PostProcessingVolume

Overview

The PostProcessVolume actor in Unreal Engine 5 controls how the final rendered image is perceived by the player. It operates at the end of the rendering pipeline, after all scene elements—lighting, materials, atmosphere, and volumetrics—have already been calculated.

Rather than affecting the physical world itself, the PostProcessVolume modifies how that world is seen.

Where It Fits in the Pipeline

The rendering flow can be thought of as:

1. Geometry, materials, and lighting are rendered
2. Atmospheric and volumetric effects are applied
3. A final image is produced
4. PostProcessVolume modifies that image

This means PostProcessVolume does not change:

• Light intensity at the source
• Material properties
• Atmospheric scattering itself

Instead, it changes:

• Brightness and exposure
• Glare and bloom
• Color grading and tone mapping
• Depth of field and motion blur

Camera vs Human Vision

Many PostProcessVolume effects are designed to simulate a camera, not the human eye. Examples include:

• Lens Flare (internal lens reflections)
• Chromatic Aberration (lens distortion)
• Film Grain (sensor noise)

For projects aiming at realism—especially simulation-style environments—it is often preferable to treat PostProcessVolume as a model of human perception instead of a cinematic camera.

In such cases:

• Exposure represents eye adaptation
• Bloom represents retinal glare and light scatter
• Camera-specific artifacts are typically disabled

Volumes and Blending

PostProcessVolumes can be placed in the world as:

• Bound volumes (affect only a specific area)
• Unbound volumes (affect the entire world)

Multiple volumes can overlap and will blend together based on:

• Priority
• Blend weight
• Camera position

This allows different environments (e.g., indoors vs outdoors, clear vs cloud layer) to have different visual responses.

Overrides and Checkboxes

Each setting in the PostProcessVolume has a checkbox:

• Unchecked → Engine default or another volume controls the value
• Checked → This volume overrides the value

This is critical: > Values are ignored unless their checkbox is enabled

Key Systems Controlled

Commonly used PostProcess systems include:

• Exposure (Auto Exposure / Eye Adaptation)
  • Controls overall brightness and dynamic adjustment

• Bloom
  • Controls how bright light spreads into surrounding pixels

• Color Grading
  • Adjusts overall color tone and mood

• Depth of Field
  • Simulates focus blur (camera-style)

• Motion Blur
  • Simulates motion streaking (camera-style)

Practical Guidance

For physically grounded environments (such as planetary atmospheres):

• Treat PostProcessVolume as perception tuning
• Avoid relying on it to "fix" lighting problems
• First establish:
  • Directional Light intensity
  • SkyAtmosphere scattering
  • Volumetric behavior
• Then use PostProcessVolume to refine how the result is perceived

Summary

The PostProcessVolume is best understood as:

> A final-stage perception layer that controls how the rendered world appears to the player, rather than how the world itself behaves.

Settings

For the current Arms of Venus third-person fighter view, the PostProcessVolume should be tuned to simulate human eye adaptation and broad atmospheric glare, not cinematic camera artifacts. Local Exposure is currently left disabled to avoid haloing or cutout effects around the aircraft silhouette against the bright Venusian sky.

Bloom

Use Bloom to create a soft, overwhelming solar glare rather than stylized lens artifacts.

• Enable Bloom Intensity
  • Intensity: 1.2

• Enable Gaussian Intensity
  • Intensity: 1.2

• Enable Gaussian Threshold
  • Threshold: 0.0

• Enable Gaussian Advanced Size Scale
  • Size Scale: 6.0

• Enable Gaussian Advanced #1 Size
  • #1 Size: 0.5

• Enable Gaussian Advanced #2 Size
  • #2 Size: 2.0

• Enable Gaussian Advanced #3 Size
  • #3 Size: 8.0

• Enable Gaussian Advanced #4 Size
  • #4 Size: 24.0

• Leave the following disabled for now:
  • Preferred Method override
  • #5 Size
  • #6 Size
  • All Tint overrides
  • Entire Convolution section

Bloom Notes

• This setup is intended to create a continuous atmospheric glow around the sun rather than layered or ring-like bloom artifacts.
• Lens Flare should generally remain off for a naked-eye presentation, since lens flare is primarily a camera lens artifact rather than a human-vision effect.

Exposure (Auto Exposure / Eye Adaptation)

This is the Unreal system that simulates eye adaptation to changing brightness.

• Enable Min EV100
  • Min EV100: -2.0

• Enable Max EV100
  • Max EV100: 4.0

• Enable Speed Up
  • Speed Up: 3.0

• Enable Speed Down
  • Speed Down: 1.0

• Enable Exposure Compensation
  • Exposure Compensation: 0.5

• Leave the following disabled for now:
  • Metering Mode override
  • Exposure Compensation Curve
  • Exposure Metering Mask
  • Low Percent
  • High Percent
  • Histogram Min EV100
  • Histogram Max EV100
  • All other advanced histogram tuning

Exposure Notes

• Setting both Min EV100 and Max EV100 to the same value effectively disables adaptation. The values above restore controlled eye adaptation.
• Speed Up controls how quickly the eye adjusts when returning from darker viewing conditions.
• Speed Down controls how quickly the eye is overwhelmed by brighter conditions. A slightly slower value helps preserve the feeling of solar glare.
• This range should allow the environment to feel bright and hostile without causing the sun to completely destroy scene readability.

Local Exposure

• Disabled for now

Local Exposure Notes

• In a third-person fighter view, Local Exposure can sometimes create unwanted edge brightening or haloing around the aircraft when viewed against a bright sky.
• It may be revisited later if additional readability is needed, but the current preferred approach is to rely on:
  • global Exposure
  • Bloom
  • Sky Atmosphere scattering
  • directional light balance

Summary

The current PostProcessVolume philosophy is:

• Use Exposure for eye adaptation
• Use Bloom for solar glare and atmospheric overwhelm
• Do not rely on Lens Flare for naked-eye realism
• Leave Local Exposure off unless gameplay readability later demands subtle regional contrast assistance