TY - JOUR A1 - Zachow, Stefan A1 - Hege, Hans-Christian A1 - Deuflhard, Peter T1 - Computer assisted planning in cranio-maxillofacial surgery JF - Journal of Computing and Information Technology Y1 - 2006 VL - 14(1) SP - 53 EP - 64 ER - TY - JOUR A1 - Benger, Werner A1 - Bartsch, Hauke A1 - Hege, Hans-Christian A1 - Kitzler, Hagen A1 - Shumilina, Anna A1 - Werner, Annett T1 - Visualizing neuronal structures in the human brain via Diffusion Tensor MRI JF - Int. Journal of Neuroscience Y1 - 2006 VL - 116(4) SP - 461 EP - 514 ER - TY - JOUR A1 - Maye, Alexander A1 - Wenckebach, Thomas A1 - Hege, Hans-Christian T1 - Visualization, reconstruction, and integration of neuronal structures in digital brain atlases JF - Int. Journal of Neuroscience Y1 - 2006 VL - 116(4) SP - 431 EP - 459 ER - TY - GEN A1 - Petz, Christoph A1 - Weinkauf, Tino A1 - Streckwall, Heinrich A1 - Salvatore, Franceso A1 - Noack, Bernd R. A1 - Hege, Hans-Christian T1 - Vortex Structures at a Rotating Ship Propeller Y1 - 2006 PB - Presented at the 24th Annual Gallery of Fluid Motion exhibit, held at the 59th Annual Meeting of the American Physical Society, Division of Fluid Dynamics, Tampa Bay ER - TY - JOUR A1 - Ziegler, Günter M. A1 - Hege, Hans-Christian A1 - Duda, Georg T1 - Neue Bilder für die Medizin? JF - DFN-Mitteilungen Y1 - 2005 VL - 13(3) SP - 163 EP - 167 ER - TY - GEN A1 - Hege, Hans-Christian T1 - Hintergrundinformationen zum Artikel ‘Neue Bilder für die Medizin?’ Y1 - 2005 PB - DFG-Research Center Matheon, Report, 19 pages ER - TY - CHAP A1 - Sahner, Jan A1 - Weinkauf, Tino A1 - Hege, Hans-Christian ED - Brodlie, K. ED - Duke, D. ED - Joy, K. T1 - Galilean invariant extraction and iconic representation of vortex core lines T2 - Proc. Eurographics / IEEE VGTC Symposium on Visualization (EuroVis ’05) Y1 - 2005 U6 - https://doi.org/10.2312/VisSym/EuroVis05/151-160 SP - 151 EP - 160 CY - Leeds, UK ER - TY - CHAP A1 - Theisel, Holger A1 - Sahner, Jan A1 - Weinkauf, Tino A1 - Hege, Hans-Christian A1 - Seidel, Hans-Peter T1 - Extraction of parallel vector surfaces in 3D time-dependent fields and application to vortex core line tracking T2 - Proc. IEEE Visualization 2005 Y1 - 2005 SP - 559 EP - 566 CY - Minneapolis, USA ER - TY - CHAP A1 - Colditz, Carsten A1 - Coconu, Liviu A1 - Deussen, Oliver A1 - Hege, Hans-Christian ED - Buhmann, Erich ED - Paar, Philip ED - Bishop, Ian ED - Lange, Eckart T1 - Real-time rendering of complex photorealistic landscapes using hybrid level-of-detail approaches T2 - Trends in Real-Time Landscape Visualization and Participation Y1 - 2005 SP - 97 EP - 106 PB - Wichmann Verlag ER - TY - CHAP A1 - Coconu, Liviu A1 - Colditz, Carsten A1 - Hege, Hans-Christian A1 - Deussen, Oliver ED - Buhmann, Erich ED - Paar, Philip ED - Bishop, Ian ED - Lange, Eckart T1 - Seamless integration of stylized renditions in computer-generated landscape visualization T2 - Trends in Real-Time Landscape Visualization and Participation Y1 - 2005 SP - 88 EP - 96 PB - Wichmann Verlag CY - Heidelberg ER - TY - CHAP A1 - Clasen, Malte A1 - Hege, Hans-Christian ED - Buhmann, Erich ED - Paar, Philip ED - Bishop, Ian ED - Lange, Eckart T1 - Realistic illumination of vegetation in real-time environments T2 - Trends in Real-Time Landscape Visualization and Participation Y1 - 2005 SP - 107 EP - 114 PB - Wichmann Verlag ER - TY - JOUR A1 - Werner, Armin A1 - Deussen, Oliver A1 - Döllner, Jürgen A1 - Hege, Hans-Christian A1 - Paar, Philip A1 - Rekittke, Jörg ED - Buhmann, Erich ED - Paar, Philip ED - Bishop, Ian ED - Lange, Eckart T1 - Lenné 3D walking through landscape plan JF - Trends in Real-Time Landscape Visualization and Participation Y1 - 2005 SP - 48 EP - 59 PB - Wichmann Verlag ER - TY - CHAP A1 - Hege, Hans-Christian T1 - Visual analysis of molecular dynamics data using geometric and topological methods T2 - Forum "Math for Industry" 2014 Y1 - 2014 VL - 57 SP - 45 EP - 46 PB - Institute of Mathematics for Industry, Kyushu University CY - Fukuoka, Japan ER - TY - CHAP A1 - Bonneau, Georges-Pierre A1 - Hege, Hans-Christian A1 - Johnson, Chris R. A1 - Oliveira, Manuel M. A1 - Potter, Kristin A1 - Rheingans, Penny A1 - Schultz, Thomas T1 - Overview and State-of-the-Art of Uncertainty Visualization T2 - Scientific Visualization - Uncertainty, Multifield, Biomedical, and Scalable Visualization N2 - The goal of visualization is to effectively and accurately communicate data. Visualization research has often overlooked the errors and uncertainty which accompany the scientific process and describe key characteristics used to fully understand the data. The lack of these representations can be attributed, in part, to the inherent difficulty in defining, characterizing, and controlling this uncertainty, and in part, to the difficulty in including additional visual metaphors in a well designed, potent display. However, the exclusion of this information cripples the use of visualization as a decision making tool due to the fact that the display is no longer a true representation of the data. This systematic omission of uncertainty commands fundamental research within the visualization community to address, integrate, and expect uncertainty information. In this chapter, we outline sources and models of uncertainty, give an overview of the state-of-the-art, provide general guidelines, outline small exemplary applications, and finally, discuss open problems in uncertainty visualization. Y1 - 2014 SN - 978-1-4471-6496-8 U6 - https://doi.org/10.1007/978-1-4471-6497-5_1 SP - 3 EP - 27 PB - Springer ER - TY - JOUR A1 - Goubergrits, Leonid A1 - Schaller, Jens A1 - Kertzscher, Ulrich A1 - Petz, Christoph A1 - Hege, Hans-Christian A1 - Spuler, Andreas T1 - Reproducibility of Image-Based Analysis of Cerebral Aneurysm Geometry and Hemodynamics: An In-Vitro Study of Magnetic Resonance Imaging, Computed Tomography, and Three-Dimensional Rotational Angiography JF - Journal of Neurological Surgery, Part A: Central European Neurosurgery Y1 - 2013 U6 - https://doi.org/10.1055/s-0033-1342937 VL - 74 IS - 5 SP - 294 EP - 302 ER - TY - JOUR A1 - Sips, Mike A1 - Kothur, Patrick A1 - Unger, Andrea A1 - Hege, Hans-Christian A1 - Dransch, Doris T1 - A Visual Analytics Approach to Multiscale Exploration of Environmental Time Series JF - IEEE Transactions on Visualization and Computer Graphics N2 - We present a Visual Analytics approach that addresses the detection of interesting patterns in numerical time series, specifically from environmental sciences. Crucial for the detection of interesting temporal patterns are the time scale and the starting points one is looking at. Our approach makes no assumption about time scale and starting position of temporal patterns and consists of three main steps: an algorithm to compute statistical values for all possible time scales and starting positions of intervals, visual identification of potentially interesting patterns in a matrix visualization, and interactive exploration of detected patterns. We demonstrate the utility of this approach in two scientific scenarios and explain how it allowed scientists to gain new insight into the dynamics of environmental systems. Y1 - 2012 U6 - https://doi.org/10.1109/TVCG.2012.191 VL - 18 IS - 12 SP - 2899 EP - 2907 ER - TY - JOUR A1 - Weinkauf, Tino A1 - Hege, Hans-Christian A1 - Theisel, Holger T1 - Advected Tangent Curves: A General Scheme for Characteristic Curves of Flow Fields JF - Computer Graphics Forum N2 - We present the first general scheme to describe all four types of characteristic curves of flow fields – stream, path, streak, and time lines – as tangent curves of a derived vector field. Thus, all these lines can be obtained by a simple integration of an autonomous ODE system. Our approach draws on the principal ideas of the recently introduced tangent curve description of streak lines. We provide the first description of time lines as tangent curves of a derived vector field, which could previously only be constructed in a geometric manner. Furthermore, our scheme gives rise to new types of curves. In particular, we introduce advected stream lines as a parameter-free variant of the time line metaphor. With our novel mathematical description of characteristic curves, a large number of feature extraction and analysis tools becomes available for all types of characteristic curves, which were previously only available for stream and path lines. We will highlight some of these possible applications including the computation of time line curvature fields and the extraction of cores of swirling advected stream lines. Y1 - 2012 U6 - https://doi.org/10.1111/j.1467-8659.2012.03063.x VL - 31 IS - 2pt4 SP - 825 EP - 834 ER - TY - CHAP A1 - Heller, Markus O. A1 - Wurl, Alexander A1 - Perka, Carsten A1 - Hege, Hans-Christian T1 - In vivo gluteus medius volume and shape variations across gender and disease status BT - Proceedings of ESB2012 - 18th Congress of the European Society of Biomechanics, Lisbon, Portugal, 1–4 July 2012 T2 - Journal of Biomechanics Y1 - 2012 U6 - https://doi.org/10.1016/S0021-9290(12)70359-7 VL - 45, Suppl. 1 SP - S358 ER - TY - CHAP A1 - Pfister, Hanspeter A1 - Kaynig, Verena A1 - Botha, Charl P. A1 - Bruckner, Stefan A1 - Dercksen, Vincent J. A1 - Hege, Hans-Christian A1 - Roerdink, Jos B.T.M. ED - Hansen, Charles D. ED - Chen, Min ED - Johnson, Christopher R. ED - Kaufman, Arie E. ED - Hagen, Hans T1 - Visualization in Connectomics T2 - Scientific Visualization - Uncertainty, Multifield, Biomedical, and Scalable Visualization N2 - Connectomics is a branch of neuroscience that attempts to create a connectome, i.e., a complete map of the neuronal system and all connections between neuronal structures. This representation can be used to understand how functional brain states emerge from their underlying anatomical structures and how dysfunction and neuronal diseases arise. We review the current state-of-the-art of visualization and image processing techniques in the field of connectomics and describe a number of challenges. After a brief summary of the biological background and an overview of relevant imaging modalities, we review current techniques to extract connectivity information from image data at macro-, meso- and microscales. We also discuss data integration and neural network modeling, as well as the visualization, analysis and comparison of brain networks. Y1 - 2014 SN - 978-1-4471-6496-8 U6 - https://doi.org/10.1007/978-1-4471-6497-5_21 SP - 221 EP - 245 PB - Springer ER - TY - JOUR A1 - Goubergrits, Leonid A1 - Spuler, Andreas A1 - Schaller, Jens A1 - Wiegmann, Nils A1 - Berthe, Andre A1 - Hege, Hans-Christian A1 - Affeld, Klaus A1 - Kertzscher, Ulrich T1 - In vitro study of hemodynamic treatment improvement: Hunterian ligation of a fenestrated basilar artery aneurysm after coiling JF - The International Journal of Artificial Organs N2 - Hunterian ligation affecting hemodynamics in vessels was proposed to avoid rebleeding in a case of a fenestrated basilar artery aneurysm after incomplete coil occlusion. We studied the hemodynamics in vitro to predict the hemodynamic changes near the aneurysm remnant caused by Hunterian ligation. A transparent model was fabricated based on three-dimensional rotational angiography imaging. Arteries were segmented and reconstructed. Pulsatile flow in the artery segments near the partially occluded (coiled) aneurysm was investigated by means of particle image velocimetry. The hemodynamic situation was investigated before and after Hunterian ligation of either the left or the right vertebral artery (LVA/RVA). Since post-ligation flow rate in the basilar artery was unknown, reduced and retained flow rates were simulated for both ligation options. Flow in the RVA and in the corresponding fenestra vessel is characterized by a vortex at the vertebrobasilar junction, whereas the LVA exhibits undisturbed laminar flow. Both options (RVA or LVA ligation) cause a significant flow reduction near the aneurysm remnant with a retained flow rate. The impact of RVA ligation is, however, significantly higher. This in vitro case study shows that flow reduction near the aneurysm remnant can be achieved by Hunterian ligation and that this effect depends largely on the selection of the ligated vessel. Thus the ability of the proposed in vitro pipe-line to improve hemodynamic impact of the proposed therapy was successfully proved. Y1 - 2014 U6 - https://doi.org/10.5301/ijao.5000314 VL - 37 IS - 4 SP - 325 EP - 335 ER - TY - CHAP A1 - Stoppel, Sergej A1 - Hege, Hans-Christian A1 - Wiebel, Alexander T1 - Visibility-driven depth determination of surface patches in direct volume rendering T2 - EuroVis - Short Papers 2014 N2 - This paper presents an algorithm called surfseek for selecting surfaces on the most visible features in direct volume rendering (DVR). The algorithm is based on a previously published technique (WYSIWYP) for picking 3D locations in DVR. The new algorithm projects a surface patch on the DVR image, consisting of multiple rays. For each ray the algorithm uses WYSIWYP or a variant of it to find the candidates for the most visible locations along the ray. Using these candidates the algorithm constructs a graph and computes a minimum cut on this graph. The minimum cut represents a visible and typically rather smooth surface. In the last step the selected surface is displayed. We provide examples for results using artificially generated and real-world data sets. Y1 - 2014 U6 - https://doi.org/10.2312/eurovisshort.20141164 SP - 97 EP - 101 ER - TY - JOUR A1 - Goubergrits, Leonid A1 - Hellmeier, Florian A1 - Bruening, Jan Joris A1 - Spuler, Andreas A1 - Hege, Hans-Christian A1 - Voss, Samuel A1 - Janiga, Gábor A1 - Saalfeld, Sylvia A1 - Beuing, Oliver A1 - Berg, Philipp T1 - Multiple Aneurysms AnaTomy CHallenge 2018 (MATCH): Uncertainty Quantification of Geometric Rupture Risk Parameters JF - BioMedical Engineering OnLine N2 - Background Geometric parameters have been proposed for prediction of cerebral aneurysm rupture risk. Predicting the rupture risk for incidentally detected unruptured aneurysms could help clinicians in their treatment decision. However, assessment of geometric parameters depends on several factors, including the spatial resolution of the imaging modality used and the chosen reconstruction procedure. The aim of this study was to investigate the uncertainty of a variety of previously proposed geometric parameters for rupture risk assessment, caused by variability of reconstruction procedures. Materials 26 research groups provided segmentations and surface reconstructions of five cerebral aneurysms as part of the Multiple Aneurysms AnaTomy CHallenge (MATCH) 2018. 40 dimensional and non-dimensional geometric parameters, describing aneurysm size, neck size, and irregularity of aneurysm shape, were computed. The medians as well as the absolute and relative uncertainties of the parameters were calculated. Additionally, linear regression analysis was performed on the absolute uncertainties and the median parameter values. Results A large variability of relative uncertainties in the range between 3.9 and 179.8% was found. Linear regression analysis indicates that some parameters capture similar geometric aspects. The lowest uncertainties < 6% were found for the non-dimensional parameters isoperimetric ratio, convexity ratio, and ellipticity index. Uncertainty of 2D and 3D size parameters was significantly higher than uncertainty of 1D parameters. The most extreme uncertainties > 80% were found for some curvature parameters. Conclusions Uncertainty analysis is essential on the road to clinical translation and use of rupture risk prediction models. Uncertainty quantification of geometric rupture risk parameters provided by this study may help support development of future rupture risk prediction models. Y1 - 2019 U6 - https://doi.org/10.1186/s12938-019-0657-y VL - 18 IS - 35 ER - TY - JOUR A1 - Fröhler, Bernhard A1 - Elberfeld, Tim A1 - Möller, Torsten A1 - Hege, Hans-Christian A1 - Weissenböck, Johannes A1 - De Beenhouwer, Jan A1 - Sijbers, Jan A1 - Kastner, Johann A1 - Heinzl, Christoph T1 - A Visual Tool for the Analysis of Algorithms for Tomographic Fiber Reconstruction in Materials Science JF - Computer Graphics Forum N2 - We present visual analysis methods for the evaluation of tomographic fiber reconstruction algorithms by means of analysis, visual debugging and comparison of reconstructed fibers in materials science. The methods are integrated in a tool (FIAKER) that supports the entire workflow. It enables the analysis of various fiber reconstruction algorithms, of differently parameterized fiber reconstruction algorithms and of individual steps in iterative fiber reconstruction algorithms. Insight into the performance of fiber reconstruction algorithms is obtained by a list‐based ranking interface. A 3D view offers interactive visualization techniques to gain deeper insight, e.g., into the aggregated quality of the examined fiber reconstruction algorithms and parameterizations. The tool was designed in close collaboration with researchers who work with fiber‐reinforced polymers on a daily basis and develop algorithms for tomographic reconstruction and characterization of such materials. We evaluate the tool using synthetic datasets as well as tomograms of real materials. Five case studies certify the usefulness of the tool, showing that it significantly accelerates the analysis and provides valuable insights that make it possible to improve the fiber reconstruction algorithms. The main contribution of the paper is the well‐considered combination of methods and their seamless integration into a visual tool that supports the entire workflow. Further findings result from the analysis of (dis‐)similarity measures for fibers as well as from the discussion of design decisions. It is also shown that the generality of the analytical methods allows a wider range of applications, such as the application in pore space analysis. Y1 - 2019 U6 - https://doi.org/10.1111/cgf.13688 VL - 38 IS - 3 SP - 273 EP - 283 ER - TY - CHAP A1 - Hanik, Martin A1 - Hege, Hans-Christian A1 - von Tycowicz, Christoph T1 - Bi-invariant Two-Sample Tests in Lie Groups for Shape Analysis T2 - Shape in Medical Imaging N2 - We propose generalizations of the T²-statistics of Hotelling and the Bhattacharayya distance for data taking values in Lie groups. A key feature of the derived measures is that they are compatible with the group structure even for manifolds that do not admit any bi-invariant metric. This property, e.g., assures analysis that does not depend on the reference shape, thus, preventing bias due to arbitrary choices thereof. Furthermore, the generalizations agree with the common definitions for the special case of flat vector spaces guaranteeing consistency. Employing a permutation test setup, we further obtain nonparametric, two-sample testing procedures that themselves are bi-invariant and consistent. We validate our method in group tests revealing significant differences in hippocampal shape between individuals with mild cognitive impairment and normal controls. Y1 - 2020 U6 - https://doi.org/10.1007/978-3-030-61056-2_4 SP - 44 EP - 54 PB - Springer International Publishing CY - Cham ER - TY - CHAP A1 - Hanik, Martin A1 - Hege, Hans-Christian A1 - Hennemuth, Anja A1 - von Tycowicz, Christoph T1 - Nonlinear Regression on Manifolds for Shape Analysis using Intrinsic Bézier Splines T2 - Proc. Medical Image Computing and Computer Assisted Intervention (MICCAI) N2 - Intrinsic and parametric regression models are of high interest for the statistical analysis of manifold-valued data such as images and shapes. The standard linear ansatz has been generalized to geodesic regression on manifolds making it possible to analyze dependencies of random variables that spread along generalized straight lines. Nevertheless, in some scenarios, the evolution of the data cannot be modeled adequately by a geodesic. We present a framework for nonlinear regression on manifolds by considering Riemannian splines, whose segments are Bézier curves, as trajectories. Unlike variational formulations that require time-discretization, we take a constructive approach that provides efficient and exact evaluation by virtue of the generalized de Casteljau algorithm. We validate our method in experiments on the reconstruction of periodic motion of the mitral valve as well as the analysis of femoral shape changes during the course of osteoarthritis, endorsing Bézier spline regression as an effective and flexible tool for manifold-valued regression. Y1 - 2020 U6 - https://doi.org/10.1007/978-3-030-59719-1_60 SP - 617 EP - 626 PB - Springer International Publishing CY - Cham ER - TY - JOUR A1 - Nava-Yazdani, Esfandiar A1 - Hege, Hans-Christian A1 - Sullivan, T. J. A1 - von Tycowicz, Christoph T1 - Geodesic Analysis in Kendall's Shape Space with Epidemiological Applications JF - Journal of Mathematical Imaging and Vision N2 - We analytically determine Jacobi fields and parallel transports and compute geodesic regression in Kendall’s shape space. Using the derived expressions, we can fully leverage the geometry via Riemannian optimization and thereby reduce the computational expense by several orders of magnitude over common, nonlinear constrained approaches. The methodology is demonstrated by performing a longitudinal statistical analysis of epidemiological shape data. As an example application we have chosen 3D shapes of knee bones, reconstructed from image data of the Osteoarthritis Initiative (OAI). Comparing subject groups with incident and developing osteoarthritis versus normal controls, we find clear differences in the temporal development of femur shapes. This paves the way for early prediction of incident knee osteoarthritis, using geometry data alone. Y1 - 2020 U6 - https://doi.org/10.1007/s10851-020-00945-w VL - 62 IS - 4 SP - 549 EP - 559 ER - TY - CHAP A1 - Nava-Yazdani, Esfandiar A1 - Hege, Hans-Christian A1 - von Tycowicz, Christoph T1 - A Geodesic Mixed Effects Model in Kendall's Shape Space T2 - Proc. 7th MICCAI workshop on Mathematical Foundations of Computational Anatomy (MFCA) N2 - In many applications, geodesic hierarchical models are adequate for the study of temporal observations. We employ such a model derived for manifold-valued data to Kendall's shape space. In particular, instead of the Sasaki metric, we adapt a functional-based metric, which increases the computational efficiency and does not require the implementation of the curvature tensor. We propose the corresponding variational time discretization of geodesics and apply the approach for the estimation of group trends and statistical testing of 3D shapes derived from an open access longitudinal imaging study on osteoarthritis. Y1 - 2019 U6 - https://doi.org/10.1007/978-3-030-33226-6_22 VL - 11846 SP - 209 EP - 218 ER - TY - JOUR A1 - Agudo Jácome, Leonardo A1 - Hege, Hans-Christian A1 - Paetsch, Olaf A1 - Pöthkow, Kai T1 - Three-dimensional reconstruction and quantification of dislocation substructures from transmission electron microscopy stereo pairs JF - Ultramicroscopy N2 - A great amount of material properties is strongly influenced by dislocations, the carriers of plastic deformation. It is therefore paramount to have appropriate tools to quantify dislocation substructures with regard to their features, e.g., dislocation density, Burgers vectors or line direction. While the transmission electron microscope (TEM) has been the most widely-used equipment implemented to investigate dislocations, it usually is limited to the two-dimensional (2D) observation of three-dimensional (3D) structures. We reconstruct, visualize and quantify 3D dislocation substructure models from only two TEM images (stereo pairs) and assess the results. The reconstruction is based on the manual interactive tracing of filiform objects on both images of the stereo pair. The reconstruction and quantification method are demonstrated on dark field (DF) scanning (S)TEM micrographs of dislocation substructures imaged under diffraction contrast conditions. For this purpose, thick regions (>300 nm) of TEM foils are analyzed, which are extracted from a Ni-base superalloy single crystal after high temperature creep deformation. It is shown how the method allows 3D quantification from stereo pairs in a wide range of tilt conditions, achieving line length and orientation uncertainties of 3% and 7°, respectively. Parameters that affect the quality of such reconstructions are discussed. Y1 - 2018 U6 - https://doi.org/10.1016/j.ultramic.2018.08.015 VL - 195 SP - 157 EP - 170 ER - TY - CHAP A1 - Papazov, Chavdar A1 - Hege, Hans-Christian T1 - Blue-noise Optimized Point Sets Based on Procrustes Analysis T2 - SIGGRAPH Asia 2017 Technical Briefs Y1 - 2017 U6 - https://doi.org/10.1145/3145749.3149442 SP - 20:1 EP - 20:4 ER - TY - JOUR A1 - Oeltze-Jaffra, Steffen A1 - Meuschke, Monique A1 - Neugebauer, Mathias A1 - Saalfeld, Sylvia A1 - Lawonn, Kai A1 - Janiga, Gabor A1 - Hege, Hans-Christian A1 - Zachow, Stefan A1 - Preim, Bernhard T1 - Generation and Visual Exploration of Medical Flow Data: Survey, Research Trends, and Future Challenges JF - Computer Graphics Forum N2 - Simulations and measurements of blood and air flow inside the human circulatory and respiratory system play an increasingly important role in personalized medicine for prevention, diagnosis, and treatment of diseases. This survey focuses on three main application areas. (1) Computational Fluid Dynamics (CFD) simulations of blood flow in cerebral aneurysms assist in predicting the outcome of this pathologic process and of therapeutic interventions. (2) CFD simulations of nasal airflow allow for investigating the effects of obstructions and deformities and provide therapy decision support. (3) 4D Phase-Contrast (4D PC) Magnetic Resonance Imaging (MRI) of aortic hemodynamics supports the diagnosis of various vascular and valve pathologies as well as their treatment. An investigation of the complex and often dynamic simulation and measurement data requires the coupling of sophisticated visualization, interaction, and data analysis techniques. In this paper, we survey the large body of work that has been conducted within this realm. We extend previous surveys by incorporating nasal airflow, addressing the joint investigation of blood flow and vessel wall properties, and providing a more fine-granular taxonomy of the existing techniques. From the survey, we extract major research trends and identify open problems and future challenges. The survey is intended for researchers interested in medical flow but also more general, in the combined visualization of physiology and anatomy, the extraction of features from flow field data and feature-based visualization, the visual comparison of different simulation results, and the interactive visual analysis of the flow field and derived characteristics. Y1 - 2019 U6 - https://doi.org/10.1111/cgf.13394 VL - 38 IS - 1 SP - 87 EP - 125 PB - Wiley ER - TY - CHAP A1 - Fröhler, Bernhard A1 - da Cunha Melo, Lucas A1 - Weissenböck, Johannes A1 - Kastner, Johann A1 - Möller, Torsten A1 - Hege, Hans-Christian A1 - Gröller, Eduard M. A1 - Sanctorum, Jonathan A1 - De Beenhouwer, Jan A1 - Sijbers, Jan A1 - Heinzl, Christoph T1 - Tools for the analysis of datasets from X-ray computed tomography based on Talbot-Lau grating interferometry T2 - Proceedings of iCT 2019, (9th Conference on Industrial Computed Tomography, Padova, Italy – iCT 2019, February 13-15, 2019) N2 - This work introduces methods for analyzing the three imaging modalities delivered by Talbot-Lau grating interferometry X-ray computed tomography (TLGI-XCT). The first problem we address is providing a quick way to show a fusion of all three modal- ities. For this purpose the tri-modal transfer function widget is introduced. The widget controls a mixing function that uses the output of the transfer functions of all three modalities, allowing the user to create one customized fused image. A second problem prevalent in processing TLGI-XCT data is a lack of tools for analyzing the segmentation process of such multimodal data. We address this by providing methods for computing three types of uncertainty: From probabilistic segmentation algorithms, from the voxel neighborhoods as well as from a collection of results. We furthermore introduce a linked views interface to explore this data. The techniques are evaluated on a TLGI-XCT scan of a carbon-fiber reinforced dataset with impact damage. We show that the transfer function widget accelerates and facilitates the exploration of this dataset, while the uncertainty analysis methods give insights into how to tweak and improve segmentation algorithms for more suitable results. Y1 - 2019 N1 - PDF | open access: https://www.ndt.net/article/ctc2019/papers/iCT2019_Full_paper_52.pdf IS - paper 52 ER - TY - CHAP A1 - Coconu, Liviu A1 - Ullmer, Brygg A1 - Paar, Philip A1 - Liu, Jing A1 - Konkel, Miriam A1 - Hege, Hans-Christian T1 - A smartphone-based tangible interaction approach for landscape visualization. T2 - PerDis ’18 Proceedings of the 7th ACM International Symposium on Pervasive Displays, Munich, Germany, June 6-8, 2018 N2 - The use of tangible interfaces for navigation of landscape scenery – for example, lost places re-created in 3D – has been pursued and articulated as a promising, impactful application of interactive visualization. In this demonstration, we present a modern, low-cost implementation of a previously-realized multimodal gallery installation. Our demonstration centers upon the versatile usage of a smartphone for sensing, navigating, and (optionally) displaying element on a physical surface in tandem with a larger, more immersive display. Y1 - 2018 U6 - https://doi.org/10.1145/3205873.3210707 SP - no. 23 PB - ACM CY - New York, NY, USA ER - TY - CHAP A1 - Ullmer, Brygg A1 - Paar, Philip A1 - Coconu, Liviu A1 - Liu, Jing A1 - Konkel, Miriam A1 - Hege, Hans-Christian T1 - An 1834 mediterranean garden in Berlin – engaged from 2004, 2018, 2032, and 2202 T2 - PerDis ’18 – 7th ACM International Symposium on Pervasive Displays, Munich, Germany, June 6-8, 2018 N2 - In 2004, a team of researchers realized a semi-immersive interactive gallery installation, visualizing an 1834 Mediterranean garden, introduced as “italienisches Kunststück” (Italian legerdemain) by Peter Joseph Lenné. The park was originally realized on the grounds of Schloss Sanssouci in Potsdam, Germany. The installation centered on highly detailed renderings of hundreds of plants projected upon a panoramic display. Interactivity was expressed with a tangible interface which (while presently dated) we believe remains without near-precedent then or since. We present the installation (experienced by roughly 20,000 visitors), focusing on the interaction aspects. We introduce new book and table/door-format mockups. Drawing upon a heuristic of the scientist-philosopher Freeman Dyson, we consider grounded future prospect variations in the contexts of 2018, 2032, and 2202. We see this exercise as prospectively generalizing to a variety of similar and widely diverse application domains. Y1 - 2018 U6 - https://doi.org/10.1145/3205873.3205894 SP - no. 12 PB - ACM CY - New York, NY, USA ER - TY - CHAP A1 - Lindow, Norbert A1 - Baum, Daniel A1 - Hege, Hans-Christian T1 - Atomic Accessibility Radii for Molecular Dynamics Analysis T2 - Workshop on Molecular Graphics and Visual Analysis of Molecular Data N2 - In molecular structure analysis and visualization, the molecule’s atoms are often modeled as hard spheres parametrized by their positions and radii. While the atom positions result from experiments or molecular simulations, for the radii typically values are taken from literature. Most often, van der Waals (vdW) radii are used, for which diverse values exist. As a consequence, different visualization and analysis tools use different atomic radii, and the analyses are less objective than often believed. Furthermore, for the geometric accessibility analysis of molecular structures, vdW radii are not well suited. The reason is that during the molecular dynamics simulation, depending on the force field and the kinetic energy in the system, non-bonded atoms can come so close to each other that their vdW spheres intersect. In this paper, we introduce a new kind of atomic radius, called atomic accessibility radius’, that better characterizes the accessibility of an atom in a given molecular trajectory. The new radii reflect the movement possibilities of atoms in the simulated physical system. They are computed by solving a linear program that maximizes the radii of the atoms under the constraint that non-bonded spheres do not intersect in the considered molecular trajectory. Using this data-driven approach, the actual accessibility of atoms can be visualized more precisely. Y1 - 2018 SN - 978-3-03868-061-1 U6 - https://doi.org/10.2312/molva.20181101 PB - The Eurographics Association ER - TY - JOUR A1 - Lindow, Norbert A1 - Baum, Daniel A1 - Leborgne, Morgan A1 - Hege, Hans-Christian T1 - Interactive Visualization of RNA and DNA Structures JF - IEEE Transactions on Visualization and Computer Graphics N2 - The analysis and visualization of nucleic acids (RNA and DNA) is playing an increasingly important role due to their fundamental importance for all forms of life and the growing number of known 3D structures of such molecules. The great complexity of these structures, in particular, those of RNA, demands interactive visualization to get deeper insights into the relationship between the 2D secondary structure motifs and their 3D tertiary structures. Over the last decades, a lot of research in molecular visualization has focused on the visual exploration of protein structures while nucleic acids have only been marginally addressed. In contrast to proteins, which are composed of amino acids, the ingredients of nucleic acids are nucleotides. They form structuring patterns that differ from those of proteins and, hence, also require different visualization and exploration techniques. In order to support interactive exploration of nucleic acids, the computation of secondary structure motifs as well as their visualization in 2D and 3D must be fast. Therefore, in this paper, we focus on the performance of both the computation and visualization of nucleic acid structure. We present a ray casting-based visualization of RNA and DNA secondary and tertiary structures, which enables for the first time real-time visualization of even large molecular dynamics trajectories. Furthermore, we provide a detailed description of all important aspects to visualize nucleic acid secondary and tertiary structures. With this, we close an important gap in molecular visualization. Y1 - 2019 U6 - https://doi.org/10.1109/TVCG.2018.2864507 VL - 25 IS - 1 SP - 967 EP - 976 ER - TY - JOUR A1 - Mahnke, Heinz-Eberhard A1 - Arlt, Tobias A1 - Baum, Daniel A1 - Hege, Hans-Christian A1 - Herter, Felix A1 - Lindow, Norbert A1 - Manke, Ingo A1 - Siopi, Tzulia A1 - Menei, Eve A1 - Etienne, Marc A1 - Lepper, Verena T1 - Virtual unfolding of folded papyri JF - Journal of Cultural Heritage N2 - The historical importance of ancient manuscripts is unique since they provide information about the heritage of ancient cultures. Often texts are hidden in rolled or folded documents. Due to recent impro- vements in sensitivity and resolution, spectacular disclosures of rolled hidden texts were possible by X-ray tomography. However, revealing text on folded manuscripts is even more challenging. Manual unfolding is often too risky in view of the fragile condition of fragments, as it can lead to the total loss of the document. X-ray tomography allows for virtual unfolding and enables non-destructive access to hid- den texts. We have recently demonstrated the procedure and tested unfolding algorithms on a mockup sample. Here, we present results on unfolding ancient papyrus packages from the papyrus collection of the Musée du Louvre, among them objects folded along approximately orthogonal folding lines. In one of the packages, the first identification of a word was achieved, the Coptic word for “Lord”. Y1 - 2020 U6 - https://doi.org/10.1016/j.culher.2019.07.007 VL - 41 SP - 264 EP - 269 PB - Elsevier ER - TY - JOUR A1 - Willie, Bettina M. A1 - Pap, Thomas A1 - Perka, Carsten A1 - Schmidt, Carsten Oliver A1 - Eckstein, Felix A1 - Arampatzis, Adamantios A1 - Hege, Hans-Christian A1 - Madry, Henning A1 - Vortkamp, Andrea A1 - Duda, Georg T1 - OVERLOAD – Rolle der Gelenküberlastung in der primären Arthrose – Die Krankheitsprogression verstehen und vermeiden JF - Zeitschrift für Rheumatologie N2 - Intakte Gelenke sind eine Voraussetzung für das Funktionieren des Skeletts und die Mobilität im Lebensalltag. Ein gesunder Bewegungsapparat ist die Grundlage für die Funktionsfähigkeit des Herz-Kreislauf-Systems wie auch der Immunabwehr. Bewegungs- und Physiotherapie sowie verschiedene Formen der Patientenaktivität stellen essenzielle klinische Ansätze in der Behandlung von neurodegenerativen Erkrankungen, Schlaganfall, Diabetes und Krebs dar. Kommt es zu degenerativen Veränderungen von Gelenken, bedeutet dies eine wesentliche Beeinträchtigung der Mobilität. Nächtliche Schmerzen und Schlafstörungen treten in fortgeschrittenen Stadien auf und sind besonders belastend. Arthrose wird auch als degenerative Gelenkerkrankung bezeichnet. Sie geht mit Veränderungen in der Struktur und Zusammensetzung des Gelenkknorpels wie auch des verkalkten Knorpels, der subchondralen Kortikalis, der subchondralen Spongiosa, des Meniskus, der Gelenkkapsel und der Synovialis einher, was schließlich zur Degeneration dieser Gewebe führt, aus denen sich die Synovialgelenke zusammensetzen. Y1 - 2015 U6 - https://doi.org/10.1007/s00393-014-1561-2 VL - 74 SP - 618 EP - 621 ER - TY - JOUR A1 - Willie, Bettina M. A1 - Pap, Thomas A1 - Perka, Carsten A1 - Schmidt, Carsten Oliver A1 - Eckstein, Felix A1 - Arampatzis, Adamantios A1 - Hege, Hans-Christian A1 - Madry, Henning A1 - Vortkamp, Andrea A1 - Duda, Georg T1 - OVERLOAD of joints and its role in osteoarthritis - Towards understanding and preventing progression of primary osteoarthritis JF - Zeitschrift für Rheumatologie N2 - Intact joints are necessary for skeletal function and mobility in daily life. A healthy musculoskeletal system is the basis for a functional cardiovascular system as well as an intact immune system. Locomotion, physiotherapy, and various forms of patient activity are essential clinical therapies used in the treatment of neurodegeneration, stroke, diabetes, and cancer. Mobility is substantially impaired with degeneration of joints and, in advanced stages, nighttime pain and sleep disturbance are particularly cumbersome. Osteoarthritis (OA) is also known as degenerative joint disease. OA involves structural and compositional changes in the articular cartilage, as well as in the calcified cartilage, subchondral cortical bone, subchondral cancellous bone, meniscus, joint capsular tissue, and synovium; which eventually lead to degeneration of these tissues comprising synovial joints. Y1 - 2015 U6 - https://doi.org/10.1007/s00393-014-1561-2 VL - 76 IS - Suppl. 1 SP - 1 EP - 4 ER - TY - CHAP A1 - Krämer, Martin A1 - Herrmann, Karl-Heinz A1 - Boeth, Heide A1 - Tycowicz, Christoph von A1 - König, Christian A1 - Zachow, Stefan A1 - Ehrig, Rainald A1 - Hege, Hans-Christian A1 - Duda, Georg A1 - Reichenbach, Jürgen T1 - Measuring 3D knee dynamics using center out radial ultra-short echo time trajectories with a low cost experimental setup T2 - ISMRM (International Society for Magnetic Resonance in Medicine), 23rd Annual Meeting 2015, Toronto, Canada Y1 - 2015 ER - TY - CHAP A1 - Coconu, Liviu A1 - Hege, Hans-Christian ED - Gibson, Simon ED - Debevec, Paul T1 - Hardware-Accelerated Point-Based Rendering of Complex Scenes T2 - Proceedings of the 13th Eurographics Workshop on Rendering Techniques Y1 - 2002 SP - 43 EP - 52 CY - Pisa, Italy ER - TY - JOUR A1 - Vohra, Sumit Kumar A1 - Harth, Philipp A1 - Isoe, Yasuko A1 - Bahl, Armin A1 - Fotowat, Haleh A1 - Engert, Florian A1 - Hege, Hans-Christian A1 - Baum, Daniel T1 - A Visual Interface for Exploring Hypotheses about Neural Circuits JF - IEEE Transactions on Visualization and Computer Graphics N2 - One of the fundamental problems in neurobiological research is to understand how neural circuits generate behaviors in response to sensory stimuli. Elucidating such neural circuits requires anatomical and functional information about the neurons that are active during the processing of the sensory information and generation of the respective response, as well as an identification of the connections between these neurons. With modern imaging techniques, both morphological properties of individual neurons as well as functional information related to sensory processing, information integration and behavior can be obtained. Given the resulting information, neurobiologists are faced with the task of identifying the anatomical structures down to individual neurons that are linked to the studied behavior and the processing of the respective sensory stimuli. Here, we present a novel interactive tool that assists neurobiologists in the aforementioned task by allowing them to extract hypothetical neural circuits constrained by anatomical and functional data. Our approach is based on two types of structural data: brain regions that are anatomically or functionally defined, and morphologies of individual neurons. Both types of structural data are interlinked and augmented with additional information. The presented tool allows the expert user to identify neurons using Boolean queries. The interactive formulation of these queries is supported by linked views, using, among other things, two novel 2D abstractions of neural circuits. The approach was validated in two case studies investigating the neural basis of vision-based behavioral responses in zebrafish larvae. Despite this particular application, we believe that the presented tool will be of general interest for exploring hypotheses about neural circuits in other species, genera and taxa. Y1 - 2023 U6 - https://doi.org/10.1109/TVCG.2023.3243668 ER - TY - JOUR A1 - Hoerth, Rebecca M. A1 - Baum, Daniel A1 - Knötel, David A1 - Prohaska, Steffen A1 - Willie, Bettina M. A1 - Duda, Georg A1 - Hege, Hans-Christian A1 - Fratzl, Peter A1 - Wagermaier, Wolfgang T1 - Registering 2D and 3D Imaging Data of Bone during Healing JF - Connective Tissue Research Y1 - 2015 U6 - https://doi.org/10.3109/03008207.2015.1005210 VL - 56 IS - 2 SP - 133 EP - 143 PB - Taylor & Francis ER - TY - JOUR A1 - Mikula, Natalia A1 - Dörffel, Tom A1 - Baum, Daniel A1 - Hege, Hans-Christian T1 - An Interactive Approach for Identifying Structure Definitions JF - Computer Graphics Forum N2 - Our ability to grasp and understand complex phenomena is essentially based on recognizing structures and relating these to each other. For example, any meteorological description of a weather condition and explanation of its evolution recurs to meteorological structures, such as convection and circulation structures, cloud fields and rain fronts. All of these are spatiotemporal structures, defined by time-dependent patterns in the underlying fields. Typically, such a structure is defined by a verbal description that corresponds to the more or less uniform, often somewhat vague mental images of the experts. However, a precise, formal definition of the structures or, more generally, concepts is often desirable, e.g., to enable automated data analysis or the development of phenomenological models. Here, we present a systematic approach and an interactive tool to obtain formal definitions of spatiotemporal structures. The tool enables experts to evaluate and compare different structure definitions on the basis of data sets with time-dependent fields that contain the respective structure. Since structure definitions are typically parameterized, an essential part is to identify parameter ranges that lead to desired structures in all time steps. In addition, it is important to allow a quantitative assessment of the resulting structures simultaneously. We demonstrate the use of the tool by applying it to two meteorological examples: finding structure definitions for vortex cores and center lines of temporarily evolving tropical cyclones. Ideally, structure definitions should be objective and applicable to as many data sets as possible. However, finding such definitions, e.g., for the common atmospheric structures in meteorology, can only be a long-term goal. The proposed procedure, together with the presented tool, is just a first systematic approach aiming at facilitating this long and arduous way. Y1 - 2022 U6 - https://doi.org/10.1111/cgf.14543 VL - 41 IS - 3 SP - 321 EP - 332 ER - TY - JOUR A1 - Fröhler, Bernhard A1 - Elberfeld, Tim A1 - Möller, Torsten A1 - Hege, Hans-Christian A1 - De Beenhouwer, Jan A1 - Sijbers, Jan A1 - Kastner, Johann A1 - Heinzl, Christoph T1 - Analysis and comparison of algorithms for the tomographic reconstruction of curved fibres JF - Nondestructive Testing and Evaluation N2 - We present visual methods for the analysis and comparison of the results of curved fibre reconstruction algorithms, i.e., of algorithms extracting characteristics of curved fibres from X-ray computed tomography scans. In this work, we extend previous methods for the analysis and comparison of results of different fibre reconstruction algorithms or parametrisations to the analysis of curved fibres. We propose fibre dissimilarity measures for such curved fibres and apply these to compare multiple results to a specified reference. We further propose visualisation methods to analyse differences between multiple results quantitatively and qualitatively. In two case studies, we show that the presented methods provide valuable insights for advancing and parametrising fibre reconstruction algorithms, and support in improving their results in characterising curved fibres. Y1 - 2020 U6 - https://doi.org/10.1080/10589759.2020.1774583 VL - 35 IS - 3 SP - 328 EP - 341 ER - TY - CHAP A1 - Hanik, Martin A1 - Hege, Hans-Christian A1 - von Tycowicz, Christoph T1 - A Nonlinear Hierarchical Model for Longitudinal Data on Manifolds T2 - 2022 IEEE 19th International Symposium on Biomedical Imaging (ISBI) N2 - Large longitudinal studies provide lots of valuable information, especially in medical applications. A problem which must be taken care of in order to utilize their full potential is that of correlation between intra-subject measurements taken at different times. For data in Euclidean space this can be done with hierarchical models, that is, models that consider intra-subject and between-subject variability in two different stages. Nevertheless, data from medical studies often takes values in nonlinear manifolds. Here, as a first step, geodesic hierarchical models have been developed that generalize the linear ansatz by assuming that time-induced intra-subject variations occur along a generalized straight line in the manifold. However, this is often not the case (e.g., periodic motion or processes with saturation). We propose a hierarchical model for manifold-valued data that extends this to include trends along higher-order curves, namely Bézier splines in the manifold. To this end, we present a principled way of comparing shape trends in terms of a functional-based Riemannian metric. Remarkably, this metric allows efficient, yet simple computations by virtue of a variational time discretization requiring only the solution of regression problems. We validate our model on longitudinal data from the osteoarthritis initiative, including classification of disease progression. Y1 - 2022 U6 - https://doi.org/10.1109/ISBI52829.2022.9761465 SP - 1 EP - 5 ER - TY - JOUR A1 - Udvary, Daniel A1 - Harth, Philipp A1 - Macke, Jakob H. A1 - Hege, Hans-Christian A1 - de Kock, Christiaan P. J. A1 - Sakmann, Bert A1 - Oberlaender, Marcel T1 - The Impact of Neuron Morphology on Cortical Network Architecture JF - Cell Reports N2 - The neurons in the cerebral cortex are not randomly interconnected. This specificity in wiring can result from synapse formation mechanisms that connect neurons depending on their electrical activity and genetically defined identity. Here, we report that the morphological properties of the neurons provide an additional prominent source by which wiring specificity emerges in cortical networks. This morphologically determined wiring specificity reflects similarities between the neurons’ axo-dendritic projections patterns, the packing density and cellular diversity of the neuropil. The higher these three factors are the more recurrent is the topology of the network. Conversely, the lower these factors are the more feedforward is the network’s topology. These principles predict the empirically observed occurrences of clusters of synapses, cell type-specific connectivity patterns, and nonrandom network motifs. Thus, we demonstrate that wiring specificity emerges in the cerebral cortex at subcellular, cellular and network scales from the specific morphological properties of its neuronal constituents. Y1 - 2022 U6 - https://doi.org/10.1016/j.celrep.2022.110677 VL - 39 IS - 2 ER - TY - CHAP A1 - Harth, Philipp A1 - Vohra, Sumit A1 - Udvary, Daniel A1 - Oberlaender, Marcel A1 - Hege, Hans-Christian A1 - Baum, Daniel T1 - A Stratification Matrix Viewer for Analysis of Neural Network Data T2 - Eurographics Workshop on Visual Computing for Biology and Medicine (VCBM) N2 - The analysis of brain networks is central to neurobiological research. In this context the following tasks often arise: (1) understand the cellular composition of a reconstructed neural tissue volume to determine the nodes of the brain network; (2) quantify connectivity features statistically; and (3) compare these to predictions of mathematical models. We present a framework for interactive, visually supported accomplishment of these tasks. Its central component, the stratification matrix viewer, allows users to visualize the distribution of cellular and/or connectional properties of neurons at different levels of aggregation. We demonstrate its use in four case studies analyzing neural network data from the rat barrel cortex and human temporal cortex. Y1 - 2022 U6 - https://doi.org/10.2312/vcbm.20221194 CY - Vienna, Austria ER - TY - GEN A1 - Dercksen, Vincent J. A1 - Oberlaender, Marcel A1 - Sakmann, Bert A1 - Hege, Hans-Christian ED - Linsen, Lars ED - Hagen, Hans ED - Hamann, Bernd ED - Hege, Hans-Christian T1 - Interactive Visualization – a Key Prerequisite for Reconstruction of Anatomically Realistic Neural Networks T2 - Visualization in Medicine and Life Sciences II Y1 - 2012 UR - http://www.zib.de/visual/publications/sources/src-2012/DercksenVMLS2012web.pdf SP - 27 EP - 44 PB - Springer, Berlin ER - TY - JOUR A1 - Herter, Felix A1 - Hege, Hans-Christian A1 - Hadwiger, Markus A1 - Lepper, Verena A1 - Baum, Daniel T1 - Thin-Volume Visualization on Curved Domains JF - Computer Graphics Forum N2 - Thin, curved structures occur in many volumetric datasets. Their analysis using classical volume rendering is difficult because parts of such structures can bend away or hide behind occluding elements. This problem cannot be fully compensated by effective navigation alone, because structure-adapted navigation in the volume is cumbersome and only parts of the structure are visible in each view. We solve this problem by rendering a spatially transformed view into the volume so that an unobscured visualization of the entire curved structure is obtained. As a result, simple and intuitive navigation becomes possible. The domain of the spatial transform is defined by a triangle mesh that is topologically equivalent to an open disc and that approximates the structure of interest. The rendering is based on ray-casting in which the rays traverse the original curved sub-volume. In order to carve out volumes of varying thickness, the lengths of the rays as well as the position of the mesh vertices can be easily modified in a view-controlled manner by interactive painting. We describe a prototypical implementation and demonstrate the interactive visual inspection of complex structures from digital humanities, biology, medicine, and materials science. Displaying the structure as a whole enables simple inspection of interesting substructures in their original spatial context. Overall, we show that transformed views utilizing ray-casting-based volume rendering supported by guiding surface meshes and supplemented by local, interactive modifications of ray lengths and vertex positions, represent a simple but versatile approach to effectively visualize thin, curved structures in volumetric data. Y1 - 2021 U6 - https://doi.org/10.1111/cgf.14296 VL - 40 IS - 3 SP - 147 EP - 157 PB - Wiley-Blackwell Publishing Ltd. CY - United Kingdom ER - TY - JOUR A1 - Nava-Yazdani, Esfandiar A1 - Hege, Hans-Christian A1 - von Tycowicz, Christoph T1 - A Hierarchical Geodesic Model for Longitudinal Analysis on Manifolds JF - Journal of Mathematical Imaging and Vision N2 - In many applications, geodesic hierarchical models are adequate for the study of temporal observations. We employ such a model derived for manifold-valued data to Kendall's shape space. In particular, instead of the Sasaki metric, we adapt a functional-based metric, which increases the computational efficiency and does not require the implementation of the curvature tensor. We propose the corresponding variational time discretization of geodesics and employ the approach for longitudinal analysis of 2D rat skulls shapes as well as 3D shapes derived from an imaging study on osteoarthritis. Particularly, we perform hypothesis test and estimate the mean trends. Y1 - 2022 U6 - https://doi.org/10.1007/s10851-022-01079-x VL - 64 IS - 4 SP - 395 EP - 407 ER -