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I'm currently designing a project for a local museum through Purdue University's engineering class. My team has come down to three options:

  • Trying on a space suit with functioning parts
  • Looking though a telescope that uses a VR-type experience that displays the Hubble telescope images in a 3D like manner on the end of the telescope,
  • Or a mars rc rover that uses a QR reader to "scan" various objects on a "martian" surface and displays info to the user.

My team is looking for information on just how reliable QR code readers would be. We would only be using 2-3 simple designs (vertical lines, horizontal lines, and a circle). I could not find much information online other than "best ios QR reader" or "best QR readers!", so if anyone could give some insight to the range of precision that the reader would have (i.e. angle from normal that it would still work, etc) that would be awesome. The reader and code itself would always be at the same height.

Obviously budgets are a factor for this project, and each QR reader differs, but on average how does the QR code reader and software hold up?

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    $\begingroup$ In general barcodelike mass storeages are very reliable. How far you can read depends on your optics and available light. $\endgroup$ – joojaa Nov 21 '16 at 14:48
  • $\begingroup$ Do you know anything about the angle and accuracy relation? $\endgroup$ – Deek3117 Nov 21 '16 at 15:42
  • $\begingroup$ Like i said that is up to your optics. Optical devices range from 1 dollar to 100,000,000 dollars so do their capabilities, the furthest i have tried to read a barcode is 5 meters which was no problem $\endgroup$ – joojaa Nov 22 '16 at 4:34
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QR codes are very accurate. QR Code was originally invented in automotive assembly environments to allow for high-speed scanning of components and parts. To allow for them to be scanned at high speeds, they must be able to be scanned very accurately to ensure no errors during the assembly process which can lead to Quality Assurance and Quality Control issues.

So how accurate are they? Well that depends on the code design. Depending on the error-correction level and QR Code version, some labels allow for more errors than others. To quote Wikipedia:

Codewords are 8 bits long and use the Reed–Solomon error correction algorithm with four error correction levels. The higher the error correction level, the less storage capacity. The following table lists the approximate error correction capability at each of the four levels:

  • Level L (Low) 7% of codewords can be restored.
  • Level M (Medium) 15% of codewords can be restored.
  • Level Q (Quartile) 25% of codewords can be restored.
  • Level H (High) 30% of codewords can be restored.

In larger QR symbols, the message is broken up into several Reed–Solomon code blocks. The block size is chosen so that at most 15 errors can be corrected in each block; this limits the complexity of the decoding algorithm. The code blocks are then interleaved together, making it less likely that localized damage to a QR symbol will overwhelm the capacity of any single block.

Due to error correction, it is possible to create artistic QR codes that still scan correctly, but contain intentional errors to make them more readable or attractive to the human eye, as well as to incorporate colors, logos, and other features into the QR code block.

It is also possible to design artistic QR codes without reducing the error correction capacity by manipulating the underlying mathematical constructs.

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Is a analog QR code reader necessary? Couldn't you use a camera to take a photo, and then use something like OpenCV to write a program to crop the QR code from the photo, and then parse it using the extracted image?

SuDoKu Grabber in OpenCV

Look at this tutorial to see what I mean.

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    $\begingroup$ This answer doesn't address the question, which is about the precision and accuracy of reading QR codes. Although the OP seems to think there is some sort of "QR reader" that exists specifically for reading QR codes, there is no indication that they are trying to build an analog reader $\endgroup$ – BarbalatsDilemma Jan 3 '17 at 1:37

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