1. R F I G : RFID + Geometry Photosensing Wireless Tags for Precise Location and Complex Geometric Procedures
Ramesh Raskar,
Paul Dietz, Paul Beardsley, Darren Leigh, Jeroen van Baar

2. Problem Example: Tagged Books in a Library
Id : List of books in RF range
No Precise Location Data
(Are books in sorted order ? Which book is upside down ?)
The solution: RFIG

3. What is RFIG? RFIG = RF Id + Geometry
RFIG is a system for finding location of (photosensitive) RF tags using a hand-held projector
Photosensing Wireless Tags
LED
Projector
Interactive stabilized projection

4. Visual Feedback of location with Photosensing RFID + Pocket Projector Movie
11/15/2018

5. Mitsubishi Electric Pocket Projector DLP based with R, G, B LEDs Instant on, battery-pack Available Now

6. From RFID to RFIG Conventional RFID Photosensing RFID Tag RFIG System
11/15/2018

7. RFIG Operation Procedure Steps
RF reader initializes system; projector produces a sequence of aiming patterns
Temporal signal at each tag photodiode is decoded at the tag, and this uniquely defines its position
Tag transmits via RF its ID#, its coordinates (and other information, as required by the application)
Reading system processes the information and determines the designating pattern that the projector has to produce in order to help the user accomplish the task

8. Step 1: Project Sequential Aiming Patterns Step 2: Tag Decodes its Position
Sequence example
for determining
x - coordinate
t = 4T
t = 3T
t = 2T
t = T
t = 0
Tag
photodiode
Total
projected
area
x = 1 1
0 = 20

9. Example: Complete Set of 5-bit 2D Aiming Patternsy
N = # of illumination patterns per axis (= # of bits)
For example: N=10, Illuminated area size = 10 m
==> Spatial resolution = 1 cm

10. Step 3: Tag Transmits ID & {x,y} Coordinates Step 4: Projector Provides User Feedback
Example:
• Project green spots on items that have to be moved to store front
• Project red spots on items that need to be returned to supplier

11. First Experimental Set-Up
Tag
Modified Projector

12. Advantages and Limitations
Enhanced functionality
High-accuracy location determination
Ability to communicate with tags selectively
RF collision avoidance
Minimal impact on tag in terms of
Cost
Size
Power consumption
Limiting requirements
Line of sight
Modified packaging

13. Alternative RF+Optical Approaches
Yoshikawa
RF Systems
(125 kHz)
PHOCI
(Cliffton Labs) Blinking LEDs + Special Camera
LED /
CCD
RFIG
long
Range
LED /
RFID
short
yes no
Battery

14. RFIG Application Example: Surveillance Detect Arrangement Change Without Fixed Camera and In Any Lighting Condition
Before
After
Record coordinates of tags from one view
Compare with new coordinates from a different view

15. Application Example: 3D from 2 Projector Views (Structure from Motion)
Two+ unknown projector views
Correspondence is trivial
Applications
Detect 3D deformations
Asset tracking facilitation
Trajectory grouping

16. RFIG Application Example: Factory Robots Laser Guided Robot

17. Application Examples Location tracking Occlusion detection
Hospitals, locating medicines
Asset tracking, warehouses
Factory automation,
Sorting, routing, directing packaging
Positioning products on assembly line
Entertainment, games, motion capture
Occlusion detection
Railway tracks
Occupancy in public areas
Change detection
Surveillance, Monitoring buildings and bridges structures
Augmented reality
Visual feedback in control rooms, HCI

18. Other RFID Projects iGlassWare
IEEE Sensors 2002

19. The iGlassware System The prototype instrumented glass
IEEE Sensors 2002

20. The Reader
IEEE Sensors 2002

21. (Radio Frequency Id & Geometry)
R F I G
R F I D
(Radio Frequency Id & Geometry)
Photosensing Wireless Tags
Find tag location using handheld Projector
Simultaneous readers without RF Collision
Many geometric ops
Google search term: RFIG