Technology
- Video
Capture
- Spot Finding
- Event
Handling
Our technology consists of three components: video capture, spot finding, and event handling.
Video Capture
The main component of video capture is the camera. At first we used a
Sony DCR-TRV20 MiniDV camera. This was chosen because of it's Night Mode
which allows the camera to see infrared as well as normal night vision
(amplification of ambient light). The night vision portion was suppressed
using an infrared only filter (filters out all light except infrared).
Look at the examples below and notice how the IR LED is only visible with
the IR filter on.
 |
 |
 |
| Normal | Night Mode | Night Mode w/ IR Filter |
The camera was connected to the computer using IEEE 1394 (Firewire). Due to some technical issues (which were eventually solved), we switched to a simple USB Webcam which we found worked far better for purposes than the Sony MiniDV. The video itself was captured using a program given to us by Audience Interactivity.
Spot
Finding
Once the video is in the computer, we need to find the infrared LED in
the video image and track its movement from frame to frame. For this we
wrote a program that finds the brightest group of pixels on the screen.
This is always the LED due to the infrared filter. The center of the group
is the X,Y coordinates that are used in event handling.
Event Handling
The X,Y coordinates are then used to generate a mouse event in the EventScope
software. When the LED is first activated, a mouse down event is sent
and when the LED disappears, a mouse up event is sent. The combination
of these two allows a user to click as well as drag and drop with whatever
is shown on the table. These events are passed to EventScope where there
are processed as usual.