如何修复创建锚点的“ AR_ERROR_NOT_TRACKING”

Question

我正在尝试使用给定的坐标放置标记图像，而不是使用hitReuslt，但是当执行session.createAnchor时，应用程序会由于错误而崩溃：

status.cc:156 ArStatusErrorSpace::AR_ERROR_NOT_TRACKING: Cannot create anchors while the camera is not tracking.

以及此错误：

Unable to start activity ComponentInfo{ar.navi/ar.navi.TestActivity}: com.google.ar.core.exceptions.NotTrackingException

下面是我的代码：

    private ArFragment fragment;
    private Session mSession;
    private ModelRenderable markerRenderable;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if (!checkIsSupportedDeviceOrFinish(this)){
            return;
        }
        setContentView(R.layout.activity_navigation);

        fragment = (ArFragment) getSupportFragmentManager().findFragmentById(R.id.sceneform_fragment);

        if (mSession == null){
            try {
                mSession = new Session(this);
                fragment.getArSceneView().setupSession(mSession);
            } catch (UnavailableArcoreNotInstalledException e) {
                e.printStackTrace();
            } catch (UnavailableApkTooOldException e) {
                e.printStackTrace();
            } catch (UnavailableSdkTooOldException e) {
                e.printStackTrace();
            } catch (UnavailableDeviceNotCompatibleException e) {
                e.printStackTrace();
            }
        }

        // When you build a Renderable, Sceneform loads its resources in the background while returning
        // a CompletableFuture. Call thenAccept(), handle(), or check isDone() before calling get().
        ModelRenderable.builder()
                .setSource(this, Uri.parse("marker.sfb"))
                .build()
                .thenAccept(renderable -> markerRenderable = renderable)
                .exceptionally(
                        throwable -> {
                            Toast toast =
                                    Toast.makeText(this, "Unable to load andy renderable", Toast.LENGTH_LONG);
                            toast.setGravity(Gravity.CENTER, 0, 0);
                            toast.show();
                            return null;
                        });

        Session session = fragment.getArSceneView().getSession();
        //Pose pose = Pose.makeTranslation((float)deviceLocation.getLatitude(), (float)deviceLocation.getLatitude(), 0);

        if (session != null){
            try{
                session.resume();
            } catch (CameraNotAvailableException e){
                e.printStackTrace();
            }
            float[] position = { 0, 0, (float)-0.75};       // 75 cm away from camera
            float[] rotation = { 0, 0, 0, 1 };
            //createAnchor always crashes the app and saying camera is not trakcing
            Anchor anchor = session.createAnchor(new Pose(position, rotation));
            AnchorNode anchorNode = new AnchorNode(anchor);
            anchorNode.setRenderable(markerRenderable);
            anchorNode.setParent(fragment.getArSceneView().getScene());
        }
    }

我已经调试并找出session.createAnchor是使应用程序崩溃且无法正常工作的部分，有人可以指出我做错了什么吗？