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Inaccurate position of augmentations on iPadPro + iOS11 and black strips

January 18, 2018 - 1:07pm #1

Hi everyone,

I’m begging for your help this time as I’ve been dealing with this problem for a couple of days and it’s driving me crazy.

I have a new iPad Pro with iOS 11.2 installed and an old iPad Mini 2 with iOS 10.2 installed.

I’m using the Core Samples Unity project to make sure it’s not me doing something silly.

I have three problems to report, which I believe are related:

1. The first problems is that the position of the augmentations on iOS11 and iPad Pro are not at all accurate and very unreliable. To illustrate what I mean I’ve placed a 3D cube aligned on top of the “N” letter on the Mars Oxygen Image Target (please see image “InUnity.png” to see how this looks like inside the project).

In image “OniOS11_incorrect1.jpg” you can see that when running the app on iPad Pro + iOS 11.2, the cube is not positioned correctly on the image target. In this case I was displaying the image target on my computer.

In image “OniOS11_incorrect2.jpg” you can see again that the position of the cube is not accurate, and it fact it’s also totally different than in the previous example. This time I was displaying the image target on my iPad Mini.

In image “OniOS11_correct.jpg” you can see that this time the cube is positioned correctly BUT there are two black strips on the sides of the background image. I’ve tested this a million times and every single time that the cube was set correctly, those black strips were present, so I’m pretty sure these two problems are somehow related.

Finally, in image “OniOS10_correct.png” you can see that everything looks correct. The position of the cube is perfect and there are no black strips.

Other important info: this only happens with the back camera, not the front camera. The problem was also present for iOS 11.0.

2. The second problem is that setting the camera focus on iOS11 + iPad Pro is totally ignored the first time it’s set (during the OnVuforiaStart function in the CameraSettings.cs script). This means that when the app starts the first time the background image is totally out of focus. Only by tapping the screen, which triggers again the call to SetFocusMode, the focus is set properly.

3. The third problem is regarding the appearance of the black strips that I briefly mentioned above. These strips never appear when the app first launches. They appear when the application is paused and resumed again.

Sorry for the long write-up and please let me know if you need any other information to be able to reproduce the problem. The app that I’m building needs the augmentations to be placed accurately so solving this is really super important.

A million thanks in advance for your help!

P.S. Never had any of these problems on Android.

Image icon InUnity.png502.02 KB
Image icon OniOS11_incorrect1.jpg324.1 KB
Image icon OniOS11_incorrect2.jpg363.14 KB
Image icon OniOS11_correct.jpg367.01 KB
Image icon OniOS10_correct.PNG4.9 MB

Inaccurate position of augmentations on iPadPro + iOS11 and black strips

November 9, 2018 - 11:05am #8


I got the same problem...

Is there a solution? Or the problem persists?



Inaccurate position of augmentations on iPadPro + iOS11 and black strips

August 16, 2018 - 10:42am #7

Hello @bsc2fast,

Thanks for the investigation and summary.

Similar information, and guidance from the Vuforia team on these issues, has been captured in various forum threads.

-Vuforia Engine Support

Inaccurate position of augmentations on iPadPro + iOS11 and black strips

August 16, 2018 - 12:54am #6

Hi fkoch, martejpad & vuforia team,


Recently I found the reason and the solution for this shocking problem (Inaccurate/ drifted AR augmented positions for marker based tracking). I also experienced the same problem a couple of days ago. Then I started digging into the problem. Luckily I got it sorted and you guys can also solve yours by doing these simple steps.


If you are using unity 2017.4.0f1 (or any related 2017 version) upgrade your project to 2018.1.1f1 (or any related 2018 version).

  • After successful upgrade and build, If you experience black screen for vuforia camera view, it is something else. Simply build your project to xcode 9.2 and make sure latest IOS developer support files are copied in xcode 9.2 platform support directories. (Said to be fixed in latest Unity versions)
  • Unity 2018 API is little different from 2017 API. So backup your older project and scripts. May be you need to update some obsolete methods.
  • It's your responsibility to get your project up and running by making necessary script updates and settings changes.


Most probably this issue is not depending on unity version but on Vuforia version. Since it is embedded with unity editor, changing unity version will also update inbuilt Vuforia version. I built basic Vuforia marker based ar test projects in both above mentioned unity versions. Inaccurate position issue is still presents when you built IOS 11.4 app from 2017.4.0f1 unity. For same device, that issue is not available in unity 2018 project. Most of older unity versions may generate the same issue for latest IOS devices. But for older IOS devices like IOS 11.2 may not suffer from this bug. As far as I understand this bug occurs due to lack of hardware support from older unity/vuforia version or may be newest IOS OS experience some complications with ARKIT commands and vuforia commands. Another reason is IOS 11.4 was not released during Unity 2017 release dates. So Unity/Vuforia may haven't addressed API changes for newest IOS.

Vuforia Team

You can advice people to use latest vuforia / unity engines. And list down this as a known issue. Else you can do a patch release which will prompt unity 2017 users to update vuforia version from the vuforia configurator script.


Hope this piece of information can save your life (project/company) !




Inaccurate position of augmentations on iPadPro + iOS11 and black strips

July 30, 2018 - 6:52am #5

I do believe that this behaviour has something to do with extended tracking... I have an app built using unity 2017.3.1 on android that doesnt have gyroscope (means no extended tracking) and the positioning is quite accurate, no drifting around. When I build it to iPad Air with iOS 11.3, the object is drifting around...

It's quite a bummer when the extended tracking can't be disabled but fortunately, there's this bug in Vuforia ( https://library.vuforia.com/articles/Release_Notes/Vuforia-SDK-Release-Notes.html ) :

"When switching to front camera, Model Targets extended tracking is disabled and will not re-enable when returning to back camera"


So, I switch camera to front camera then switch back to back camera and actually it work LoL Extended Tracking is disabled...

Inaccurate position of augmentations on iPadPro + iOS11 and black strips

January 25, 2018 - 7:07am #4

Hi guys,

I'm experiencing the same: Off-set content on image targets as well as top/bottom borders on iPad with iOS 11. Really interested in fixing this issue.

Inaccurate position of augmentations on iPadPro + iOS11 and black strips

January 24, 2018 - 3:08am #3

Hi Strasza,

First of all, thanks a million times for looking into this. I look forward to hearing the response from the internal team. Please let me know if I can do any other tests that could help you.

Regarding the positioning issue, I appreciate your explanation but I still believe there's something else going on, as the behaviour I get using iOS10 and iOS11 is totally different. I'm including below two new screen captures. As you can see in both cases the Image Target is displayed on my 13 inch computer screen, so it's the same size. I've taken the screenshots right after opening the app, after tapping once on the screen to gain focus, and without Extended Tracking.

iOS10: https://drive.google.com/open?id=1BOX98vN0t10Zjq5h_-i0wxTpPthvEnal

iOS11 (+ARKit): https://drive.google.com/open?id=1RGznphHs6fZSjjDeHG9j_1KPzQWdrYqe

As you can see the position of the cube is spot on when using iOS10, and totally off with iOS11. I'm using the Vuforia Core Samples project, the only thing I've added is the 3D cube on the scene.

I've been developing with Vuforia for almost three years and never had a similar problem, so I'm suspecting it perhaps has to do with the use of ARKit?

Thank you so much again for your help, I really appreciate it!!

Kind regards



Inaccurate position of augmentations on iPadPro + iOS11 and black strips

January 23, 2018 - 10:08am #2

Hello martejpad,

I've been digging into the 3 points you made above.

1.) This behaviour is generally expected at such a small scale using Image Targets. Based on the position of the camera, the depth value of an augmentation may alter slightly and give off the appearance of some drift. I observed this behaviour in both iOS 10, 11, and Android 7. Even after backgrounding to get the small black outline (I'll address that below), I still see this slightly drifting. It's a bit less obvious in this case.

2.) I've observed this behaviour as well. I'm forwarding this on to an internal team for further investigation. I'll update you with any news related to this.

3.) Same as above on this one. I've observed this behaviour and it doesn't appear on iOS10 and any non-ARKit device. I'll provide any updates as I get them.

Let me know if you have any further questions.


Vuforia Support

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