RFIG: Photosensing RFID for Location Aware Services
We have developed wireless tags that can be located using coded illumination. The idea can be easily adopted for passive RFID allowing a range of geometric operations. We augment each tag with a photo-sensor to significantly extend the current functionality and support radio frequency identity and geometry (RFIG) discovery. The ability to address and wirelessly access distributed photosensors creates a unique opportunity. We recover geometric information, such as 3D location of tags or shape history of tagged objects, and exploit the associated geometric operations to bring the RF tags into the realm of computer vision and computer graphics.
Background & Objective: Wireless tags such as RFID (radio frequency identification) are becoming ubiquitous in inventory management. However, it is difficult to precisely locate the tags using a handheld device. We overcome this problem by using a hybrid of radio frequency and optical communication with the tag.
Technical Discussion: The handheld device consists of a RF reader plus a data projector. The handheld device is first aimed casually in the direction of a tagged object. The handheld device sends an RF signal to synchronize the tags, followed by illumination with a sequence of binary patterns such that each projector pixel emits a unique temporal Gray-code. The tag records the Gray-code that is incident on its photo-sensor, and then makes an RF transmission of its identity plus the recorded Gray-code back to the RF-reader. The computed (x,y) projector pixel coordinate is turned on to visually indicate the location of the tag. Multiple tags can be attached to a single rigid object to compute the relative pose (3D location and orientation) of the object and to compare geometry of multiple objects.
Raskar, R.; Beardsley, P.; van Baar, J.; Wang, Y.; Dietz, P.H.; Lee, J.; Leigh, D.; Willwacher, T., “RFIG Lamps: Interacting with a Self-Describing World via Photosensing Wireless Tags and Projectors”, ACM SIGGRAPH, ISSN: 0730-0301, Vol. 23, Issue 3, pp. 406-415, August 2004 (ACM Press, TR2004-062)
Research Area: Sensor and Data Systems
Modification Date: July 7, 2008