# Unreal SDK release notes Release notes for the **AR 51 Unreal SDK**. The core plugin connects Unreal Engine to an AR 51 capture server (**Mocap Unleashed**) and drives characters from live markerless capture; optional platform plugins add VR-headset input on top. Newest release first. The SDK ships as one package per Unreal Engine version. Each core release lists the engine versions it targets. :::note[Unified versioning from 2.4.0.0] From 2.4.0.0 onward, the core plugin and every platform plugin (LiveLink, OpenXR, Pico, Quest) ship under one shared version number each release, even in releases where a given plugin has no changes. ::: --- ## Core plugin ### 2.4.0.0 _2026-07 · UE 5.3 – 5.8 · since 2.3.2.4_ Adds a full bone-mapping and character-setup workflow to the core plugin, and moves the whole Unreal SDK — core plus every platform plugin — onto one shared version number per release. #### New - **Visual bone-mapping editor.** Map a character's bones to the AR 51 skeleton with a clickable body diagram, a 3D skeleton viewport, and hand/finger mapping diagrams, with live validation of anything left unmapped. - **Auto-Map.** Matches bones automatically using name/hierarchy heuristics and an alias library for common rig conventions, with per-joint auto-detect. - **Reusable per-character mapping asset.** Author a mapping once and reuse it across characters that share a skeleton. - **"Create AR 51 Character" workflow.** Right-click a Skeletal Mesh to turn it into an AR 51 character, with a validation inspector and one-click fixes. - **Foot bounds and sole-fit tools.** Define a character's foot bounds with an in-viewport visualiser and a sole-fit helper for accurate ground contact. #### Fixed - **Packaged games no longer abort on launch** (core and LiveLink) — removed an unused plugin dependency that shipped builds didn't actually include but the plugin descriptor still required. - **Builds cleanly on Unreal Engine 5.7** (core) — corrected an editor-only compile break against 5.7's updated viewport API. - **Android packaging** now builds on Unreal Engine 5.6–5.8. - **Precompiled core links cleanly** in consuming projects, with no unresolved-symbol errors. - **Pico and RenderStream plugins** now build and package (shipped with source). #### Plugins in this release This is the first unified (lockstep) release: from 2.4.0.0 every AR 51 Unreal plugin shares one version number per release. 2.4.0.0 covers five plugins: - **Core, LiveLink, OpenXR** — Unreal Engine 5.3–5.8. - **Pico** — Unreal Engine 5.4–5.5. - **RenderStream** (Disguise) — Unreal Engine 5.3–5.7. Pico and RenderStream follow each vendor's own SDK support. **Distribution:** the Core ships as a precompiled binary — one package per engine version; the LiveLink, OpenXR, Pico and RenderStream plugins each ship as a **single source package** (engine-agnostic — it compiles against your engine), and every plugin requires the matching Core. Win64 and Android. :::info[Wave and Oculus/Quest are retired from 2.4.0.0] The dedicated **Wave** (VIVE Wave) and **Oculus/Quest** plugins are **not part of 2.4.0.0**. HTC deprecated WaveVR in favour of ViveOpenXR, and Epic folded OculusVR into OpenXR — so **HTC Vive and Meta Quest are now supported through the [OpenXR plugin](/docs/unreal-sdk/vr-platforms/htc-vive-openxr/)**. Their last builds remain available under earlier versions. ::: --- :::note[Separate versioning for 2.3.2.4 and earlier] For 2.3.2.4 and earlier, the core plugin and each platform plugin (LiveLink, OpenXR, Pico, Quest) were versioned independently — version numbers don't line up across plugins the way they do from 2.4.0.0 onward. ::: ### 2.3.2.4 _2026-03 · UE 5.6 – 5.8 · since 2.3.1.74_ Extends support to the latest Unreal Engine versions, with mapping and tracking refinements. #### Improved - Character mapping now works without requiring the Blueprint `_C` class suffix by default, while remaining backward compatible with existing setups. - Multi-bone forearm/wrist twist for more natural arm deformation. - OpenXR reports hands correctly when the anchor is applied to the camera. #### Compatibility - Adds support for **Unreal Engine 5.6, 5.7 and 5.8** (building on the 5.3–5.5 line). - Existing bone mappings and characters from the 2.3.1 line continue to work. --- ### 2.3.1.74 _2025-09 to 2025-10 · UE 5.3 – 5.5 · since 2.3.1.73_ Focused on lower latency, tighter control over which people are tracked, and steadier VR hand tracking. #### New - **Active-person camera space.** Choose whether the "active person" is picked in the camera's local space or in world space. - **Skeleton count limit.** Cap how many skeletons are consumed at once (unlimited by default). - **Capture timestamp access.** Read the timestamp of the most recent skeleton frame from Blueprints. #### Improved - **Lower end-to-end latency** through linear prediction on incoming skeleton data. - **Steadier VR hands.** Fingers are only applied when wrist confidence is valid; on bad headset data the last good hand pose is held instead of jittering. - Tracking-loss compensation is now off by default for more predictable behaviour. #### Compatibility - Targets **Unreal Engine 5.3, 5.4 and 5.5**, with broad backward-compatibility work down to UE 4.27 / 5.3. --- ### 2.3.1.73 _2025-05 · UE 5.3 – 5.4 · since 2.3.1.51_ A tracking-quality release that rolls up the spring-2025 IK and twist work. #### Improved - **Better tracking-loss compensation.** Putting on or removing a headset no longer triggers a false tracking-lost correction. - **VR fingers from the server** are respected — hands are not re-solved when the headset already provides them. - **Calf and hand correction scaling** to fix anatomical mismatches (foot-rotation artefacts and hand auto-scaling). - Single- and multi-joint **forearm twist** solving. #### Fixed - Corrected anchor transform maths so anchored content is placed correctly. - Graceful fallback when a character asset is missing, plus guards against unstable frame timing. --- :::note[Version boundaries] For versions before 2.3.1.73, changes are grouped to the nearest version rather than the exact build. ::: ### 2.3.1.51 _2025-05 · UE 5.3 – 5.4 · since 2.3.1.46_ Adds flexible control over how detected people are matched to characters. #### New - **Auto character-assignment modes** — Default, Cycle and Random — for deciding which character a newly detected person drives. - **Assign a character by Person ID or Entity ID** (by name or index) from Blueprints. - **Main-camera override** with Blueprint get/set. - **Anchor lifecycle events** (created / destroyed) and hand-stream start/stop events. #### Improved - **Confidence-aware solving.** Low-confidence joints are excluded from auto-scaling and rotation, and per-joint confidence is exposed on each person. - Stability hardening to avoid touching components after they have been cleaned up. #### Compatibility - The singleton accessor was renamed; the previous accessor still works but is **deprecated** and reports guidance to move to the new one. --- ### 2.3.1.46 _2025-02 · UE 5.3 · since 2.3.1.27_ #### Improved - **Unified platform-plugin model.** Each platform now registers a single plugin, simplifying which platform plugins you enable for OpenXR, RenderStream and others. - Quest hand tracking now roots its transform on the camera anchor for correct placement. --- ### 2.3.1.27 _2025-01 · UE 5.3 · since 2.3.1.19_ #### New - **Expanded Blueprint API.** Many skeleton-consumer and per-person operations are now callable from Blueprints, including resetting a character or the active character, plus an **active-person-changed** event. #### Improved - Both hands are now handled symmetrically before being broadcast. - The camera anchor is the default scene component, and each person can report the capture device it came from. --- ### 2.3.1.19 _2024-11 to 2024-12 · UE 5.3 + Android · since 2.3.1.10_ #### New - **Network overrides for advanced setups.** Override the local IP and the server address to skip auto-discovery, and exclude specific ports when opening connections. - **Object detection improvements.** Markers can carry a map rather than a single point, and objects can be attached to markers. - **Stable public API surface.** A clean integration interface is exposed without internal networking headers, giving integrators a stable surface to build against. #### Improved - **Android support** and multi-target packaging. - Switching a person's character at runtime, per-device ID overrides, and a skeleton parent-constraint component. #### Fixed - Crash fixes around shutdown with two editor instances and around person creation. --- ### 2.3.1.10 _2024-10 · UE 4.27 / 5.1 / 5.3 / 5.4 · initial packaged release_ The first packaged AR 51 Unreal SDK. #### New - Self-contained package that bundles the libraries it needs so the plugin runs on other machines. - Skeleton-to-character bone remapping, an inverse world-anchor constraint, and an adjustable hand-smoothing factor. - Unreal Engine 5.4 support alongside the existing 4.27 / 5.1 / 5.3 targets. --- ## Platform plugins Optional plugins that add VR-headset input or external integrations on top of the core plugin. Enable only the one(s) for your target setup. ### LiveLink plugin Streams AR 51 capture into Unreal's Live Link framework, so AR 51 subjects appear alongside your other Live Link sources. - **2.4.0.0** _(2026 · UE 5.3 – 5.8)_ — Aligned to the unified Unreal SDK version; fixed a packaged-build launch failure caused by an unused plugin dependency (same underlying fix as the core plugin). - **2.3.2.4** _(2026 · UE 5.6 – 5.8)_ — Compatibility updates for Unreal Engine 5.6 and 5.8. - **2.3.1.48 / 2.3.1.47** _(2025 · UE 5.3 – 5.5)_ — Improved clavicle handling; the Live Link source factory is now public so integrators can reference it directly. (2.3.1.48 is a version bump over the same 2.3.1.47 codebase.) - **2.3.1.10** _(2024 · UE 4.27 – 5.4)_ — Initial packaged Live Link support: multiple person subjects, virtual-subject management, a show-model option, and play-in-editor guards so AR 51 code only runs when appropriate. Ships with source. ### OpenXR plugin Adds OpenXR headset and hand-tracking input, and is the recommended path for both **HTC Vive** and **Meta Quest** headsets. - **2.4.0.0** _(2026 · UE 5.3 – 5.8)_ — Aligned to the unified Unreal SDK version; the maintained VR path for HTC Vive and Meta Quest. - **2.3.1.47** _(2025 · UE up to 5.6)_ — OpenXR now reports hands when the anchor is applied to the camera; hand-adapter fix. - **2.3.1.46** _(2025 · UE 5.3)_ — Device-platform specifiers added; a new OpenXR sample map; **fixed** a case where OpenXR on Quest never switched to "tracked," so finger input never arrived. OpenXR now registers on all platforms regardless of the selected platform. - **2.3.1.10** _(2024 · UE 4.27 – 5.3)_ — Initial OpenXR support: 3D hand visualisation, palm-width gating to reject spurious tiny hands, and guardian checks only while the headset is worn. ### Pico plugin VR input for **Pico** headsets. - **2.4.0.0** _(2026 · UE 5.4 – 5.5)_ — Now builds and packages as part of the unified release (shipped with source). - **2.3.1.51** _(2025 · UE 5.3)_ — First Pico release. Calibrates and renders hands on UE 5.3; hand material is configurable from Blueprint, hands are red by default to distinguish them from Pico's own hand rendering, hands are hidden by default, and there is an option to hide hands below a confidence threshold. ### RenderStream plugin Drives AR 51 characters inside **Disguise RenderStream** workflows. - **2.4.0.0** _(2026 · UE 5.3 – 5.7)_ — Now builds and packages as part of the unified release (shipped with source). ### Quest plugin (legacy — retired at 2.4.0.0) :::warning[Legacy — use the OpenXR plugin for Quest] The standalone Quest plugin is **not part of 2.4.0.0** and is no longer developed — Epic folded OculusVR into OpenXR. For Meta Quest headsets, use the **OpenXR plugin**, the maintained path (it also fixes Quest finger tracking). The last Quest build is 2.3.1.13. ::: - **2.3.1.13 / 2.3.1.12** _(2024 · UE 5.3 · Android)_ — Legacy Quest headset input (hand tracking via the Oculus/Quest integration). Superseded by the OpenXR plugin. ### Wave plugin (legacy — retired at 2.4.0.0) :::warning[Legacy — use the OpenXR plugin for HTC Vive] The dedicated VIVE **Wave** plugin is **not part of 2.4.0.0**. HTC deprecated the WaveVR Unreal SDK in favour of ViveOpenXR, so HTC Vive now runs through the **OpenXR plugin**. Earlier Wave builds remain available under prior versions. :::