Users Manual

Note: The TagDetect components are optional and require a separate license (Section 9.6) to be purchased.
Tag detection is made up of three steps:
1. Tag reading on the 2D image pair (see Tag reading, Section 7.3.2).
2. Estimation of the pose of each tag (see Pose estimation, Section 7.3.3).
3. Re-identification of previously seen tags (see Tag re-identification, Section 7.3.4).
In the following, the two supported tag types are described, followed by a comparison.
QR code
Fig. 7.3.1: Sample QR code
QR codes are two-dimensional bar codes that contain arbitrary user-defined data. There is wide support for
decoding of QR codes on commodity hardware such as smartphones. Also, many online and offline tools are
available for the generation of such codes.
The “pixels” of a QR code are called modules. Appearance and resolution of QR codes change with the amount
of data they contain. While the special patterns in the three corners are always 7 modules wide, the number of
modules between them increases the more data is stored. The lowest-resolution QR code is of size 21x21 modules
and can contain up to 152 bits.
Even though many QR code generation tools support generation of specially designed QR codes (e.g., containing
a logo, having round corners, or having dots as modules), a reliable detection of these tags by the rc_visard’s
TagDetect component is not guaranteed. The same holds for QR codes which contain characters that are not part
of regular ASCII.
7.3. TagDetect 75