Inconsistency when locating the same anchor multiple times

[Connor-Kerwin]

Description

Locating an anchor twice results in the second anchor locate result being invalid. It seems as though the anchor cache does not return a valid anchor when you relocate. I'm wondering if it's a package bug, because If I set my AnchorLocateCriteria BypassCache value to true, the issue goes away.

Steps to reproduce the issue

• Create a watcher with an AnchorLocateCriteria with:
  • Identifiers = Some Identifier
• Wait for the located event to fire
• Create a CloudNativeAnchor
• Invoke CloudToNative on the object with the result of the locate event
• The anchor appears at the correct place...
• Repeat these steps again...
• The anchor does not appear anywhere at all (not just inaccurate, completely missing)

Expected behavior

I'd expect that the second locate operation would result in the anchor being positioned at the same location as the first anchor.

Development information (please complete the following information)

• OS: Windows
• Development Platform\Version: Visual Studio 2022, Unity 2020.3.19f1
• Azure Spatial Anchors SDK version: 2.12.0

AR Device information (please complete the following information):

• Device: HoloLens 2
• OS: 10.0.19041:1157

Additional context

I did some additional debugging, printing out the LocalAnchor pointer values; they had different values. I'm not sure if this is expected:

[TRACE] Received located event for ID:'66f03ce1-634d-42bd-bd86-19ddfdfda66a' PTR:'1858822145808' [TRACE] Received located event for ID:'66f03ce1-634d-42bd-bd86-19ddfdfda66a' PTR:'1858813819056'

[Varnauld]

Thank you for submitting this issue (internal tracking n# 40431033) - @XiangyuL-Microsoft will be reaching out soon, thank you

[XiangyuL-Microsoft]

@Connor-Kerwin

Hi, is you app built upon Unity or not? Is it possible to get some debugging log during the reproducing? Is it possible to share some code or project with us?

Thank you very much.

[Connor-Kerwin]

@XiangyuL-Microsoft

I am using Unity. Unfortunately, I'm unable to provide the exact source code.

I attempted to write up a new script with just the behaviour which causes my issue, however I am running into another issue now. Could I ask if this script should work? I'm getting anchors locating under the floor in the distance instead of where It's expected to be... The script below is similar to how I'm currently creating and using ASA anchors.

To expand a little on what we do in our project, we make the CloudNativeAnchors and bind them to CloudSpatialAnchors ourselves using CloudToNative, but we also destroy the CloudNativeAnchors, which I think also destroys the ARAnchor which ASA uses. Is it safe to just destroy the CloudNativeAnchor like this? Do you recommend a good way to locally delete an anchor?

using System;
using UnityEngine;
using Microsoft.Azure.SpatialAnchors;
using Microsoft.Azure.SpatialAnchors.Unity;

public class ASAIssueExample : MonoBehaviour
{
    private CloudNativeAnchor instance;
    private CloudSpatialAnchorWatcher watcher;

    public CloudNativeAnchor Prefab;
    public string AnchorId;
    public SpatialAnchorManager AnchorManager;

    protected virtual void Start()
    {
        AnchorManager.SessionStarted += Event_OnSessionStarted;
        AnchorManager.AnchorLocated += Event_OnAnchorLocated;
    }

    public void LocateProcess()
    {
        // Create criteria for the anchor we want
        var criteria = new AnchorLocateCriteria
        {
            Identifiers = new string[] { AnchorId }
        };

        Debug.Log("[TRACE] Starting watcher");

        // Start watching for the anchor
        watcher = AnchorManager.Session.CreateWatcher(criteria);
    }

    private void Event_OnAnchorLocated(object sender, AnchorLocatedEventArgs args)
    {
        var anchor = args.Anchor;
        UnityDispatcher.InvokeOnAppThread(() =>
        {
            OnAnchorLocated(anchor);
        });
    }

    private void OnAnchorLocated(CloudSpatialAnchor anchor)
    {
        try
        {
            Debug.Log($"[TRACE] Anchor {anchor.Identifier} located");
            Debug.Log("[TRACE] Creating native anchor");

            // Create a cloud native anchor
            instance = Instantiate<CloudNativeAnchor>(Prefab);

            // Bind the cloud anchor to the native anchor
            instance.CloudToNative(anchor);

            Debug.Log($"[TRACE] Anchor bound to native ptr {anchor.LocalAnchor}");
        }
        catch (Exception e)
        {
            Debug.LogException(e);
        }
    }

    private void Event_OnSessionStarted(object sender, EventArgs e)
    {
        Debug.Log("[TRACE] Session Started");

        // Fire off the process
        LocateProcess();
    }

    // NOTE: This is not called by the example, we do a credential injection flow
    // to prevent having the keys in the app, this is invoked elsewhere.
    public void StartSession()
    {
        _ = AnchorManager.StartSessionAsync();
    }
}

I get this result in my log, but the anchor appears under the floor. Weirdly, it's consistently incorrect, through restarting the app, it appears in the same incorrect position way under the floor. I can also confirm that this issue occurs on multiple devices, to rule out the device being the issue.

StartSessionAsync called with but no session. Creating one.
[TRACE] Session Started
[TRACE] Starting watcher
[TRACE] Anchor 44f6c38d-1a16-4a55-84d4-e75275f2cb53 located
[TRACE] Creating native anchor
[TRACE] Anchor bound to native ptr 1693714914640

[XiangyuL-Microsoft]

@Connor-Kerwin

We just released a new version of SDK 2.13.0. Could you please try this new version of SDK to see if the problem still existing? Thank you very much.

[Varnauld]

Hello @Connor-Kerwin - were you able to resolve this with the update in July? If not, would you have some further feedback you could share please? Alternatively, if the issue is resolved, may I close it? thank you