Added object on vertical plane always rotated in ARCore

Question

I am adding an image on vertical plane in Sceneform ARFragment. But it always get rotated. The code is working fine on horizontal plane. My code for placing images on vertical Plane is as follow:

arFragment.setOnTapArPlaneListener { hitResult: HitResult, 
                                         plane: Plane, 
                                   motionEvent: MotionEvent ->

    if(!isOnceTapedOnSurface) {
        val anchor = hitResult.createAnchor()
        val anchorNode = AnchorNode(anchor)
        anchorNode.setParent(arFragment.arSceneView.scene)

        andy = TransformableNode(arFragment.transformationSystem)

        if(plane.type == Plane.Type.VERTICAL) {
            val anchorUp = anchorNode.up
            andy.setLookDirection(Vector3.up(), anchorUp)
        }

        andy.setParent(anchorNode)
        andy.renderable = andyRenderable
        andy.select()

        // arFragment.arSceneView.planeRenderer.isVisible = false
        isOnceTapedOnSurface = true
    }
}

Answer 1

To fix this issue you can use the above solution. But you should rotate an object using world rotation. Don't use local rotation. We need to zero the rotation value. If you are using local rotation, the object will behave anchor(parent) rotation. So by using world rotation we can control the object.

String planeType = "";

//When tapping on the surface you can get the anchor orientation

if (plane.getType() == Plane.Type.VERTICAL){
                planeType = "Vertical";
            }else if (plane.getType() == Plane.Type.HORIZONTAL_UPWARD_FACING){
                planeType = "Horizontal_Upward";
            }else if (plane.getType() == Plane.Type.HORIZONTAL_DOWNWARD_FACING){
                planeType = "Horizontal_Downward";
            }else {
                planeType = "Horizontal";
            }```


// First set object world rotation zero

transformableNode.setWorldRotation(Quaternion.axisAngle(new Vector3(0, 0f, 0), 0));


// check plane type is vertical or horizontal if it is vertical below logic will work.

if (planeType.equals("Vertical")) {

   Vector3 anchorUp = anchorNode.getUp();
   transformableNode.setLookDirection(Vector3.up(), anchorUp);

}

Answer 2

To fix this issue you need to set public Pose getCenterPose(). It returns the pose of the center of the detected plane, defined to have the origin. The pose's transformed +Y axis will be point normal out of the plane, with the +X and +Z axes orienting the extents of the bounding rectangle.

anchor = mySession.createAnchor(plane.getCenterPose())

When the its trackable state is TRACKING, this pose is synced with the latest frame. When its trackable state is PAUSED, an identity pose will be returned.

Your code could be the following:

Anchor newAnchor;

for (Plane plane : mSession.getAllTrackables(Plane.class)) {

    if(plane.getType() == Plane.Type.VERTICAL && 
       plane.getTrackingState() == TrackingState.TRACKING) {
          newAnchor = plane.createAnchor(plane.getCenterPose());
          break;
    }
}

One more thing from Google ARCore software engineers:

Keep objects close to anchors.

When anchoring objects, make sure that they are close to the anchor you are using. Avoid placing objects farther than a few meters from the anchor to prevent unexpected rotational movement due to ARCore's updates to world space coordinates.

If you need to place an object more than a few meters away from an existing anchor, create a new anchor closer to this position and attach the object to the new anchor.