Information Technology Reference
In-Depth Information
Fig. 2.3
An infrared camera of the OptiTrack high-speed motion capture system
cameras, its 3D position can be calculated. If several dots form a known spatial
arrangement, the object's 3D pose can also be identified. Figure 2.3 shows an Opti-
Track camera.
Electronic Markers
Electronic markers avoid some of the major problems of visual markers. Radio-
Frequency Identification (RFID) uses tags that are embedded into or applied to a
physical object. The tag consists of an integrated circuit that stores a unique ID and
manages the communication with an external reading device. Moreover, it includes
an antenna for receiving and transmitting signals. If the tag is passive, it does not
include an own battery but receives energy from the reading device via an elec-
tromagnetic field. When the RFID tag is within the range of a reading device, it
transmits its unique ID.
No direct line of sight between the tag and the reading device is necessary. How-
ever, in contrast to fiducials, RFID tags produce significant costs. To date, an RFID
tag still costs more than 0.1 USD. Depending on how paper is used in a Pen-and-
Paper Application, these costs might be prohibitive. Moreover, in contrast to fidu-
cials that can be printed directly with the paper document, an additional processing
step is necessary for applying RFID tags to paper. Finally, while the technology en-
ables to track whether a tag is within the range of a reader or not, it does not identify
its precise location. A novel technology called Near Field Communication (NFC)
enables mobile phones to act both as RFID tag and as RFID reading device. NFC
