3D Level Design: Occlusion Culling

Intro

In this article, we are going to cover how to add Occlusion Culling to help with the speed of your game. Occlusion Culling is the process of only rendering objects that are in the camera’s view. Occlusion Culling only works for elements that are STATIC or DYNAMIC elements that are tagged as STATIC.

Static Elements

The first thing is to tag the game objects that are static. In this scene, we have organized the hierarchy into objects that are STATIC (not moving) or DYNAMIC (moving). This makes it much easier to identify which objects we want to be include in Occlusion Culling.

We batch select these objects and click on the Static drop down. We have two options with tagging this options.

1. We can tag them with Occluder Static and Occludee Static. An Occluder is an object that can hide another object from view (depending on the position of the camera). An Occludee is an object that can be hidden from view (because it is occluded by another object) but that cannot, itself, hide another object from view.
2. We can tag everything, but Contribute GI. This gives you all of the effects of a STATIC element but doesn’t contribute to the Global Illumination which is a system that models how light is bounced off of surfaces onto other surfaces.

We need to open up the Occlusion Culling window.

We are going to keep the default settings for the Occlusion Bake, but if you see larger objects that are being rendered and they shouldn’t you will want to decrease the “Smallest Occluder” value.

You will hit Bake. Now, your scene will be utilizing Occlusion Culling which will optimize your scene because you are only rendering what is being seen.