Post Process Effects

Post-processing effects enable artists and designers to define the overall look and feel of the scene through a combined selection of properties and features that affect coloring, tonemapping, lighting, and more. A special type of volume, called a Post Process Volume, can be added to a Level to access these features. Multiple volumes can be placed to define the look of a specific area, or it can be set to affect the entire scene.

Using Post Process Volumes

You can add a Post Process Volume into your Level using the Place Actors panel.

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Once placed in the Level, use the Details panel to access all the available properties and features. You'll find that they are broken up into categories for the type of feature they are and what they affect.

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The Post Process Volume Settings are specific settings for this placed volume and how it interacts with the scene and with any other Post Process Volumes it may overlap with. For example, you can toggle the Infinite Extent property to make this Post Process Volume affect everywhere in the scene, or leave it unchecked to have it affect only a certain area. When Volumes overlap, you can control how they interact with one another to blend from one to another, which is useful when you have radically different looks between them.

Post Process Features and Properties

Access a Post Process Volume's properties and settings by selecting one placed in the Level. The Details panel will list the available categories and their available properties.

Unreal Engine uses some default post processing settings, even if you don't have a placed Post Process Volume in your Level. These default post process settings can be found and configured in the Project Settings in the Rendering > Default Settings section.

Configuring these options can be useful for Level Editing to stabilize auto exposure or bloom before you start working on defining the look of the scene.

Lens

The Lens category contains properties and settings that simulate common real-world effects from a camera lens.

Depth of Field

Similar to what happens with real-world cameras, Depth of Field applies a blur to a scene based on the distance in front of, or behind, a focal point. The effect is used to draw the viewer's attention to a specific subject in the shot based on depth. It also adds an aesthetic which makes the rendered image appear more like a photograph, or film.

There are two depth of field options available:

• Cinematic Depth of Field is used for desktop and console platforms. It provides a filmic look with properties that align with those found on real-world cameras. The Post Process Volume provides some settings, but primarily the camera properties found on a Cinematic Camera Actor should be used to control depth of field.
• Mobile Depth of Field is an optimized, low-cost option that works for mobile platforms. It uses gaussian blurring to set a focal region with near and far transition areas.

For more information, see Depth of Field

Bloom

Bloom is a lighting artifact of real-world cameras that also adds to the perceived realism of the rendered image by reproducing glow around lights and reflective surfaces. Bloom is an effect that works with other effects, like lens flares and dirt masks, but those are not covered by the general bloom properties.

For more information, see Bloom

Exposure and Local Exposure

The engine automatically controls exposure — though it's sometimes called eye adaptation — which adjusts how bright, or dark, the scene becomes for the current view based on current scene luminance. This effect recreates the experience of human eyes adjusting to different lighting conditions, like when walking from a dimly lit interior to a brightly lit exterior, or the other way around.

The Exposure category contains properties to select the type of exposure method to use and to specify how bright or dark it should allow the scene to become over a given time.

There is an additional control for exposure called Local Exposure that has its own category or properties. These properties apply local adjustments to exposure (within artist-controlled parameters) using edge-aware data structure while preserving luminance detail. This makes it particularly useful in challenging high contrast scenes, such as indoor scenes with very bright outdoors that are visible through doors and windows.

For more information, see Exposure

Chromatic Aberration

Chromatic Aberration is an effect that simulates the color shifts in real-world camera lenses. It's a phenomena where light rays enter a lens at different points causing separation of RGB colors.

Dirt Mask

The Dirt Mask is a texture-driven effect that brightens up the Bloom in defined areas of the screen. It can be useful to create a specific look of a camera lens and its imperfections, or something like dirt and dust that has gotten on the lens.

Camera

A set of properties controlling the camera shutter and cinematic depth of field.

Full properties and physically based properties of the camera should be set on the Cinematic Camera Actor.

Lens Flare

The Lens Flare effect is an image-based technique that simulates the scattering of light when viewing bright objects due to imperfections in the camera lens.

Image Effects: Vignette

Vignette is an image-based effect that creates a borderless window that fades the image out towards the edges.

Vignette Intensity controls darkening of the screen corners to create a borderless window from the rendered image to the edge of the window. Larger values increase the amount of vignetting. 0 is no vignetting.

Color Grading and Tonemapper

Color Grading and Film are two categories that work together to define a large part of the look of your project. The Color Grading category contains properties that allow for color correction of the rendered scene.

Color Grading

The Color Grading category includes properties to control the contrast, color, saturation, and much more for full artistic control of the look of the scene.

You'll find sections for:

• Color temperature control
• Color balance properties for global, shadows, midtones, and highlights
• Additional miscellaneous properties, such as expanded gamut and look-up tables (Luts)

For more information, see Coloring Grading and Filmic Tonemapper

Additional Color Grading Topics

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Film

The Film category includes properties that meet the Academy Color Encoding System (ACES) for television and film. These properties ensure that consistent color is preserved across multiple formats and displays while also future proofing the source material to not have to adjust it for each new medium that comes along.

The properties in this category enable you to set values that mimic different types of film stock.

For more information, see Coloring Grading and Filmic Tonemapper

Global Illumination

The Post Process Volume Settings for Global Illumination enable you to select the type of dynamic global illumination to use, advanced properties enable you to adjust the intensity and color of some global illumination methods, such as precomputed lighting.

Dynamic global illumination methods can be selected from from the Method dropdown menu:

• Lumen Global Illumination and Reflections
• Screen Space Global Illumination
• Ray Tracing Global Illumination

Under the Advanced section, the Indirect Lighting Color and Indirect Lighting Intensity to use a color picker to adjust the color of the indirect lighting and intensity will increase or lessen the amount of indirect lighting being applied.

For more information, see Global Illumination.

Lumen Global Illumination

Lumen Global Illumination is a fully dynamic global illumination system that works with all lights, emissive materials casting light, and sky light occlusion. It renders diffuse interreflection with infinite bounces and indirect specular reflections in large, detailed environments at scales ranging from millimeters to kilometers.

The only property available is the Final Gather Quality property that scales Lumen's the amount of noise artifacts that are visible. Larger scales reduce noise, but greatly increase GPU cost.

Screen Space Global Illumination

Screen Space Global Illumination is a low-cost dynamic global illumination method, but it is limited to information visible on the screen. It's best used as an additive feature with precomputed lighting data from CPU Lightmass or GPU Lightmass.

There are not any properties to adjust in the Post Process Volume settings, but you can increase the quality using console commands found under r.SSGI.*.

Ray Tracing Global Illumination

Ray Traced Global Illumination (RTGI) is deprecated and may be removed in a future release.

Requires that Support Hardware Ray Tracing and DirectX 12 be enabled for the project.

Ray Tracing Global Illumination

Reflections

The Post Process Volume settings enable you to select from the types of dynamic reflections you want to use with the Method dropdown selection.

Choose between:

• Lumen Global Illumination and Reflections
• Screen Space Reflections
• Standalone Ray Traced Reflections

For more information, see Reflections Environment

Lumen Reflections

Lumen reflections are part of the dynamic lighting system Lumen Global Illumination and Reflections. It works the vast majority of features to support all lights, emissive materials casting light, and sky lighting.

Lumen only has a single Quality property which scales the reflection noise quality. Larger scales reduce the amount of noise in reflections, but greatly increases GPU cost.

Screen Space Reflections

Screen Space Reflections are a low-cost, view-dependent reflection system, but it is limited to information present within the current screen view.

Ray Tracing Reflections

Ray Tracing Reflections is deprecated and may be removed in a future release.

Requires that Support Hardware Ray Tracing and DirectX 12 be enabled for the project.

Ray Tracing Reflections simulate physical light properties with multiple bounces of light on surfaces.

Rendering Features

The following are general rendering features that are set and controlled by the Post Process Volume.

Post Process Materials

Post Process Materials allow for materials that have their Domain set to Post Process to create visual screen effects. These can be used for just about anything you can do in a material and have that affect gameplay or the visual look of the scene. For example, it can be used for applying a damage effect, creating a stylized or video effect to the screen.

For more information, see Post Process Material

Ambient Cubemap

The Ambient Cubemap lights the scene from a provided cubemap texture. The image is mapped to a sphere in the far distance (implemented as a cubemap texture with mipmaps storing pre-blurred versions of the image). The pre-blurred versions of the cubemap are computed in a way that they can be used for specular highlighting with varying glossiness (sharp versus blurry reflections), and they can be used for diffuse lighting as well. This effect is independent of the position a material is lit from. Viewer position, material roughness (for specular effects), and the material surface normal are all taken into account.

The Ambient Cubemap has limited local shadowing (screen space ambient occlusion only). Use a Sky Light instead when representing the sky's lighting. The Ambient Cubemap is only intended to be used for a subtle directional ambient term (useful in games with completely dynamic lighting), or for model viewer applications. Because light comes from many directions, it cannot simply use shadowmaps for this light type. Screen Space Ambient Occlusion is applied to get contact shadows from nearby geometry.

Ambient Occlusion

The Ambient Occlusion properties control the screen space effect called Screen Space Ambient Occlusion (SSAO), which approximates the attenuation of light due to self-occlusion. This is a screen space effect that is limited to information available within the current view. Ambient Occlusion is generally used as a subtle effect, in addition to global illumination, that darkens corners, crevices, and other features to bring a more natural, realistic look to the scene.

Ray Tracing Ambient Occlusion

Requires that Support Hardware Ray Tracing and DirectX 12 be enabled for the project.

Ray Tracing Ambient Occlusion (RTAO) accurately shadows areas to ground objects in the environment. Similarly to baked lighting, ambient shadowing is not screen space dependent. RTAO adds depth to the scene, producing natural looking shadowing in indirectly lit areas, such as under objects, or in corners and crevices.

For more information, see Hardware Ray Tracing.

Motion Blur

Motion Blur is the blurring of objects based on its motion. In photography and film (like with a sequence of frames), motion blur is the result of an object moving before the image has been captured, creating the blurring effect that is seen. Depending on how fast the object is moving can determine how much motion blur there is for the object.

The motion blur system in the engine uses a full screen velocity map, and objects are blurred based on their contribution to this map. The following properties control the contribution of objects in the scene to the velocity map.

Motion blur is visualized in the editor using the Level Viewport Show > Visualize > Motion Blur.

Ray Tracing Translucency

This feature of ray tracing is deprecated and may be removed in a future release.

Requires that Support Hardware Ray Tracing and DirectX 12 be enabled for the project.

The Post Process Volume settings enable you to decide how you want translucency to be rendered, with traditional raster translucency or ray-traced. Ray Tracing Translucency uses rays to trace the path of light through translucent materials based on real-world physical properties.

For more information, see Hardware Ray Tracing.

Path Tracing

The Path Tracer is a progressive, hardware-accelerated rendering mode that produces physically correct global illumination, reflections, refractions, and more. It shares the same ray tracing architecture as Hardware Ray Tracing to create comparable results to offline renders.

When path tracing is enabled for the Level Viewport (View Modes > Path Tracing), the properties in the category enables you to configure how the path tracer accumulates samples and renders the frame.

For more information, see Path Tracer

Film Grain

Film Grain is an optical effect that simulates the look of processed photographic film. It can appear as tiny, randomized particles and adds a filmic look to the rendered frame.