Are there are other systems that enable a user to capture information about objects in the real world?
Listed below are several such technologies, along with a brief description of each and how it differs from radio frequency identification.
2-D Bar Codes: There are a variety of methods for encoding serial numbers, URLs and other information in 2-D bar codes. Their strength is that they are cheap to create, but their weakness is that they require line of sight, and usually a person's presence to scan the bar code and retrieve the data. They also have a limited capacity for data storage.
Ultrasound: Ultrasound uses mechanical sound waves rather than electromagnetic waves. The tags emit a sound humans cannot hear, but a receiver can pick it up and decode the signal in order to identify an object. Ultrasound's strength is that it does not pass through walls, so you could put a receiver in each room and know that a tagged object was in a specific room. With RFID, you sometimes can't tell if an object is actually in a given room or merely in the hallway outside. Ultrasound's disadvantage is that you would need a greater number of receivers than you would with an active RFID system to cover, say, a hospital wing. And tagged items within a closet cannot be located, whereas an active RFID tag's signal would penetrate walls and closet doors.
Infrared: Infrared's advantage is that it is short-range and can be used to locate an object within a specific area of, for instance, a hospital room. Its disadvantage is that it requires line of sight—cover an infrared tag with a blanket, and you won't be able to read it.
Video: With the cost of computing power falling rapidly, video analytics is becoming more common. You can, for example, use the technology in a mall to monitor traffic patterns, and it could also be used to identify items on shelves, or to determine when shelves are out of stock. With video analytics, you need not tag items. But creating algorithms to identify goods that might be similar but not the same is neither simple nor inexpensive, and video requires line of sight. A video analytics system will never be able to tell you how many shirts are inside a box, nor whether a stack of jeans on a shelf are all size 32-34 or a mix of 32-24 and other sizes.
All of the above technologies have their usefulness for certain business applications, but none offer the broad capabilities that RFID provides. That's why I am certain RFID will become ubiquitous, while the above technologies will remain relegated to certain niches.
—Mark Roberti, Founder and Editor, RFID Journal
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