I'm trying to write an app for detecting "where you are" in a building use ARCore. I'd like to use previously learnt and then saved feature points to provide the initial sync position as well as then helping to continuously update position accurately. But this feature does not currently appear to be supported in ARCore.
Currently I'm using tracked images as a way to do an initial sync. It works, but not brilliantly - alignment is often a few degrees off and you have to approach the image pretty slowly and deliberately. And then once synced there is drift... Yes, loop closing works pretty well when it gets back to somewhere it recognises, but it needs to build up that map every time you start the session.
So, obvious solution: are there any plans for Google to implement "Area Learning" as it was back in Google Tango? It looks like Cloud Anchors might be some attempt to do this, but clearly that's all hosted on Google, and it strictly limited as to how long that data is stored. Currently that's just not a possible solution. OTOH, Apple's ARKit seems to now provide just what is needed:
https://developer.apple.com/documentation/arkit/saving_and_loading_world_data
Does this mean that Apple / ARKit is the only way to go for the app? Hope not...
You might want to check out persistent cloud anchors that is still in development.
From documentation:
Note: We’re currently developing persistent Cloud Anchors, which can
be resolved for much longer. Before making the feature broadly
available, we’re looking for more developers to help us explore and
test persistent Cloud Anchors in real world apps at scale. See here if
you’re interested.
Related
We're looking to share AR experiences (ARWorldMap) over the web (not necessarily to devices nearby, I'm referring to data that can be stored to some server and then retrieved by another user).
Right now we're looking into ARWorldMap which is pretty awesome, but I think it only works on the same device AND with devices nearby. We want to be able to delete these constraints (and therefore save the experience over the web on some server) so that everyone else can automatically see 3D things with their devices (not necessarily at the same time) exactly where they were places.
Do you know if it's possible to send the archived data (ARWorldMap) to some server in some kind of format so that another user can later retrieve that data and load the AR experience on their device?
The ARWorldMap contains the feature points in the enviroment around the user. For example, the exact position and size of a table but including all the other points found by the camera. You can visualize those with the debugOptions.
It does not make sense to share those to a user that is not in the same room.
What you want to do is share the interactions between the users, eg when an object was placed or rotated.
This is something you would need to implement yourself anyway since ARWorldMap only contains anchors and features.
I can recommend Inside Swift Shot from last years WWDC as a starting point.
Yep technically it’s possible as according to docs here. You will have to use the nsssecure coding protocol, might have to extend if you aren’t using a swift backend though. It’s still possible as the arkit anchors are defined by a mix of point maps, rotational data , and image algos. Just implement portions of codable to JSON and voila it’s viable for most backends. Of course this is easier said then done.
What is the best way, if any, to use Apple's new ARKit with multiple users/devices?
It seems that each devices gets its own scene understanding individually. My best guess so far is to use raw features points positions and try to match them across devices to glue together the different points of views since ARKit doesn't offer any absolute referential reference.
===Edit1, Things I've tried===
1) Feature points
I've played around and with the exposed raw features points and I'm now convinced that in their current state they are a dead end:
they are not raw feature points, they only expose positions but none of the attributes typically found in tracked feature points
their instantiation doesn't carry over from frame to frame, nor are the positions exactly the same
it often happens that reported feature points change by a lot when the camera input is almost not changing, with either a lot appearing or disappearing.
So overall I think it's unreasonable to try to use them in some meaningful way, not being able to make any kind of good point matching within one device, let alone several.
Alternative would to implement my own feature point detection and matching, but that'd be more replacing ARKit than leveraging it.
2) QR code
As #Rickster suggested, I've also tried identifying an easily identifiable object like a QR code and getting the relative referential change from that fixed point (see this question) It's a bit difficult and implied me using some openCV to estimate camera pose. But more importantly very limiting
As some newer answers have added, multiuser AR is a headline feature of ARKit 2 (aka ARKit on iOS 12). The WWDC18 talk on ARKit 2 has a nice overview, and Apple has two developer sample code projects to help you get started: a basic example that just gets 2+ devices into a shared experience, and SwiftShot, a real multiplayer game built for AR.
The major points:
ARWorldMap wraps up everything ARKit knows about the local environment into a serializable object, so you can save it for later or send it to another device. In the latter case, "relocalizing" to a world map saved by another device in the same local environment gives both devices the same frame of reference (world coordinate system).
Use the networking technology of your choice to send the ARWorldMap between devices: AirDrop, cloud shares, carrier pigeon, etc all work, but Apple's Multipeer Connectivity framework is one good, easy, and secure option, so it's what Apple uses in their example projects.
All of this gives you only the basis for creating a shared experience — multiple copies on your app on multiple devices all using a world coordinate system that lines up with the same real-world environment. That's all you need to get multiple users experiencing the same static AR content, but if you want them to interact in AR, you'll need to use your favorite networking technology some more.
Apple's basic multiuser AR demo shows encoding an ARAnchor
and sending it to peers, so that one user can tap to place a 3D
model in the world and all others can see it. The SwiftShot game example builds a whole networking protocol so that all users get the same gameplay actions (like firing slingshots at each other) and synchronized physics results (like blocks falling down after being struck). Both use Multipeer Connectivity.
(BTW, the second and third points above are where you get the "2 to 6" figure from #andy's answer — there's no limit on the ARKit side, because ARKit has no idea how many people may have received the world map you saved. However, Multipeer Connectivity has an 8 peer limit. And whatever game / app / experience you build on top of this may have latency / performance scaling issues as you add more peers, but that depends on your technology and design.)
Original answer below for historical interest...
This seems to be an area of active research in the iOS developer community — I met several teams trying to figure it out at WWDC last week, and nobody had even begun to crack it yet. So I'm not sure there's a "best way" yet, if even a feasible way at all.
Feature points are positioned relative to the session, and aren't individually identified, so I'd imagine correlating them between multiple users would be tricky.
The session alignment mode gravityAndHeading might prove helpful: that fixes all the directions to a (presumed/estimated to be) absolute reference frame, but positions are still relative to where the device was when the session started. If you could find a way to relate that position to something absolute — a lat/long, or an iBeacon maybe — and do so reliably, with enough precision... Well, then you'd not only have a reference frame that could be shared by multiple users, you'd also have the main ingredients for location based AR. (You know, like a floating virtual arrow that says turn right there to get to Gate A113 at the airport, or whatever.)
Another avenue I've heard discussed is image analysis. If you could place some real markers — easily machine recognizable things like QR codes — in view of multiple users, you could maybe use some form of object recognition or tracking (a ML model, perhaps?) to precisely identify the markers' positions and orientations relative to each user, and work back from there to calculate a shared frame of reference. Dunno how feasible that might be. (But if you go that route, or similar, note that ARKit exposes a pixel buffer for each captured camera frame.)
Good luck!
Now, after releasing ARKit 2.0 at WWDC 2018, it's possible to make games for 2....6 users.
For this, you need to use ARWorldMap class. By saving world maps and using them to start new sessions, your iOS application can now add new Augmented Reality capabilities: multiuser and persistent AR experiences.
AR Multiuser experiences. Now you may create a shared frame of a reference by sending archived ARWorldMap objects to a nearby iPhone or iPad. With several devices simultaneously tracking the same world map, you may build an experience where all users (up to 6) can share and see the same virtual 3D content (use Pixar's USDZ file format for 3D in Xcode 10+ and iOS 12+).
session.getCurrentWorldMap { worldMap, error in
guard let worldMap = worldMap else {
showAlert(error)
return
}
}
let configuration = ARWorldTrackingConfiguration()
configuration.initialWorldMap = worldMap
session.run(configuration)
AR Persistent experiences. If you save a world map and then your iOS application becomes inactive, you can easily restore it in the next launch of app and in the same physical environment. You can use ARAnchors from the resumed world map to place the same virtual 3D content (in USDZ or DAE format) at the same positions from the previous saved session.
Not bulletproof answers more like workarounds but maybe you'll find these helpful.
All assume the players are in the same place.
DIY ARKit sets up it's world coordinate system quickly after the AR session has been started. So if you can have all players, one after another, put and align their devices to the same physical location and let them start the session there, there you go. Imagine the inside edges of an L square ruler fixed to whatever available. Or any flat surface with a hole: hold phone agains surface looking through the hole with camera, (re)init session.
Medium Save the player aligning phone manually, instead detect a real world marker with image analysis just like #Rickster described.
Involved Train an Core ML model to recognize iPhones and iPads and their camera location. Like it's done with human face and eyes. Aggregate data on a server, then turn off ML to save power. Note: make sure your model is cover-proof. :)
I'm in the process of updating my game controller framework (https://github.com/robreuss/VirtualGameController) to support a shared controller capability, so all devices would receive input from the control elements on the screens of all devices. The purpose of this enhancement is to support ARKit-based multiplayer functionality. I'm assuming developers will use the first approach mentioned by diviaki, where the general positioning of the virtual space is defined by starting the session on each device from a common point in physical space, a shared reference, and specifically I have in mind being on opposite sides of a table. All the devices would launch the game at the same time and utilize a common coordinate space relative to physical size, and using the inputs from all the controllers, the game would remain theoretically in sync on all devices. Still testing. The obvious potential problem is latency or disruption in the network and the sync falls apart, and it would be difficult to recover except by restarting the game. The approach and framework may work for some types of games fairly well - for example, straightforward arcade-style games, but certainly not for many others - for example, any game with significant randomness that cannot be coordinated across devices.
This is a hugely difficult problem - the most prominent startup that is working on it is 6D.ai.
"Multiplayer AR" is the same problem as persistent SLAM, where you need to position yourself in a map that you may not have built yourself. It is the problem that most self driving car companies are actively working on.
The question is already quite direct and short:
Can the Hololens be used as a virtual reality glasses?
Sorry beforehand if the question is clear for those who have tried them out, but I had not yet the chance.
From what I read I know that they have been designed to be a very good augmented reality tool. This approach is clear for everybody.
Just thinking that may be applications where you simply don't want the user to have any spatial contact with the reality for some moments, or others where you want the user to forget in the complete experience about were s-he is, then a complete environment should be shown as we are used to with the virtual reality glasses.
How are the Hololens ready for this? I think there are two key sub-questions that may be answered for this:
How solid are the holograms?
Does the screen where holograms can be placed covers the complete view?
As others already pointed out, this is a solid No due to the limited viewing window.
Apart from that, the current hardware capabilities of the Hololens is not capable of providing a full immersive experience. You can check the specifications here.
As of now, when the environment is populated with more than a few holograms (depends on the triangle count of each hologram) the device's fps count drops and a certain lag is visible. I'm sure more processing power would be added to the device in future versions, but as of right now, with the current power of the device, I seriously doubt its capabilities to populate an entire environment to give a fully immersive experience.
1) The holograms quality is defined by the following specs:
- Holographic Resolution: 2.3M total light points
- Holographic Density: 2.5k light points per radian
It is worth to say that Microsoft holograms disappear under a certain distance indicated here in 0.85m
Personal note: in the past I worked also on Google Project Tango and I can tell you from these personal experiences that the stability of Microsoft holograms is absolutely superior. Also, the holograms are kept once the device is turned off, so if you place something and you reboot the device you will find them again where you left them, without the need to restart from scratch
2) Absolutely not: "[The field of view] amounts to the size of a monitor in front of you – equivalent to 15 inches" as stated here. And it will not be addressed as reported also here. So if the holograms size exceeds this space they will be shown partially [i.e. cut]. Moreover the surrounding environment is always visible because the device purpose is interacting with the real environment adding another layer on top
Hololens is not intended to be a VR rig, there is no complete immersion that I am aware of, yes you can have solid holograms, but you can always see the real world.
VR is related with substituting the real world that is why VR goggles are always blind. HoloLens are type of see-through so you can see the hologram and the real world. There are created for augmented reality where you augment the real world. That is why you can't use HoloLens for VR purpous
Actually my initial question is: can the Hololens be used AS WELL for VR applications?
No is the answer because of its small window (equivalent to 15'' screen) where the holograms can be placed to.
I am sure this will evolve sooner or later in order to improve the AR experience. As soon as the screen does not cover toe complete view VR won't be possible with the Hololens.
The small FOV is a problem for total immersion, but there is an app for HoloLens called HoloTour, which is VR (with a few AR scenes in the beginning). In the game, the user can travel to Rome and Peru. While you can still see through the holograms, in my personal experience, people playing it will really get into it and will forget about the limitations. After a scene or two, they feel immersed. So while it certainly isn't as good at VR as a machine designed for that, it is capable, and it is still typically enjoyable to the users. There are quite a few measures to prevent nausea in the users (I can use mine for hours at a time with no problem) so I would actually prefer it to poorer VR implementations, such as a GearVR (which made me sick after 10 minutes of use!). Surely a larger FOV is in the works, so this will be less of a limitation in future releases.
So I'm looking to create a niche market static yelp-style wine/dine restaurant finder. After asking around, I was suggested to look into cloud kit since apple provides asset storage and synchronization. I'm looking to provide misc. information in regards to restaurants: menu, location, open times, images; this information will be provided by myself.
With that in mind... here is the problem. It appears that cloud kit may be the perfect fit, unfortunately beginner-type tutorials are insufficient in explanation or outdated (obj-c - I only know swift). So for one, would you be able to recommend any tutorials?
Nonetheless, here is the meat of the question...
I am aware that a public database held in a container will be able to hold numerous bits of information: strings, integers, assets, date, etc.
However, would cloud kit (as in, off the device), hold the entirety of instances of a struct in the cloud or are only variables held? In other words, what is held on the device and what is held in the cloud when using cloud kit?
Also, should I create a iCloud id just for development usage or should I use my existing iCloud if?
Jon,
There is a lot of questions here.
1. CloudKit is very easy to get started, but a little bit of a challenge to use in a real app.
2. You can store basic types + assets in cloud kit; an asset being an image for example or just a glob of data.
3. The https://www.raywenderlich.com/video-tutorials#cloudkit website has a number of good tutorials on the subject in SWIFT, although no its not free, you need to pay a small monthly charge; although its worth it if you want to learn more about code development.
I'am creating a new feature for my iOS app. After I publish the app I wants to show the new feature only for 50% of the users, so I can do some testing which version makes more orders. I have no idea how to do it without using some third parties like Optimizely.
Also is it possible to do this using Google Tag Manager(GTM).
So can someone please help me to figure this out.
Thank you very much for your time.:)
It’s hard to do it on your own, though not impossible of course: Optimizelys of the world are just programs. You’ll need to solve these problems:
Targeting: Some algorithm that will assign user session to either control or (one of) treatment(s). This has to be random, of course, or you may as well stop there.
Routing: Send sessios to the targeted experience.
Logging: You’ll need to intelligently log events from sessions as they traverse their targeted experience. These may be many, so be careful not to add latency to your app path. Your statistical analysis will be based on these.
Experience stability: how do you ensure (if you do) that a returning user sees the same experience he’s already seen.
Note as well, that Optimizely will only help you if all your changes are on the device and not on the server. If you need to instrument server changes as well, you’ll have to look into Sitespect or Variant.
I finally figured out how to do the A/B testing with 'Google Tag Manager'(GTM).
In GTM you can create a variable called 'Google Analytics Content Experiment'. With this variable you can select how many percentage of users going to see each Variation(your experiments). You can create up to 10 variations for single experiment.
GTM is so cool and powerful. GTM contains so many features that could save lot of time and I totally recommend it for anyone who is going to do A/B testing.