlusion culling.
Read time 2 minutesLast updated 23 days ago
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 scene’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 mesh 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 GameObjects 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 error.
Failure in split phaseCause
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.