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Scanning QR Code from a long distance

asked 2019-10-01 09:23:05 -0500

updated 2019-10-01 09:24:29 -0500


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 :

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.

image description

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.

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answered 2019-10-01 10:05:14 -0500

Eduardo gravatar image

updated 2019-10-01 10:06:49 -0500

Ability to detect a tag should depend mostly on how big it appears in the image (other criterion are image quality, image sharpness, blurness, image lightness, ...).

How big it appears in the image depends on the following:

  • camera focal length
  • image resolution
  • working distance
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Thank you for your answer, yes i think for me it's the auto focus, the camera i am using doesn't have it.

Kitnos gravatar imageKitnos ( 2019-10-01 15:06:07 -0500 )edit
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Asked: 2019-10-01 09:23:05 -0500

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Last updated: Oct 01 '19