Scroll, Tilt or Move It
Using Mobile Phones to Continuously Control Pointers on Large Public Displays
Particularly large display technologies are starting to appear in our everyday lives. Not only can they be found in private environments (e.g., large-scale TVs, projectors or monitors), but more and more in public spaces such as airports, subway stations or shopping malls, where they mostly act as large ambient information displays. Instead of allowing users to capture interesting information or influencing the display's content, the usage models of these displays tend to be static, offering only unidirectional broadcast without possibilities for bidirectional interaction. In addition, home-installed large screens, e.g., projectors or flat panels, mostly lack sophisticated input capabilities beyond those of a TV remote.
On the other hand, small portable devices such as personal digital assistants (PDAs) and mobile phones are available at low prices and are by now usual companions in our everyday lives. Despite their limited visual output capabilities compared to large screens, they come with various built-in input options such as a joystick, a stylus, a keypad or touch-screens. Hence, combining the users' mobile devices and large public displays, for example, allow the control of a personal pointer on the public display, turning the phone into a ubiquitous input device for large screens. The interaction techniques need to be efficient, enjoyable and easy to learn. Unfortunately, each of them has its limitations in terms of accuracy, operation speed, efficiency and ergonomics.
We discuss three different techniques to control a pointer on a large public display by using a selection of mobile device input and sensing capabilities. We developed three distinct strategies for continuously controlling the user's pointer: first, the pointer can be moved constantly by pressing the phone's joystick in the respective direction (Scrolling). Second, the pointer is accelerated by tilting the mobile phone in the desired direction (Tilting), and third, the pointer's movement is linearly mapped to the phone's movement (Moving). We discuss the different input strategies followed by an extensive evaluation in which we analyze the feasibility of each input mapping in detail. Based on the findings in our evaluation, we provide insights on how to design pointer interaction on large screens using mobile devices.