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Item Real-Time Gaze Mapping in Virtual Environments(The Eurographics Association, 2019) Kraus, Matthias; Kilian, Timon Urs; Fuchs, Johannes; Madeiras Pereira, João and Raidou, Renata GeorgiaIn order to analyze an analyst's behavior in an immersive environment, his or her eye movements can be monitored using eye trackers. Hereby, points of individual interest can be objectively identified, for instance, to assess the usability and intuitiveness of a framework. However, this technique can be used not only as a post-event analysis tool but also to assist an ongoing exploration of a virtual environment. With this poster, we present a technique that allows a real-time gaze map creation which supports the immersed analyst by providing real-time feedback on the user's own activity. In our approach, all surfaces in the virtual environment are enwrapped with a mesh structure. The grid structure recognizes when a user drifts with his or her eyes above it and increments weights of activated node points. This allows highlighting areas that have been observed, but also those that have not been observed - also when they are occluded by other objects or surfaces. We tested our technique in a preliminary qualitative expert study and received helpful feedback for further improvements.Item Compacting Voxelized Polyhedra via Tree Stacking(The Eurographics Association and John Wiley & Sons Ltd., 2019) Hao, Yue; Lien, Jyh-Ming; Lee, Jehee and Theobalt, Christian and Wetzstein, GordonVolume compaction is a geometric problem that aims to reduce the volume of a polyhedron via shape transform. Compactable structures are easier to transport and in some cases easier to manufacture, therefore, they are commonly found in our daily life (e.g. collapsible containers) and advanced technology industries (e.g., the recent launch of 60 Starlink satellites compacted in a single rocket by SpaceX). It is known in the literature that finding a universal solution to compact an arbitrary 3D shape is computationally challenging. Previous approaches showed that stripifying mesh surface can lead to optimal compaction, but the resulting structures were often impractical. In this paper, we propose an algorithm that cuts the 3D orthogonal polyhedron, tessellated by thick square panels, into a tree structure that can be transformed into compact piles by folding and stacking. We call this process tree stacking. Our research found that it is possible to decompose the problem into a pipeline of several solvable local optimizations. We also provide an efficient algorithm to check if the solution exists by avoiding the computational bottleneck of the pipeline. Our results show that tree stacking can efficiently generate stackable structures that have better folding accuracy and similar compactness comparing to the most compact stacking using strips.Item Curvature Continuity Conditions Between Adjacent Toric Surface Patches(The Eurographics Association and John Wiley & Sons Ltd., 2018) Sun, Lanyin; Zhu, Chungang; Fu, Hongbo and Ghosh, Abhijeet and Kopf, JohannesToric surface patch is the multi-sided generalization of classical Bézier surface patch. Geometric continuity of the parametric surface patches plays a crucial role in geometric modeling. In this paper, the necessary and sufficient conditions of curvature continuity between toric surface patches are illustrated with the theory of toric degeneration. Furthermore, some practical sufficient conditions of curvature continuity of toric surface patches are also developed.Item Assessment of Virtual Reality Environments for Design Activities(The Eurographics Association, 2014) Trakunsaranakom, Channarong; Marin, Philippe; Noel, Frederic; Jerome Perret and Valter Basso and Francesco Ferrise and Kaj Helin and Vincent Lepetit and James Ritchie and Christoph Runde and Mascha van der Voort and Gabriel ZachmannThe aim of this research is the performance assessment of 3D visualization and interaction devices for design activities. Experiments are expected to determine the virtual environments that best fit the dedicated activities. Classification of technologies is proposed on the basis of its apparent relevance to reach intuitive support to the design activity but a method to provide a more complete and objective assessment is proposed. To check the proposed assessment method, a simple assembly activity has been selected as a use case where the use of stereoscopic screen versus classical 2D display on one hand and an haptic arm with versus without force feedback on the other hand must be compared. Experimental measures are performed by the use of objective sensors: duration and gesture instability along the task are tracked. The comparison was done on the assembly of the jig and fixture system. The experimental measures are analysed both with their absolute values and their evolution when training users. This paper is a positioning paper where the intention is to build a framework where more abstract qualification of virtual environments may be extracted: intuitiveness, tangibility, ergonomic and by the end utility should be the final assessment.Item Highly Efficient Controlled Hierarchical Data Reduction techniques for Interactive Visualization of Massive Simulation Data(The Eurographics Association, 2019) Dubois, Jérôme; Lekien, Jacques-Bernard; Johansson, Jimmy and Sadlo, Filip and Marai, G. ElisabetaWith the constant increase in compute power of supercomputers, high performance computing simulations are producing higher fidelity results and possibly massive amounts of data. To keep visualization of such results interactive, existing techniques such as Adaptive Mesh Refinement (AMR) can be of use. In particular, Tree-Based AMR methods (TB-AMR) are widespread in simulations and are becoming more present in general purpose visualization pipelines such as VTK. In this work, we show how TB-AMR data structures could lead to more efficient exploration of massive data sets in the Exascale era. We discuss how algorithms (filters) should be designed to take advantage of tree-like data structures for both data filtering or rendering. By introducing controlled hierarchical data reduction we greatly reduce the processing time for existing algorithms, sometimes with no visual impact, and drastically decrease exploration time for analysts. Also thanks to the techniques and implementations we propose, visualization of very large data is made possible on very constrained resources. These ideas are illustrated on million to billion-scale native TB-AMR or resampled meshes, with the HyperTreeGrid object and associated filters we have recently optimized and made available in the Visualisation Toolkit (VTK) for use by the scientific community.Item Comparative Analysis with Heightmaps in Virtual Reality Environments(The Eurographics Association, 2019) Kraus, Matthias; Buchmüller, Juri; Schweitzer, Daniel; Keim, Daniel A.; Fuchs, Johannes; Madeiras Pereira, João and Raidou, Renata Georgia3D heightmaps can be considered as an extension of heatmaps using the third dimension to encode the respective value by height, often in addition to encoding it by color. In contrast to 2D heatmaps, 3D heightmaps allow a superposition without aggregation. However, they also have the general disadvantages of 3D visualizations, such as occlusion and perceptual distortion. Previous research has revealed various advantages of stereoscopic displays and virtual reality (VR) in the context of 3D visualizations, for example, concerning memorization, depth perception, and collaboration. In this paper, we present a novel technique to compare heightmaps in VR by introducing a multi-layer approach of stacked heightmaps. We demonstrate the applicability and usefulness of our method by means of a use case on comparative crime data analysis.