WorldAnchorTransferBatch.ImportAsync never completes

I need to share anchors between different apps on the Hololens, so I followed the guide at

https://docs.microsoft.com/en-us/windows/mixed-reality/shared-experiences-in-unity

to store the anchor information into a byte array. When I try to load the anchor from this byte array the call to WorldAnchorTransferBatch.ImportAsync never completes (i.e., a Debug line in the OnComplete function never gets called even if I wait for 15 minutes).

Here is a rough outline of the code:

Code (CSharp):

1. byte[] anchordata = new byte[] {};
2. bool completed_storing=false;
3.  
4. public void StoreAnchor()
5. {
6.     UnityEngine.XR.WSA.Sharing.WorldAnchorTransferBatch transferBatch = new UnityEngine.XR.WSA.Sharing.WorldAnchorTransferBatch();
7.     transferBatch.AddWorldAnchor("Anchor", this.gameObject.GetComponent<UnityEngine.XR.WSA.WorldAnchor>());
8.     UnityEngine.XR.WSA.Sharing.WorldAnchorTransferBatch.ExportAsync(transferBatch, OnExportDataAvaliable, OnExportComplete);
9. }
10.  
11. private void OnExportDataAvaliable(byte[] data)
12. {
13.     anchordata = anchordata.Concat(data).ToArray();
14. }
15.  
16. protected void OnExportComplete(UnityEngine.XR.WSA.Sharing.SerializationCompletionReason completionReason)
17. {
18.     if (completionReason != UnityEngine.XR.WSA.Sharing.SerializationCompletionReason.Succeeded)
19.     {
20.         Debug.Log("Failed Export: " + completionReason.ToString());
21.     }
22.     else
23.     {
24.         Debug.Log("export completed");
25.         completed_storing = true;
26.     }
27. }
28.  
29. void Update()
30. {
31.     if (completed_storing)
32.     {
33.         completed_storing = false;
34.         Debug.Log("loading");
35.         UnityEngine.XR.WSA.Sharing.WorldAnchorTransferBatch.ImportAsync(anchordata, OnImportComplete);
36.     }
37.  
38. private void OnImportComplete(UnityEngine.XR.WSA.Sharing.SerializationCompletionReason completionReason, UnityEngine.XR.WSA.Sharing.WorldAnchorTransferBatch deserializedTransferBatch)
39. {
40.     Debug.Log("Loading completed");
41. }

The same problem persists when I store the information to a file and try to load it on program start.

I have built and deployed the application in .NET and IL2CPP to the actual Hololens. The Debug information (and the file stored on the device) shows that the anchor is about 5-10 MB. I tried building the app in Unity 2017.4, 2018.2.4, 2018.3 with the same result.

Has anyone else experienced something similar?

 

That raises several questions, why would I need a store if WorldAnchorTransferBatch works for each anchor object (from the documentation it is not clear that a store is required in any way).

Even adding the anchor to the store through

Code (CSharp):

1.  
2.  
3. UnityEngine.XR.WSA.Persistence.WorldAnchorStore store;
4. UnityEngine.XR.WSA.Persistence.WorldAnchorStore.GetAsync(StoreLoaded);
5.  
6. and
7.  
8. store.Save("Anchor", this.gameObject.GetComponent<UnityEngine.XR.WSA.WorldAnchor>());
9.  

changes nothing. It I use only WorldAnchorStore to save and load the anchor it works perfectly, which is ok if I run only 1 app. But it does not allow sharing with other applications that should reuse the same anchor.

For now I am making a workaround where all apps are bundled into a single app and the user can select which one he wants to execute.

 

Sorry to ressurect this old thread, but this is currently an issue for me too. I am trying to Import an anchor from a file, but the ImportAsync onComplete method is never called. My anchor is roughly 16MB.

 

Hi, thanks for your reply. I actually am using legacy XR support in Unity 2019.4 and targeting UWP for HoloLens 2 deployment. When I try to Import the anchor, my app either freezes (anchor bytes transfered via socket; anchor is available upon restart), or does nothing (anchor bytes via file; anchor never becomes available)