We introduce a conceptual model for scalability designed for visualization research. With this model, we systematically analyze over 120 visualization publications from 1990 to 2020 to characterize the different notions of scalability in these works. While many papers have addressed scalability issues, our survey identifies a lack of consistency in the use of the term in the visualization research community. We address this issue by introducing a consistent terminology meant to help visualization researchers better characterize the scalability aspects in their research. It also helps in providing multiple methods for supporting the claim that a work is “scalable.” Our model is centered around an effort function with inputs and outputs. The inputs are the problem size and resources, whereas the outputs are the actual efforts, for instance, in terms of computational run time or visual clutter. We select representative examples to illustrate different approaches and facets of what scalability can mean in visualization literature. Finally, targeting the diverse crowd of visualization researchers without a scalability tradition, we provide a set of recommendations for how scalability can be presented in a clear and consistent way to improve fair comparison between visualization techniques and systems and foster reproducibility.

The increase of data collection in various domains calls for an adaptation of methods of visualization to tackle magnitudes exceeding the number of available pixels on screens and challenging interactivity. This growth of datasets size has been supported by the advent of accessible and scalable storage and computing infrastructure. Similarly, visualization systems need perceptual and interactive scalability. We present a complete system, complying with the constraints of aforesaid environment, for visual exploration of large multidimensional data with parallel coordinates. Perceptual scalability is addressed with data abstraction while interactions rely on server-side data-intensive computation and hardware-accelerated rendering on the client-side. The system employs a hybrid computing method to accommodate pre-computing time or space constraints and achieves responsiveness for main parallel coordinates plot interaction tools on billions of records.

We report on the process and design for our visual analytics graph analysis challenge winning entry. Specifically, our team addressed the IEEE VAST 2020 Mini-Challenge 1 that asked participants to identify a group of people that accidentally caused an internet outage. To identify this group we were given a network profile and a large multi-variate social network to search in. Our approach involved statistical and graphical analysis as well as the design of three custom visual analytics tools. The submitted solution and visualizations are available at https://graphletmatchmaker.github.io/.

In the context of multiple views, coordination is essential to navigate and grasp the relationships lying behind the different juxtaposed views. Linked highlighting is a typical example of coordination where a subset of the data points is emphasized simultaneously on all views. The strength of this approach is that the selected data can be studied within its context. Other approaches have been used to implement coordination such as using varying levels of transparency or visual links. We propose to use spatial distortion to contribute a similar effect in multiple views. It is particularly suited to the context of multiple views since it alleviates the lack of screen space by reallocating it based on a certain definition of user interest. The proposed method targets coordination between views that represent the same entities and readily adapts to various visualization forms. It is based on a user degree-of-interest function, defined on these entities, that acts as a common ground for the distortion of all views. Views are distorted such that empty areas and areas holding entities of lesser interest are compressed to the benefit of areas holding entities of higher interest. To demonstrate its feasibility and versatility, we describe how to technically apply our approach to several common visualization techniques.

La visualisation interactive est un outil essentiel pour l'exploration, la compréhension et l'analyse de données. L'exploration interactive efficace de jeux de données grands ou complexes présente cependant deux difficultés fondamentales. La première est visuelle et concerne les limitations de la perception et cognition humaine, ainsi que celles des écrans. La seconde est computationnelle et concerne les limitations de capacité mémoire ou de traitement des machines standards. Dans cette thèse, nous nous intéressons aux techniques de passage à l'échelle relativement à ces deux difficultés, pour plusieurs contextes d'application.Pour le passage à l'échelle visuelle, nous présentons une approche versatile de mise en évidence de sous-ensembles d'éléments par déformation spatiale appliquée aux vues multiples et une représentation abstraite et multi-/échelle de coordonnées parallèles. Sur les vues multiples, la déformation spatiale vise à remédier à la diminution de l'efficacité de la surbrillance lorsque les éléments graphiques sont de taille réduite. Sur les coordonnées parallèles, l'abstraction multi-échelle consiste à simplifier la représentation tout en permettant d'accéder interactivement au détail des données, en les pré-agrégeant à plusieurs niveaux de détail.Pour le passage à l'échelle computationnelle, nous étudions des approches de pré-calcul et de calcul à la volée sur des infrastructures distribuées permettant l'exploration de jeux de données de plus d'un milliard d'éléments en temps interactif. Nous présentons un système pour l'exploration de données multi-dimensionnelles dont les interactions et l'abstraction respectent un budget en nombre d'éléments graphiques qui, en retour, fournit une borne théorique sur les latences d'interactions dues au transfert réseau entre client et serveur. Avec le même objectif, nous comparons des stratégies de réduction de données géométrique pour la reconstruction de cartes de densité d'ensembles de points.