Ultrasonic mid-air haptic feedback enables the tactile exploration of virtual objects in digital environments. However, an object’s shape and texture is perceived multimodally, commencing before tactile contact is made. Visual cues, such as the spatial distribution of surface elements, play a critical first step in forming an expectation of how a texture should feel. When rendering surface texture virtually, its verisimilitude is dependent on whether these visually inferred prior expectations are experienced during tactile exploration. To that end, our work proposes a method where the visual perception of roughness is integrated into the rendering algorithm of mid-air haptic texture feedback. We develop a machine learning model trained on crowd-sourced visual roughness ratings of texture images from the Penn Haptic Texture Toolkit (HaTT). We establish tactile roughness ratings for different mid-air haptic stimuli and match these ratings to our model’s output, creating an end-to-end automated visuo-haptic rendering algorithm. We validate our approach by conducting a user study to examine the utility of the mid-air haptic feedback. This work can be used to automatically create tactile virtual surfaces where the visual perception of texture roughness guides the design of mid-air haptic feedback.

Touch is a powerful vehicle for communication between humans. The way we touch (how) embraces and mediates certain emotions such as anger, joy, fear, or love. While this phenomenon is well explored for human interaction, HCI research is only starting to uncover the fine granularity of sensory stimulation and responses in relation to certain emotions. Within this paper we present the findings from a study exploring the communication of emotions through a haptic system that uses tactile stimulation in mid-air. Here, haptic descriptions for specific emotions (e.g., happy, sad, excited, afraid) were created by one group of users to then be reviewed and validated by two other groups of users. We demonstrate the non-arbitrary mapping between emotions and haptic descriptions across three groups. This points to the huge potential for mediating emotions through mid-air haptics. We discuss specific design implications based on the spatial, directional, and haptic parameters of the created haptic descriptions and illustrate their design potential for HCI based on two design ideas.

We present a method for creating three-dimensional haptic shapes in mid-air using focused ultrasound. This approach applies the principles of acoustic radiation force , whereby the non-linear effects of sound produce forces on the skin which are strong enough to generate tactile sensations. This mid-air haptic feedback eliminates the need for any attachment of actuators or contact with physical devices. The user perceives a discernible haptic shape when the corresponding acoustic interference pattern is generated above a precisely controlled two-dimensional phased array of ultrasound transducers. In this paper, we outline our algorithm for controlling the volumetric distribution of the acoustic radiation force field in the form of a three-dimensional shape. We demonstrate how we create this acoustic radiation force field and how we interact with it. We then describe our implementation of the system and provide evidence from both visual and technical evaluations of its ability to render different shapes. We conclude with a subjective user evaluation to examine users' performance for different shapes.

We introduce UltraHaptics, a system designed to provide multi-point haptic feedback above an interactive surface. UltraHaptics employs focused ultrasound to project discrete points of haptic feedback through the display and directly on to users' unadorned hands. We investigate the desirable properties of an acoustically transparent display and demonstrate that the system is capable of creating multiple localised points of feedback in mid-air. Through psychophysical experiments we show that feedback points with different tactile properties can be identified at smaller separations. We also show that users are able to distinguish between different vibration frequencies of non-contact points with training. Finally, we explore a number of exciting new interaction possibilities that UltraHaptics provides.

Although there is significant research and development into information security areas such as confidentiality and availability, scope remains for attention to the third fundamental security property: integrity. The Biba and Clark-Wilson models are still the most recognised for managing integrity of data in systems. After identifying several desirable extensions to the original ideas in these models, we present a new integrity framework, which can allow for a more flexible, quantitative, and context sensitive management of data integrity on a system wide basis.

Managing the appearance of images across different display environments is a difficult problem, exacerbated by the proliferation of high dynamic range imaging technologies. Tone reproduction is often limited to luminance adjustment and is rarely calibrated against psychophysical data, while color appearance modeling addresses color reproduction in a calibrated manner, albeit over a limited luminance range. Only a few image appearance models bridge the gap, borrowing ideas from both areas. Our take on scene reproduction reduces computational complexity with respect to the state-of-the-art, and adds a spatially varying model of lightness perception. The predictive capabilities of the model are validated against all psychophysical data known to us, and visual comparisons show accurate and robust reproduction for challenging high dynamic range scenes.

Recent advances in fluid simulations have yielded exceptionally realistic imagery. However, most algorithms have computational requirements that are prohibitive for real-time simulations. Using Fourier based solutions mitigates this issue, although due to wraparound, boundary conditions are not naturally available, leading to inconsistencies near the boundary. We show that slip boundary conditions can be imposed by solving the mass conservation step using cosine and sine transforms instead of the Fourier transform. Further, we show that measures against density dissipation can be computed using cosine transforms and we describe a new method to compute surface tension in the same domain. This combination of related algorithms leads to real-time simulations with boundary conditions.