What Is Occlusion Culling In Unity?

Occlusion Culling is a method to significantly reduce the processing power required to render a scene for a user, by only rendering required parts of the scene at runtime.

Today’s Objective: Add Occlusion Culling to my Unity scene, limiting unnecessary draw calls.

Note: This project is created in the Universal Rendering Pipeline, so if you are using Standard or HDRP, some options may look slightly different.

Preparing for Occlusion Culling:

In order to prepare a scene to use Occlusion Culling, you must go through all the objects in your scene and decide if they are:

An Occluder: A static object that other objects could be hidden behind.
An Occludee: A static object that could be hidden behind other objects.
Neither: An object that, for any number of reasons, should not affect OC.

To set an object as one of these options, simply use it’s Static Flags:

If it‘ i’s an *Occluder*, tick *Occluder Static*, and vice-versa for an *Occludee*. If both, tick both, and if neither, tick neither. Pretty straight-forward.

After you’ve done that for all appropriate objects in your scene, you’re almost done.

Make sure that the Occlusion Culling checkbox is ticked on the camera in your scene:

I am using URP, so my camera component looks a bit different compared to other pipelines.

Generating the Occlusion Culling Information:

After your scene is set up, we must move on to baking the OC data (yes, just like you would bake lighting data).

Open “Window/Rendering/Occlusion Culling”:

Under the “Bake” tab, you will find a few parameters that you can change if necessary (usually they are fine as-is). Through any tab, you will also see buttons at the bottom, one-of-which will also be called “Bake”: