Scenario 1: (a) when touching the screen over a small target,
target acquisition is a problem. (b) Shift responds by displaying a callout containing a copy of the occluded area with a pointer representing the hotspot of the finger. (c) Without lifting the finger the user moves the pointer to the desired target and (d) selects the target by lifting the finger, which (e) removes the shifted display.
Scenario 2: When acquiring a large target occlusion is not a problem, Shift does not “escalate” and instead behaves like a regular, unmodified touch screen. This allows for particularly fast usage.
Retrieving the stylus of a pen-based device takes
time and requires a second hand. Especially for short, intermittent
interactions many users therefore choose to use their bare fingers
instead. Although convenient, this increases targeting times and error
rates. We argue that the main reason is the occlusion of the target by
the user’s finger. We propose a pointing technique we call Shiftthat is designed to address this issue. When the user touches
the screen, Shift creates a callout showing a copy of the occluded
screen area and places it in a non-occluded location. The callout also
shows a pointer representing the hotspot of the finger. Using this
visual feedback, users guide the pointer into the target by moving their
finger on the screen surface and commit the target acquisition by
lifting the finger. Over large targets, in contrast, no callout is
created and users enjoy the full performance of an unaltered touch
screen. In our user study, participants acquired targets faster when using Shift
than when using the traditional offset cursor technique.
Vogel, D. and Baudisch, P. Shift: A Technique for Operating Pen-Based Interfaces
Using Touch In Proceedings of CHI 2007,San Jose,
CA, Apr 28-May 18, 2007.
PDF (1.5M) |
CHI 2007 BEST PAPER AWARD
In collaboration with
Dan Vogel during his 2007
internship at Microsoft Research