Wrong Detection? How to properly calibrate?

[jmariller]

Hi @RivoLink

First of all thanks a lot for providing this application, it helped me a lot to start building a prototype based on ArUco - I needed to adapt your implementation slightly so that it works under Android 11 (e.g. cannot use mode world readable for preferences), but it eventually ran.

Now I am facing another challenge: the calibration seems to be working, as it effectively stores values in preferences which seem okay, however when I run the detection part of the application, the axis look all messed up - worse, when I am filming the full board the application hangs. Any idea what I am doing wrong, how do you properly calibrate the board? I assume 15-20 frames shall be captured from different viewpoints, right?

Many thanks in advance for your help!

[jmariller]

One more input after further checking: it seems like the orientation of the device (e.g. a smartphone in this case) has an impact on the calibration. When I capture frames, and calibrate in portrait with a single marker, tracking is working okay - however in landscape mode the axis are looking wrong.

[RivoLink]

Hello

I'm glad this application has help you.

In addition to the 15-20 frames, did you capture at least 10 markers in each frame?

I have never encountered this kind of calibration error, maybe because I have never tested the application on android 11.
Can you check if the calibration parameters pass from the camera-calibration application to the app on android 11?

On my side, I will update the application so that it supports android 11.

Thank you.

[jmariller]

Hi,

Thanks for your quick feedback!

Yes, I did capture at least 10 markers in each frame.

Some further information: in my project I am using the OpenCV-Contrib V.4.5.3 from QuickBird Studio.

Another thing I noticed is that the org.opencv.android.JavaCameraView component is showing the "rotated" camera - or to put it differently, I need to use my phone in landscape mode to properly see what the camera sees. In your app it works no matter what, but I could not find any specific settings for this?

One final comment: in my app I eventually grouped the calibration & tracking into a single app to still be able to use shared preferences.

Thanks!

[rgm-22]

Hi @RivoLink!

Thank you very much for sharing this project.

I'm also trying to implement it on Android 11 and we are facing the following error:

"Error: Can't load camera parameters."

Perhaps this is about @jmariller is mentioning:

"...in my app I eventually grouped the calibration & tracking into a single app to still be able to use shared preferences."

Thank you in advance! :)

[rgm-22]

I got it!
Yes, it seems to be that :)

Thank you!