bimanual

We explore the idea of using vision-based hand tracking over a constrained tabletop surface area to perform multi-finger and whole-hand gestural interactions with large displays from a distance. We develop bimanual techniques to support a variety of asymmetric and symmetric interactions, including fast targeting and navigation to all parts of a large display from the comfort of a desk and chair, as well as techniques that exploit the ability of the vision-based hand tracking system to provide multi-finger identification and full 2D hand segmentation. We also posit a design that allows for handling multiple concurrent users.

We present an evaluation of three mouse-based techniques for aligning digital images. We investigate the physical image alignment task and discuss the implications for interacting with virtual images. In a formal evaluation we show that a symmetric bimanual technique outperforms an asymmetric bimanual technique which in turn outperforms a unimanual technique. We show that even after mode switching times are removed, the symmetric technique outperforms the single mouse technique. Subjects also exhibited more parallel interaction using the symmetric technique than when using the asymmetric technique.

We explore the design space of a two-sided interactive touch table, designed to receive touch input from both the top and bottom surfaces of the table. By combining two registered touch surfaces, we are able to offer a new dimension of input for co-located collaborative groupware. This design accomplishes the goal of increasing the relative size of the input area of a touch table while maintaining its direct-touch input paradigm. We describe the interaction properties of this two-sided touch table, report the results of a controlled experiment examining the precision of user touches to the underside of the table, and a series of application scenarios we developed for use on inverted and two-sided tables. Finally, we present a list of design recommendations based on our experiences and observations with inverted and two-sided tables.

Touch is a compelling input modality for interactive devices; however, touch input on the small screen of a mobile device is problematic because a user's fingers occlude the graphical elements he wishes to work with. In this paper, we present LucidTouch, a mobile device that addresses this limitation by allowing the user to control the application by touching the back of the device. The key to making this usable is what we call pseudo-transparency: by overlaying an image of the user's hands onto the screen, we create the illusion of the mobile device itself being semi-transparent. This pseudo-transparency allows users to accurately acquire targets while not occluding the screen with their fingers and hand. Lucid Touch also supports multi-touch input, allowing users to operate the device simultaneously with all 10 fingers. We present initial study results that indicate that many users found touching on the back to be preferable to touching on the front, due to reduced occlusion, higher precision, and the ability to make multi-finger input.

This paper presents a new GUI architecture for creating advanced interfaces. This model is based on a limited set of general principles that improve flexibility and provide capabilities for implementing information visualization techniques such as magic lenses, transparent tools or semantic zooming. This architecture also makes it possible to create multiple views and application-sharing systems (by sharing views on multiple computer screens) in a simple and uniform way and to handle bimanual interaction and multiple pointers. An experimental toolkit called Ubit was implemented to test the feasibility of this approach. It is based on a pseudo-declarative C++ API that tries to simplify GUI programming by providing a higher level of abstraction.

We present a computer vision technique to detect when the user brings their thumb and forefinger together (a pinch gesture) for close-range and relatively controlled viewing circumstances. The technique avoids complex and fragile hand tracking algorithms by detecting the hole formed when the thumb and forefinger are touching; this hole is found by simple analysis of the connected components of the background segmented against the hand. Our Thumb and Fore-Finger Interface (TAFFI) demonstrates the technique for cursor control as well as map navigation using one and two-handed interactions.