Open Access
Content adaptation and depth perception in an affordable multi-view display
(MDPI, 2020) Ezcurdia Aguirre, Íñigo Fermín; Arregui Roldán, Adriana; Ardaiz Villanueva, Óscar; Ortiz, Amalia; Marzo Pérez, Asier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Gobierno de Navarra / Nafarroako Gobernua, 0011-1365-2019-000086; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA1923
We present SliceView, a simple and inexpensive multi-view display made with multiple parallel translucent sheets that sit on top of a regular monitor; each sheet reflects different 2D images that are perceived cumulatively. A technical study is performed on the reflected and transmitted light for sheets of different thicknesses. A user study compares SliceView with a commercial light-field display (LookingGlass) regarding the perception of information at multiple depths. More importantly, we present automatic adaptations of existing content to SliceView: 2D layered graphics such as retro-games or painting tools, movies and subtitles, and regular 3D scenes with multiple clipping z-planes. We show that it is possible to create an inexpensive multi-view display and automatically adapt content for it; moreover, the depth perception on some tasks is superior to the one obtained in a commercial light-field display. We hope that this work stimulates more research and applications with multi-view displays.
Open Access
Nonlinear trapping stiffness of mid-air single-axis acoustic levitators
(American Institute of Physics, 2018) Fushimi, Tatsuki; Hill, Thomas L.; Marzo Pérez, Asier; Drinkwater, Bruce W.; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
We describe and experimentally explore a nonlinear stiffness model of the trapping of a solid particle in a single-axis acoustic levitator. In contrast to the commonly employed linear stiffness assumption, our nonlinear model accurately predicts the response of the system. Our nonlinear model approximates the acoustic field in the vicinity of the trap as a one-dimensional sinusoid and solves the resulting dynamics using numerical continuation. In particular, we predict a softening of stiffness with amplitude as well as period-doubling bifurcations, even for small excitation amplitudes of 2% of the wavelength. These nonlinear dynamic features are observed experimentally in a single-axis levitator operating at 40 kHz and trapping millimetre-scale expanded polystyrene spheres. Excellent agreement between the observed and predicted behaviour is obtained suggesting that this relatively simple model captures the relevant physical phenomena. This new model enables the dynamic instabilities of trapped particles to be accurately predicted, thereby benefiting contactless transportation and manipulation applications
Open Access
Interactions with digital mountains: tangible, immersive and touch interactive virtual reality
(Association for Computing Machinery (ACM), 2020) Ardaiz Villanueva, Óscar; Marzo Pérez, Asier; Baztán Larrea, Rubén; Ezcurdia Aguirre, Íñigo Fermín; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Gobierno de Navarra / Nafarroako Gobernua, PI043-2019; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Digitization of Earth mountains and terrains has facilitated to plan journeys, manage natural resources, and learn about the Earth from the comfort of our homes. We aim to develop new interactions on digital mountains with novel interfaces: 3D printed representation of a mountain, an immersive virtual reality visualization, and two different touch interactive interfaces for immersive virtual reality visualizations: a 3D printed mountain with touch sensors and a multitouch tablet. We show how we have built such prototypes based on digital data retrieved from a map provider, and which interactions are possible with each interaction device. We explain how we design and conduct evaluation.
Open Access
A multi-object grasp technique for placement of objects in virtual reality
(MDPI, 2022) Fernández Ortega, Unai Javier; Elizondo Martínez, Sonia; Iriarte Cárdenas, Naroa; Morales, Rafael; Ortiz Nicolás, Amalia; Marichalar Baraibar, Sebastian Roberto; Ardaiz Villanueva, Óscar; Marzo Pérez, Asier; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Some daily tasks involve grasping multiple objects in one hand and releasing them in a determined order, for example laying out a surgical table or distributing items on shelves. For training these tasks in Virtual Reality (VR), there is no technique for allowing users to grasp multiple objects in one hand in a realistic way, and it is not known if such a technique would benefit user experience. Here, we design a multi-object grasp technique that enables users to grasp multiple objects in one hand and release them in a controlled way. We tested an object placement task under three conditions: real life, VR with single-object grasp and VR with multi-object grasp. Task completion time, distance travelled by the hands and subjective experience were measured in three scenarios: sitting in front of a desktop table, standing up in front of shelves and a room-size scenario where walking was required. Results show that the performance in a real environment is better than in Virtual Reality, both for single-object and multi-object grasping. The single-object technique performs better than the multi-object, except for the room scenario, where multi-object leads to less distance travelled and reported physical demand. For use cases where the distances are small (i.e., desktop scenario), single-object grasp is simpler and easier to understand. For larger scenarios, the multi-object grasp technique represents a good option that can be considered by other application designers.
Open Access
Hand-as-a-prop: using the hand as a haptic proxy for manipulation in virtual reality
(Springer, 2023) Marichalar Baraibar, Sebastian Roberto; Ezcurdia Aguirre, Íñigo Fermín; Morales González, Rafael; Ortiz Nicolás, Amalia; Marzo Pérez, Asier; Ardaiz Villanueva, Óscar; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Haptic feedback can be almost as important as visual information in virtual reality environments. On the one hand, in Active Haptic Feedback, specialized devices such as vibrotactile gloves are employed; however, these solutions can be expensive, vendor-specific or cumbersome to setup. On the other hand, Passive Haptic Feedback approaches use inexpensive objects as proxies for the virtual entities; but mapping virtual objects to real props is not scalable nor flexible. We propose the Hand-as-a-Prop technique, which consists in using human hands as object props. We implemented two modalities: Self, where the user¿s non-dominant hand act as the virtual object while the dominant hand grabs, translates and releases it; and External, where the hand of another person is used. Hand-as-a-Prop can represent multiple shapes with a single prop and does not require extra hardware. We performed an evaluation comparing both Self and External Hand-as-a-Prop with traditional Object Props in terms of user experience (goodness, ease, realism, fatigue, and preference) and performance (task completion time and translation time). Results showed that Hand-as-a-Prop was rated as neutral tending to positive, and in some cases, the performance was similar to Object Props. Users preferred Self Hand-as-a-Prop over External Hand-as-a-Prop and also obtained better results.
Open Access
Contactless pick-and-place of millimetric objects using inverted near-field acoustic levitation
(American Institute of Physics, 2020) Brizzotti Andrade, Marco Aurélio; Ramos, Tiago S.; Adamowski, Julio C.; Marzo Pérez, Asier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
We model and realize an ultrasonic contactless pick-and-place device capable of picking, self-centering, self-orienting, translating, and releasing flat millimetric objects. The device is an ultrasonic Langevin transducer operating at 21 kHz that radiates into air through a tapered tip. Objects are trapped few micrometers below the tip due to the near-field acoustic levitation phenomenon. We first investigate the conditions to achieve an attractive force on the object depending on its size and the device operating frequency. Second, we use a 3D acoustic model that describes the converging forces and torque that provide the self-centering and self-orienting capabilities. Third, a more advanced Computational Fluid Dynamics model based on the Navier-Stokes equations explains the small gap between the tip and the trapped object. The contactless manipulation capabilities of the device are demonstrated by picking, transporting, and releasing a Surface Mount Device in air. The presented manipulation concept can be an interesting alternative for manipulating delicate objects such as microelectromechanical devices, silicon dies, or micro-optical devices.
Open Access
Comparing a mid-air two-hand pinching point-and-click technique with mouse, keyboard and touchfree
(Association for Computing Machinery, 2024-01-18) Lafuente Duque, Melchor; Elizondo Martínez, Sonia; Fernández Ortega, Unai Javier; Marzo Pérez, Asier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
Some of our daily activities are performed by interacting with public touchscreens, such as food kiosks, bank tellers and newsstands. Nonetheless, the physical contact with these screens that are used by different people may be considered unhygienic. To avoid contact, some screens already integrate one-hand contactless interaction technologies, i.e. Leap Motion Controller, though they may lead to arm fatigue and slow performance. We present LeapPointer, a mid-Air two-hand pinching point-And-click technique. Specifically, this technique relies on a Leap Motion device to track both hands, and proposes a new software tool that allows bimanual selection through pointing and pinching gestures. A user study was performed to compare LeapPointer with two other techniques: The common mouse/keyboard and the current UltraLeap's TouchFree technique. Task completion time and accuracy as well as subjective data were gathered. The analysis of these data suggested that LeapPointer is significantly faster than the other touchless technique although less accurate. Self-reported fatigue was less with LeapPointer than with TouchFree.
Open Access
Customized and high-performing acoustic levitators for contact-free experiments
(Elsevier, 2024) Argyri, Smaragda-Maria; Andersson, Carl; Paillet, Nicolas; Evenäs, Lars; Ahrens, Jens; Marzo Pérez, Asier; Contreras, Víctor; Bordes, Romain; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
Acoustic levitators are becoming increasingly common research instrumentation for contact-free, lab-in-a-droplet studies. Recently, levitators that employ multiple, small, ultrasonic transducers have gained popularity, given their low price, temperature and spatial stability, low voltage, and accessibility. Yet, the current state-of-the-art device, TinyLev, presents limitations for certain applications in terms of stability, strength, and compactness. Herein, we developed three new levitators and evaluated the effect of the construction parameters (e.g., distance of opposing arrays, number and arrangement of transducers, etc.) on their performance. The best performing levitator from this work had half the number of transducers, compared to TinyLev, though presented 1.7 and 3.5 times higher levitation capacity along the horizontal and vertical configurations, respectively, and 4.7 and 2.0 times higher horizontal and vertical stability of a levitated object, respectively. Additionally, we present a direct means to evaluate the acoustic radiation net force acting on a deformable object for uniaxial levitators, without the use of a microphone or a schlieren deflectometer for this type of levitators. The theoretical and experimental observations provide insights for adapting the acoustic levitator design for specific applications. Finally, we developed an open-source software which allows the evaluation of the acoustic pressure field generated by customized designs and provides the necessary files for 3D printing the scaffold of the levitator. This study aims to increase accessibility and promote further developments in contact-free experiments.
Open Access
Avatarians: playing with your friends' data
(ACM, 2012) Marzo Pérez, Asier; Ardaiz Villanueva, Óscar; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Gobierno de Navarra / Nafarroako Gobernua
This article describes a new game mechanic called Game Entity Social Mapping (GESM) based on using social networking data fetched from a remote site about the player and his contacts to create characters, items or scenarios. A preliminary evaluation consisting of applying this mechanic to three different games was conducted. A small number of users tested those games to measure the enjoyment and learning about their contacts information.
Open Access
Acoustic lock: position and orientation trapping of non-spherical sub-wavelength particles in mid-air using a single-axis acoustic levitator
(American Institute of Physics, 2018) Cox, L; Croxford, A; Drinkwater, Bruce W.; Marzo Pérez, Asier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC
We demonstrate acoustic trapping in both position and orientation of a non-spherical particle of sub-wavelength size in mid-air. To do so, we multiplex in time a pseudo-one-dimensional vertical standing wave and a twin-trap; the vertical standing wave provides converging forces that trap in position, whereas the twin-trap applies a stabilising torque that locks the orientation. The device operates at 40 kHz, and the employed multiplexing ratio of the 2 acoustic fields is 100:50 (standing:twin) periods. This ratio can be changed to provide tunability of the relative trapping strength and converging torque. The torsional spring stiffness of the trap is measured through simulations and experiments with good agreement. Cubes from k/5.56 (1.5 mm) to k/2.5 (3.4 mm) side length were stably locked. We also apply this technique to lock different non-spherical particles in midair: cubes, pyramids, cylinders, and insects such as flies and crickets. This technique adds significant functionality to mid-air acoustic levitation and will enable applications in micro-scale manufacturing as well as containment of specimens for examination and 3D-scanning.