Preview 1 of the upcoming 4.27 release is available now on the Launcher and GitHub. We are making this Preview available so you can try our new features and help us catch issues before the final release. As fixes are implemented, we will release updated previews throughout the development cycle.
Please be aware that preview releases are not fully quality tested, are still under heavy active development, and that they should be considered as unstable until the final release. Developers should not convert their projects for active development on preview releases. Please test on copies of your project instead.
Links to known and fixed issues for this release are provided below. If you discover any additional issues with this preview release, please report them using the guidelines in the link: How to Report a Bug.
Known & Fixed Issues
- Unresolved issues in 4.27 Preview targeted to be fixed by the 4.27 Release
- Unresolved issues in 4.27 Preview
- Issues fixed in 4.27 (the fix may not be included in the current available Preview)
4.27 Preview Summary
This list provides a brief summary of updates in this Preview which may benefit from additional testing. Not all updates may be listed. Full release notes will be made available with the final 4.27 release.
- Quartz Improvements. Updates include:
- Quartz can now run without an audio device, providing audio designers with the ability to run it on a dedicated server.
- Quartz has new Clock Handle Blueprint functions that provide audio designers with quality of life improvements - including starting, stopping and pausing the current clock.
- “NONE” has been added as an option to the Quantization enumeration to allow Quartz commands to execute as soon as possible.
Cinematic and Virtual Production Updates:
Take Recorder Shortcut. If the Take Recorder plugin is enabled, the Start Recording button will now appear in the playback controls. It can be used to start recording any selected actor into the current sequence, whether they are bound to that sequence or not.
Sequencer Director Shortcut. A shortcut to opening the Sequencer Director window has been added to Sequencer’s toolbar.
Property Multipliers. You can now multiply the properties of Template Sequence, allowing for scaling the intensities of animations and other properties from them. Right-click on a template sequence section and locate Property Multipliers.
Render Tool Selection. If the Movie Render Queue plugin is enabled, then the Render button in the Sequencer toolbar will now open Movie Render Queue. You can also specify which renderer you want to open with a dropdown menu next to it.
Object ID Groups. You can now specify Object ID groups in Movie Render Queue. Examples of groupings are by actor, material, folder, or layer.
Command Line Encoding. Movie Render Queue now supports Command Line Encoding, allowing for custom video render formats, such as using FFmpeg and the codecs it provides.
MRQ Config Asset Editing. Movie Render Queue config assets are now editable directly by opening the preset assets from the Content Browser. Previously these were only editable from the MRQ editor. This applies to Movie Pipeline Queue, Movie Pipeline Master Config, and Movie Pipeline Shot Config assets.
Virtual Camera Improvements. We continued to stabilize the Virtual Camera system, including improving Multi-User support for Virtual Camera.
Remote Control Improvements (Beta). We’ve made improvements to how you can remotely control the engine in a live environment. There have been several improvements so that you can control more properties and functions, and replicate them properly.
Remote Control Presets now support:
- Per-property metadata
- Rebinding properties
- Ability to expose custom events
- Actor functions
- Thumbnail previews over WebSockets
- Remote Control Replication over nDisplay
Remote Control Plugins for DMX, OSC, and MIDI. You can now use existing live show protocols, such as DMX, OSC, and MIDI, with the Remote Control system in Unreal Engine.
Remote Control C++ API. The Remote Control system now includes a C++ API to provide more ways to access and control the engine remotely. Previously, you could only access properties in the engine through web applications that used the Remote Control’s HTTP and WebSocket APIs. With the C++ API, you can now also control the engine and use the exposed Remote Control properties in external desktop applications.
UI Builder and Improved UX for the Remote Control Web Application. You can now quickly build complex web widgets without any code using the new drag-and-drop interface. We also redesigned the widget interfaces, and added more widget types focused on Virtual Production scenarios, including:
- Stage Position
- Wall Color Corrections
- Light Cards
- Level Snapshots
- Green Screens
nDisplay Improvements. This release, we focused on improving the user experience with nDisplay by redefining the workflow around setting up your nDisplay cluster. There’s a new nDisplay Root Actor to consolidate all nDisplay-related features and settings into one UAsset, and a 3D Config Editor to design your nDisplay setup.
This new workflow replaces the previous method of modifying configuration text files outside of the engine to create your nDisplay network. You can import previously created .cfg and JSON configuration files to convert them to the new UAsset format.
nDisplay Supports MipMaps on the Inner Frustum.
Improved mGPU Support in nDisplay (Beta). Effectively offload viewport rendering to another GPU using the improved mGPU feature for nDisplay. Increased parallelization and reduced lockstep overhead maximises further the expected performance gains from mGPU-enabled systems.
nDisplay Overscan (Experimental). By overscanning, you can now achieve continuity across multiple nDisplay render nodes for visually impactful post-processing effects such as bloom, ambient occlusion, and motion blur. Overscanning does come at a configurable performance cost.
This feature works with simple screens and projection policies, but more advanced policies, such as Mesh, are currently not supported.
Linux Support in nDisplay (Experimental). We added preliminary support for Linux in nDisplay and its tools ecosystem. Linux support is dependent on graphics card drivers, and some rendering features, such as ray tracing and Vulkan, are not currently supported.
nDisplay Synchronization. Leveraging previous work in 4.25 and 4.26 releases, we made improvements to Sync Policy #2 in both performance and usability. Improvements include:
- NVIDIA drivers 461.72 and later that support non-blocking present
- A refined internal sync render-thread barrier management, which will fix crashes and timing issues
- Exposed cvars to help with debugging
OpenColorIO Support in nDisplay. We added support for OpenColorIO in nDisplay to enable accurate color calibration that connects content creation in Unreal Engine to what the real world camera sees on the LED volume.
Level Snapshots (Beta). With Level Snapshots, you can record the current state of the level in a snapshot. Later, you can choose what to restore from that snapshot to update the level. This tool is especially useful for stage operators on a Virtual Production shoot because you can accommodate complex restore requests from filmmakers, such as “Go back to Take 6 and move all the trees, except for these five.”
Lens Distortion (Beta). Unreal Engine now supports Lens Distortion for projects using live camera tracking and live compositing. We created a Lens Distortion Shader based on the Brown-Conrady model and a new Lens Distortion Asset. The Lens Distortion Asset supports multiple zoom and focus calibration points and multiple STMaps.
We’ve also added support for Lens Distortion in Unreal’s tools, including:
- Live Link
- CG Layers with Composure
- Movie Render Queue
Live Link Improvements. We made improvements to Live Link, including adding rebroadcast support for virtual subjects.
Live Link FreeD Plugin (Beta). Live Link now supports the FreeD data protocol, which is a commonly used protocol for camera tracking and Pan, Tilt, Zoom (PTZ) cameras. Many PTZ cameras, such as the Panasonic AW-UE150 and the Sony BRC-X1000, are now supported through this protocol, and can be a cost-effective way to add tracking data to your projects.
Live Link VRPN Plugin (Beta). VRPN is a commonly used protocol for virtual reality and virtual production. The Live Link VRPN plugin allows multiple tracked devices to be distributed and replicated over nDisplay. This solution is replacing the previous workflow of setting up VRPN through nDisplay.
Frame-Accurate Sync of Videos with Sequencer and Movie Render Queue. Playback of videos with Media Framework will be frame-accurately synced to the timeline in Sequencer independently of the media player’s real-time behavior. Sequencer internally handles communication and setup for this synchronization with the media player.
Currently, only ImageMediaPlayer supports this new synchronization. If you use a media player that doesn’t support this feature, playback will start or stop close to what is indicated by the Sequencer timeline; however, frame-by-frame alignment could be random.
EXR Mipmap Support for Image Sequences in Media Framework. Media Framework’s image sequence playback now supports mipmapped EXR images. Mipmaps can be used in image sequences to reduce the amount of data loaded in. In UE, the mip level is selected based on an estimated pixel-to-texel density for each object displaying the image, unless otherwise set in the settings.
DMX Improvements. We continued to improve the DMX plugin, increasing its overall performance and stability under stress conditions, including improvements to protocol, Blueprint, and sACN. We also added integration with other engine features, such as Remote Control and nDisplay, and replaced Controllers by Ports with the new network settings DMX Ports.
DMX Pixel Mapping (Beta). We revamped the Pixel Mapping UI panel and core functionality. You can now effectively drive low-resolution panels or matrix fixtures by fetching the scene buffer, or any live texture, to generate the required DMX data at high performance.
Per-User Take Recorder Control in Multi-User. You can now control which nodes in a Multi-User session contribute to a Take Recorder capture. This means you can set nodes as recording nodes that contain additional simulated or animated data that is not visible to the Multi-User main operator.
Switchboard Improvements. We continued to improve Switchboard, adding the following features:
- Switchboard Listener remote binary updates
- Remote UE command execution on nDisplay nodes
- More telemetry information such as temperature and RAM usage
- Auto Multi-User server builds
- Improved p4 sync performance
- Ability to set the priority of launched Unreal and nDisplay processes
- Auto-scroll checkbox and line-wrap checkbox added to the log window
- nDisplay-only projects can set the name of the executable
Core, Iteration, and Cooking Updates:
Georeferencing. Georeferencing associates physical locations, like an area of a planet’s surface, with virtual locations, like UE4 levels. UE4 supports geographic, geocentric, and projected Coordinate Reference Systems to map real or fictional locations, including support for systems such as latitude/longitude and UTM coordinates, to your in-engine levels.
UE-As-Lib. With UE-As-Lib, you can build the UE4 runtime as a library and interact with it through a minimal, built-in API. This API starts UE4, optionally accepting a command-line and window handle, updates (ticks) it, receives Windows messages, and can shut it down. You can expand the API to suit your needs, exposing any existing or new functionality for external use.
Datasmith and Import Updates:
Datasmith Exporter Plugin for ArchiCAD. This release features a new Datasmith Exporter plugin for ArchiCAD. This plugin brings the Direct Link workflow and the ability to export .udatasmith files to Twinmotion and Unreal Engine-based applications.
- Geometry and hierarchy data exported in a structured way with Metadata
Datasmith Exporter Plugin for Sketchup. The Datasmith Exporter for Sketchup has been completely redone, adding support for the Direct Link workflow and Sketchup Pro 2021. This release also brings a new PBR Material graph, support for Metadata, and new batch exporting options.
Datasmith Exporter Plugin for Rhino Improvements. We have made a number of improvements to the popular Datasmith Exporter Plugin for Rhino. With this release, we have added Direct Link functionality between Rhino and Unreal Engine-based applications, such as Twinmotion.
- Support for a wide range of geometry modifiers
- Support for Worksessions
- Named views are now exported as Cameras
Datasmith Exporter Plugin Improvements. 4.27 brings the release of several enhancements and quality of life improvements to our existing Datasmith plugins. Beyond improvements to plugin stability and reliability we have added support for new versions of Rhino, Revit, 3ds Max, and Navisworks.
Visual Dataprep Improvements. Visual Dataprep provides you the ability to automate the process of importing and preparing your 3d data using a visual interface. In this release, we have made a number of enhancements and quality of life improvements:
- New Operators. A variety of new operators have been added, such as Plane Cut, Set Collision Complexity, Set Max Texture Size, and Select by Volume.
- UX Improvements. We have added a new Statistics panel, as well as added the ability to resize Action nodes.
- Core Improvements. We now have support for Actor components and per file format settings.
Universal Scene Description (USD) Improvements. This release features several enhancements to our Universal Scene Description (USD) toolset, with the largest focus being additional export options. This includes the ability to export Levels and Sublevels to USD, and support for Foliage and Landscapes. Unreal Engine 4.27 also features additional support for multi-user editing, additional options at runtime, and support for the Nvidia Material Definitions Language (MDL) schema.
Alembic Improvements. Unreal Engine continues to expand support for Alembic. We have expanded support for hair and fur by making it possible to bind Grooms to Alembic data that has been imported as a GeometryCache. We are also excited to introduce the ability to import an animated groom directly from Alembic to a GroomCache asset that can be used as part of a GroomComponent.
Design Configuration Template and Product Configurator Template Improvements. With Unreal Engine 4.27, we have released the Design Configurator template, an updated version of the Product Configurator template, into the Architecture, Engineering, and Construction category. This new template demonstrates the same interactive features and best practices for buildings as the Product Configurator template does for vehicles and products.
Both templates feature many UI enhancements and configurable interface options.
LiDAR Point Cloud Plugin Improvements. Unreal Engine 4.27 brings several enhancements to the LiDAR Point Cloud plugin that improve the import and manipulation of point cloud data.
This release contains the several improvements:
- Better Point Size Algorithm. The scalable algorithm has also been improved and a fixed point mode has been added. This new mode can be especially useful when working with a noisy asset.
- Improved Performance and Stability. Several improvements to the processing and streaming of the point cloud data have significantly improved performance for the end user.
- Improved Save/Load Performance. The serializer and streaming mechanic has been significantly improved.
- Simple Gap Filling. Points are enlarged and rendered using a new technique that minimizes visible overlap.
- Disable Frustum Culling. It is now possible to disable Frustum Culling which can help with the data stream delay when shooting cinematics.
- New Selection Methods. New Polygonal, Lasso, and Paint selection methods have been added.
Enhanced Input (Experimental). A streamlined but highly configurable input handling system supporting run time input remapping and complex customizable trigger rules.
Game Features and Modular Gameplay. Using the Game Features and Modular Gameplay plugins, you can create standalone features or data sets that are easy to add to, or remove from, your project. These plugins keep your project’s codebase clean and readable, while avoiding accidental interactions or dependencies between unrelated features. This is particularly important when developing live products that change their feature sets over time, or large and complex projects where minimizing unintended interactions between features is important for stability.
Data Registries. You can use Data Registries to load and cache global USTRUCT data based on discovery and caching rules that you configure. Data Registries provide an efficient way to store and access data from sources like data tables, integrate with the Game Features and Modular Gameplay plugins, and support dynamic resolution.
Mobile Rendering Improvements.The mobile rendering pipeline is improved, including both optimizations of existing features and newly available post-processes. The highlights of these improvements are:
- Distance Field Shadows, Fast Approximate Anti-Aliasing (FXAA), and Temporal Anti-Aliasing (TAA). These features are now available in the Mobile renderer.
- The Mobile Deferred Renderer. This feature’s performance and stability are significantly improved, and it runs on a wider range of Android devices. It also now supports Light Functions, IES light profiles, and simple lights.
Mobile Toolchain Improvements. We have revised the toolchains for iOS and Android in 4.27 to make them more useable and reliable.
- Android Toolchain Improvements
- Added Android memory profiler support.
- Added support for Visual Studio debugging for Android projects.
- Android Toolchain Improvements
Niagara Visual Effects Updates:
Module Versioning. You can now version a module, function, or dynamic input. This gives you flexibility when making your own modules, since you can set the functionality and save it to a version number. When you create a new version of the module, each time you add that module to your system you can choose which version of the module you want to use.
Behavior Examples. When you create a new Emitter you now have the option of selecting Behavior Examples. These are pre-filled emitters that are used to show one particular functionality within the Niagara system. They can help you to learn and explore Niagara functionality.
Niagara Debugger. This new panel gives you the option to turn on a HUD that will show detailed information about the Niagara system. It will also give you some options to help you debug your Niagara system in the Level Editor, such as:
- Play, pause, and stop Niagara simulations.
- Speed up or slow down Niagara simulations.
- Display detailed information on each particle in the system.
- Display a summary of information on each Niagara system in the level.
Debug Drawing. This functionality allows you to see a visual representation of some modules in Niagara systems, such as sphere, box, and more. You can debug your system and adjust the parameters of the module as needed.
Mesh Arrays in a Mesh Renderer. You can now add more than one mesh to a Mesh Renderer. By adding more than one mesh, you are creating a Mesh Array. You can either randomly spawn particles of those meshes, or you can use them in sequence as a flipbook.
Curve Editor Improvements.
- The Curve Editor within Niagara has been updated to match the Curve Editor in Sequencer. This gives you more advanced editing tools to adjust keys and retiming.
- Inline curve editors, which are displayed in the Selection panel, have also been updated. You can click on pre-made templates to quickly apply those commonly-used curves.
- There have also been performance improvements in the Curve Editor in this version, resolving an issue that was causing slowdown when dragging keys.
Parameter Definition Libraries. There is a new asset in Niagara called Parameter Definition Libraries. You can create a Parameter Definition Library to assign a collection of parameter definitions to a set of Niagara assets. Assets that use Parameter Definition Libraries are subscribed to those libraries, so that when a change is made to the source library that change is synchronized to the subscriber assets.
Select Node. There is a new node for Niagara scripts called the Select node. You can specify a selector type (integer, bool, or enum). You can use this node to define if, then statements. Depending on the value that is input into the Select node, it will output a specified value.
Hash Functions. There are two new nodes for hash functions, Hash Integer and Hash Float. By providing a set of integer inputs, they will output a random value. The difference between the Hash functions and the Seeded Random is that given the same inputs, Hash will always output the same value. In contrast, Seeded Random will generate a different output each time.
UX Improvements. There have been a number of UX improvements across the Niagara editor. This is included but not limited to:
- Auto-fill all options are available in the Filtered Bones and Filtered Sockets lists for Skeletal Meshes.
- Hotkey support for Niagara: J and K to cycle forwards and backwards in playback. S to isolate selected emitters. D to disable selected emitters.
- New and improved menus for Niagara scripts, modules, and dynamic inputs.
- Added a Library Only checkbox to the script actions menus.
- Suggested feature that lets you pre-label an asset as Suggested. These actions will appear at the top of the list as a section during search. In the case of dynamic inputs and modules they show at the top without searching.
- Many of the data interface functions now show helpful tooltips.
RAD Tools Integration:
Oodle Compression. Oodle Compression is now part of Unreal Engine, including the following products:
Oodle Data. This feature provides the fastest and highest ratio compressors for game data. Oddle Data Compression is now enabled by default in Unreal Engine, providing significant compression and faster loading for packaged projects.
Oodle Texture. This feature, combined with Rate Distortion Optimization (RDO), are the fastest and highest-quality encoders for block-compressed BC1-BC7 textures. Oodle Texture compression is enabled by default in Unreal Engine and RDO encoding can be enabled in the Project Settings.
Oodle Network. This feature provides a unique solution for real-time compression of network traffic, greatly reducing the bandwidth required by game servers. Oodle Network compression is used by Fortnite already, and can be turned on and trained for your game’s own network streams.
Path Tracer (Beta). Unreal Engine 4’s reference Path Tracer has now moved to Beta and is closing the gap between real-time Ray Tracing features. It includes physically correct and compromise-free global illumination, physically correct refractions, feature complete materials within reflections and refractions, and super-sampled anti-aliasing.
Improvements in 4.27 include, support for more Material Shading Models and Blend Modes, light transmission with glass (including approximate caustics), a wide range of light parameters, nearly unlimited number of lights in the scene, improved sampling techniques to reduce noise, support for Orthographic cameras, and improved support for Movie Render Queue.
GPU Lightmass (Beta) Improvements. GPU Lightmass continues to add improvements with features that include support for a wide range of light parameters, baking for Levels of Detail (LOD) meshes, colored translucent shadows, improved Multi-GPU (mGPU) support through Nvidia NVLink and SLI capable graphics cards, along with many bug and stability fixes.
Hair and Fur Rendering Improvements. Hair and fur rendering now supports two new cache-related features: attaching hair grooms to an Alembic Cache and the ability to import grooms that have already been simulated and contain cached per-frame hair data.
During import of an Alembic groom, the importer detects if the groom has animation or not. If so, it automatically generates two Groom Caches: one for the strands that have been animated and one for the guides that have been animated, which use simulation to animate the strands being rendered.
The Groom Cache can be assigned to a Groom Component using the Groom Cache assignment slot.
OpenXR Improvements. We added general improvements to the current set of features, and support for the following new features in Unreal Engine’s OpenXR plugin:
- Stereo Layers
- Splash Screens
- Motion Controller Visualization
Redesigned VRTemplate. We built the new VRTemplate using the OpenXR framework. The template is designed to be a starting point for all your VR projects. It includes encapsulated logic for teleport locomotion and common input actions, such as grabbing and attaching items to your hand.
The VR platforms currently supported by VRTemplate include:
- Oculus Quest 1 and 2
- Oculus Quest with Oculus Link
- Oculus Rift S
- Valve Index
- HTC Vive
- Windows Mixed Reality
Eye-Tracked Foveated Rendering (Experimental). Foveated Rendering is a technique that improves performance on VR devices by reducing image quality in the peripheral vision. Foveated rendering delivers a significant GPU performance boost with little perceptual loss of quality.
In 4.26, we offered support for fixed foveated rendering on Oculus Quest when running Vulkan. Now in 4.27, we’ve broadened our support to include eye-tracked foveated rendering using NVIDIA’s Variable Rate Shading (VRS).
This feature is currently only supported on Windows platforms with DX12 and GPUs that support VRS Tier 2.
Collaborative Viewer Template Improvements:
- Multi-scale support
- Section tool
- Works with Datasmith runtime, but the Datasmith files must be accessible by all participants