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7.25 laservisualbarcode


Andrew Howard ahoward(at)

Figure 7.5: A sample laser visual barcode.
\epsfig{file=laservisualbeacon.eps, height=40mm}\end{center}\end{figure}


The laser visual barcode detector uses both searches for fiducials that are both retro-reflective and color-coded. Fiducials can be either planar or cylindical, as shown in Figure 7.5. For planar targets, the range, bearing, orientation and identity will be determined; for cylindrical targets, the orientation will be undefined. The target size and shape can be set in the configuration file.

The laser visual barcode detector searches the laser range data to find retro-reflective targets, points the camera at each of these targets in turn, then uses color information to determine the presence and identity of fiducials. Thus, this detector makes use of three underlying devices: a laser range finder, a pan-tilt-zoom camera and a color blob detector. Note that the laser is used to determine the geometry of the fidicual (range, bearing and orientation), while the camera is used to determine its identity.

The range at which fiducials can be both detected and identified depends on a number of factors, including the size of the fiducial and the angular resolution of the laser. Generally speaking, however, this detector has better range than the laserbarcode detector, but produces fewer observations.

See also the laserbar and laserbarcode drivers.


Supported interfaces:

Required devices:

Supported configuration requests:

Configuration file options

Name Type Default Meaning
laser integer 0 Index of the laser device to be used.
ptz integer 0 Index of the ptz device to be used.
blobfinder integer 0 Index of the blobfinder device to be used.
shape string ``cylinder'' Target shape: ``plane'' or ``cylinder''. Planar fiducials are currently not supported.
bit_count integer 8 The number of bits in the barcode.
bit_width length 0.05 The width of each bit in the barcode (m).
bit_height length 0.05 The height of each bit in the barcode (m).


Setting up the laser-visual barcode detector can be a bit tricky, since it involves so many underlying devices. Users should first check that the laser, ptz and blobfinder devices are working before attempting to use the laservisualbarcode driver. Note that the blobfinder device must be calibrated to detect the particular colors used in the fiducials, and that the identity assigned to each fiducial is determined by the color-to-channel mapping chosen during this configuration.

For more information on the laserbarcode driver, ask Andrew Howard:

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Next: 7.26 lifo-mcom Up: 7. Device Drivers Previous: 7.24 laserbarcode   Contents