Handhelds gain space

By Kimberly Patch, Technology Research News

Although a keyhole is quite small, putting your eye close to it lets you see a significant portion of a room. Being able to move the keyhole around would widen the view.

A researcher at the University of California at Berkeley has rigged up a device that turns the small screen of a handheld computer into a movable keyhole. Rather than pressing scroll buttons to get to a position in a document, a user simply moves the handheld computer.

The screen is a window onto a larger virtual document. To navigate to the lower left corner of an on-screen map, a user would move the computer in and to the left. "The handheld computer scrolls its display as you move it, in order to maintain the illusion that you are viewing a small part of a large, fixed workspace," said Ka-Ping Yee, researcher at the University of California at Berkeley.

The illusion goes both ways, allowing input into the larger virtual space as well. "You can interact with the workspace using [a] pen while moving the screen around to see different parts of that space," said Yee.

The idea sprung from real-world frustration over the sluggishness of small-screen navigation. "I was motivated by wanting to position the view directly instead of having to wait for the view to scroll," Yee said.

Yee put the device together by hooking up a handheld computer to tracking equipment. "I tried three different methods, and there are probably many other ways that it could be done as well," said Yee.

The three proof-of-concept prototypes include a partially deconstructed mechanical mouse and fishing line, which allows users to move the computer freely through space; the innards of an optical mouse affixed to a handheld computer, which requires that the handheld be moved only along a surface, and an ultrasonic transmitter, which allows for free movement, but is more sluggish than the other methods.

Key to making viable prototypes was getting the handheld screen to update fast enough to maintain the illusion, said Yee. "I had to get the [handheld] to update its screen quickly so that it would respond smoothly while the screen was being moved," he said.

Yee tested the usability of the peephole computing concept by having 24 participants perform several simple tasks using both a conventional handheld computer and the peephole prototype. They browsed using one hand to move the display around, and performed as well as the usual two-handed method -- using one hand to hold the PDA and a pen to scroll the display, said Yee. The subjects also found it easier to browse a map using the one-handed peephole method, he said.

The subjects were also able to draw 32 percent faster using the peephole prototype, and said they strongly preferred the method, said Yee. Many of the participants made larger drawings when using the peephole method even though the canvas sizes were the same; this suggests that the participants felt less constrained using the peephole interface, according to Yee.

And 17 of the participants naturally used both hands when drawing with the peephole prototype, moving the handheld with one hand to be able to make longer pen strokes with the other, according Yee.

Allowing the user's non-dominant hand to navigate by moving the handheld computer enables the dominant hand to work beyond the spatial boundary that ordinarily forces the user to stop and scroll, according to Yee.

Yee also expanded the virtual peephole space into three dimensions with applications that allow users to switch views by moving the handheld device vertically. "This technique lets you manipulate information in multiple planes at once, because you can also raise or lower the display," he said. "That enables you to organize information in some pretty interesting new ways," he said.

A three-dimensional peephole calendar allows users to scan horizontally to view events in the coming week and vertically to delve down to the details of a particular time of day.

And adding a third dimension to the sketch pad made it possible to have a clipboard plane where users can drag-and-drop items. Unlike ordinary computer clipboards, the clipboard plane is viewable, which makes it possible for users to place more than one item on it, and to keep things organized, according to Yee. To help the user stay oriented, Yee gave the planes different background colors.

The work extends the idea of a handheld view port onto a virtual workspace conceived by University of Toronto researcher George Fitzmaurice a decade ago, according to Yee. Fitzmaurice used a handheld color TV connected to a desktop computer to produce the illusion that the TV was a palm computing device.

Yee added pen input to the concept and implemented it on a handheld computer. "Fitzmaurice's work was mostly about just viewing the information. I've taken it a little further by exploring how you can use both hands together to interact with information in the virtual workspace," said Yee.

It is a very good idea, and there are some nice applications, said Brad Myers, a senior research scientist at Carnegie Mellon University. The next step toward making a practical implementation is replacing the string and pulleys used to keep track of the handheld's position, according to Myers.

The work addresses a modern-day screen-size paradox, said Robert Jacob, an associate professor of computer science at Tufts University. "As we move away from desktop computers, we see interfaces becoming both smaller and bigger -- smaller for portability and personal use, bigger for larger display surfaces and information spaces," he said. "This work attempts to bridge that gap by providing a large virtual user interface and work surface using a small physical device."

Yee's spatially-aware-display is aimed at generally improving the mechanics of using PDAs. The idea is to decouple the size of a computer from the size of the information space a person has to work with, said Yee.

"What I'm envisioning is a personal information space, where... information like your address book and your calendar are associated with the space around you," said Yee. "They would follow you wherever you go... you could pull out your PDA and find your calendar always located on your right, and your address book on your left," he said.

The concept can also be applied to mobile phones. Yee wrote an application for his prototype that leverages the peephole concept to make it easier to select items from a handheld screen using only one hand. The one-handed selector program allows the user to move the handheld device vertically in order to move a highlight bar up or down the screen, then select an item by pressing a button.

The concept could also be applied to expert interfaces as a way to make many layers of information easily accessible, said Yee.

The concept could be turned into a practical device within five years, said Yee.

The research is scheduled for presentation at the ACM Conference on Human Factors in Computing Systems in April, 2003 (CHI 2003) in Fort Lauderdale. The research was funded by an IBM Ph.D. fellowship.

Timeline:   5 years
Funding:   Corporate
TRN Categories:  Human-Computer Interaction
Story Type:   News
Related Elements:  Technical paper, "Peephole Displays: Pen Interaction on Spatially Aware Handheld Computers," scheduled for presentation at the Association for Computing Machinery's (ACM) Conference on Human Factors in Computing Systems in April, 2003 (CHI 2003) in Fort Lauderdale.


February 26/March 5, 2003

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