QRC Codes and CCTV

Sep 20, 2012 4 Replies

Anyone have a link to camera resolution vs QRC reading error (failure) rates?



I've got an idea that involves reading these things from a distance and I need to to a quick calculation to determine camera resolution, field of view, etc. necessary to reliably read these things. I haven't defined 'reliably' yet. The customer will help if this is within the realm of possibility.


Paul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ Any sufficiently advanced technology is indistinguishable from a rigged demo.

Trigonometry? And camera lens dependant.

From the combination of the camera resolution and the lens' angle-of-view you can determine a distance where the QRC dot-size matches the effective projected pixel size.

For reliability you might want more than one camera pixel per QRC dot.

To get more distance you need higher zoom lenses or higher resolution camera sensors.

HTH.

Chris.

Right. But how does this reliability vary with pixels per QRC dot?

I'm sure its s/w dependant to a degree. But I'd like to find out where the knee in the curve is, so I know when spending more on camera resolution stops buying me better performance.

Paul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ Ubuntu - Bantu for "I don't know how to configure Debian."

I'm not familiar with QRC decoding algorithms, sorry. I deal mostly with OCR and as a rule-of-thumb we work with 2 pixels per character stroke.

For best results you should also be using a monochrome sensor (to avoid the bayer filter effects of colour sensors) and zero image compression.

Chris.

Might want to try some lens calc. sites. I have no idea about error rates.

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See also the other calcs. on the LhS of that page.

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