Indoor Positioning System How-to

Description

This document describes an infra-red based indoor positioning system. The system uses up to 8 cameras to provide position information on infra red sources within their view. The cameras are static (no pan/zoom), so they can't perform any tracking. But we believe that 8 cameras should be more than adequate to provide full coverage of an average-sized classroom or laboratory. We are experimenting to determine the coverage we can get and to determine how many IR sources can be in the environment simultaneously without taxing the processor capturing the data.

Contacts

To get more information or help with the system, contact Anind Dey or Joe Bayes or Gregory Abowd. The system came from the Interactive Media Technology Center here at Georgia Tech. Our contact person is Peter Presti, but please ask one of the previously mentioned people any questions, before contacting Peter.

System Components

Currently the system consists of:

custom PC board and camera box
data capture S/W (executables and C++ source) for Windows NT
4 Sony CCD cameras, filters, cables, power adaptors
data processing S/W (executables and C++ source) for Unix

Status of System

Currently we only have the positioning system running with a single camera. When we get multiple cameras working with this system, I'll update this document. We have parts for 4 cameras, although only one is assembled.

System Access

The positioning system is in Room 102 of the College of Computing. You'll have to see either Anind Dey or Joe Bayes for the password to the computer.

Instructions

Turn on the PC
When given the option of the O/S to use, just hit RETURN
When prompted for login, press CTRL-ALT-DEL
Login using name and password obtained from Anind or Joe
Once the system is done loading, start the capture.exe file located in C:/Capture directory
Once the program has loaded, under the View menu, choose View Camera 1
Connect camera cable to DC IN/SYNC connector of the camera
Connect Video Out (red) to Greyscale Video Channel 1 on the camera input box. The channels are numbered starting from 0, so you want to connect to the second connector on the top.
Connect VD In/Out (white) to Composite Sync Channel 1, second connector on the bottom
Plug camera power adaptor in
Test system using IR emitter and battery or any IR-emitting device (e.g. TV remote)
- Remember the IR emitter is a diode, so current will only flow in one direction. You may have to flip the emitter around to get it to work.
- Aim the IR source into the camera (start about 1 foot away)
- Should see a point/oval in the Camera 1 viewing window
View the actual data by selecting View Packet under the Debug menu. The data is in the following format:
x position, y position, camera number, percent intensity
Change the view by selecting (checkmark) the Show Centroids option in the Control Panel. I think the control is mapped incorrectly. When the option is checkmarked, you only see a single point representing the IR source. When the option is blank, you see a red oval representing the IR source.
Write the data to a port by selecting the Serve Data Over Network in the Control Panel.
On any SGI, run ~anind/CyberGuide/Tracker/Simul. This connects to the positioning system computer and reads the positioning data. It does a little processing (time averaging of data and some other stuff - to be determined) and writes the data to the screen in the following format:
x position, y position, 8 bit intensity, camera number
for each point/centroid the camera sees.
To shut down the system:
- stop the Simul program running on the SGI
- exit the capture program (File menu)
- unplug the power adaptor
- shut down the PC using the Windows Start menubar
- power down the PC

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Last updated: 4/21/97