About AR Foundation

AR Foundation allows you to work with augmented reality platforms in a multi-platform way within Unity. This package presents an interface for Unity developers to use, but doesn't implement any AR features itself. To use AR Foundation on a target device, you also need separate provider plug-in packages for the target platforms officially supported by Unity:

AR Foundation is a set of MonoBehaviours and APIs for dealing with devices that support the following concepts:

  • Device tracking: track the device's position and orientation in physical space.
  • Plane detection: detect horizontal and vertical surfaces.
  • Point clouds, also known as feature points.
  • Anchor: an arbitrary position and orientation that the device tracks.
  • Light estimation: estimates for average color temperature and brightness in physical space.
  • Environment probe: a means for generating a cube map to represent a particular area of the physical environment.
  • Face tracking: detect and track human faces.
  • 2D image tracking: detect and track 2D images.
  • 3D object tracking: detect 3D objects.
  • Meshing: generate triangle meshes that correspond to the physical space.
  • Body tracking: 2D and 3D representations of humans recognized in physical space.
  • Colaborative participants: track the position and orientation of other devices in a shared AR experience.
  • Human segmentation: determines a stencil texture and depth map of humans detected in the camera image.
  • Raycast: queries physical surroundings for detected planes and feature points.
  • Pass-through video: optimized rendering of mobile camera image onto touch screen as the background for AR content.
  • Session management: manipulation of the platform-level configuration automatically when AR Features are enable or disabled.
  • Occlusion: allows for occlusion of virtual content by detected environmental depth (environment occlusion) or by detected human depth (human occlusion).

Platform support

AR Foundation does not implement any AR features itself but, instead, defines a multi-platform API that allows you to work with functionality common to multiple platforms.

Feature support per platform

You can refer to this table to understand which parts of AR Foundation are relevant on specific platforms:

ARCore ARKit OpenXR
Device tracking ✓ ✓ ✓
Plane tracking ✓ ✓
Point clouds ✓ ✓
Anchors ✓ ✓ ✓
Light estimation ✓ ✓
Environment probes ✓ ✓
Face tracking ✓ ✓
2D Image tracking ✓ ✓
3D Object tracking ✓
Meshing ✓ ✓
2D & 3D body tracking ✓
Collaborative participants ✓
Human segmentation ✓
Raycast ✓ ✓
Pass-through video ✓ ✓
Session management ✓ ✓ ✓
Occlusion ✓ ✓

Note: To use ARCore cloud anchors, download and install Google's ARCore Extensions for Unity's AR Foundation.

Supported platform packages

The following platform packages and later implement the AR Foundation features indicated above:

Package Name Version
Google ARCore XR Plug-in 5.0
Apple ARKit XR Plug-in 5.0
OpenXR Plug-in 1.2

Subsystems

AR Foundation is built on subsystems. A subsystem is a platform-agnostic interface for surfacing different types of information. The AR-related subsystems in this package uses the namespace UnityEngine.XR.ARSubsystems. For more details, see Subsystems.

Each subsystem handles specific functionality and is independent from other subsystems. For example, XRPlaneSubsystem provides the plane detection interface.

Providers

A provider is a concrete implementation of a subsystem. For example, the Google ARCore XR Plug-in package contains the ARCore implementation for many of the AR-related subsystems.

Because different providers have varying support for specific features, each subsystem also has a descriptor that indicates which specific subsystem features it supports. For example, the XRPlaneSubsystemDescriptor contains properties indicating whether it supports horizontal or vertical plane detection.

Each individual provider determines how to implement each subsystem. In general, they wrap that platform's native SDK (for example, ARKit on iOS and ARCore on Android).

Installing AR Foundation

To install this package, follow the instructions in the Package Manager documentation.

Provider plug-in setup

A provider plug-in is a separate package containing AR Foundation providers for a given platform. To use AR Foundation, you must also install at least one provider plug-in, either from the Package Manager or the XR Plug-in Management window as shown below.

XR Plug-in Management window
XR Plug-in Management window

Glossary

Term Description
Tracking The AR device's ability to determine its relative position and orientation in the physical world. If the environment is too dark, for example, the device might "lose tracking", which means it can no longer accurately report its position.
Trackable A real-world feature, such as a planar surface, that the AR device tracks and/or detects.
Feature Point A specific point in a point cloud. An AR device uses the device’s camera and image analysis to track specific points in the world, and uses these points to build a map of its environment. These are usually high-frequency elements, such as a knot in a wood-grain surface.
Session An AR instance.
Session Space The coordinate system relative to the beginning of the AR session. For example, session space (0, 0, 0) refers to the position at which the AR session was created. An AR device typically reports trackables and tracking information relative to its XR origin.

Using AR Foundation

Samples

For examples, see the ARFoundation Samples GitHub repository.

Scene setup

To create an AR experience using AR Foundation, there are two necessary components to have in your Scene: an ARSession and an XROrigin. To create an ARSession or an XROrigin, right-click in the scene Hierarchy window, and select one of the following options from the context menu.

  • XR > AR Session
  • XR > XR Origin (Mobile AR)

Create XR Origin and AR Session
Create XR Origin and AR Session

After adding both an ARSession and XROrigin to the Scene, the hierarchy will look like the one below.

Scene graph containing AR Session and XR Origin
Scene graph containing AR Session and XR Origin

This is the default Scene setup, but you can move, reparent, or further configure the components according to your project needs. These components and their configuration are explained in more detail below.

ARSession

The ARSession component controls the lifecycle of an AR experience by enabling or disabling AR on the target platform.

AR Session
AR Session

When you disable the ARSession, the system no longer tracks features in its environment. Then if you enable it at a later time, the system attempts to recover and maintain previously-detected features.

If you set Attempt Update to true, the device tries to install AR software if possible. Support for this feature is platform-dependent.

Note

Multiple ARSession components in the same Scene can conflict with each other, therefore Unity recommends that you only put one ARSession component in each Scene.

Checking for device support

Some platforms might support a limited subset of devices. On these platforms, your application needs to be able to detect support for AR Foundation so it can provide an alternative experience when AR is not supported.

The ARSession component has a static coroutine that you can use to determine whether AR is supported at runtime, as shown below.

public class MyComponent {
    [SerializeField] ARSession m_Session;

    IEnumerator Start() {
        if ((ARSession.state == ARSessionState.None) ||
            (ARSession.state == ARSessionState.CheckingAvailability))
        {
            yield return ARSession.CheckAvailability();
        }

        if (ARSession.state == ARSessionState.Unsupported)
        {
            // Start some fallback experience for unsupported devices
        }
        else
        {
            // Start the AR session
            m_Session.enabled = true;
        }
    }
}

Session state

To determine the current state of the session (for example, whether the device is supported, if AR software is being installed, and whether the session is working), use ARSession.state. You can also subscribe to the ARSession.stateChanged event to receive a callback when the session state changes.

ARSessionState Description
None The AR System has not been initialized and availability is unknown.
Unsupported The current device doesn't support AR.
CheckingAvailability The system is checking the availability of AR on the current device.
NeedsInstall The current device supports AR, but AR support requires additional software to be installed.
Installing AR software is being installed.
Ready AR is supported and ready.
SessionInitialized An AR session is initializing (that is, starting up). This usually means AR is working, but hasn't gathered enough information about the environment.
SessionTracking An AR session is running and is tracking (that is, the device is able to determine its position and orientation in the world).

XR Origin

The XROrigin component transforms trackable features, such as planar surfaces and feature points, into their final position, rotation, and scale in the Unity scene.

XR Origin
XR Origin

More specifically, the XROrigin transforms trackables from an AR device's "session space", which is an unscaled space relative to the beginning of the AR session, into Unity world space.

This concept is similar to the difference between "model" or "local" space and world space when working with other Assets in Unity. For instance, if you import a house asset from a DCC tool, the door's position is relative to the modeler's origin. This is commonly called "model space" or "local space". When Unity instantiates it, it also has a world space that's relative to Unity's origin.

Likewise, trackables that an AR device produces, such as planes, are produced in the platform's session space, relative to the device's coordinate system. The XROrigin provides a mapping from the platform's session space to Unity world space, allowing trackables to appear in the correct location in the Scene.

Scale

XROrigin also allows you to scale virtual content. To apply scale to the XR Origin, set its transform's scale. This has the effect of scaling all the data coming from the device, including the AR Camera's position and any detected trackables. Larger values make AR content appear smaller. For example, a scale of 10 would make your content appear 10 times smaller, while 0.1 would make your content appear 10 times larger.

Device targets

XROrigin is a shared class between AR Foundation and the XR Interaction Toolkit package. XR Interaction Toolkit is an optional additional package that can used to build AR experiences with Unity.

The default XROrigin in AR Foundation is pre-configured for mobile AR experiences; however, if you wish to target AR HMD's with handheld controller inputs, you can install XR Interaction Toolkit for additional XROrigin configurations. For more information on XROrigin configurations, see the full XROrigin documentation.

AR Camera Manager

The ARCameraManager component enables features for the AR Camera, including the management of the device camera textures and properties that set the light estimation modes. By default, there is an AR Camera Manager component on 'Main Camera', a child GameObject of XROrigin.

AR Camera Manager
AR Camera Manager

Setting Function
Auto Focus Enables or disables the hardware camera's automatic focus mode. When disabled, the focus is fixed and doesn't change automatically. Note: Availability of Auto Focus depends on camera hardware so this preference might be ignored at runtime.
Light Estimation Estimates lighting properties of the environment. There are five options:
  • Ambient Intensity: Estimates the overall average brightness
  • Ambient Color: Estimates the overall average color
  • Ambient Spherical Harmonics: Estimates the spherical harmonics describing the scene. Spherical harmonics are used to produce more realistic lighting calculations.
  • Main Light Direction: Estimates the direction of the primary light source. The direction points away from the light (so that it matches the light's direction).
  • Main Light Intensity: Estimates the brightness of the primary light source.
While you can request any of these simultaneously, support for each of these varies greatly among devices. Some platforms may not be able to be simultaneously provide all options, or it may depend on other features (for example, camera facing direction).
Facing Direction Controls which camera is used for pass through video. This can be World or User. On handheld mobile devices like phones and tablets, World refers to the rear camera and User refers to the front-facing (that is, "selfie") camera.

AR Camera Background

The ARCameraBackground component renders video feed from the device camera as the background of the Scene at runtime. This is not required, but common for AR apps. By default, there is an ARCameraBackground component on 'Main Camera', a child GameObject of XROrigin.

AR Camera Background
AR Camera Background

If set Use Custom Material to true, ARCameraBackground uses the Custom Material you specify for background rendering. The Custom Material property is optional, and typically you don't need to set it. The provider plug-in packages contain their own shaders for background rendering.

If you have multiple XROrigins (for example, to selectively render different content at different scales), you should use separate Cameras for each XROrigin and a separate, single AR Camera for the ARCameraBackground.

Configuring ARCameraBackground with the Universal Render Pipeline (URP)

See this additional documentation to configure an AR Foundation project with a URP.

Automatic occlusion

Some devices offer depth information about the real world. For instance, with a feature known as person occlusion, iOS devices with the A12 Bionic chip (and newer) provide depth information for humans detected in the AR Camera frame. Newer Android phones and iOS devices equipped with a LiDAR scanner can provide an environment depth image where each pixel contains a depth estimate between the device and physical surroundings.

Adding the AROcclusionManager component to the Camera with the ARCameraBackground component automatically enables the background rendering pass to incorporate any available depth information when rendering the depth buffer. This allows for rendered geometry to be occluded by detected geometry from the real world. For example, in the case of iOS devices that support person occlusion, detected humans occlude rendered content that exists behind them.

Copying the Camera Texture to a Render Texture when accessing the camera image on the GPU

Camera Textures are likely external Textures and might not last beyond a frame boundary. It can be useful to copy the Camera image to a Render Texture to persist it or process it further. The following code sets up a command buffer that will clear the render target and then perform a GPU copy or "blit" to a Render Texture of your choice immediately:

var commandBuffer = new CommandBuffer();
commandBuffer.name = "AR Camera Background Blit Pass";
var texture = !m_ArCameraBackground.material.HasProperty("_MainTex") ? null : m_ArCameraBackground.material.GetTexture("_MainTex");
Graphics.SetRenderTarget(renderTexture.colorBuffer, renderTexture.depthBuffer);
commandBuffer.ClearRenderTarget(true, false, Color.clear);
commandBuffer.Blit(texture, BuiltinRenderTextureType.CurrentActive, m_ArCameraBackground.material);
Graphics.ExecuteCommandBuffer(commandBuffer);

Note: Graphics.SetRenderTarget will overwrite the current render target after executing the command buffer.

Accessing the Camera Image on the CPU

See documentation on camera images.

AR Input Manager

The ARInputManager component enables world tracking; without it, the XROrigin can't acquire a world-space pose for the device. By default, an ARInputManager component is included on the ARSession GameObject.

AR Input Manager
AR Input Manager

You can move the ARInputManager anywhere in your Scene hierarchy, but you shouldn't have more than one per Scene.

Trackable managers

See documentation on trackable managers.

Visualizing trackables

Trackable components don't do anything on their own; they contain data associated with each trackable. There are many ways to visualize trackables, so AR Foundation includes some visualizers that you can use for debugging or as a starting point to create a visualizer suitable for your application.

Ray casting

See ARRaycastManager.

Meshing

See ARMeshManager.

Technical details

Requirements

This version of AR Foundation is compatible with the following versions of the Unity Editor:

  • 2021.2
  • 2021.3
  • 2022.1

* Apple and ARKit are trademarks of Apple Inc., registered in the U.S. and other countries and regions.