Why does bloom look stronger on my second camera?

In URP’s Camera Stack, a Base camera renders the scene with post-processing, then Overlay cameras render on top. If the Overlay camera also has post-processing enabled, the bloom from the Base camera’s output is re-bloomed by the Overlay. The result: bright pixels appear over-glowy.

How do I configure a Camera Stack correctly?

Set Render Type = Base on the main camera with post-processing enabled. Set Render Type = Overlay on UI/transition cameras with post-processing disabled. Add the Overlay cameras to the Base camera’s Stack list. Post-processing runs once on the final composited image.

What's the Volume layer for in URP?

Each camera samples Volumes on its Volume Mask layer. Two cameras with different masks can get different post-processing profiles. Use this to apply specific bloom only to first-person UI elements, for example, while keeping the world’s bloom at a different intensity.

Fix: Unity URP Post-Process Bloom Double-Applied

Quick answer: Disable Post Processing on every Overlay camera in your Camera Stack. Only the Base camera should run post-processing — otherwise bloom gets applied per overlay pass.

A scene that looks fine in the test layout becomes overexposed when the UI camera is added. Bright emissive materials — neon signs, particle effects — bloom into white blobs. Disabling the UI camera fixes it. Something about the second camera is doubling the effect.

How URP Camera Stacks Render

URP supports a Camera Stack: one Base camera plus zero or more Overlay cameras. The Base camera renders the scene, applies post-processing (bloom, color grading, tone mapping), and writes the result. Each Overlay camera then renders on top, potentially adding UI or HUD elements.

If an Overlay camera has Post Processing enabled, the bloom pass re-runs on the already-bloomed Base camera output. Bright pixels are convolved twice. The result is visibly over-glowy.

The Fix

On each Overlay camera:

Select the camera in the hierarchy.
In the Inspector, find Rendering → Post Processing.
Uncheck it.
Save the scene.

Only the Base camera should have Post Processing enabled. Confirm by selecting the Base camera and looking at its Stack list — Overlay cameras listed there now contribute geometry without re-running effects.

UI-Only Cameras Special Case

For dedicated UI cameras (UGUI Overlay), you typically don’t want bloom or any color grading on the UI text. Setting Render Type = Overlay and disabling Post Processing is the right configuration. The UI renders crisply on top of the post-processed world.

Volume Mask Isolation

For cases where you do want different post-processing on different cameras — e.g., a first-person weapon view with its own bloom — use Volume layers:

Main Camera:
  Render Type: Base
  Volume Mask: Default
  Post Processing: enabled

Weapon Camera:
  Render Type: Overlay (in main camera’s stack)
  Volume Mask: WeaponVolumes
  Post Processing: enabled (rare; usually disabled)

Place world Volume objects on Default and weapon-specific ones on WeaponVolumes. Each camera reads only its own layer.

Verifying

Take a screenshot before and after the fix. Compare bright emissive areas. After the fix, bloom should be roughly half as intense visually — the “double-applied” appearance is gone. Use the Frame Debugger (Window → Analysis → Frame Debugger) to confirm only one Bloom pass runs per frame; before the fix you’ll see Bloom listed twice.

“Post-processing runs per camera with PP enabled. Stack cameras compose final output once — not once per stack entry.”

Audit Camera Stack settings whenever bloom “suddenly” got stronger after a UI change.