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Publications

Publications by Daniel Mendes

2024

4Doodle: Two-handed Gestures for Immersive Sketching of Architectural Models

Authors
Fonseca, F; Sousa, M; Mendes, D; Ferreira, A; Jorge, JA;

Publication
CoRR

Abstract

2024

Incidental visualizations: How complexity factors influence task performance

Authors
Moreira, J; Mendes, D; Gonçalves, D;

Publication
VISUAL INFORMATICS

Abstract
Incidental visualizations convey information to a person during an ongoing primary task, without the person consciously searching for or requesting that information. They differ from glanceable visualizations by not being people's main focus, and from ambient visualizations by not being embedded in the environment. Instead, they are presented as secondary information that can be observed without a person losing focus on their current task. However, despite extensive research on glanceable and ambient visualizations, the topic of incidental visualizations is yet a novel topic in current research. To bridge this gap, we conducted an empirical user study presenting participants with an incidental visualization while performing a primary task. We aimed to understand how complexity contributory factors - task complexity, output complexity, and pressure - affected primary task performance and incidental visualization accuracy. Our findings showed that incidental visualizations effectively conveyed information without disrupting the primary task, but working memory limitations should be considered. Additionally, output and pressure significantly influenced the primary task's results. In conclusion, our study provides insights into the perception accuracy and performance impact of incidental visualizations in relation to complexity factors. (c) 2024 The Authors. Published by Elsevier B.V. on behalf of Zhejiang University and Zhejiang University Press Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

2024

Cues to fast-forward collaboration: A Survey of Workspace Awareness and Visual Cues in XR Collaborative Systems

Authors
Assaf, R; Mendes, D; Rodrigues, R;

Publication
COMPUTER GRAPHICS FORUM

Abstract
Collaboration in extended reality (XR) environments presents complex challenges that revolve around how users perceive the presence, intentions, and actions of their collaborators. This paper delves into the intricate realm of group awareness, focusing specifically on workspace awareness and the innovative visual cues designed to enhance user comprehension. The research begins by identifying a spectrum of collaborative situations drawn from an analysis of XR prototypes in the existing literature. Then, we describe and introduce a novel classification for workspace awareness, along with an exploration of visual cues recently employed in research endeavors. Lastly, we present the key findings and shine a spotlight on promising yet unexplored topics. This work not only serves as a reference for experienced researchers seeking to inform the design of their own collaborative XR applications but also extends a welcoming hand to newcomers in this dynamic field.

2023

Exploring Pseudo-Haptics for Object Compliance in Virtual Reality

Authors
Lousada, C; Mendes, D; Rodrigues, R;

Publication
ICGI

Abstract
Virtual Reality (VR) has opened avenues for users to immerse themselves in virtual 3D environments, simulating reality across various domains like health, education, and entertainment. Haptic feedback plays a pivotal role in achieving lifelike experiences. However, the accessibility of haptic devices poses challenges, prompting the exploration of alternatives. In response, Pseudo-Haptic feedback has emerged, utilizing visual and auditory cues to create illusions or modify perceived haptic feedback. Given that many pseudo-haptic techniques are yet to be tailored for VR, our proposal involves combining and adapting multiple techniques to enhance compliance perception in virtual environments. By modifying the Mass-Spring-Damper model and incorporating hand-tracking software along with an inverse kinematics algorithm, our aim is to deliver compliance feedback through visual stimuli, thereby elevating the realism of the overall experience. The outcomes were encouraging, with numerous participants expressing their ability to easily discern various compliance levels with high confidence, all within a realistic and immersive environment. Additionally, we observed an impact of object scale on the perception of compliance in specific scenarios, as participants noted a tendency to perceive smaller objects as more compliant.

2023

TouchRay: Towards Low-effort Object Selection at Any Distance in DeskVR

Authors
Monteiro, J; Mendes, D; Rodrigues, R;

Publication
2023 IEEE INTERNATIONAL SYMPOSIUM ON MIXED AND AUGMENTED REALITY, ISMAR

Abstract
DeskVR allows users to experience Virtual Reality (VR) while sitting at a desk without requiring extensive movements. This makes it better suited for professional work environments where productivity over extended periods is essential. However, tasks that typically resort to mid-air gestures might not be suitable for DeskVR. In this paper, we focus on the fundamental task of object selection. We present TouchRay, an object selection technique conceived specifically for DeskVR that enables users to select objects at any distance while resting their hands on the desk. It also allows selecting objects' sub-components by traversing their corresponding hierarchical trees. We conducted a user evaluation comparing TouchRay against state-of-the-art techniques targeted at traditional VR. Results revealed that participants could successfully select objects in different settings, with consistent times and on par with the baseline techniques in complex tasks, without requiring mid-air gestures.

2023

SIT6: Indirect touch-based object manipulation for DeskVR

Authors
Almeida, D; Mendes, D; Rodrigues, R;

Publication
COMPUTERS & GRAPHICS-UK

Abstract
Virtual reality (VR) has the potential to significantly boost productivity in professional settings, especially those that can benefit from immersive environments that allow a better and more thorough way of visualizing information. However, the physical demands of mid-air movements make it difficult to use VR for extended periods. DeskVR offers a solution that allows users to engage in VR while seated at a desk, minimizing physical exhaustion. However, developing appropriate motion techniques for this context is challenging due to limited mobility and space constraints. This work focuses on object manipulation techniques, exploring touch-based and mid-air-based approaches to design a suitable solution for DeskVR, hypothesizing that touch-based object manipulation techniques could be as effective as mid-air object manipulation in a DeskVR scenario while less physically demanding. Thus, we propose Scaled Indirect Touch 6-DOF (SIT6), an indirect touch-based object manipulation technique incorporating scaled input mapping to address precision and out-of-reach manipulation issues. The implementation of our solution consists of a state machine with error-handling mechanisms and visual indicators to enhance interaction. User experiments were conducted to compare the SIT6 technique with a baseline mid-air approach, revealing comparable effectiveness while demanding less physical exertion. These results validated our hypothesis and established SIT6 as a viable option for object manipulation in DeskVR scenarios. (c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

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