Voxlines: Streamline Transparency through Voxelization and View-Dependent Line Orders

As tractography datasets continue to grow in size, there is a need for improved visualization methods that can capture structural patterns occurring in large tractography datasets. Transparency is an increasingly important aspect of finding these patterns in large datasets but is inaccessible to tractography due to performance limitations. In this paper, we propose a rendering method that achieves performant rendering of transparent streamlines, allowing for exploration of deeper brain structures interactively. The method achieves this through a novel approximate order-independent transparency method that utilizes voxelization and caching view-dependent line orders per voxel. We compare our transparency method with existing tractography visualization software in terms of performance and the ability to capture deeper structures in the dataset.Comment: 12 pages. 4 figures. Accepted at Computational Diffusion MRI Workshop (CDMRI) at Medical Image Computing and Computer Assisted Intervention (MICCAI) 202

Cushion Treemaps: Visualization of Hierarchical Information

A new method is presented for the visualization of hierarchical information, such as directory structures and organization structures. Cushion treemaps inherit the elegance of standard treemaps: compact, space-filling displays of hierarchical information, based on recursive subdivision of a rectangular image space. Intuitive shading is used to provide insight in the hierarchical structure. During the subdivision ridges are added per rectangle, which are rendered with a simple shading model. The result is a surface that consists of recursive cushions. The method is efficient, effective, easy to use and implement, and has a wide applicability. 1 Introduction Hierarchical structures of information are ubiquitous: family trees, directory structures, organization structures, catalogues, computer programs, etcetera. Small hierarchical structures are very effective to locate information, but the content and organization of large structures is much harder to grasp. We present a new visualiza..

Chain codes and their application in curve design

A representation for discrete curves based on the notion of chain codes is defined; the parameterization of these curves is also part of the representation, which renders these curves well-suited, e.g., for specifying motion paths in computer animation. Algorithms are defined for both generation and manipulation of these curves

The power of interactively linked hierarchy visualizations

This paper describes an interactive web-based tool for visualizing hierarchical data including the recently developed concept of space-reclaiming icicle plots and several more traditional hierarchy visualizations. The tool provides ways to upload, share, explore, and compare hierarchical data using a multitude of different linked hierarchy visualizations. The current version supports up to eight hierarchy visualizations, focusing on user-friendly interactive navigation by a dynamic graphical user interface with a variety of functions while each visualization is interactive by itself. Moreover, color deficiency issues are taken into account in the tool, further improving the usability for this user group. All of the visualizations can be shown in linked views while typical hierarchy parameters and visual variables can be changed on user demand. The interactive tool makes use of OpenGL and Angular, an industry standard JavaScript platform, and runs in a web browser. We illustrate the usefulness of the visualization tool by applying it to the NCBI taxonomy that consists of more than 300,000 hierarchically organized species while filtering for the tetrapoda subhierarchy as an application example. To further test the usability of the tool we did a performance test with increasing sizes of processed hierarchy datasets and even support a GPU implementation. Also user feedback on the eight visualizations was collected. Finally, we explain implementation details and discuss limitations and scalability issues of the linked visualization techniques

Space-Reclaiming Icicle Plots

This paper describes the space-reclaiming icicle plots, hierarchy visualizations based on the visual metaphor of icicles. As a novelty, our approach tries to reclaim empty space in all hierarchy levels. This reclaiming results in an improved visibility of the hierarchy elements especially those in deeper levels. We implemented an algorithm that is capable of producing more space-reclaiming icicle plot variants. Several visual parameters can be tweaked to change the visual appearance and readability of the plots: among others, a space-reclaiming parameter, an empty space shrinking parameter, and a gap size. To illustrate the usefulness of the novel visualization technique we applied it, among others, to an NCBI taxonomy dataset consisting of more than 300,000 elements and with maximum depth 42. Moreover, we explore the parameter and design space by applying several values for the visual parameters. We also conducted a controlled user study with 17 participants and received qualitative feedback from 112 students from a visualization course