1,720,961 research outputs found
A cup of coffee in Mixed Reality: analysis of movements' smoothness from real to virtual
No full textMixed Reality (MR) is promising to fuse the visualization potentialities of Virtual Reality (VR) with the physical properties of the real world, thus allowing a more natural interaction in virtual environments and preserving visuo-motor coordination and tactile perception. In this work, we perform an interaction task, taking a cup of coffee, which involves hand movements and grasping. We consider three scenarios: an MR environment implementing an ecological object substitution technique, in which the user touches real objects tracked in real-time and sees a virtual counterpart; a classical VR environment, in which virtual objects do not have any real counterpart; the corresponding real scenario. In MR, the tracked real object can be either with a shape like the virtual one or a simpler real object. We compute the Minimum Jerk Cost function as a metric to compare movements in the different modalities, assuming that a major goal of motor coordination is producing the smoothest possible movement of the hand. From a pilot study, movements cost in VR is 5.1 times higher than the cost of the movements in the real world. This could be due to the lack of physicality when grabbing virtual objects without a real counterpart. Furthermore, the cost of movements obtained in MR is only 2.8 times higher than the one obtained in the real scenario, indicating that such a system could lead to more realistic and efficient human movements with respect to a VR system
Passive Haptic Feedback for More Realistic and Efficient Grasping Movements in Virtual Environments
No full textAchieving natural interaction in virtual environments is essential to create realistic simulations in various fields, including healthcare and education. The ability to interact in Virtual Reality (VR) in a natural way, through a combination of visual and physical feedback can greatly enhance the experience and effectiveness of these simulations. Recent works have shown that the lack of haptic and tactile feedback produces significant differences in grasping actions performed in immersive VR, with respect to the same actions performed in the real world. The passive haptics approach, which relies on physical proxies to introduce tactile feedback in VR, has been explored to address this issue. This work focuses on a specific interaction task that involves both hand movements and grasping: pouring coffee into a cup and mimicking the action of drinking it. We take into account three different scenarios: a traditional VR environment where virtual objects don’t have any real counterparts; an MR environment that uses an ecological object substitution technique where the user can interact with real objects that are tracked in real-time and see a virtual counterpart; and the corresponding real scenario. We compute the Minimum Jerk Cost and the Dynamic Time Warping distance between trajectories as metrics to compare movements in the different modalities in terms of their smoothness and trajectory shape, respectively. Our results show that movements in MR environments are smoother and produce more similar trajectories to real-world movements compared to classical VR environments. This indicates that MR with passive haptic feedback could produce more realistic and efficient human movements in virtual environments
A 3D Visual Programming Language for Tangible Coding in Extended Reality
No full textIn recent years, Augmented and Virtual technology has been extensively applied in the educational domain, opening up new methods and opportunities in the field of digital learning. A Virtual Reality (VR) environment can offer new forms of interactive learning, especially for subjects from the STEM (Science, technology, engineering, and mathematics) area and Computer Science is no exception. We present XRBlocks, a Visual Programming Language developed for an eXtended Reality (XR)-based block coding system called XRCoding. XRCoding provides an innovative immersive environment for learning the basics of computational thinking in an immersive VR environment. The XRBlocks language provides a very basic instruction set that can be used to build exercises for introductory programming courses. Passive haptics is used to improve interaction and give tactile feedback to the users. Physical placeholders are tracked in real-time, and aligned with the XR coding blocks. The language has been designed to increase engagement in computer education, and has been preliminarily tested with secondary school students. In the paper, we present the design principles for the XRBlocks language and for the XRCoding system, and we provide examples of coding exercises designed to control different types of arcade games
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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