Instant anchoring with multiple independent models

[m-paunovic-vegait]

Hi!

What would be the best way to have several models instantly anchor around a common point without overlapping (i.e. arranged in a line or a circle or whatever), but still be able to be independently moved around and rotated? I've tried several things with centerOrigin and onAnchorChanged, but all my models either bunch up in the center, or behave strangely when moved.

Thanks in advance!

edit: I seem to be making some progress with the CursorNode and messing with the worldPosition of the newly-loaded models, but if I spawn them in on the first time the cursor's onPoseChanged fires, the models appear in the distance. Is there something like a confidence rating for the cursor's position that I can use, or do I just add a timeout and hope for the best?

[grassydragon]

Hi!
I think that you can either use a parent node while placing the models or dynamically calculate and update their positions from a central point that is determined by a hit result. Once the models are placed you can extract them from the parent node and anchor to their current positions.

[ThomasGorisse]

edit: I seem to be making some progress with the CursorNode and messing with the worldPosition of the newly-loaded models, but if I spawn them in on the first time the cursor's onPoseChanged fires, the models appear in the distance. Is there something like a confidence rating for the cursor's position that I can use, or do I just add a timeout and hope for the best?

By default the ArModelNode (so the CursorNode) is using the PlacementMode.BEST_AVAILABLE defined with instantPlacementFallback = true

sceneview-android/arsceneview/src/main/java/io/github/sceneview/ar/node/ArNode.kt

Lines 503 to 509 in 6260bf7

	/**
	* ### Place nodes on every detected surfaces
	*
	* The node will be placed instantly and then adjusted to fit the best accurate, precise,
	* available placement.
	*/
	BEST_AVAILABLE(instantPlacementFallback = true);

And as mentioned here

sceneview-android/arsceneview/src/main/java/io/github/sceneview/ar/node/ArNode.kt

Lines 443 to 444 in 6260bf7

	* @param instantPlacementFallback Fallback to instantly place nodes at a fixed orientation and an
	* approximate distance when the base placement type is not available yet or at all.

the ArNode will be first placed using instant placement which is not meant to be used for accuracy.
You can disable the instant placement fallback:

arNode.placementMode.instantPlacementFallback = false

or listen for CursorNode.onHitResult and manage if the model should be visible or not:

cursorNode.onHitResult = { _, hitResult ->
    val isAccurate = hitResult?.isTracking == true &&
            hitResult.trackable !is InstantPlacementPoint
    // Set the CursorNode color to red if not accurate
    cursorNode.isTracking = isAccurate
    // Hide or show the model
    modelNode.isVisible = isAccurate
}

Have a look at this part:

sceneview-android/arsceneview/src/main/java/io/github/sceneview/ar/arcore/ArFrame.kt

Lines 268 to 284 in a6e4bd3

	fun Collection<HitResult>.firstValid(
	camera: Camera,
	plane: Boolean,
	depth: Boolean,
	instantPlacement: Boolean
	): HitResult? {
	return firstOrNull { hitResult ->
	when (val trackable = hitResult.trackable!!) {
	is Plane -> plane && trackable.isPoseInPolygon(hitResult.hitPose) &&
	hitResult.hitPose.calculateDistanceToPlane(camera.pose) > 0.0f
	is DepthPoint -> depth && trackable.isTracking
	is Point -> depth && trackable.orientationMode == Point.OrientationMode.ESTIMATED_SURFACE_NORMAL
	is InstantPlacementPoint -> instantPlacement
	else -> false
	}
	}
	}