Volumes

Volumes are bounded region actors that affect what's inside them. They share a common base — AVolume — and differ only in what their bounding region does. UE 5.7 ships ~15 production volume types covering post-FX, gameplay, navigation, audio, streaming, and volumetric rendering.

The catalog

Volume	Purpose	Pages
PostProcessVolume	Per-region post FX, exposure, bloom, color grading	→
TriggerVolume / TriggerBox	Gameplay overlap triggers	→
BlockingVolume	Invisible collision	→
PhysicsVolume	Override gravity / damping / fluid for actors inside	→
AudioVolume	Reverb effect + audio occlusion zone	→
NavMeshBoundsVolume	Defines where navmesh is built	→
CullDistanceVolume	Per-region culling distances by mesh size	→
LightmassImportanceVolume	Restrict Lightmass GI to important regions	→
PrecomputedVisibilityVolume	Bake static visibility for low-end perf	→
LevelStreamingVolume	Stream sublevels in/out by player presence	→
PCGVolume	Bounds for PCG generation	→
HeterogeneousVolume / SparseVolumeTexture	True 3D voxel volumes for clouds, smoke, OpenVDB	→
KillZVolume / PainCausingVolume	Damage / kill regions	→
MeshMergingVolume	Auto-merge static meshes inside for HLOD	→

Common ancestry

Every volume inherits from AVolume → ABrush → AActor. The bounding shape comes from a UBrushComponent and is editable with the geometry editing tool (Mode Selector → Brush). Most volumes also accept convex shape components for non-box bounds.

Quick decision tree

graph TD
  A[What do you want this region to do?] --> B{Affect rendering?}
  B -->|Post FX| PP[PostProcessVolume]
  B -->|Lighting bake| LM[LightmassImportanceVolume]
  B -->|Mesh culling| CD[CullDistanceVolume]
  B -->|Static visibility| PV[PrecomputedVisibilityVolume]
  B -->|3D fog/clouds| HV[HeterogeneousVolume]
  A --> C{Affect gameplay?}
  C -->|Triggers| TV[TriggerVolume]
  C -->|Block movement| BV[BlockingVolume]
  C -->|Hurt actors| KZ[KillZVolume]
  C -->|Override gravity / fluid| PHV[PhysicsVolume]
  A --> D{Affect audio?}
  D -->|Reverb / occlusion| AV[AudioVolume]
  A --> E{Affect streaming?}
  E -->|Sublevel load| LS[LevelStreamingVolume]
  E -->|Navmesh build| NB[NavMeshBoundsVolume]
  A --> F{Procedural?}
  F -->|PCG bounds| PCG[PCGVolume]

Per-page deep dives

Each volume page covers:

1. What it does
2. Required plugins (if any)
3. Properties cheat-sheet
4. Blueprint events / C++ hooks
5. Gotchas
6. Cross-links to related systems

Start with the most-used: PostProcessVolume, TriggerVolume, AudioVolume, PCGVolume, HeterogeneousVolume.