检索结果-内蒙古大学图书馆

Interactive focus+context rendering for hexahedral mesh inspection

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Neuhauser, Christoph Wang, Junpeng Westermann, Rüdiger Computer Graphics & Visualization Group Technische Universität München Garching Germany

The visual inspection of a hexahedral mesh with respect to element quality is difficult due to clutter and occlusions that are produced when rendering all element faces or their edges simultaneously. Current approaches overcome this problem by using focus on specific elements that are then rendered opaque, and carving away all elements occluding their view. In this work, we make use of advanced GPU shader functionality to generate a focus+context rendering that highlights the elements in a selected region and simultaneously conveys the global mesh structure in the surrounding. To achieve this, we propose a gradual transition from edge-based focus rendering to volumetric context rendering, by combining fragment shader-based edge and face rendering with per-pixel fragment lists. A fragment shader smoothly transitions between wireframe and face-based rendering, including focus-dependent rendering style and depth-dependent edge thickness and halos, and per-pixel fragment lists are used to blend fragments in correct visibility order. To maintain the global mesh structure in the context regions, we propose a new method to construct a sheet-based level-of-detail hierarchy and smoothly blend it with volumetric information. The user guides the exploration process by moving a lens-like hotspot. Since all operations are performed on the GPU, interactive frame rates are achieved even for large meshes. Copyright © 2020, The Authors. All rights reserved.

关键词： Program processors

Improving Uncertainty-Error Correspondence in Deep Bayesian Medical Image Segmentation

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Mody, Prerak Chaves-De-Plaza, Nicolas F. Rao, Chinmay Astrenidou, Eleftheria de Ridder, Mischa Hoekstra, Nienke Hildebrandt, Klaus Staring, Marius Department of Radiology Leiden University Medical Center Leiden Netherlands HollandPTC consortium Erasmus Medical Center Rotterdam Holland Proton Therapy Centre Delft Leiden University Medical Center Leiden and TU Delft Delft Netherlands Computer Graphics and Visualization Group EEMCS TU Delft Delft Netherlands Department of Radiation Oncology Leiden University Medical Center Leiden Netherlands Department of Radiation Oncology University Medical Center Utrecht Netherlands

Increased usage of automated tools like deep learning in medical image segmentation has alleviated the bottleneck of manual contouring. This has shifted manual labour to quality assessment (QA) of automated contours which involves detecting errors and correcting them. A potential solution to semi-automated QA is to use deep Bayesian uncertainty to recommend potentially erroneous regions, thus reducing time spent on error detection. Previous work has investigated the correspondence between uncertainty and error, however, no work has been done on improving the "utility" of Bayesian uncertainty maps such that it is only present in inaccurate regions and not in the accurate ones. Our work trains the FlipOut model with the Accuracy-vs-Uncertainty (AvU) loss which promotes uncertainty to be present only in inaccurate regions. We apply this method on datasets of two radiotherapy body sites, c.f. head-and-neck CT and prostate MR scans. Uncertainty heatmaps (i.e. predictive entropy) are evaluated against voxel inaccuracies using Receiver Operating Characteristic (ROC) and Precision-Recall (PR) curves. Numerical results show that when compared to the Bayesian baseline the proposed method successfully suppresses uncertainty for accurate voxels, with similar presence of uncertainty for inaccurate voxels. Code to reproduce experiments is available at https://***/prerakmody/bayesuncertainty-error-correspondence. © 2024, CC BY.

关键词： Image segmentation

The 3D Trajectory-based Stress Visualizer

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Wang, Junpeng Neuhauser, Christoph Wu, Jun Gao, Xifeng Westermann, Rüdiger The Computer Graphics & Visualization Group Technische Universität München Garching Germany The Department of Sustainable Design Engineering Delft University of Technology Delft Netherlands The Lightspeed & Quantum Studio Tencent America United States

We present the 3D Trajectory-based Stress Visualizer (3D-TSV), a visual analysis tool for the exploration of the principal stress directions in 3D solids under load. 3D-TSV provides a modular and generic implementation of key algorithms required for a trajectory-based visual analysis of principal stress directions, including the automatic seeding of space-filling stress lines, their extraction using numerical schemes, their mapping to an effective renderable representation, and rendering options to convey structures with special mechanical properties. In the design of 3D-TSV, several perceptual challenges have been addressed when simultaneously visualizing three mutually orthogonal stress directions via lines. We present a novel algorithm for generating a space-filling and evenly spaced set of mutually orthogonal lines. The algorithm further considers the locations of lines to obtain a more regular pattern repetition, and enables the extraction of a Focus+Context representation with user-selected levels of detail for individual stress directions. To further reduce visual clutter, the system provides the combined visualization of two selected principal directions via appropriately oriented ribbons. The rendering uses depth cues to better convey the spatial relationships between trajectories and improves ribbon rendering on steep angles. 3D-TSV is accessible to end users via a C++- and OpenGL-based rendering frontend that is seamlessly connected to a MATLAB-based extraction backend. A TCP/IP-based communication interface supports the flexible integration of alternative rendering frontends. The code (BSD license) of 3D-TSV is made publicly available. Copyright © 2021, The Authors. All rights reserved.

关键词： Stresses

POS0562 Evaluation of Small bowel Involvement in Systemic Sclerosis Using Morpho-Functional Image Analysis Assisted by Artificial Intelligence

学校读者我要写书评

暂无评论

Annals of the Rheumatic Diseases 2025年 84卷 764-765页

作者： L.G. Alcala-gonzalez L. Hui P. Gilabert A. Guillen-Del-Castillo A. Aguilar C. Barber C. Codina L. Triginer J. Serra E. Monclus S. Segui C.P. Simeón-Aznar C. Malagelada Digestive System Research Unit Department of Digestive Diseases Vall d'Hebron University Hospital Barcelona Spain Visualization Virtual Reality and Graphics Interaction Research Group UPC-BarcelonaTech Barcelona Spain Department of Mathematics and Computer Science Universitat de Barcelona Barcelona Spain Systemic Autoimmune Diseases Unit Internal Medicine Department Vall d'Hebron University Hospital Barcelona Spain Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd) Barcelona Spain Universitat Autonoma de Barcelona Department of Medicine Barcelona Spain

Background: In systemic sclerosis (SSc), the symptoms and signs of small bowel involvement encompass a broad clinical spectrum, ranging from non-specific symptoms such as abdominal pain, distension, nausea, or vomiting to complications such as small intestinal bacterial overgrowth and, in severe cases, intestinal pseudo-obstruction. Currently, manometry is the gold-standard test for small bowel motility evaluation. However, this test is invasive and only available at specialized centers. In recent years, our laboratory has focused on developing innovative non-invasive technologies to evaluate small bowel motor function, focusing on computerized analysis of images obtained by abdominal CT and capsule endoscopy. Objectives: The aim of this pilot study was to evaluate intestinal motor function in patients with SSc using novel imaging technologies and to compare the results with the gold-standard manometry evaluation. Methods: Prospective study including consecutive patients with SSc and digestive symptoms between June 2021 and June 2024. On separate days, small bowel motility was assessed by high-resolution jejunal manometry, intraluminal images of the small bowel were obtained by capsule endoscopy, and external images by abdominal CT. Jejunal manometry was performed using a 35-channel high-resolution catheter for 5h (3h fasting and 2h postprandial). Tracings were analyzed according to established criteria for small bowel dysmotility and categorized as neuropathic (abnormal contractile activity with preserved amplitude), myopathic (decreased amplitude over the whole tracing), or apparently normal motility. Endoluminal image analysis of capsule endoscopy images was performed using a computer vision program specifically designed to detect contractile patterns (phasic luminal closure and radial wrinkles), non-contractile patterns (tunnel appearance) and turbid-static intestinal content (using color decomposition analysis) (Figure 1A). Morpho-volumetric analysis of CT scan

关键词：

Visualizing confidence in cluster-based ensemble weather forecast analyses

学校读者我要写书评

暂无评论

TechRxiv

TechRxiv 2020年

作者： Kumpf, Alexander Tost, Bianca Baumgart, Marlene Riemer, Michael Westermann, Rüdiger Rautenhaus, Marc The Computer Graphics & Visualization Group Technische Universität München Garching Germany The Institute of Atmospheric Physics Johannes Gutenberg Universität Mainz Mainz Germany

In meteorology, cluster analysis is frequently used to determine representative trends in ensemble weather predictions in a selected spatio-temporal region, e.g., to reduce a set of ensemble members to simplify and improve their analysis. Identified clusters (i.e., groups of similar members), however, can be very sensitive to small changes of the selected region, so that clustering results can be misleading and bias subsequent analyses. In this article, we –a team of visualization scientists and meteorologists– deliver visual analytics solutions to analyze the sensitivity of clustering results with respect to changes of a selected region. We propose an interactive visual interface that enables simultaneous visualization of a) the variation in composition of identified clusters (i.e., their robustness), b) the variability in cluster membership for individual ensemble members, and c) the uncertainty in the spatial locations of identified trends. We demonstrate that our solution shows meteorologists how representative a clustering result is, and with respect to which changes in the selected region it becomes unstable. Furthermore, our solution helps to identify those ensemble members which stably belong to a given cluster and can thus be considered similar. In a real-world application case we show how our approach is used to analyze the clustering behavior of different regions in a forecast of "Tropical Cyclone Karl", guiding the user towards the cluster robustness information required for subsequent ensemble analysis. © 2020, CC BY-NC-SA.

关键词： visualization

A comparison of rendering techniques for large 3D line sets with transparency

学校读者我要写书评

暂无评论

arXiv 2019年

作者： Kern, Michael Neuhauser, Christoph Maack, Torben Han, Mengjiao Usher, Will Westermann, Rüdiger Computer Graphics & Visualization Group Technische Universität München Garching Germany Scientific Computing and Imaging Institute University of Utah United States

This paper presents a comprehensive study of interactive rendering techniques for large 3D line sets with transparency. The rendering of transparent lines is widely used for visualizing trajectories of tracer particles in flow fields. Transparency is then used to fade out lines deemed unimportant, based on, for instance, geometric properties or attributes defined along them. Since accurate blending of transparent lines requires rendering the lines in back-to-front or front-to-back order, enforcing this order for 3D line sets with tens or even hundreds of thousands of elements becomes challenging. In this paper, we study CPU and GPU rendering techniques for large transparent 3D line sets. We compare accurate and approximate techniques using optimized implementations and a number of benchmark data sets. We discuss the effects of data size and transparency on quality, performance and memory consumption. Based on our study, we propose two improvements to per-pixel fragment lists and multi-layer alpha blending. The first improves the rendering speed via an improved GPU sorting operation, and the second improves rendering quality via a transparency-based bucketing. Copyright © 2019, The Authors. All rights reserved.

关键词： Transparency

OMiCroN - Oblique Multipass Hierarchy Creation while Navigating

学校读者我要写书评

暂无评论

arXiv 2020年

作者： da Silva, Vinícius Esperança, Claudio Marroquim, Ricardo Computer Graphics and Visualization Group Van Mourik Broekmanweg 6 Delft Netherlands VISGRAF Lab Estrada Dona Castorina 110 Jardim Botânico Rio de Janeiro - RJCEP: 22460-320 Brazil Cidade Universitária Centro de Tecnologia Block H Rio de Janeiro - RJ21941-972 Brazil

Rendering large point clouds ordinarily requires building a hierarchical data structure for accessing the points that best represent the object for a given viewing frustum and level-of-detail. The building of such data structures frequently represents a large portion of the cost of the rendering pipeline both in terms of time and space complexity, especially when rendering is done for inspection purposes only. This problem has been addressed in the past by incremental construction approaches, but these either result in low quality hierarchies or in longer construction times. In this work we present OMiCroN – Oblique Multipass Hierarchy Creation while Navigating – which is the first algorithm capable of immediately displaying partial renders of the geometry, provided the cloud is made available sorted in Morton order. OMiCroN is fast, being capable of building the entire data structure in memory spending an amount of time that is comparable to that of just reading the cloud from disk. Thus, there is no need for storing an expensive hierarchy, nor for delaying the rendering until the whole hierarchy is read from disk. In fact, a pipeline coupling OMiCroN with an incremental sorting algorithm running in parallel can start rendering as soon as the first sorted prefix is produced, making this setup very convenient for streamed *** Codes [2010]: 68U05 Copyright © 2020, The Authors. All rights reserved.

关键词： Data structures

Guest editors' introduction: Special section on IEEE PacificVis 2019

学校读者我要写书评

暂无评论

IEEE Pacific Visualization Symposium

IEEE Pacific visualization Symposium 2019年 2019-April卷 XIV-XV页

作者： Maciejewski, Ross Seo, Jinwook Westermann, Rüdiger School of Computing Informatics and Decision Systems Engineering Arizona State University TempeAZ United States Department of Computer Science and Engineering Seoul National University Seoul Korea Republic of Computer Graphics and Visualization Group Technische Universitat Munchen Garching Germany

A Voxel-based rendering pipeline for large 3D line sets

学校读者我要写书评

暂无评论

arXiv 2018年

作者： Kanzler, Mathias Rautenhaus, Marc Westermann, Rüdiger Computer Graphics and Visualization Group Technische Universität München Garching Germany

We present a voxel-based rendering pipeline for large 3D line sets that employs GPU ray-casting to achieve scalable rendering including transparency and global illumination effects that cannot be achieved with GPU rasterization. Even for opaque lines we demonstrate superior rendering performance compared to GPU rasterization of lines, and when transparency is used we can interactively render large amounts of lines that are infeasible to be rendered via rasterization. To achieve this, we propose a direction-preserving encoding of lines into a regular voxel grid, along with the quantization of directions using face-to-face connectivity in this grid. On the regular grid structure, parallel GPU ray-casting is used to determine visible fragments in correct visibility order. To enable interactive rendering of global illumination effects like low-frequency shadows and ambient occlusions, illumination simulation is performed during ray-casting on a level-of-detail (LoD) line representation that considers the number of lines and their lengths per voxel. In this way we can render effects which are very difficult to render via GPU rasterization. A detailed performance and quality evaluation compares our approach to rasterization-based rendering of lines. Copyright © 2018, The Authors. All rights reserved.

关键词： Transparency