Frustum Culling
Skip what the camera can’t see
Definition
Frustum culling discards objects whose bounding volumes lie entirely outside the camera frustum before they reach the GPU. It is the cheapest, most automatic optimization in any engine — but it is only as good as the bounding volumes of your assets. Hero assets with tight bounds cull well; assets with stretched dummy bones, rigid-bind animations, or oversized particle emitters break culling and stay drawn off-screen.
In production
In Unreal Engine 5, frustum culling runs automatically per-primitive against the view frustum, but it interacts badly with World Position Offset foliage and vertex-animated grass, since the engine's default bounds don't account for the offset displacement — you have to manually pad the bounding box in the material or component settings. Unity's camera culls renderers the same way but skips SkinnedMeshRenderers unless "Update When Offscreen" is disabled, which can cause a T-posed character to flash briefly when re-entering frame. A common production bug: a VFX artist scales a particle system emitter's bounds down to save performance, and the whole effect vanishes mid-shot because the emitter's origin sits outside frustum while particles are still visible on-screen. Profilers like Unreal's stat scenerendering or Unity's Frame Debugger show cull counts directly, the first place a technical artist checks when a scene's draw calls don't match expectations.
