NXT-Spy – Testing the QR code (flag) processing

For the QR code processing, I implemented the XZing library quite quickly thanks to the documentation of it. And I printed the QR codes for the letters B and R in full size on two A4 sheets.

At first, I didn’t have really good results : the barcode were decoded only when the camera was at a distance of 0.5m and with a good luminosity.

After some thought, I realized that the very low resolution I used so far was probably not big enough to allow ZXing to decode the complex QR code precisely.

So I almost doubled it to 320 x 240 and got way better results : QR codes are now decoded from as far as 1.5m and with and angle of something like 30 degrees with the flag. Obviously, I have a lower frame-rate, but it is still acceptable as long as we are working in optimal conditions (a powerful Linksys router with no encryption key).

Supervisor’s comment:

I am impressed that you are able to read the ‘flags’ from such a distance as 1.5 m and also from an acute angle.
Its now a case of getting all the bits and pieces to talk to each other in a coherent manner that allows the balls to be sorted!
Next week is the review with Kevin, so remember to bring i  the robot and show him those buts that already work and those bits that are still under development.

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