Unreal Engine 4.18 Released

Unreal Engine 4.18 Released

The new version adds Volumetric Lightmaps, multi-bounce indirect lighting from Skylights, Find in Blueprints search and advanced Material Editor preview.

The new version adds Volumetric Lightmaps, multi-bounce indirect lighting from Skylights, Find in Blueprints search and advanced Material Editor preview.

Epic released another colossal update to Unreal Engine 4. The newest version (4.18) features a number of very cool additions and over a hundred of updates. Let’s have a look at some of the most interesting ones.

Volumetric Lightmaps

The new Volumetric Lightmaps enable high quality lighting on movable objects from low cost precomputed lighting! Characters, particle systems, instanced foliage, and other dynamic objects appear more grounded to the environment than ever before.

Volumetric Lightmaps store precomputed lighting at all points in space by covering the entire Lightmass Importance Volume with 4x4x4 bricks of lighting samples. Bricks are placed with higher density near static geometry, where indirect lighting is changing the most. This data structure allows efficient interpolation of indirect lighting to any point in space on the GPU. The Volumetric Lightmap is interpolated to each pixel instead of once for the whole component and has more reliable detail than our previous Indirect Lighting Cache method, resulting in fewer cases of light leaking.

For more information and details on using Volumetric Lightmaps in your project, see the Volumetric Lightmaps documentation.

Precomputed lighting on Volumetric Fog

Volumetric Fog now interpolates precomputed lighting to its position in space using Volumetric Lightmaps enabling Stationary lights – which have their indirect lighting stored in lightmaps – to affect fog. Static and Emissive lights affect fog without costing anything, since they’re all merged into the Volumetric Lightmap.

Skylights are also now shadowed properly, preventing indoor areas from becoming over-fogged.

1 – Uniform skylight on fog has leaking, 2 – Skylight on fog is shadowed properly


  • Volumetric Lightmaps on a third person character cost .02ms of GPU time on PlayStation 4. All Indirect Lighting Cache Rendering thread cost is removed.
  • Memory usage in Paragon’s Monolith map went from 5Mb with the Indirect Lighting Cache up to 30Mb with Volumetric Lightmaps at default DetailCellSize settings. Memory usage can be seen under ‘stat memory’.

Detailed Comparison

Volumetric LightmapPrecomputed Light Volumes / Indirect Lighting Cache
Efficient interpolation on GPUCostly interpolation on CPU
Per-pixel interpolationPer-object interpolation, even on instanced components
Applied to Volumetric FogCannot affect Volumetric Fog
Placed with high density around all static surfacesPlaced with high density only on top of static surfaces, frequent leaking from low density samples
Border voxels are stretched to cover area outside Importance VolumeBlack indirect outside Importance Volume
Does not currently support level streaming Supports level streaming

Improved Static Skylight Directionality

Skylights used to be represented to Lightmass with a third order Spherical Harmonic, which didn’t capture the detail present in a sunrise or sunset. We are now using a filtered cubemap with much higher resolution by default. Lightmass chooses the appropriate mip of the cubemap based on the size of the Final Gather rays to avoid aliasing. You can see the most difference in heavily occluded scenes, with a skylight cubemap that has a lot of brightness and color variation.

1 – Original Static Skylight, 2 – New filtered cubemap Static Skylight

The smaller the opening, the more directional sky lighting will become. It is even possible to recreate a pinhole camera effect with a small enough opening.

Multi-bounce Indirect Lighting from Skylights

We now have support for multiple indirect lighting bounces from static and stationary Skylights through a new ‘Num Sky Lighting Bounces’ setting in World Settings -> Lightmass. Thanks to forum user Luoshuang for the first implementation of this feature.

1 – Single skylight bounce, 2 – Multiple skylight bounces

Your materials need to have a high diffuse value for multiple skylight bounces to be noticeable in most cases. For example, with a diffuse value of .18 (18% grey), the second skylight bounce will only contribute .18^3 = .006 of the light’s emitted energy which is very subtle. With a diffuse value of .5, the second skylight bounce will contribute .125 of the light’s emitted energy and be noticeable.

As a bonus we also get multiple bounces from Emissive meshes:

Lightmass uses a Radiosity Solver to compute multiple bounces for Skylights and Emissive meshes. Each bounce increases non-distributable build times, so use with care.

Сlothing Tools

We have added a completely revamped toolset for creating and configuring clothing in the Skeletal Mesh Editor!

There is now a Clothing pane for editing an expanded set of clothing-specific properties that provide more control over clothing constraints, self collision vertex culling, inertia scaling. Enhanced paint tools enable painting per-vertex clothing parameters directly on the mesh. The new paint tools include: Brush, Gradient, Smooth, Fill. Painted parameters can be switched out instead of overwriting to aid iteration.

The clothing tools have been Integrated with Physics Assets for collision authoring. A new LOD pipeline for creating and replacing simulation meshes in a Clothing Data object that includes a parameter mapping system for mapping your painted parameters onto new LODs or replacement geometry which estimates lower detail LOD parameters from higher detail LOD parameters! It is also much easier to create clothing data in the Skeletal Mesh Editor by right clicking the mesh section to convert.

Improved Physics Asset Editor

The Physics Asset Editor (formerly known as PhAT) has been completely overhauled to significantly improve usability and expand functionality! The UI has a new look and feel with an upgraded Skeleton Tree view that provides better filtering and display of all scene elements and a new Graph view for setting up constraints between bodies visually using nodes. You can even set up of loops of constraints – something that was not possible before.

UI elements have been sanitized. Many things have moved or changed to more logical locations. For example, the Show menu now allows access to animation-related settings like in the Animation Editors. Animations can now be chosen at any time, paused, scrubbed etc. (previously this was only available once simulation had started). Simulation can also be engaged and disengaged at any time while animating and works in a similar way to the Level Editor, with a single prominent “Simulate” button and options underneath.

Additional Updates and Improvements:

  • Time dilation works with animation and physics together and is quickly set in the viewport menu, like in the Animation Editors.
  • Recording is now controlled from the transport controls like in other Animation Editors.
  • Physical animation and constraint profiles have a revamped UI. This allows easy selection, assignment and management of constraint and physics profiles.
  • Constraint & body mode are no more. We now display constraints and bodies together. Rendering of each can be enabled/disabled and filtered in the tree view & viewport.
  • New body creation has been moved to a new ‘Tools’ tab instead of the modal dialog we had before. This improves iteration times on new assets, removing 3 clicks each time. The same widget is re-used when we create new Physics Assets, as before.
  • Physics Assets can now be created directly from the Content Browser. Previously they could only be created from a hidden context menu option of Skeletal Mesh assets.
  • Operations that can be performed on bodies/constraints are now in all context menus, in addition to the keyboard shortcuts required previously.

Global Find in Blueprints

It is now possible to perform a “Find in All Blueprints” search without also requiring a Blueprint Editor window to be open. Up to 4 global “Find in Blueprints” tabs can now remain open and/or docked in a different window at any time. These are now available in the main “Window” menu.


In the Blueprint Editor menu, choosing Edit->Find in Blueprints (or pressing CTRL-SHIFT-F with the Blueprint Editor window in focus) will also now open a new global Find in Blueprints tab (or switch to the first global tab that’s open and unlocked). This tab will remain open even after the Blueprint Editor’s window is closed if the tab is open or docked somewhere outside of the Blueprint Editor’s window.

The global Find in Blueprints tab also includes a Lock button so that the current set of results can be locked to the current tab. Invoking Edit->Find in Blueprints from the Blueprint Editor will open up a new global Find in Blueprints tab if any of the currently-open tab(s) are locked.

Choosing Edit->Find (or pressing CTRL-F) in the Blueprint Editor menu will still open a local Find Results tab for performing a search within the current Blueprint only. Clicking the “Find in all Blueprints” button will allow you to perform the same search over all Blueprint assets in a global Find in Blueprints tab.

The new behavior can be switched off if necessary by unchecking the option titled “Host Find in Blueprints in Global Tab” in Editor Preferences->Blueprint Editor->Workflow.

Advanced Material Preview Viewport

The Material Editor and Material Instance Editor now have Advanced Preview Scenes for previewing your material in the viewport. This enables you to change view settings such as the scene lighting and environment cube map, as well as to rotate the environment around your preview mesh in the scene.

You can change the settings for the preview under Window > Preview Scene Settings.

You can find the full list of updates and improvements here. It’s a lot of reading.


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