GRAPP 2024 Abstracts

Area 1 - Geometry and Modeling
Full Papers Short Papers
Area 2 - Rendering
Full Papers Short Papers
Area 3 - Animation and Simulation
Full Papers Short Papers
Area 4 - Interactive Environments
Full Papers Short Papers

Area 1 - Geometry and Modeling

Full Papers
Paper Nr: 219
Title:

Between Gaming and Microclimate Simulations: Temperature Estimation of an Urban Area
Authors:

Eva Strauss and Dimitri Bulatov
Abstract: With the rising awareness and interest from researchers, local authorities, and industry in the urban heat island effect, thermal remote sensing data is needed as it allows for identification, tracking, or analysis of land surface temperatures. Yet, the accessibility of appropriate thermal data in both the spatial and temporal domain states an inhibiting factor. Whilst thermal satellite data suffers from both low spatial and temporal resolution, airborne imagery might enable adequate resolutions, however, is not acquired without time and cost consumption. One way to overcome this drawback is the generation of synthetic data, which comprises the simulation of surface temperatures. These rather simplified simulations are either quite fast, as desired in gaming applications, however, highly inaccurate, or rather complex, holistic, time-consuming and computationally intensive, like applied in urban microclimate considerations. In this paper, we present an in-between approach towards the estimation of urban surface temperatures that aims to fill this gap between holistic microclimate simulations and climate maps.
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Paper Nr: 231
Title:

TreeSpecies-PC2DT: Automated Tree Species Modeling from Point Clouds to Digital Twins
Authors:

Like Gobeawan, Xuan Liu, Chi W. Lim, Venugopalan Raghavan, Joyjit Chattoraj, Jan Schindler and Feng Yang
Abstract: 3D digital twin trees for a city-scale have been limited to low-resolution, static shape models due to challenges in automation/scalability, cost performance, tree growth dynamics, species complexities and compatibilities with simulations and virtual city platforms. To address those challenges for high-resolution tree models, we propose an automated workflow of generating large-scale, lightweight, dynamic digital-twin tree species models from point cloud data. Species digital twins are modelled as detailed hierarchical branch structures by solving for all species profile parameters through stages of branch reconstruction from point cloud data, species profiling by machine learning, tropism transfer, optimisation and species growth modelling based on botany and limited field survey. We show that the generated high-resolution tree models can be lightweight while representing their true species characteristics and dynamic botanical architecture (branching patterns and growth processes).
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Paper Nr: 249
Title:

Parameter-Free Connectivity for Point Clouds
Authors:

Diana Marin, Stefan Ohrhallinger and Michael Wimmer
Abstract: Determining connectivity in unstructured point clouds is a long-standing problem that has still not been addressed satisfactorily. In this paper, we analyze an alternative to the often-used k-nearest neighborhood (kNN) graph - the Spheres of Influence Graph (SIG). We show that the edges that are neighboring each vertex are spatially bounded, which allows for fast computation of SIG. Our approach shows a better encoding of the ground truth connectivity compared to the kNN for a wide range of k, and additionally, it is parameter-free. Our result for this fundamental task offers potential for many applications relying on kNN, e.g., parameter-free normal estimation, and consequently, surface reconstruction, motion planning, simulations, and many more.
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Paper Nr: 447
Title:

Pseudo-Curvature of Fractal Curves for Geometric Control of Roughness
Authors:

Mohamad Janbein, Christian Gentil, Céline Roudet and Clement Poull
Abstract: Fractal geometry is a valuable formalism for synthesizing and analyzing irregular curves to simulate non-smooth geometry or roughness. Understanding and controlling these geometries remains challenging because of the complexity of their shapes. This study focuses on the curvature of fractal curves defined from an Iterated Function System (a set of contractive operators). We introduce the Differential Characteristic Function (DCF), a new tool for characterizing and analyzing their differential behavior. We associate a family of DCF to the fixed point of each operator. For each dyadic point of the curve, there exist left and right families of DCF inducing left and right ranges of curvatures: the pseudo-curvatures. A set of illustrations shows the influence of these pseudo-curvatures on the geometry of fractal curves. We propose a first approach for applying our results to roughness generation and control.
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Short Papers
Paper Nr: 19
Title:

Polyline Simplification with Predefined Edge Directions by Mixed Integer Linear Programs
Authors:

Steffen Goebbels and Jochen Rethmann
Abstract: Mixed integer linear programs are presented that simplify polylines such that edges follow only some predefined directions from a given set. Under this constraint, solutions are computed that are closest to the given vertices, or only close to the original data, but with a minimum number of edges, or with a minimum length. The algorithms are applied to 3D building modeling from point clouds. Boundaries of roof facets (roof polygons) are simplified by considering directions of roof plane gradients and intersection lines between roof planes.
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Paper Nr: 122
Title:

A Predictor for Triangle Mesh Compression Working in Tangent Space
Authors:

Petr Vaněček, Filip Hácha and Libor Váša
Abstract: Triangle mesh compression has been a popular research topic for decades. Since a plethora of algorithms has been presented, it is becoming increasingly difficult to come up with significant performance improvements. Some of the recent advances in compression efficiency come at the cost of rather steep implementation and/or computational expense, which has profound consequences on their practicality. Ultimately it becomes increasingly difficult to come up with improvements that are reasonably easy to implement and do not harm the computational efficiency of the compression/decompression procedure. In this paper, we analyze a combination of two previously known techniques, namely using the local coordinates for expressing compression residuals and weighted parallelogram prediction, which were not previously investigated together. We report that such approach outperforms industry standard Draco on a large set of test meshes in terms of rate/distortion ratio, while retaining beneficial properties such as simplicity and computational efficiency.
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Paper Nr: 404
Title:

Detection of Local Symmetry Polylines of Polygons Based on Sweeping Paradigm
Authors:

Martin Safko, Luka Lukač, Borut Žalik and Ivana Kolingerová
Abstract: Symmetry is a fundamental property of many objects of interest allowing us to simplify computation or reduce complexity and is also a contributing factor of beauty for a human brain. In this work, we try to identify polylines satisfying the local reflection symmetry of polygons and show how to use them for shape characterization, segmentation or to find global approximate reflection symmetries. We describe an algorithm based on a sweep-line paradigm to efficiently compute the polylines by scanning through a polygon at various angles.
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Paper Nr: 72
Title:

Towards Generating 3D City Models with GAN and Computer Vision Methods
Authors:

Sarun Poolkrajang and Anand Bhojan
Abstract: City generation for video games is a resource and time-consuming task. With the increasing popularity of open-world games, studies on building virtual environments have become increasingly important for the game research community and industry. The game development team must engage in urban planning, designate important locations, create population assets, integrate game design, and assemble these elements into a cohesive-looking city. Based on our limited knowledge and survey, we are the first to propose a holistic approach that integrates all features in generating a city, including the natural features surrounding it. We employ a generative adversarial network architecture to create a realistic layout of an entire city from scratch. Subsequently, we utilize classical computer vision techniques to post-process the layout into separate features. The chosen model is a simple Convolutional GAN, trained on a modest dataset of 2x2 km² snippets from over two thousand cities around the world. Although the method is somewhat constrained by the resolution of the images, the results indicate that it can serve as a solid foundation for building realistic 3D cities.
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Paper Nr: 73
Title:

ML-Tree and MRL-Tree: Combining Mass-Spring System, Rigid-Body Dynamics and L-Systems to Model Physical Effects on Trees
Authors:

See Min Lim and Like Gobeawan
Abstract: We apply physically-based modeling methods to a biological tree model for a hybrid model with a better accuracy. Physical aspects of tree growth, such as wind, tropisms, gravity and soil resistance are modelled. The hybrid model also includes the handling of boundary conditions such as momentum conservation and switching between the L-System, Mass-Spring System (MSS) and Rigid-Body Dynamics (RBD) methods. This paper demonstrates resulting models and their potential applications such as tree stress prediction.
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Paper Nr: 202
Title:

Efficiency of 3D Fractal Generation Through Raymarching
Authors:

Anna Semrau and Dariusz Sawicki
Abstract: The use of fractal geometry in computer graphics enables the modeling of natural objects which mathematical description using traditional Euclidean geometry is difficult. However, fractals, due to their properties and specific description, create application problems, especially related to computational and memory efficiency. There are known attempts to solve these problems using graphic hardware and special algorithms. One of the methods that could bring good results is the quite old and rarely used algorithm of raymarching with SDF (Signed Distance Functions). The aim of the article is to analyze the possibility of using this method to increase the efficiency of fractal modeling. Demonstration application that allows testing various modeling cases has been developed, also taking into account the hardware of modern graphics cards. Research was carried out for 5 different types of fractals (Sierpinski pyramid, Menger sponge, Julia set, Mandelbulb object, fractal tree). The fractal image generation time and memory consumption were considered. For the Menger sponge, different model generation methods were also compared: traditional boundary generation and those using raymarching with SDF. The conducted research has shown that raymarching is a method worth considering. Moreover, the application of raymarching with SDF can bring many measurable benefits.
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Paper Nr: 226
Title:

Automatic Registration of 3D Point Cloud Sequences
Authors:

Natálie Vítová, Jakub Frank and Libor Váša
Abstract: Surface registration is a well-studied problem in computer graphics and triangle mesh processing. A plethora of approaches exists that align a partial 3D view of a surface to another, which is a central task in 3D scanning, where usually each scan only provides partial information about the shape of the scanned object due to occlusion. In this paper, we address a slightly different problem: a pair of depth cameras is observing a dynamic scene, each providing a sequence of partial scans. The scanning devices are assumed to remain in a constant relative position throughout the process, and therefore there exists a single rigid transformation that aligns the two sequences of partial meshes. Our objective is to find this transformation based on the data alone, i.e. without using any specialized calibration tools. This problem can be approached as a set of static mesh registration problems; however, such an interpretation leads to problems when enforcing a single global solution. We show that an appropriate modification of a previously proposed consensus-based registration algorithm is a more viable solution that exploits information from all the frames simultaneously and naturally leads to a single global solution.
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Area 2 - Rendering

Full Papers
Paper Nr: 330
Title:

Automated Palette Cycling Animations
Authors:

Ali S. Javid and David Mould
Abstract: We propose an automated method for palette cycling, a technique for animation storage and playback. A palette cycling animation uses a fixed map of indices over the entire animation; each frame, the color lookup table accesses by the indices changes. Historically, palette cycling animations were created manually. Here, we present a method that automatically creates a set of palettes and an index map from an input video. We use optimization, alternating between phases of choosing per-frame palettes and determining an index map given a fixed set of palettes. Our method is highly effective for scenarios such as time-lapse video, where the lighting changes dramatically but there is little overall motion. We show that it can also produce plausible outcomes for videos containing large-scale motion and moving backgrounds; palette rotations with these features are especially difficult to craft by hand. We demonstrate results over a variety of input videos with different levels of complexity, motion, and subject matter.
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Paper Nr: 451
Title:

Non-Photorealistic Rendering of 3D Point Clouds Using Segment-Specific Image-Space Effects
Authors:

Ole Wegen, Josafat-Mattias Burmeister, Max Reimann, Rico Richter and Jürgen Döllner
Abstract: 3D point clouds are a widely used representation for surfaces and object geometries. However, their visualization can be challenging due to point sparsity and acquisition inaccuracies, leading to visual complexity and ambiguity. Non-photorealistic rendering (NPR) addresses these challenges by using stylization techniques to abstract from certain details or emphasize specific areas of a scene. Although NPR effectively reduces visual complexity, existing approaches often apply uniform styles across entire point clouds, leading to a loss of detail or saliency in certain areas. To address this, we present a novel segment-based NPR approach for point cloud visualization. Utilizing prior point cloud segmentation, our method applies distinct rendering styles to different segments, enhancing scene understanding and directing the viewer’s attention. Our emphasis lies in integrating aesthetic and expressive elements through image-based artistic rendering, such as watercolor or cartoon filtering. To combine the per-segment images into a consistent final image, we propose a user-controllable depth inpainting algorithm. This algorithm estimates depth values for pixels that lacked depth information during point cloud rendering but received coloration during image-based stylization. Our approach supports real-time rendering of large point clouds, allowing users to interactively explore various artistic styles.
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Short Papers
Paper Nr: 301
Title:

Hierarchical Bitmask Implicit Grids for Efficient Point-in-Volume Queries on the GPU
Authors:

Julius Ikkala, Tuomas Lauttia, Pekka Jääskeläinen and Markku Mäkitalo
Abstract: We propose “Hierarchical Bitmask Implicit Grids”, a novel, memory-efficient spatial index data structure for querying bounding volumes based on a contained point, targeting real-time use cases on GPUs. Like grid structures based on 3D arrays, implicit grids allow for nearly array-like direct lookups of cells without traversal through a spatial tree structure. However, the space complexity of this structure is O(n) with respect to resolution as opposed to O(n 3 ), which allows for dramatically higher resolutions than would be feasible with a 3D array. We demonstrate the effectiveness of this data structure by applying it to two example use cases: light culling and decal rendering. We measure both cases with ray tracing and multi-view rendering. We show that with tens of thousands of entries, our data structure can be built in 0.1–0.2 milliseconds, being ∼ 2.9x faster than the compared state-of-the-art decal method and orders of magnitude faster than dense 3D arrays, while delivering at least similar or even up to doubled rendering performance.
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Paper Nr: 320
Title:

Sparse Spatial Shading in Augmented Reality
Authors:

Rikard Olajos and Michael Doggett
Abstract: In this work, we present a method for acquiring, storing, and using scene data to enable realistic shading of virtual objects in an augmented reality application. Our method allows for sparse sampling of the environment’s lighting condition while still delivering a convincing shading to the rendered objects. We use common camera parameters, provided by a head-mounted camera, to get lighting information from the scene and store them in a tree structure, saving both locality and directionality of the data. This makes our approach suitable for implementation in augmented reality applications where the sparse and unpredictable nature of the data samples captured from a head-mounted device can be problematic. The construction of the data structure and the shading of virtual objects happen in real time, and without requiring high-performance hardware. Our model is designed for augmented reality devices with optical see-through displays, and in this work we used Microsoft’s HoloLens 2.
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Paper Nr: 347
Title:

Adaptation Speed for Exposure Control in Virtual Reality
Authors:

Claus B. Madsen and Johan W. Kristensen
Abstract: We address the topic of real-time, view-dependent exposure control in Virtual Reality (VR). For VR to realistically recreate the dynamic range of luminance levels in natural scenes, it is necessary to address exposure control. In this paper we investigate user preference regarding the temporal aspects of exposure adaptation. We design and implement a VR experience that enables users to individually tune how fast they prefer the adaptive exposure control to respond to luminance changes. Our experiments show that 60% of users feel the adaptation significantly improves the experience. Approximately half the of users prefer a fast adaptation over about 1-2 seconds, and the other half prefer a more gradual adaptation over about 10 seconds.
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Paper Nr: 363
Title:

Exploring Foveation Techniques for Virtual Reality Environments
Authors:

Razeen Hussain, Manuela Chessa and Fabio Solari
Abstract: Virtual reality technology is constantly advancing leading to the creation of novel experiences for the user. High-resolution displays often are accompanied by higher processing power needs. Foveated rendering is a potential solution to circumvent this issue as it can significantly reduce the computational load by rendering only the area where the user is looking with higher detail. In this work, we compare different foveated rendering algorithms in terms of the quality of the final rendered image. The focus of this work is on evaluating 4K images. These algorithms are also compared based on computational models of human visual processing. Our analysis revealed that the non-linear content-aware algorithm performs best.
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Area 3 - Animation and Simulation

Full Papers
Paper Nr: 29
Title:

Trajectory Augmentation for Robust Neural Locomotion Controllers
Authors:

Dhruv Agrawal, Mathias König, Jakob Buhmann, Robert Sumner and Martin Guay
Abstract: Neural Locomotion Controllers are promising real-time character controllers that can learn directly from motion data. However, the current state of the art models suffer from artifacts such as Pose Blocking and Foot Skating caused by poor generalization to real world control signals. We show that this is due to training on unbalanced biased datasets with poor representation for many important gaits and transitions. To solve this poor data problem, we introduce Trajectory Augmentation (TrajAug), a fully automatic data augmentation technique that generates synthetic motion data by using motion matching to stitch sequences from the original dataset to follow random trajectories. By uniformly sampling these trajectories, we can rebalance the dataset and introduce sharper turns that are commonly used in-game but are hard to capture. TrajAug can be easily integrated into the training of existing neural locomotion controllers without the need for adaptation. We show that TrajAug produces better results than training on only the original dataset or a manually augmented dataset.
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Paper Nr: 75
Title:

Real-Time Desertscapes Simulation with CUDA
Authors:

Alexander M. Nilles, Lars Günther and Stefan Müller
Abstract: We propose a new GPU-based method capable of simulating dune formation, propagation and aeolian sand transport, based on the Desertscape Simulation model. Our method improves upon the original as well as an existing real-time GPU implementation by introducing bilinear interpolation and removing randomness, which leads to a more robust and noise-free method. We implement our method with CUDA and use atomic adds on floats to remove a previous limitation that required block-based discretization of elevation values. A new sand distribution scheme for sand avalanching is proposed that converges faster than the previous work. We propose and evaluate a new method for reptation, which was previously neglected. Our method further improves on the performance compared with the previous real-time method and can generate results that more closely resemble dune evolution with a bidirectional wind scheme as predicted by an accurate offline method. Our method can generate detailed, physically plausible desert environments very quickly, with possible applications in both computer graphics as well as geomorphology. With some restrictions, our method could even be used during gameplay.
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Paper Nr: 334
Title:

Transformer-Based Two-level Approach for Music-driven Dance Choreography
Authors:

Yanbo Cheng and Yingying Wang
Abstract: Human dance motions are complex, creative, and artistic expressions. Synthesizing high-quality dance motions and synchronizing them to music has always been a challenge in animation research. Three problems in synthesizing dance motions are presented: 1) dance movements are complex non-linear motions that follow high-level structures of the dance genre over a long horizon, yet must maintain a stylistic consistency; 2) even for the same genre, dance movements require diversity, expressiveness, and nuances to appear natural and realistic; 3) spatial-temporal features of dance movements can be influenced by music. In this paper, we address these issues using a novel two-level transformer-based dance generation system that can synthesize dance motions to match the audio input. Our high-level transformer network performs the choreography and generates dance movements with consistent long-term structure, and our low-level implementer infuses diversity and realizes actual dance performances. This two-level approach not only allows us to generate dances that are consistent in structure, but also enables us to effectively add styles learnt from a wide range of dance datasets. When training the choreography model, our approach fully utilizes existing dance datasets, even those without musical accompaniment, and thus differs from previous research that requires dance training data to be accompanied by music. Results in this work demonstrate that our two-level system generates high-quality dance motions that flexibly adapt to varying musical conditions trained on a dataset of dance sequences without accompanying music.
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Short Papers
Paper Nr: 143
Title:

Using the Polynomial Particle-in-Cell Method for Liquid-Fabric Interaction
Authors:

Robert Dennison and Steve Maddock
Abstract: Liquid-fabric interaction simulations using particle-in-cell (PIC) based models have been used to simulate a wide variety of phenomena and yield impressive visual results. However, these models suffer from numerical damping due to the data interpolation between the particles and grid. Our paper addresses this by using the polynomial PIC (PolyPIC) model instead of the affine PIC (APIC) model that is used in current state-of-theart wet cloth models. Theoretically, PolyPIC has lossless energy transfer and so should avoid any problems of undesirable damping and numerical viscosity. Our results show that PolyPIC does enable more dynamic coupled simulations. The use of PolyPIC allows for simulations with reduced numerical dissipation and improved resolution of vorticial details over previous work. For smaller scale simulations, there is minimal impact on computational performance when using PolyPIC instead of APIC. However, as simulations involve a larger number of particles and mesh elements, PolyPIC can require up to a 2.5× as long to generate 4.0s of simulation due to a requirement for a decrease in timestep size to remain stable.
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Paper Nr: 256
Title:

Data-Driven Viscosity Solver for Fluid Simulation
Authors:

Wonjung Park, Hyunsoo Kim and Jinah Park
Abstract: We propose a data-driven viscosity solver based on U-shaped convolutional neural network to predict velocity changes due to viscosity. Our solver takes velocity derivatives, fluid volume, and solid indicator quantities as input. The traditional marker-and-cell (MAC) grid stores velocities at the edges of the grid, causing the dimensions of the velocity field vary from axis to axis. In our work, we suggest a symmetric MAC grid that maintains consistent dimensions across axes without interpolation or symmetry breaking. The proposed grid effectively transfers spatial fluid quantities such as partial derivatives of velocity, enabling networks to generate accurate predictions. Additionally, we introduce a physics-based loss inspired by the variational formulation of viscosity to enhance the network’s generalization for a wide range of viscosity coefficients. We demonstrate various fluid simulation results, including 2D and 3D fluid-rigid body scenes and a scene exhibiting the buckling effect.
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Area 4 - Interactive Environments

Full Papers
Paper Nr: 98
Title:

Real-Time Editing of Path-Traced Scenes with Prioritized Re-Rendering
Authors:

Annalena Ulschmid, Bernhard Kerbl, Katharina Krösl and Michael Wimmer
Abstract: With recent developments in GPU ray tracing performance and (AI-accelerated) noise reduction techniques, Monte Carlo Path Tracing at real-time rates becomes a viable solution for interactive 3D scene editing, with growing support in popular software. However, even for minor edits (e.g., adjusting materials or moving small objects), current solutions usually discard previous samples and the image formation process is started from scratch. In this paper, we present two adaptive, priority-based re-rendering techniques with incremental updates, prioritizing the reconstruction of regions with high importance, before gradually moving to less important regions. The suggested methods automatically identify and schedule sampling and accumulation of immediately affected regions. An extensive user study analyzes whether such prioritized renderings are beneficial to interactive scene editing, comparing them with same-time conventional re-rendering. Our evaluation shows that even with simple priority policies, there is a significant preference for such incremental rendering techniques for interactive editing of small objects over full-screen re-rendering with denoising.
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Paper Nr: 213
Title:

Viewpoint Selection for Molecular Visualization: Analysis and Applications
Authors:

Vincent Larroque, Maxime Maria, Stéphane Mérillou and Matthieu Montes
Abstract: Molecular systems are often visually complex and abstract. It can be difficult, even for experts, to explore and find meaningful viewpoints. Research in viewpoint selection methods has mainly focused on general real-world objects and only a few works tackled molecular scenes. In this paper, we present a study of 20 state-of-the-art viewpoint selection methods from the general field, applied to molecular visualization. Our goal is to determine if these methods can find two important geometrical configurations for molecules. Additionally, we propose an automatic generation of informative and visually pleasing molecular tours to help the study and the communication around molecules.
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Paper Nr: 260
Title:

Handing Pedagogical Scenarios Back over to Domain Experts: A Scenario Authoring Model for VR with Pedagogical Objectives
Authors:

Mathieu Risy, Valérie Gouranton and Bruno Arnaldi
Abstract: Teachers and trainers make pedagogical decisions for their training courses, so why not do the same for Virtual Reality (VR) training courses? Virtual Environments for Training (VETs) are becoming prominent educational tools. However, VET models have yet to propose scenario authoring aligned with pedagogical objectives that can account for the diversity of approaches available to teachers. This paper proposes a scenario authoring model for VET that directly involves domain experts and validates their pedagogical objectives. In addition, it proposes the coexistence of multiple pedagogical scenarios within the same VET, using three types of scenarios. The validity of the model is then discussed using a VR welding application as a use case.
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Paper Nr: 367
Title:

Thinking on Your Feet: Enhancing Foveated Rendering in Virtual Reality During User Activity
Authors:

David Petrescu, Paul A. Warren, Zahra Montazeri, Gabriel Strain and Steve Pettifer
Abstract: As prices fall, VR technology is experiencing renewed levels of consumer interest. Despite wider access, VR still requires levels of computational ability and bandwidth that often cannot be achieved with consumer-grade equipment. Foveated rendering represents one of the most promising methods for the optimization of VR content while keeping the quality of the user’s experience intact. The user’s ability to explore and move through the environment with 6DOF separates VR from traditional display technologies. In this work, we explore if the type of movement (Active versus Implied) and attentional task type (Simple Fixations versus Fixation, Discrimination, and Counting) affect the extent to which a dynamic foveated rendering method using Variable Rate Shading (VRS) optimizes a VR scene. Using psychophysics methods we conduct user studies and recover the Maximum Tolerated Diameter (MTD) at which users fail to notice drops in quality. We find that during self-movement, performing a task that requires more attention masks severe shading reductions and that only 31.7% of the headset’s FOV is required to be rendered at the native pixel sampling rate.
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Paper Nr: 377
Title:

An Evaluation Research on Dynamic Hit Stop Using Eye Gaze
Authors:

Rena Tomizawa and Tomokazu Ishikawa
Abstract: The purpose of this study was to verify whether the response changes when hit stop, one of the elements of GameFeel, is changed according to gaze information. First, several participants play the action game by changing the hit stop duration and answer a questionnaire. Based on the results of this questionnaire, the boundary between pleasant and unpleasant hit stop duration is determined based on the idea of discriminant analysis method. Next, within a comfortable hit stop duration range, we examined whether the response is different when the hit stop duration is changed according to the gazing duration. As a result, designing hit stop duration that corresponds to staring duration is important to improve GameFeel.
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Paper Nr: 390
Title:

Exploring the Effect of Display Type on Co-Located Multiple Player Gameplay Performance, Immersion, Social Presence, and Behavior Patterns
Authors:

Wenge Xu, Ruichen Zheng, Diego Monteiro, Vijayakumar Nanjappan, Yihong Wang and Hai-Ning Liang
Abstract: With advances in virtual reality (VR) technology, immersive head-mounted displays (HMDs) have become widely accessible. These devices have made social games and platforms like VRChat popular. Although the literature points to several factors that affect immersion and social presence, there has been no study that has explored the effect of social display setup on immersion and gameplay in multi-player social games. This work aims to shed light on this issue and investigates the effect of social display setup on gameplay performance and experience (i.e., immersion and social presence) in a multi-player competitive social game (i.e., Jenga). We conducted a one-way between-subjects experiment with 24 participants equally distributed in three groups (4 pairs of 2 participants in each group, who were all strangers to each other) according to three social display setups (2 small-screen tablets, 1 shared 40-inch large TV, and 2 VR HMDs). Our results indicate that (1) players gave a lower rating to challenge in the VR-based social setting than in the small-screen tablet display setting, and (2) gameplay behavior patterns are different among these social display setups.
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Paper Nr: 401
Title:

HandWindowTeleportation: Locomotion with Hand Gestures for Virtual Reality Games
Authors:

Hibiki Kirihata and Tomokazu Ishikawa
Abstract: This study designs and evaluates a novel one-handed gesture-based control method for teleportation within a VR game space. For three different stages, we measured travel time, number of moving maneuvers, and accuracy in achieving checkpoints, and used two questionnaires, NASA-TLX and SUS, to evaluate the subject’s workload and the usability of proposed system. It was suggested that the proposed teleportation method using hand gestures is appropriate for games that require agility, such as action games, and is less tiring and has better ease of use than the previous method and a method on existing products.
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Short Papers
Paper Nr: 262
Title:

Real-Time 3D Information Visualization on Mobile Devices: Efficient Occlusion Detection for Geospatial Applications
Authors:

Agata Migalska
Abstract: The rapid advancement of geospatial applications on mobile devices has revolutionized outdoor activities and professions by providing invaluable tools for navigating, exploring, and highlighting geographic features. These applications often face notable challenges, including limited connectivity as well as battery and storage constraints. The objective of this paper is to provide users with a seamless user experience and augmented reality interactions in diverse outdoor scenarios within geospatial applications on mobile devices. Towards this goal, we introduce visibility map of a point that contains distances from the point to the closest obstacles at multiple angular viewpoints. We propose that every point of interest is associated with a such a visibility map, pre-calculated on a digital world model, in order to render annotated data in real-time without relying on time-consuming depth estimation. We specifically address the aspect of displaying 3D virtual information that is registered at different elevations, justified by the importance of elevation information in domains such as earth science, culture science or construction and by a lack of methods that would allow that. Through our study, we demonstrate the real-time rendering capability and accuracy of our proposed method. We present the findings, discuss potential limitations, and suggest future research directions.
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Paper Nr: 345
Title:

Virtual Reality for Detailed Visualization and Generation of Proximal and Distal Bone Fracture Patterns
Authors:

J. J. Jiménez-Delgado, F. D. Pérez-Cano, G. Parra-Cabrera and I. Remolar-Quintana
Abstract: This paper articulates the application of virtual reality (VR) in facilitating the study of bone fractures, particularly those affecting the proximal and distal end segments of long bones, areas of the bone in which there are a large number of irregularities. With the increasing prevalence of bone fractures due to aging and increased life expectancy, we present an innovative virtual reality system that meticulously generates and visualizes bone fracture patterns in three dimensions. The system allows users, including healthcare professionals, to interact with 3D bone models and delineate fracture patterns in a realistic environment. It features haptic feedback, simulating the sensation of drawing on a real bone. The tool also provides an exporting functionality for the drawn fractures, enabling the integration into other medical platforms. Experts have evaluated the interaction and representation of the fracture patterns in a highly positive evaluation. The experts assessed the system positively, emphasizing its potential towards enhancing surgical planning, improving patient outcomes, and fostering educational advancements. Future work aims at improving the degree of realism within the VR environment and refining the precision of closing fracture lines.
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Paper Nr: 91
Title:

Pure Physics-Based Hand Interaction in VR
Authors:

Mohammed-Bashir Mahdi, Erwan Guillou, Alexandre Meyer, Arash Habibi and Saïda Bouakaz
Abstract: Interaction in Virtual Reality is still mainly done using controllers. However, since the early 2000s, there has been a desire to find a way to interact within the virtual environment using only our hands. Pinch motion detection was introduced to detect a grasping action. Since then, hands’ motion capture has been highly developed until being directly integrated in VR headsets. Thus, multiple research projects were done in order to exploit this technology for better grasping techniques. Recent works tend to bring physical hand interaction to VR. However, they introduce physical heuristics to determine if an object is grasped or not, but in reality, motion is purely kinematic. In our paper, we introduce a purely physical method based on Hooke’s spring law that eliminates the need for a grasping mode. Additionally, we incorporate visual feedback methods to compensate for the absence of the sense of touch. Consequently, with this approach, we can lift objects, throw them, stack them, and interact with them naturally. We carried out extensive tests with several people who had no previous experience, to validate our technique.
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Paper Nr: 357
Title:

A Virtual Reality Prototype as a Tool Against Verbal Abuse in Classrooms: A Multidisciplinary Approach
Authors:

Irene Fondon, Mar Elena, Irene J. Lagares and Susana P. Gaytan
Abstract: The exploration of affective response and its vegetative correlate to verbal abuse (VA) is a relevant research area to prevent bullying at schools. Taking advantage of the possibilities that virtual reality offers regarding to immersion in non-real environments inducing feelings in the users, this paper presents a virtual reality application focused on the study of VA in a school context. The versatility of the proposed project is directly related to its applicability. It has been designed under the premises of the psycho-neural effect of VA. The tool is intended to be used under professional and parental supervision, to perform experiments regarding bulling awareness. In this first stage, the authors propose a prototype that will be optimized and upgraded in future versions.
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