In several visionOS apps, we readjust our scenes to the user's eye level (their heads). But, we have encountered issues whereby the WorldTrackingProvider returns bad/incorrect positions for the first x number of frames.
See below code which you can copy paste in any Immersive Space. Relaunch the space and observe the numberOfBadWorldInfos value is inconsistent.
a. what is the most reliable way to get the devices's position?
b. is this indeed a bug?
c. are we using worldInfo improperly?
d. as a workaround, in our apps we set to 10 the number of frames to let pass before using worldInfo, should we set our threshold differently?
import ARKit
import Combine
import OSLog
import SwiftUI
import RealityKit
import RealityKitContent
let SUBSYSTEM = Bundle.main.bundleIdentifier!
struct ImmersiveView: View {
let logger = Logger(subsystem: SUBSYSTEM, category: "ImmersiveView")
let session = ARKitSession()
let worldInfo = WorldTrackingProvider()
@State var sceneUpdateSubscription: EventSubscription? = nil
@State var deviceTransform: simd_float4x4? = nil
@State var numberOfBadWorldInfos = 0
@State var isBadWorldInfoLoged = false
var body: some View {
RealityView { content in
try? await session.run([worldInfo])
sceneUpdateSubscription = content.subscribe(to: SceneEvents.Update.self) { event in
guard let pose = worldInfo.queryDeviceAnchor(atTimestamp: CACurrentMediaTime()) else {
return
}
// `worldInfo` does not return correct values for the first few frames (exact number of frames is unknown)
// - known SO: https://stackoverflow.com/questions/78396187/how-to-determine-the-first-reliable-position-of-the-apple-vision-pro-device
deviceTransform = pose.originFromAnchorTransform
if deviceTransform!.columns.3.y < 1.6 {
numberOfBadWorldInfos += 1
logger.warning("\(#function) \(#line) deviceTransform.columns.3.y \(deviceTransform!.columns.3.y), numberOfBadWorldInfos \(numberOfBadWorldInfos)")
} else {
if !isBadWorldInfoLoged {
logger.info("\(#function) \(#line) deviceTransform.columns.3.y \(deviceTransform!.columns.3.y), numberOfBadWorldInfos \(numberOfBadWorldInfos)")
}
isBadWorldInfoLoged = true // stop logging.
}
}
}
}
}
ARKit
RSS for tagIntegrate iOS device camera and motion features to produce augmented reality experiences in your app or game using ARKit.
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Hello
RemoteDeviceIdentifier returns nil and therefore it crashes the HoverEffect sample project.
I have vision26 beta 2 on both devices
what the correct method of running this code sample ?
My ARViewContainer code is not working. I don't know how to debug the issue and I don't know or see where my results is going to. I need help to resolve this issue. please help debug. See code below:
Hi all,
I'm running into an issue with an app that previously worked fine on device using visionOS 2.0. After updating to visionOS 26, the same code runs fine in the simulator but crashes on the device with the following error:
-[MTLDebugComputeCommandEncoder _validateThreadsPerThreadgroup:]:1330:
failed assertion `(threadsPerThreadgroup.width(32) * threadsPerThreadgroup.height(32) * threadsPerThreadgroup.depth(1))(1024) must be <= 832. (kernel threadgroup size limit)`
Is there any documented way to check or increase the allowed threadsPerThreadgroup size on Apple Vision Pro? Or any recommended workaround for this regression?
Thanks in advance!
Hi, I called it "perspective problem", but I'm not quite sure what it is. I have a tag that I track with builtin camera. I calculate its pose, then use extrinsics and device anchor to calculate where to place entity with model.
When I place an entity that overlaps with physical object and start to look at it from different angles, the virtual object begins to move. Initially I thought that it's something wrong with calculations, or some image distortion closer to camera edges is affecting tag detection. To check, I calculated the position only once and displayed entity there, the physical tracked object is not moving. Now, when I move my head, so the object is more to the left, or right in my field of view, the virtual object becomes misaligned to the left, or right. It feels like a parallax effect, but distance from me to entity and to physical object are exactly the same.
Is that expected, because of some passthrough correction magic? And if so, can I somehow correct it back, so the entity always overlaps with object? I'm currently on v26 beta 5.
I also don't quite understand the camera extrinsics, because it seems that I need to flip it around X by 180 degrees to make it work in deviceAnchor * extrinsics.inverse * tag (shouldn't it be in same coordinates as all other RealityKit things?).
Is there any way to render a RealityView to an Image/UIImage like we used to be able to do using SCNView.snapshot() ?
ImageRenderer doesn't work because it renders a SwiftUI view hierarchy, and I need the currently presented RealityView with camera background and 3D scene content the way the user sees it
I tried UIHostingController and UIGraphicsImageRenderer like
extension View {
func snapshot() -> UIImage {
let controller = UIHostingController(rootView: self)
let view = controller.view
let targetSize = controller.view.intrinsicContentSize
view?.bounds = CGRect(origin: .zero, size: targetSize)
view?.backgroundColor = .clear
let renderer = UIGraphicsImageRenderer(size: targetSize)
return renderer.image { _ in
view?.drawHierarchy(in: view!.bounds, afterScreenUpdates: true)
}
}
}
but that leads to the app freezing and sending an infinite loop of
[CAMetalLayer nextDrawable] returning nil because allocation failed.
Same thing happens when I try
return renderer.image { ctx in
view.layer.render(in: ctx.cgContext)
}
Now that SceneKit is deprecated, I didn't want to start a new app using deprecated APIs.
We are working on a world scale AR app that leverages the device location and heading to place objects in the streets, so that they are correctly and stably anchored to certain locations.
Since the geo-tracking imagery is only available in certain cities and areas, we are trying to figure out how to fallback when geo-tracking is not available as the device move away, to still retain good AR camera accuracy. We might need to come up with some algorithm using the device GPS, to line up the ARCamera with our objects.
Question: Does geo-tracking always provide greater than or equal to the accuracy of world tracking, for a GPS outdoor AR experience?
If so, we can simply use the ARGeoTrackingConfiguration for the entire time, and rely on the ARView keeping itself aligned. Otherwise, we need to switch between it and ARWorldTrackingConfiguration when geo-tracking is not available and/or its accuracy is low, then roll our own algorithm to keep the camera aligned.
Thanks.
My development team admin requested the Enterprise API for camera access on the vision pro. We got that granted, got a license for usage, and got instructions for integrating it with next steps.
We did the following:
Even when I try to download and run the sample project for "Accessing the Main Camera", and follow all the exact instructions mentioned here: https://developer.apple.com/documentation/visionos/accessing-the-main-camera
I am just unable to receive camera frames.
I added the capabilities, created a new provisioning profile with this access, added the entitlements to info.plist and entitlements, replaced the dummy license file with the one we were sent, and also have a matching bundle identifier and development certificate, but it is still not showing camera access for some reason.
"Main Camera Access" shows up in our Signing & Capabilities tab, and we also added the NSMainCameraDescription in the Info.plist and allow access while opening the app. None of this works. Not on my app, and not on the sample app that I just downloaded and tried to run on the Vision Pro after replacing the dummy license file.
I am using AccessoryTrackingProvider from ARKit to get the transform of the PSVR2 controller via originFromAnchorTransform of the AccessoryAnchor. I also am trying to use AnchorEntity on the controller using RealityKit
However, none of the three options for Accessory.LocationName, which should be used to define the AnchorEntity target, seem to match the position on the controller which is being sent from ARKit.
The picture attached is showing two transforms:
RealityKit - using .gripSurface to define the AnchoringComponent.Target.accesssory location.
ARKit - using originFromAnchorTransform for AccessoryTrackingProvider.
They are not aligned at the same point.
As for the other options of Accessory.LocationName, using .aim is located at the tip of the controller and .grip is the same position as .gripSurface but with a different orientation.
I am wondering why there is not an option for Accessory.LocationName that actually matches the transform captured by ARKit?
I am developing an ARKit based application that requires plane detection of the tabletop at which the user is seated. Early testing was with an iPhone 8 and iPhone 8+. With those devices, ARKit rapidly detected the plane of the tabletop when it was only 8 to 10 inches away. Using iPhone 15 with the same code, it seems to require me to move the phone more like 15 to 16 inches away before detecting the plane of the table. This is an awkward motion for a user seated at a table. To validate that it was not necessarily a feature of my code, I determined that the same behavior results with Apple's sample AR Interaction application. Has anyone else experienced this, and if so, have suggestions to improve the situation?
Hello,
I have downloaded and run the sample object tracking app for visionos.
Now I'm working on my own objects for tracking. I have made a model using Create ML using images of my object.
However, I cannot see how to convert the Create ML output file (xxx.mlmodel) into a reference object like the files in the sample project.
is there a tool for converting them?
TIA
Topic:
Spatial Computing
SubTopic:
ARKit
As I understand it there are two ways I can track a hand, or a joint, in RealityKit:
either, create an AnchorEntity, for example AnchorEntity(.hand(.left, location: .palm))
or, set up an ARSession with a HandTrackingProvider ( a lot more code which I haven't repeated here).
Assuming this is correct, when would I want to use one over the other?
In ARKit for visionOS, I can track the user's head with a HeadAnchor, but it will not give the location. However, I can get the device's transform by calling queryDeviceAnchor(atTimestamp: CACurrentMediaTime()) on a WorldTrackingProvider.
Why the difference? - if I know the device's transform, I effectively know the head's transform.
I am using Entity of RealityKit to display virtual content, however I find that sometimes the real object in front of the virtual content can not occulude the virtual content.
For example, I place an Entity in a room, but when I walk into another room, I can still see the Entity through the wall.
I wonder how should I fix the problem. Thank you!
I am currently creating an app where two people share an instance of an immersive space so that they are able to point to certain things in the immersive space. Right now, other people are hidden behind the immersive space, and even with people awareness enabled for everything, people are still too difficult to see. I've found this documentation (https://developer.apple.com/documentation/arkit/occluding-virtual-content-with-people) which describes what I want to do, but it is only listed as working on iOS an iPadOS. Is there anything similar to this that will work on VisionOS?
We applied for the visionOS enterprise permission license, which can help us improve object tracking capabilities on Vision Pro. However, we are unsure how to use it in Unity, specifically how to implement object tracking in Unity and increase the tracking speed.
Is it possible to detect distance from the vision pro to real live objects and people? I tried using scene.raycast to perform a raycast forward from the center of the viewport, but it doesn't seem to react to real life objects, only entities.
I see mentioned here: https://developer.apple.com/forums/thread/776807?answerId=829576022#829576022, that a raycast with scene reconstruction should allow me to measure that distance, as long as the object is non-moving. How could I accomplish that?
As far as I know, Apple hasn’t opened access to the Vision Pro camera for developers yet, so I’m trying to find possible workarounds within the current capabilities. I’m wondering if there’s any way to apply a mesh to a person in the scene in Vision Pro, or if there’s an alternative approach to roughly detect a human shape in front of the user?
I am looking for a material that functions in the same way that Occlusion Material does, except that it only partially occludes whatever is behind it. One way that I have thought of doing this was to change the opacity of the entity that was covered in Occlusion Material, however this did not change anything. Please let me know if this is possible.
Hi, I'm playing now with hand tracking. I want to get position of hand inside a system update function. I was not sure if transform I'm getting from hand attached AnchorEntity (with trackingMode: .predicted) would give same results as handAnchors(at:) from hand tracking provider, so I started to read them both and compare. For handAnchors i tried using context.scene.timebase.sourceTimebase!.sourceClock!.time.seconds and CACurrentMediaTime() as timestamp source. They seem to use exactly same clock, so that doesn't matter, but:
for some reason update handler is always called twice with same context.deltaTime, but first time the query finds 0 entities, second time it finds them all. The query is the standard EntityQuery(where: .has(MyComponent.self)) and in update (matching: Self.query, updatingSystemWhen: .rendering). Here's part of logs:
System update called, entity count: 0, dt: 0.01000458374619484, absTime: 4654.222593541
System update called, entity count: 11, dt: 0.01000458374619484, absTime: 4654.22262525
System update called, entity count: 0, dt: 0.009999999776482582, absTime: 4654.249390875
System update called, entity count: 11, dt: 0.009999999776482582, absTime: 4654.249425
accounting for the double update calling I started to calculate time delta of absolute time between calls and they're most of the time much bigger, or much smaller than advertised by system's context.deltaTime, only sometimes they kind of match, for example:
system: (dt: 0.01000458374619484)
scene : (dt: 0.021419291667371) (absTime: 4654.222628125001)
and the very next call
system: (dt: 0.010009 166784584522)
scene : (dt: 0.0013097083328830195) (absTime: 4654.223937833334)
but sometimes
system: (dt: 0.009999999776482582)
scene : (dt: 0.009 112249999816413) (absTime: 4654.351299 166668)
Shouldn't those be more or less equal, or am I missing something?
In the end it seems that getting hand position from AnchorEntity and with handAnchors(at:) gives kind of same results, but at different time points, so I'd love to understand what's the correct way to use them and why time flows differently :).
--Edit--
P.S. Had to put spaces everywhere in logs between "9" and "1", otherwise post was blocked due to "sensitive content" :D