Stacking-based visualization of trajectory attribute data

Visualizing trajectory attribute data is challenging because it involves showing the trajectories in their spatio-temporal context as well as the attribute values associated with the individual points of trajectories. Previous work on trajectory visualization addresses selected aspects of this problem, but not all of them. We present a novel approach to visualizing trajectory attribute data. Our solution covers space, time, and attribute values. Based on an analysis of relevant visualization tasks, we designed the visualization solution around the principle of stacking trajectory bands. The core of our approach is a hybrid 2D/3D display. A 2D map serves as a reference for the spatial context, and the trajectories are visualized as stacked 3D trajectory bands along which attribute values are encoded by color. Time is integrated through appropriate ordering of bands and through a dynamic query mechanism that feeds temporally aggregated information to a circular time display. An additional 2D time graph shows temporal information in full detail by stacking 2D trajectory bands. Our solution is equipped with analytical and interactive mechanisms for selecting and ordering of trajectories, and adjusting the color mapping, as well as coordinated highlighting and dedicated 3D navigation. We demonstrate the usefulness of our novel visualization by three examples related to radiation surveillance, traffic analysis, and maritime navigation. User feedback obtained in a small experiment indicates that our hybrid 2D/3D solution can be operated quite well

Dynamic Influence Networks for Rule-based Models

We introduce the Dynamic Influence Network (DIN), a novel visual analytics technique for representing and analyzing rule-based models of protein-protein interaction networks. Rule-based modeling has proved instrumental in developing biological models that are concise, comprehensible, easily extensible, and that mitigate the combinatorial complexity of multi-state and multi-component biological molecules. Our technique visualizes the dynamics of these rules as they evolve over time. Using the data produced by KaSim, an open source stochastic simulator of rule-based models written in the Kappa language, DINs provide a node-link diagram that represents the influence that each rule has on the other rules. That is, rather than representing individual biological components or types, we instead represent the rules about them (as nodes) and the current influence of these rules (as links). Using our interactive DIN-Viz software tool, researchers are able to query this dynamic network to find meaningful patterns about biological processes, and to identify salient aspects of complex rule-based models. To evaluate the effectiveness of our approach, we investigate a simulation of a circadian clock model that illustrates the oscillatory behavior of the KaiC protein phosphorylation cycle.Comment: Accepted to TVCG, in pres

DRLViz: Understanding Decisions and Memory in Deep Reinforcement Learning

We present DRLViz, a visual analytics interface to interpret the internal memory of an agent (e.g. a robot) trained using deep reinforcement learning. This memory is composed of large temporal vectors updated when the agent moves in an environment and is not trivial to understand due to the number of dimensions, dependencies to past vectors, spatial/temporal correlations, and co-correlation between dimensions. It is often referred to as a black box as only inputs (images) and outputs (actions) are intelligible for humans. Using DRLViz, experts are assisted to interpret decisions using memory reduction interactions, and to investigate the role of parts of the memory when errors have been made (e.g. wrong direction). We report on DRLViz applied in the context of video games simulators (ViZDoom) for a navigation scenario with item gathering tasks. We also report on experts evaluation using DRLViz, and applicability of DRLViz to other scenarios and navigation problems beyond simulation games, as well as its contribution to black box models interpretability and explainability in the field of visual analytics

‘Geoliteracia’, ‘cartologia’, desenvolvimento cognitivo e um jogo móvel

Some researches in education science develop educative games on mobile devices for letting elementary school students play outdoor to learn geographic facts, concepts, and patterns. The challenge is about improving their geographic literacy and fluency, or ‘geoliteracy’, and their map-reading competencies, called cartology, before adolescence. There a critical stumbling ‘threshold’ can impede their geospatial cognitive development, which result in a majority of adults being not geographically literate neither efficient, in real-life context, for reading and using maps. Designing a mobile educative serious game implies applying conceptual and pragmatic methods for both learning and teaching geospatial competencies accordingly to school curriculum. The theoretical framework presented links maps to cartographical semiology, the children’s cognitive development stages for geospatial representation, and an experiential learning cycle model. The latter sequentially supports three main cartographic processes of map-making: reflexive visualization, and map-reading, which sustain any geographical reasoning. The mobile game proposed combines components of increasing complexity where the map plays the main role in the course of different activities: scenarios of typical “rounds” and rules of the game within local terrain; types of geometrical and geospatial trajectories to trace and follow while playing; and specific themes relevant to school subjects. Thus, geographical discussions stop worrying about where, to worry about the reason of situations and the occurrence of phenomena.Algunas investigaciones en ciencias de la educación desarrollan juegos educativos en dispositivos móviles para incentivar el aprendizaje de hechos, conceptos y modelos geográficos en estudiantes de escuelas primarias. El desafío consiste en mejorar su alfabetización y fluidez geográfica, o geoalfabetización, y sus competencias en lectura de mapas antes de la adolescencia, sintetizadas aquí bajo la denominación de cartología, la cual parece ser un umbral crítico que obstruye el desarrollo cognitivo geoespacial de los adultos. Diseñar un juego educativo móvil implica integrar métodos conceptuales y prácticos para la enseñanza y aprendizaje de las competencias geoespaciales, conforme al currículo escolar. El marco teórico que se presenta vincula los mapas con la semiología cartográfica, las etapas de desarrollo cognitivo del niño referentes a la representación del espacio geográfico y el ciclo de aprendizaje experiencial. Este último supone una serie de procesos cartográficos esenciales que sirven de base a cualquier análisis o razonamiento geográfico: creación de mapas, visualización reflexiva y lectura cartográfica. El juego que se propone conjuga componentes de creciente complejidad en los cuales el mapa es protagonista en el transcurso de diferentes actividades: rondas típicas con reglas particulares sobre terrenos determinados; trayectorias geométricas y geoespaciales por trazar y seguir durante el juego; temas específicos relacionados con las asignaturas escolares y con los objetivos propuestos por los maestros, etc. Así, las discusiones geográficas dejan de preocuparse por el dónde para inquietarse por el porqué de las situaciones y el acontecer de los fenómenos.Algumas pesquisas nas ciências da educação desenvolvem jogos educativos para dispositivos móveis através dos quais alunos da escola primária aprendem fatos, conceitos e modelos geográficos brincando ao ar livre. O desafio é melhorar a literacia e a fluência geográfica desses alunos, ou sua ‘geoliteracia’, e suas competências para ler mapas, a chamada ‘cartologia’, antes da adolescência, quando surge um limiar crítico que pode impedir o desenvolvimento cognitivo geoespacial das crianças. A maioria de adultos não são geograficamente letrados nem eficientes para ler e usar mapas. Conceber um jogo educativo móvel integra métodos conceituais e práticos para o ensino e a aprendizagem das competências geoespaciais, conforme o currículo escolar. O quadro teórico apresentado conecta os mapas à semiologia cartográfica, os estágios de desenvolvimento cognitivo das crianças no que se refere às representações do espaço geográfico e o ciclo de aprendizagem experiencial. Este último supõem uma sequência de três processos cartográficos principais que servem de base a qualquer raciocínio geográfico: criação de mapas, visualização reflexiva e leitura de mapas. O jogo que é proposto combina componentes de complexidade crescente onde o mapa é o protagonista no decorrer de diferentes atividades: cenários com ‘rondadas’ e regras típicas do jogo num determinado terreno; tipos de trajetórias geométricas e geoespaciais a serem traçadas e seguidas durante o jogo; temas específicos pertinentes aos assuntos escolares. Assim, as discussões geográficas deixam de se preocupar sobre onde para questionar a razão das situações e a ocorrência dos fenômenos