ScaleTrotter: Illustrative Visual Travels Across Negative Scales

We present ScaleTrotter, a conceptual framework for an interactive, multi-scale visualization of biological mesoscale data and, specifically, genome data. ScaleTrotter allows viewers to smoothly transition from the nucleus of a cell to the atomistic composition of the DNA, while bridging several orders of magnitude in scale. The challenges in creating an interactive visualization of genome data are fundamentally different in several ways from those in other domains like astronomy that require a multi-scale representation as well. First, genome data has intertwined scale levels---the DNA is an extremely long, connected molecule that manifests itself at all scale levels. Second, elements of the DNA do not disappear as one zooms out---instead the scale levels at which they are observed group these elements differently. Third, we have detailed information and thus geometry for the entire dataset and for all scale levels, posing a challenge for interactive visual exploration. Finally, the conceptual scale levels for genome data are close in scale space, requiring us to find ways to visually embed a smaller scale into a coarser one. We address these challenges by creating a new multi-scale visualization concept. We use a scale-dependent camera model that controls the visual embedding of the scales into their respective parents, the rendering of a subset of the scale hierarchy, and the location, size, and scope of the view. In traversing the scales, ScaleTrotter is roaming between 2D and 3D visual representations that are depicted in integrated visuals. We discuss, specifically, how this form of multi-scale visualization follows from the specific characteristics of the genome data and describe its implementation. Finally, we discuss the implications of our work to the general illustrative depiction of multi-scale data

Abstraction spatiale intégrée de molécules génétiques

The human genome consists mainly of DNA, a macromolecule consisting of a long linear sequence of bases, tightly packed to fit in the relatively small nucleus. The packing gives rise to multiple hierarchical organizational levels. Recent research has shown that, along with the linear sequence, the spatial arrangement of the genome plays an important role in the genome’s function and activity. The visualization of both linear and spatial aspects of genome data is therefore necessary. In this thesis, we focus on the concept of continuous visual abstraction for multiscale data, applied to the visualization of the human genome. Visual abstraction is a concept inspired by illustrations that makes the job of visual processing simpler, by guiding the attention of the viewer to important aspects. We first extract characteristics of multiscale data and makes a parallel comparison between genome and astronomical data. The existing differences create the need for different approaches. A common point however is the need for continuous transitions that helps viewers grasp the relationships and relative size differences between scales. To satisfy the conditions posed by the two aspects of the multiscale genome data, we present two conceptual frameworks, based on the same data. The first framework, ScaleTrotter, represents the spatial structure of the genome, on all available levels. It gives users the freedom to travel from the nucleus of a cell to the atoms of the bases, passing through the different organizational levels of the genome. To make the exploration of the structure of all levels possible, smooth temporal transitions are used. Even though all the scales are not simultaneously visible, the temporal transition used superimposes two representations of the same element at consecutive scales emphasizing their relationship. To ensure the understandability and interactivity of the data, unnecessary parts of the data are abstracted away with the use of a scale-dependent camera. The second framework, Multiscale Unfolding, focuses on aspects that are not visible in ScaleTrotter: the linear sequence and a simultaneous overview of all the organizational levels. The data is straightened to unfold the packing that occurs on several levels in a way that conserves the connectivity between the elements. To represent all the available levels, we use smooth spatial transitions between the levels. These spatial transitions are based on the same concept of the temporal transitions of the previous framework, superimposing scales and emphasizing on their relationship and size difference. We introduce an interaction technique called Multiscale Zliding that allows the exploration of the data and further emphasizes the size differences between the levels. In each framework, one of either linear of spatial aspect of genome data is sacrificed to emphasize the other. The thesis concludes with a discussion about the possibility of combining the two frameworks, minimizing the sacrifices to explore the two equally important aspects of the genome. In this thesis, we take a step closer to fully understanding the activity of the genome.Le génome humain est principalement constitué d'ADN, une macromolécule constituée d'une longue séquence linéaire de bases, étroitement serrée pour s'insérer dans le noyau relativement petit. L'empaquetage donne lieu à de multiples niveaux hiérarchiques d'organisation. Des recherches récentes ont montré que, parallèlement à la séquence linéaire, l'agencement spatial du génome joue un rôle important dans la fonction et l'activité du génome. La visualisation des aspects li-né-aires et spatiaux des données du génome est donc nécessaire. Dans cette thèse, nous nous concentrons sur le concept d'abstraction visuelle continue pour les données multi-échelles, appliqué à la visualisation du génome humain. L'abstraction visuelle est un concept inspiré par des illustrations qui simplifie le travail de traitement visuel, en guidant l'attention du spectateur vers les aspects importants.Nous commençons par extraire les caractéristiques des données multi-échelles et faisons une comparaison parallèle entre le génome et les données astronomiques. Les différences existantes créent le besoin d'approches différentes. Un point commun cependant est la nécessité de transitions continues qui aident les spectateurs à saisir les relations et les différences de taille relative entre les échelles. Pour satisfaire aux conditions posées par les deux aspects des données génomiques multi-échelles, nous présentons deux cadres conceptuels, basés sur les mêmes données. Le premier cadre, ScaleTrotter, représente la structure spatiale du génome, à tous les niveaux disponibles. Il donne à l'utilisateur la liberté de voyager du noyau d'une cellule aux atomes des bases, en passant par les différents niveaux d'organisation du génome. Pour rendre possible l'exploration de la structure de tous les niveaux, des transitions temporelles fluides sont utilisées. Même si toutes les échelles ne sont pas visibles simultanément, la transition temporelle utilisée superpose deux représentations d'un même élément à des échelles consécutives, ce qui met en évidence leur relation. Pour garantir la compréhensibilité et l'interactivité des données, les parties inutiles des données sont extraites à l'aide d'une caméra dépendante de l'échelle. Le deuxième cadre, Multiscale Unfolding, se concentre sur des aspects qui ne sont pas visibles dans ScaleTrotter : la séquence linéaire et une vue d'ensemble simultanée de tous les niveaux organisationnels. Les données sont redressées pour déplier l’empaquetage qui se produit à plusieurs niveaux de manière à conserver la connectivité entre les éléments. Pour représenter tous les niveaux disponibles, nous utilisons des transitions spatiales douces entre les niveaux. Ces transitions spatiales sont basées sur le même concept que les transitions temporelles du cadre précédent, en superposant les échelles et en mettant l'accent sur leur relation et leur différence de taille. Nous introduisons une technique d'interaction appelée Multiscale Zliding qui permet l'exploration des données et met davantage l'accent sur les différences de taille entre les niveaux. Dans chaque cadre conceptuel, l'un des deux aspects linéaire ou spatial des données sur le génome est sacrifié pour mettre l'accent sur l'autre. La thèse se termine par une discussion sur la possibilité de combiner les deux cadres, en minimisant les sacrifices pour explorer les deux aspects du génome qui sont d'égale importance. Dans cette thèse, nous faisons un pas de plus vers la compréhension complète de l'activité du génome

Multiscale Unfolding: Illustratively Visualizing the Whole Genome at a Glance

International audienceWe present Multiscale Unfolding, an interactive technique for illustratively visualizing multiple hierarchical scales of DNA in a single view, showing the genome at different scales and demonstrating how one scale spatially folds into the next. The DNA's extremely long sequential structure---arranged differently on several distinct scale levels---is often lost in traditional 3D depictions, mainly due to its multiple levels of dense spatial packing and the resulting occlusion. Furthermore, interactive exploration of this complex structure is cumbersome, requiring visibility management like cutaways. In contrast to existing temporally controlled multiscale data exploration, we allow viewers to always see and interact with any of the involved scales. For this purpose we separate the depiction into constant-scale and scale transition zones. Constant-scale zones maintain a single-scale representation, while still linearly unfolding the DNA. Inspired by illustration, scale transition zones connect adjacent constant-scale zones via level unfolding, scaling, and transparency. We thus represent the spatial structure of the whole DNA macro-molecule, maintain its local organizational characteristics, linearize its higher-level organization, and use spatially controlled, understandable interpolation between neighboring scales. We also contribute interaction techniques that provide viewers with a coarse-to-fine control for navigating within our all-scales-in-one-view representations and visual aids to illustrate the size differences. Overall, Multiscale Unfolding allows viewers to grasp the DNA's structural composition from chromosomes to the atoms, with increasing levels of "unfoldedness," and can be applied in data-driven illustration and communication

ScaleTrotter: Illustrative Visual Travels Across Negative Scales

International audienceWe present ScaleTrotter, a conceptual framework for an interactive, multi-scale visualization of biological mesoscale data and, specifically, genome data. ScaleTrotter allows viewers to smoothly transition from the nucleus of a cell to the atomistic composition of the DNA, while bridging several orders of magnitude in scale. The challenges in creating an interactive visualization of genome data are fundamentally different in several ways from those in other domains like astronomy that require a multi-scale representation as well. First, genome data has intertwined scale levels---the DNA is an extremely long, connected molecule that manifests itself at all scale levels. Second, elements of the DNA do not disappear as one zooms out---instead the scale levels at which they are observed group these elements differently. Third, we have detailed information and thus geometry for the entire dataset and for all scale levels, posing a challenge for interactive visual exploration. Finally, the conceptual scale levels for genome data are close in scale space, requiring us to find ways to visually embed a smaller scale into a coarser one. We address these challenges by creating a new multi-scale visualization concept using a scale-dependent camera model that controls the visual embedding of the scales into their respective parents, the rendering of a subset of the scale hierarchy, and the location, size, and scope of the view. In traversing the scales, ScaleTrotter is roaming between 2D and 3D visual representations that are depicted in integrated visuals. We discuss, specifically, how this form of multi-scale visualization is a consequence of the specific characteristics of the genome data and describe its implementation. Finally, we discuss the implications of our work to the general illustrative depiction of multi-scale data

Molecumentary: Scalable Narrated Documentaries Using Molecular Visualization

We present a method for producing documentary-style content using real-time scientific visualization. We produce molecumentaries, i.e., molecular documentaries featuring structural models from molecular biology. We employ scalable methods instead of the rigid traditional production pipeline. Our method is motivated by the rapid evolution of interactive scientific visualization, which shows great potential in science dissemination. Without some form of explanation or guidance, however, novices and lay-persons often find it difficult to gain insights from the visualization itself. We integrate such knowledge using the verbal channel and provide it along an engaging visual presentation. To realize the synthesis of a molecumentary, we provide technical solutions along two major production steps: 1) preparing a story structure and 2) turning the story into a concrete narrative. In the first step, information about the model from heterogeneous sources is compiled into a story graph. Local knowledge is combined with remote sources to complete the story graph and enrich the final result. In the second step, a narrative, i.e., story elements presented in sequence, is synthesized using the story graph. We present a method for traversing the story graph and generating a virtual tour, using automated camera and visualization transitions. Texts written by domain experts are turned into verbal representations using text-to-speech functionality and provided as a commentary. Using the described framework we synthesize automatic fly-throughs with descriptions that mimic a manually authored documentary. Furthermore, we demonstrate a second scenario: guiding the documentary narrative by a textual input

Molecumentary: Adaptable Narrated Documentaries Using Molecular Visualization

To appearInternational audienceWe present a method for producing documentary-style content using real-time scientific visualization. We introduce molecumentaries, i. e., molecular documentaries featuring structural models from molecular biology, created through adaptable methods instead of the rigid traditional production pipeline. Our work is motivated by the rapid evolution of scientific visualization and it potential in science dissemination. Without some form of explanation or guidance, however, novices and lay-persons often find it difficult to gain insights from the visualization itself. We integrate such knowledge using the verbal channel and provide it along an engaging visual presentation. To realize the synthesis of a molecumentary, we provide technical solutions along two major production steps: (1) preparing a story structure and (2) turning the story into a concrete narrative. In the first step, we compile information about the model from heterogeneous sources into a story graph. We combine local knowledge with external sources to complete the story graph and enrich the final result. In the second step, we synthesize a narrative, i. e., story elements presented in sequence, using the story graph. We then traverse the story graph and generate a virtual tour, using automated camera and visualization transitions. We turn texts written by domain experts into verbal representations using text-to-speech functionality and provide them as a commentary. Using the described framework, we synthesize fly-throughs with descriptions: automatic ones that mimic a manually authored documentary or semi-automatic ones which guide the documentary narrative solely through curated textual input