Scanning QR Code from a long distance

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Hello,

I have a question if you can help me about the distance of QR code detection, i am using the code in this link and it's working very well :

https://www.learnopencv.com/opencv-qr...

For example if i use a QR code with a dimension (3.5 x 3.5) cm, the scanning distance to detect this QR code is 40 cm, a distance bigger than that i can't detect the QR code.

I calculate this distance and it's close to the theoretical values, i used this relation :

And i find the same result, for a QR code with the size 3.5 cm the scanning distance is 41 cm.

The number of rows is : 21

I am using a camera with a resolution 400x600

My question is : there is some application that can read the same QR code (3.5 x 3.5) cm from a long distance than 40 cm, what is the difference between this applications and the function of Opencv, of maybe the problem is the resolution of the camera?

And thank you.