In this special issue of IEEE Transactions on Visualization and Computer Graphics (TVCG), we are pleased to present the top papers from the 32nd IEEE Conference on Virtual Reality and 3D User Interfaces (IEEE VR 2025), held March 8–12, 2025, in Saint-Malo, France.

Navigating topographic charts involves nuanced skills and real-world correspondence, influenced by individual learning styles. Traditionally, 2D and 3D representations bridge map-reality gaps, but sandboxes often introduce manual errors and reliance on personal interpretation. This paper examines VR's potential in military planning, focusing on terrain interpretation, data visualization, and scale transitions. A study with 36 army cadets investigates VR's effectiveness in enhancing spatial perception and real-world task performance. Findings suggest that VR improves position choices and grades and reduces result disparities, particularly benefiting users with lower spatial skills. The research also evaluates the impact of different scales on VR planning, offering insights into potential advantages and challenges. Future studies should explore control issues and completion times in real-world scenarios.

This paper reviews the literature on the visualization of individual mobility data, with a focus on thematic integration. It emphasizes the importance of visualization in understanding mobility patterns within a population and how it helps mobility experts to address domain-specific questions. We analyze 38 papers published between 2010 and 2024 in GIS and VIS venues that describe visualizations of multidimensional data related to individual movements in urban environments, concentrating on individual mobility rather than traffic data. Our primary aim is to report advances in interactive visualization for individual mobility analysis, particularly regarding the representation of thematic information about people’s motivations for mobility. Our findings indicate that the thematic dimension is only partially represented in the literature, despite its critical significance in transportation. This gap often stems from the challenge of identifying data sources that inherently provide this information, necessitating visualization designers and developers to navigate multiple, heterogeneous data sources. We identify the strengths and limitations of existing visualizations and suggest potential research directions for the field. • Analysis of 38 visual analytics solutions designed to aid the exploration of individual mobility data across spatial, temporal, and thematic dimensions. • An analysis of how visualization tools incorporate the theme dimension and which thematic properties are addressed. • Analysis of how the subject is approached within GIS and VIS communities.

Current visualization research has identified the potential of more immersive settings for data exploration, leveraging VR and AR technologies. To explore how a traditional visualization system could be adapted into an immersive framework, and how it could benefit from this, we decided to revisit a landmark paper presented ten years ago at IEEE VIS. TaxiVis, by Ferreira et al., enabled interactive spatio-temporal querying of a large dataset of taxi trips in New York City. Here, we reimagine how TaxiVis’ functionalities could be implemented and extended in a 3D immersive environment. Among the unique features we identify as being enabled by the Immersive TaxiVis prototype are alternative uses of the additional visual dimension, a fully visual 3D spatio-temporal query framework, and the opportunity to explore the data at different scales and frames of reference. By revisiting the case studies from the original paper, we demonstrate workflows that can benefit from this immersive perspective. Through reporting on our experience, and on the vision and reasoning behind our design decisions, we hope to contribute to the debate on how conventional and immersive visualization paradigms can complement each other and on how the exploration of urban datasets can be facilitated in the coming years.

Trends are changes in variables or attributes over time, often represented by line plots or scatterplot variants, with time being one of the axes. Interpreting tendencies and estimating trends require observing the lines or points behavior regarding increments, decrements, or both (reversals) in the value of the observed variable. Previous work assessed variants of scatterplots like Animation, Small Multiples, and Overlaid Trails for comparing the effectiveness of trends representation using large and small displays and found differences between them. In this work, we study how best to enable the analyst to explore and perform temporal trend tasks with these same techniques in immersive virtual environments. We designed and conducted a user study based on the approaches followed by previous works regarding visualization and interaction techniques, as well as tasks for comparisons in three-dimensional settings. Results show that Overlaid Trails are the fastest overall, followed by Animation and Small Multiples, while accuracy is task-dependent. We also report results from interaction measures and questionnaires.

The design space for user interfaces for Immersive Analytics applications is vast. Designers can combine navigation and manipulation to enable data exploration with ego- or exocentric views, have the user operate at different scales, or use different forms of navigation with varying levels of physical movement. This freedom results in a multitude of different viable approaches. Yet, there is no clear understanding of the advantages and disadvantages of each choice. Our goal is to investigate the affordances of several major design choices, to enable both application designers and users to make better decisions. In this article, we assess two main factors, exploration mode and frame of reference, consequently also varying visualization scale and physical movement demand. To isolate each factor, we implemented nine different conditions in a Space-Time Cube visualization use case and asked 36 participants to perform multiple tasks. We analyzed the results in terms of performance and qualitative measures and correlated them with participants' spatial abilities. While egocentric room-scale exploration significantly reduced mental workload, exocentric exploration improved performance in some tasks. Combining navigation and manipulation made tasks easier by reducing workload, temporal demand, and physical effort.

In this special issue ofIEEE Transactions on Visualization and Computer Graphics(TVCG), we are pleased to present a subset of papers from the 29th IEEE Conference on Virtual Reality and 3D User Interfaces (IEEE VR 2022), held virtually March 12-16, 2022, in Christchurch, New Zealand.

In this work, we evaluate two standard interaction techniques for Immersive Analytics environments: virtual hands, with actions such as grabbing and stretching, and virtual ray pointers, with actions assigned to controller buttons. We also consider a third option: seamlessly integrating both modes and allowing the user to alternate between them without explicit mode switches. Easy-to-use interaction with data visualizations in Virtual Reality enables analysts to intuitively query or filter the data, in addition to the benefit of multiple perspectives and stereoscopic 3D display. While many VR-based Immersive Analytics systems employ one of the studied interaction modes, the effect of this choice is unknown. Considering that each has different advantages, we compared the three conditions through a controlled user study in the spatio-temporal data domain. We did not find significant differences between hands and ray-casting in task performance, workload, or interactivity patterns. Yet, 60% of the participants preferred the mixed mode and benefited from it by choosing the best alternative for each low-level task. This mode significantly reduced completion times by 23% for the most demanding task, at the cost of a 5% decrease in overall success rates.

Whenever accessing indoor spaces such as classrooms or auditoriums, people might attempt to analyze and choose an appropriate place to stay while attending an event. Several criteria may be accounted for, and most are not always self-evident or trivial. This work proposes the use of data visualization allied to an Augmented Reality (AR) user interface to help users defining the most convenient seats to take. We consider sets of arbitrary demands and project information directly atop the seats and all around the room. Users can also narrow down the search by switching and combining the attributes being displayed, e.g., temperature, wheelchair accessibility. The proposed approach was tested against a comparable 2D interactive visualization of the same data in usability assessments of seat-choosing tasks with a set of users (N = 16) to validate the solution. Qualitative and quantitative data indicated that the AR-based solution is promising, suggesting that AR may help users make more accurate decisions, even in an ordinary daily task. Regarding Augmented Situated Visualization, our results open new avenues for the exploration of context-aware data.

A Space-Time Cube enables analysts to clearly observe spatio-temporal features in movement trajectory datasets in geovisualization. However, its general usability is impacted by a lack of depth cues, a reported steep learning curve, and the requirement for efficient 3D navigation. In this work, we investigate a Space-Time Cube in the Immersive Analytics domain. Based on a review of previous work and selecting an appropriate exploration metaphor, we built a prototype environment where the cube is coupled to a virtual representation of the analyst's real desk, and zooming and panning in space and time are intuitively controlled using mid-air gestures. We compared our immersive environment to a desktop-based implementation in a user study with 20 participants across 7 tasks of varying difficulty, which targeted different user interface features. To investigate how performance is affected in the presence of clutter, we explored two scenarios with different numbers of trajectories. While the quantitative performance was similar for the majority of tasks, large differences appear when we analyze the patterns of interaction and consider subjective metrics. The immersive version of the Space-Time Cube received higher usability scores, much higher user preference, and was rated to have a lower mental workload, without causing participants discomfort in 25-minute-long VR sessions.

The use of novel displays and interaction resources to support immersive data visualization and improve analytical reasoning is a research trend in the information visualization community. In this work, we evaluate the use of an HMD-based environment for the exploration of multidimensional data, represented in 3D scatterplots as a result of dimensionality reduction (DR). We present a new modeling for this problem, accounting for the two factors whose interplay determine the impact on the overall task performance: the difference in errors introduced by performing dimensionality reduction to 2D or 3D, and the difference in human perception errors under different visualization conditions. This two-step framework offers a simple approach to estimate the benefits of using an immersive 3D setup for a particular dataset. Here, the DR errors for a series of roll call voting datasets when using two or three dimensions are evaluated through an empirical task-based approach. The perception error and overall task performance, on the other hand, are assessed through a comparative user study with 30 participants. Results indicated that perception errors were low and similar in all approaches, resulting in overall performance benefits in both desktop and HMD-based 3D techniques. The immersive condition, however, was found to require less effort to find information and less navigation, besides providing much larger subjective perception of accuracy and engagement.

We present the design of a handheld-based interface for collaborative manipulations of 3D objects in mobile augmented reality. Our approach combines touch gestures and device movements for fast and precise control of 7-DOF transformations. Moreover, the interface creates a shared medium where several users can interact through their point-of-view and simultaneously manipulate 3D virtual augmentations. We evaluated our collaborative solution in two parts. First, we assessed our interface in single user mode, comparing the user task performance in three conditions: touch gestures, device movements and hybrid. Then, we conducted a study with 30 participants to understand and classify the strategies that arise while working in pairs, when partners are free to make their task organization. Furthermore, we investigated the effectiveness of simultaneous manipulations compared with the individual approach.

In the context of the 3DUI Contest promoted by the IEEE VR 2018, we propose 3D interaction techniques that address three distinct tasks in a virtual environment setup: climbing a ladder, controlling a quadcopter in a first-person view flight, and building a tower by stacking a series of objects. The interaction techniques were developed so the player, our 3D-athlete, has control over the events in each task, following metaphors that facilitate the use of the interface, and having status and spatial awareness supported by clear feedback cues. Thus, the player should be able to execute the tasks with precision and agility.

Abstract 3D representations are potentially useful under many circumstances, but suffer from long known perception and interaction challenges. Current immersive technologies, which combine stereoscopic displays and natural interaction, are being progressively seen as an opportunity to tackle this issue, but new guidelines and studies are still needed, especially regarding information visualization. Many proposed approaches are impractical for actual usage, resulting in user discomfort or requiring too much time or space. In this work, we implement and evaluate an alternative data exploration metaphor where the user remains seated and viewpoint change is only realisable through physical movements. All manipulation is done directly by natural mid‐air gestures, with the data being rendered at arm's reach. The virtual reproduction of the analyst's desk aims to increase immersion and enable tangible interaction with controls and two dimensional associated information. A comparative user study was carried out against a desktop‐based equivalent, exploring a set of 9 perception and interaction tasks based on previous literature and a multidimensional projection use case. We demonstrate that our prototype setup, named VirtualDesk, presents excellent results regarding user comfort and immersion, and performs equally or better in all analytical tasks, while adding minimal or no time overhead and amplifying user subjective perceptions of efficiency and engagement. Results are also contrasted to a previous experiment employing artificial flying navigation, with significant observed improvements.

Object manipulation in 3D virtual environments demands a combined coordination of rotations, translations and scales, as well as the camera control to change the user's viewpoint. Then, for many manipulation tasks, it would be advantageous to share the interaction complexity among team members. In this paper we propose a novel 3D manipulation interface based on a collaborative action coordination approach. Our technique explores a smartphone -- the touchscreen and inertial sensors -- as input interface, enabling several users to collaboratively manipulate the same virtual object with their own devices. We first assessed our interface design on a docking and an obstacle crossing tasks with teams of two users. Then, we conducted a study with 60 users to understand the influence of group size in collaborative 3D manipulation. We evaluated teams in combinations of one, two, three and four participants. Experimental results show that teamwork increases accuracy when compared with a single user. The accuracy increase is correlated with the number of individuals in the team and their work division strategy.

Vibrotactile feedback is broadly used to support different tasks in virtual and augmented reality applications, such as navigation, communication, attentional redirection, or to enhance the sense of presence in virtual environments. Thus, we aim to include the haptic component to the most popular wearable used in VR applications: the VR headset. After studying the acuity around the head for vibrating stimuli, and trying different parameters, actuators, and configurations, we developed a haptic guidance technique to be used in a vibrotactile Head-mounted Display (HMD). Our vi-brotactile HMD was made to render the position of objects in a 3D space around the subject by varying both stimulus loci and vibration frequency. In this demonstration, the participants will interact with different scenarios where the mission is to select a number of predefined objects. However, instead of displaying occlusive graphical information to point to these objects, vibrotactile cues will provide guidance in the VR setup. Participants will see that our haptic guidance technique can be both easy to use and entertaining. (See Video: https://youtu.be/_H0MQy6QD7M).

Due to the perceptual characteristics of the head, vibrotactile Head-mounted Displays are built with low actuator density. Therefore, vibrotactile guidance is mostly assessed by pointing towards objects in the azimuthal plane. When it comes to multisensory interaction in 3D environments, it is also important to convey information about objects in the elevation plane. In this paper, we design and assess a haptic guidance technique for 3D environments. First, we explore the modulation of vibration frequency to indicate the position of objects in the elevation plane. Then, we assessed a vibrotactile HMD made to render the position of objects in a 3D space around the subject by varying both stimulus loci and vibration frequency. Results have shown that frequencies modulated with a quadratic growth function allowed a more accurate, precise, and faster target localization in an active head pointing task. The technique presented high usability and a strong learning effect for a haptic search across different scenarios in an immersive VR setup.

Communication is crucial in collaborative tasks. Multimodal strategies are commonly applied to complement, reinforce and disam-biguate information exchange. However, although multimodal communication is commonplace in Collaborative Virtual Environments, the proactive use of touch for intercommunication is surprisingly neglected regardless its importance for communication. In this paper, we look up to elements present in speech articulation to introduce the proactive haptic articulation as a novel approach for communication in CVEs. We defend the hypothesis that elements present in natural language, when added to the design of the vibro-tactile vocabulary, should provide an expressive medium for intercommunication. Moreover, we hypothesize that the ability to render tactile cues to a teammate will encourage users to adapt a given vocabulary spontaneously during its use. We implemented a case study around a collaborative puzzle task to demonstrate the use of such vocabulary. Results show that the proactive haptic articulation provided a way for participants to autonomously and dynamically adapt the provided tactile vocabulary to attend their communication needs during the task.

Communication is a fundamental process in collaborative work. In natural conditions, communication between team members is multimodal. This allows for redundancy, adaptation to different contexts, and different levels of focus. In collaborative virtual environments, however, hardware limitations and lack of appropriate interaction metaphors reduce the amount of collaboration. In this poster, we propose the design and use of a vibrotactile language to improve user intercommunication in CVE and, consequently, to increase the amount of effective collaboration.

Most human computer interfaces impose a certain level of additional cognitive load to the user task. In this project we study the use of VR to evaluate the user competency for safe behavior in work environments. We propose an assessment of two interfaces with different levels of cognitive load for locomotion in a risk perception task. We describe user experiments with two similar groups of subjects, each using one of the interfaces. We identified important open questions on the design of this kind of interface.

In this demo we present an immersive virtual reality (VR) simulator to measure risk perception in realistic working environments. It provides the ideal environment to expose people to danger with no chances to cause them any harm. However, whereas in the physical work environment workers have to perform their jobs (primary task) and be safe (secondary task), in a VR simulator they still have to deal with an additional source of cognitive load: the user interface.

Repetitive indoor exercises as running on a treadmill or cycling on an exercise bike use to be tedious and hard to keep in diary basis. In sports, social relationships are an important source of stimulus to achieve a goal. Better performances can be achieved when one compete against others, as well as when a group collaborate to achieve a common target. In this work we propose a motivational system to help people to perform better in exergames using a virtual environment and testing the effects of collaboration and competition in such environment.

We present Disambiguation canvas, a technique for selection by progressive refinement using a mobile device and consisting of two steps. During the first, the user defines a subset of objects through the orientation sensors of the device and a volume-casting pointing technique. The subsequent step consists of the disambiguation of the desired target among the previously-defined subset of objects, and is accomplished using the mobile device touchscreen. By relying on the touchscreen for the last step the user can disambiguate among hundreds of objects at once, previous progressive refinement techniques do not scale as well as ours. Disambiguation canvas is mainly developed for easy, accurate and fast selection of small objects, or objects inside cluttered virtual environments. User tests show that our technique performs faster than ray-casting for targets with ≈ 0.53° of angular size, and is also much more accurate for all the tested target sizes.

Collaboration in 3D environments has the main goal of attaining a high degree of teamwork by exposing the team to a suitable level of immersion. However, users within virtual environments have limitations to perceive the same stimuli of the real world. Particularly, the feeling of presence and nearness of the other is difficult to be generated in VR systems. This poster presents a work in progress that shows our current results on evaluating the impact of three different proximity cues for generating awareness of the presence of other. The design of each cue aims at independently stimulating the senses of sight, hearing and touch. The experiment design includes the comparison with a baseline condition in virtual environments where no specific stimulation is applied.

Any human-computer interface imposes a certain level of cognitive load to the user task. Analogously, the task itself also imposes different levels of cognitive load. It is common sense in 3D user interfaces research that a higher number of degrees of freedom increases the interface cognitive load. If the cognitive load is significant, it might compromise the user performance and undermine the evaluation of user skills in a virtual environment. In this paper, we propose an assessment of two immersive VR interfaces with varying degrees of freedom in two VR tasks: risk perception and basic object selection. We examine the effectiveness of both interfaces in these two different tasks. Results show that the number of degrees of freedom does not significantly affect a basic selection task, but it affects risk perception task in an unexpected way.

Gestural interaction has gained prominence in recent years and various devices and methods for providing it have been developed in both the Academy and the Market. Microsoft's Kinect, which is able to identify the skeleton of the interacting user in real time, is the latest example of this fact, and has been the subject of recent research. This paper presents a way to integrate Kinect on the Browser, so that the user can interact face to a high-resolution screen without having to directly manipulate any device and have all the portability and availability that the Internet provides. In the case study presented, the user interacts with a graph representing a social network and is able to identify and move nodes, in addition to pan and zoom the graph as a whole. The paper concludes that such a mechanism has great potential for use and presents future work.

BVP Path Planners generate potential fields through a differential equation whose gradient descent represents navigation routes from any point of the environment to a goal position. Resulting paths are smooth and free from local minima. In spite of these advantages, this kind of planners consumes a lot of time to produce a solution. In this paper, we present a new approach that combines our BVP Path Planner with the Full Multigrid Method, which solves elliptic partial differential equations using a hierarchical strategy. Our new approach, called Hierarchical BVP Path Planner, enables real-time performance on large environments. Results show that our proposal spends less than 1% of the time needed to compute a solution using our original planner in several environments.

Marching Cubes is a popular choice for isosurface extraction from regular grids due to its simplicity, robustness, and efficiency. One of the key shortcomings of this approach is the quality of the resulting meshes, which tend to have many poorly shaped and degenerate triangles. This issue is often addressed through post processing operations such as smoothing. As we demonstrate in experiments with several datasets, while these improve the mesh, they do not remove all degeneracies, and incur an increased and unbounded error between the resulting mesh and the original isosurface. Rather than modifying the resulting mesh, we propose a method to modify the grid on which Marching Cubes operates. This modification greatly increases the quality of the extracted mesh. In our experiments, our method did not create a single degenerate triangle, unlike any other method we experimented with. Our method incurs minimal computational overhead, requiring at most twice the execution time of the original Marching Cubes algorithm in our experiments. Most importantly, it can be readily integrated in existing Marching Cubes implementations, and is orthogonal to many Marching Cubes enhancements (particularly, performance enhancements such as out-of-core and acceleration structures).

Abstract The animation of groups of characters involves the generation of some interesting steering behaviors like following a single path, moving toward a common objective, and moving while keeping a formation. This paper presents a new approach to manage the movement of groups in dynamic environments using a simple and robust algorithm that includes a strategy to keep formations during the displacement of the group. Our method is based on a boundary value problem (BVP) involving Laplace's equation and has two layers. In the first one, agroup mapis built to allow for local control of each individual, while in the second one a path planning is performed for each group as a whole. Results show that our technique is robust to several situations and can be implemented on GPU, which results in real‐time performance for large groups. Copyright © 2008 John Wiley & Sons, Ltd.

Marching Cubes is the most popular isosurface extraction algorithm due to its simplicity, efficiency and robustness. It has been widely studied, improved, and extended. While much early work was concerned with efficiency and correctness issues, lately there has been a push to improve the quality of Marching Cubes meshes so that they can be used in computational codes. In this work we present a new classification of MC cases that we call Edge Groups, which helps elucidate the issues that impact the triangle quality of the meshes that the method generates. This formulation allows a more systematic way to bound the triangle quality, and is general enough to extend to other polyhedral cell shapes used in other polygonization algorithms. Using this analysis, we also discuss ways to improve the quality of the resulting triangle mesh, including some that require only minor modifications of the original algorithm.

Evaluating user interfaces is usually accomplished to detect design problems in layout and interaction. One possible way to evaluate image quality in computer graphics is visual inspection by experts. Information visualization techniques are usually presented showing their use in experimental situations, employing some kind of analysis. Nevertheless, few works have specifically addressed the evaluation of such techniques. This work reports our results towards the definition of criteria for evaluating information visualization techniques, addressing the evaluation of visual representation and interaction mechanisms as a first step.

This paper describes a new joint model for articulated human skeletons. The model is based in human anatomy and was conceived for use in medical applications. In this model, we try to overcome some limitations of other models used in computer graphics. For validation, we compared a knee modeled by our approach with a simulator, a plastic model of a knee, and images taken during a video-arthroscopy.

The authors propose a method to simulate human beings based on anatomy concepts. They believe that the closer the model is to reality, the better the results will be. Using this approach, they are developing a human representation. The model is divided into three different layers and is presented in three steps: the rigid body conception from a real skeleton, the muscle design and deformation based on physical concepts, and the skin generation. Integration aspects and results are also presented.

In this paper we propose a method to simulate muscle deformation in real-time, still aiming at satisfying visual results; that is, we are not attempting perfect simulation, but building a useful tool for interactive applications. Muscles are represented at 2 levels: the action lines and the muscle shape. The action line represents the force produced by a muscle on the bones, while the muscle shapes used in the simulation consist of a surface based model fitted to the boundary of medical image data. The algorithm to model muscle shapes is described. To physically simulate deformations, we used a mass-spring system with a new kind of springs called "angular springs" which were developed to control the muscle volume during simulation. Results are presented as examples at the end of the paper.