Christian Rendl

CRISTAL: a collaborative home media and device controller based on a multi-touch display

While most homes are inherently social places, existing devices designed to control consumer electronics typically only support single user interaction. Further, as the number of consumer electronics in modern homes increases, people are often forced to switch between many controllers to interact with these devices. To simplify interaction with these devices and to enable more collaborative forms of device control, we propose an integrated remote control system, called CRISTAL (Control of Remotely Interfaced Systems using Touch-based Actions in Living spaces). CRISTAL enables people to control a wide variety of digital devices from a centralized, interactive tabletop system that provides an intuitive, gesture-based interface that enables multiple users to control home media devices through a virtually augmented video image of the surrounding environment. A preliminary user study of the CRISTAL system is presented, along with a discussion of future research directions.

FlexSense: a transparent self-sensing deformable surface

We present FlexSense, a new thin-film, transparent sensing surface based on printed piezoelectric sensors, which can reconstruct complex deformations without the need for any external sensing, such as cameras. FlexSense provides a fully self-contained setup which improves mobility and is not affected from occlusions. Using only a sparse set of sensors, printed on the periphery of the surface substrate, we devise two new algorithms to fully reconstruct the complex deformations of the sheet, using only these sparse sensor measurements. An evaluation shows that both proposed algorithms are capable of reconstructing complex deformations accurately. We demonstrate how FlexSense can be used for a variety of 2.5D interactions, including as a transparent cover for tablets where bending can be performed alongside touch to enable magic lens style effects, layered input, and mode switching, as well as the ability to use our device as a high degree-of-freedom input controller for gaming and beyond.

PyzoFlex: printed piezoelectric pressure sensing foil

Ferroelectric material supports both pyro- and piezoelectric effects that can be used for sensing pressures on large, bended surfaces. We present PyzoFlex, a pressure-sensing input device that is based on a ferroelectric material. It is constructed with a sandwich structure of four layers that can be printed easily on any material. We use this material in combination with a high-resolution Anoto-sensing foil to support both hand and pen input tracking. The foil is bendable, energy-efficient, and it can be produced in a printing process. Even a hovering mode is feasible due to its pyroelectric effect. In this paper, we introduce this novel input technology and discuss its benefits and limitations.

Presstures: exploring pressure-sensitive multi-touch gestures on trackpads

In this paper, we present Presstures, an extension to current multi-touch operations that enriches common multi-finger gestures with pressure information. By using the initially applied pressure level for implicit mode switching, a gesture can be enhanced with different functionalities to enlarge the interaction space for multi-touch. To evaluate the feasibility of our concept, we conducted an experiment, which indicates good human sensorimotor skills for performing multi-touch gestures with a few number of pressure levels and without any additional feedback. Based on the experimental results, we discuss implications for the design of pressure-sensitive multi-touch gestures, and propose application scenarios that make optimal use of our concept.

proCover: Sensory Augmentation of Prosthetic Limbs Using Smart Textile Covers

Todays commercially available prosthetic limbs lack tactile sensation and feedback. Recent research in this domain focuses on sensor technologies designed to be directly embedded into future prostheses. We present a novel concept and prototype of a prosthetic-sensing wearable that offers a non-invasive, self-applicable and customizable approach for the sensory augmentation of present-day and future low to mid-range priced lower-limb prosthetics. From consultation with eight lower-limb amputees, we investigated the design space for prosthetic sensing wearables and developed novel interaction methods for dynamic, user-driven creation and mapping of sensing regions on the foot to wearable haptic feedback actuators. Based on a pilot-study with amputees, we assessed the utility of our design in scenarios brought up by the amputees and we summarize our findings to establish future directions for research into using smart textiles for the sensory enhancement of prosthetic limbs.

FlexTiles: A Flexible, Stretchable, Formable, Pressure-Sensitive, Tactile Input Sensor

In the FlexTiles demonstration, we present a flexible, stretchable, pressure-sensitive, tactile input sensor consisting of three layers of fabric. We demonstrate the implementation of FlexTiles for covering large areas, 3D objects, and deformable underlying shapes. In order to measure these large areas with high framerate, we demonstrate a simple measurement implementation. Finally, we outline the benefits of our system compared to other tactile sensing techniques.

FlexCase: Enhancing Mobile Interaction with a Flexible Sensing and Display Cover

FlexCase is a novel flip cover for smartphones, which brings flexible input and output capabilities to existing mobile phones. It combines an e-paper display with a pressure- and bend-sensitive input sensor to augment the capabilities of a phone. Due to the form factor, FlexCase can be easily transformed into several different configurations, each with different interaction possibilities. Users can use FlexCase to perform a variety of touch, pressure, grip and bend gestures in a natural manner, much like interacting with a sheet of paper. The secondary e-paper display can act as a mechanism for providing user feedback and persisting content from the main display. In this paper, we explore the rich design space of FlexCase and present a number of different interaction techniques. Beyond, we highlight how touch and flex sensing can be combined to support a novel type of gestures, which we call Grip & Bend gestures. We also describe the underlying technology and gesture sensing algorithms. Numerous applications apply the interaction techniques in convincing real-world examples, including enhanced e-paper reading and interaction, a new copy and paste metaphor, high degree of freedom 3D and 2D manipulation, and the ability to transfer content and support input between displays in a natural and flexible manner.

Kolibri: tiny and fast gestures for large pen-based surfaces

Triggering commands on large interactive surfaces is less efficient than on desktop PCs. It requires either large physical movements to reach an interaction area (e.g., buttons) or additional operations to call context menus (e.g., dwell). There is a lack of efficient ways to trigger shortcuts. We introduce Kolibri - a pen-based gesture system that allows fast access of commands on interactive whiteboards. Users can draw tiny gestures (approx. 3 mm) anywhere on the surface to trigger commands without interfering with normal inking. This approach does neither require entering a gesture mode, nor dedicated gesture areas. The implementation relies on off-the-shelf hardware only. We tested the feasibility and explored the properties of this technique with several studies. The results from a controlled experiment show significant benefits of Kolibri comparing to an existing approach.

RESi: A Highly Flexible, Pressure-Sensitive, Imperceptible Textile Interface Based on Resistive Yarns

We present RESi (Resistive tExtile Sensor Interfaces), a novel sensing approach enabling a new kind of yarn-based, resistive pressure sensing. The core of RESi builds on a newly designed yarn, which features conductive and resistive properties. We run a technical study to characterize the behaviour of the yarn and to determine the sensing principle. We demonstrate how the yarn can be used as a pressure sensor and discuss how specific issues, such as connecting the soft textile sensor with the rigid electronics can be solved. In addition, we present a platform-independent API that allows rapid prototyping. To show its versatility, we present applications developed with different textile manufacturing techniques, including hand sewing, machine sewing, and weaving. RESi is a novel technology, enabling textile pressure sensing to augment everyday objects with interactive capabilities.

cLuster: Applications for Smart Clustering of Free-Hand Sketches

Structuring and rearranging free-hand sketches on large interactive surfaces typically requires making multiple stroke selections. Without well-designed selection tools, this can be both time-consuming and fatiguing. Investigating the concept of automated clustering, we conducted a background study to understand the varying perspectives of how elements in sketches can be grouped. In response to these diverse user expectations, we present cLuster, a flexible, domain-independent clustering approach for free-hand sketches. Our approach is designed to accept an initial user selection, which is then used to calculate a linear combination of pre-trained perspectives in real-time. The remaining elements are then clustered. We demonstrate the utility of our approach in a variety of application scenarios.