The latest preview versions of AR Foundation / ARKit 4.0 provides support for the scene reconstruction feature that became available in ARKit 3.5 and is enabled on the new iPad Pro with LiDAR scanner. It is now available on Unity 2019.3 or later.
This new mesh functionality also requires Xcode 11.4 or later, and it only works on iOS devices with the LiDAR scanner, such as the new iPad Pro.
Using the LiDAR sensor, ARKit scene reconstruction scans the environment to create mesh geometry representing the real world environment. Additionally, ARKit provides an optional classification of each triangle in the scanned mesh. The per-triangle classification identifies the type of surface corresponding to the triangle’s location in the real world.
AR Mesh Manager
To use ARKit meshing with AR Foundation, you need to add the [ARMeshManager](https://docs.unity3d.com/Packages/com.unity.xr.arfoundation@4.0/api/UnityEngine.XR.ARFoundation.ARMeshManager.html) component to your scene.
Mesh Prefab
You need to set the [meshPrefab](https://docs.unity3d.com/Packages/com.unity.xr.arfoundation@4.0/api/UnityEngine.XR.ARFoundation.ARMeshManager.html#UnityEngine_XR_ARFoundation_ARMeshManager_meshPrefab) to a prefab that is instantiated for each scanned mesh. The [meshPrefab](https://docs.unity3d.com/Packages/com.unity.xr.arfoundation@4.0/api/UnityEngine.XR.ARFoundation.ARMeshManager.html#UnityEngine_XR_ARFoundation_ARMeshManager_meshPrefab) must contain at least a [MeshFilter](https://docs.unity3d.com/ScriptReference/MeshFilter.html) component.
If you want to render the scanned meshes, you will need add a [MeshRenderer](https://docs.unity3d.com/ScriptReference/MeshRenderer.html) component and a [Material](https://docs.unity3d.com/ScriptReference/Material.html) component to the [meshPrefab](https://docs.unity3d.com/Packages/com.unity.xr.arfoundation@4.0/api/UnityEngine.XR.ARFoundation.ARMeshManager.html#UnityEngine_XR_ARFoundation_ARMeshManager_meshPrefab)'s game object.
If you want to have virtual content that interacts physically with the real world scanned meshes, you will need to add [MeshCollider](https://docs.unity3d.com/ScriptReference/MeshCollider.html) component to the [meshPrefab](https://docs.unity3d.com/Packages/com.unity.xr.arfoundation@4.0/api/UnityEngine.XR.ARFoundation.ARMeshManager.html#UnityEngine_XR_ARFoundation_ARMeshManager_meshPrefab)'s game object.
This image demonstrates a mesh prefab configured with the required [MeshFilter](https://docs.unity3d.com/ScriptReference/MeshFilter.html) component, an optional [MeshCollider](https://docs.unity3d.com/ScriptReference/MeshCollider.html) component to allow for physics interactions, and optional [MeshRenderer](https://docs.unity3d.com/ScriptReference/MeshRenderer.html) & [Material](https://docs.unity3d.com/ScriptReference/Material.html) components to render the mesh.
Normals
As ARKit is constructing the mesh geometry, the vertex normals for the mesh are calculated. Disable [normals](https://docs.unity3d.com/Packages/com.unity.xr.arfoundation@4.0/api/UnityEngine.XR.ARFoundation.ARMeshManager.html#UnityEngine_XR_ARFoundation_ARMeshManager_normals) if you do not require the mesh vertex normals to save on memory and CPU time.
Concurrent Queue Size
To avoid blocking the main thread, the tasks of converting the ARKit mesh into a Unity mesh and creating the physics collision mesh (if the [meshPrefab](https://docs.unity3d.com/Packages/com.unity.xr.arfoundation@4.0/api/UnityEngine.XR.ARFoundation.ARMeshManager.html#UnityEngine_XR_ARFoundation_ARMeshManager_meshPrefab)'s game object contains a [MeshCollider](https://docs.unity3d.com/ScriptReference/MeshCollider.html) component) are moved into a job queue processed on a background thread. [concurrentQueueSize](https://docs.unity3d.com/Packages/com.unity.xr.arfoundation@4.0/api/UnityEngine.XR.ARFoundation.ARMeshManager.html#UnityEngine_XR_ARFoundation_ARMeshManager_concurrentQueueSize) specifies the number of meshes to be processed concurrently.
Other ARMeshManager settings
For the ARKit implementation, only these 3 settings affect the performance and output of ARKit meshing.
Meshing behaviors
Do note that it is typical for about 4 seconds to elapse after the meshing subsystem starts before the scanned meshes start to show up.
Additionally, the LiDAR scanner alone may produce a slightly uneven mesh on a real-world surface. If you add and enable an [ARPlaneManager](https://docs.unity3d.com/Packages/com.unity.xr.arfoundation@4.0/api/UnityEngine.XR.ARFoundation.ARPlaneManager.html) to your scene, then ARKit considers that plane information when constructing a mesh. ARKit smooths out the mesh where it detects a plane on that surface.