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4 QR Code Reading Behavior

SAFR SCAN will read all QR codes in view starting with the largest. The first QR code to be successfully read is processed for access (matched to person records or transmitted to panel). Once processed, that QR code is not read again until it leaves view. SCAN will then proceed to read the next largest QR code in view.

Normally one QR code should be presented at a time. SAFR will being to read that QR code once it reaches the minimum size. The QR code must be stable enough to allow for sufficient number of consecutive reads. SAFR is configured with optimal settings for size, motion and the number of consecutive reads, but advanced configuration is available as described below.

4.1 Advanced Configuration Properties

access.qr-code.min-size

Smallest size of QR code that will be read. QR codes smaller than this value are ignored.

access.qr-code.min-detections

Number of detections needed to read a QR code. A QR code must reach this number of detections before read is considered complete.

access.qr-code.max-motion

Maximum amount of motion between successive frames of video that will be allowed to be considered same. SAFR tracks each QR code from frame to frame. If motion is detected greater than this threshold, the number of detections counter is reset.

4.2 Read Size vs. Distance

The distance at which SAFR SCAN can read a QR code is dependent upon the size of the QR code, distance from SCAN and the amount of data encoded into the QR code.

  • The amount of data encoded into a QR code determines the resolution (number of pixels) in the QR code as described in Size vs. Error Correction table above.
  • The size of the QR code will then determine the pixel density or size of each pixel. Smaller pixels must be closer to SCAN to be read.
  • The distance from the reader has an effect on the number of pixels within the video allocated overall to the QR code. SAFR SCAN’s camera is a wide angle camera and thus size diminishes rapidly with distance.

The table below provides information on various QR codes and the distance at which they can be read.

Data Size

Print Size

Max Read Distance

UID-32

1.5”

14”

¾”

6”

UID-56

1.5”

14”

¾”

6”

128 Characters

1.5”

14”

¾”

Not readable at any distance