Quick answer: Unreal Post Process Volumes producing the wrong blend when overlapping? Volume Priority determines which overrides; BlendWeight controls strength of that override. Both must be set deliberately.
A foggy cave volume overrides exposure; a smaller dim-corner volume inside it should override more but doesn’t — its priority is equal.
Priority Decides Owner
Higher Priority wins for shared settings. If two volumes set Bloom, the higher Priority one’s value is used. Equal priorities — first-wins, but unreliable.
BlendWeight Scales
BlendWeight is a multiplier on the volume’s override effect. 0 = no contribution; 1 = full. Combine with Priority for clean transitions: fade in BlendWeight as the player enters.
Unbound vs Bound
Unbound volumes apply everywhere if the camera is “inside” their world. Bound volumes use their box. Mix carefully — an unbounded high-priority volume overrides everything bound.
BlendRadius Smooth
BlendRadius softens the volume boundary — effect fades in/out across the radius. Avoids pop on volume edges. Set radius to ~1-2m for natural transitions.
Verifying
Volumes blend predictably: smaller / more specific volumes override the larger ambient ones. Transitions are smooth with BlendRadius.
“Priority + BlendWeight + BlendRadius. Three knobs for clean volume blends.”
Document priority tiers in a project doc (Global = 0, Region = 10, Specific = 20) — the convention prevents constant priority fighting.