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This paper reports on the process of designing the UK Co-Benefits Atlas, which communicates and publicizes data for climate mitigation. Visualization atlases—an emerging type of platform to make data about complex topics comprehensive through interactive visualizations and explanatory content—pose challenges beyond traditional visualization projects. Atlases must address diverse and often uncertain audiences and use cases, support both explanatory and guided exploration, and accommodate complex, evolving data. Over 10 months, our team of visualization and domain experts conducted 8 design workshops, iterative prototyping, 15 stakeholder onboarding sessions, and continuous reflection. These intertwined processes informed the development of the Atlas, comprising over 400 pages of visualizations and explanations. They also enabled a deeper understanding of how stakeholders may critically engage with the atlas in practice, in terms of interests, potential frictions when navigating huge amounts of data, and envisioned usage scenarios. Reflecting on our design process, we identify five driving forces in atlas design—data, people, stories, context, and the atlas itself—whose shifting dynamics influence different stages of visualization atlas design in different ways. Grounded in our case study, we discuss using these forces as a conceptual starting point for structuring and reflecting on future atlas design processes.

Urban decision-making requires integrating heterogeneous spatial data. While current GIS tools handle geometric computation efficiently, they lack the semantic reasoning to guide complex workflows. Analysts manually manage data discovery, spatial boundaries, and measurement semantics, risking aggregation errors. We present UrbanTrace, a visual analytics system that transforms manual spatial data-wrangling into a transparent, node-based collaborative workflow with context-aware AI agents. Using an offline profiler to extract semantic and geometric metadata, UrbanTrace grounds LLMs in real-world data distributions. This enables specialized agents to retrieve datasets based on high-level goals and automatically enforce valid spatial aggregations. To make harmonization explicit, three interactive views: an Integration Provenance Graph, Multivariate Priority Map, and Spatial Delta Map, allow users to explore how conclusions shift across spatial configurations. We evaluate UrbanTrace on 28 urban scenarios spanning 112 datasets. Quantitative ablations show our profiling significantly outperforms baseline LLMs in data discovery, achieving 100% semantic and 87% geometric validity in spatial mapping. Through real-world case studies and expert interviews, we demonstrate that UrbanTrace turns spatial aggregation sensitivity from a methodological burden into an exploratory visual asset.

When visualizing large-scale line ensembles, trajectory continuity and visual scalability are inherently antagonistic. Trajectory-centric renderings preserve path information but rapidly degenerate into clutter as line density increases and mutual occlusion dominates. In contrast, field-based density representations enhance visibility while sacrificing structural coherence: density reflects accumulation rather than agreement, such that scalar aggregation alone cannot discriminate between consistent and conflicting configurations. Rather than replacing density-based views, we complement them with a path-integrated trajectory-fidelity measure that quantifies the agreement of each trajectory with a surrounding tensor field. By projecting this passage-centered structural support back into image space, we obtain what we call a Structural Inconsistency Field, which localizes regions where dense patterns correspond to coherent structure versus disagreement, outliers, or connectivity-induced ambiguity. Dynamic leave-one-out correction reduces self-bias in the path integral. Efficient fixed-grid updates combined with prefix-sum evaluation enable interactive analysis and iterative extraction of coherent structures. Synthetic benchmarks, scalability analyses, and real-world case studies demonstrate that, when paired with conventional density views, the proposed method disambiguates dense line patterns by exposing spatially localized coherence and structural breakdown that remain concealed in density-only representations.

Despite the growing availability of 3D urban datasets, extracting insights remains challenging due to computational bottlenecks and the complexity of interacting with data. In fact, the intricate geometry of 3D urban environments results in high degrees of occlusion and requires extensive manual viewpoint adjustments that make large-scale exploration inefficient. To address this, we propose a view-based approach for 3D data exploration, where a vector field encodes views from the environment. To support this approach, we introduce a neural field-based method that constructs an efficient implicit representation of 3D environments. This representation enables both faster direct queries, which consist of the computation of view assessment indices, and inverse queries, which help avoid occlusion and facilitate the search for views that match desired data patterns. Our approach supports key urban analysis tasks such as visibility assessments, solar exposure evaluation, and assessing the visual impact of new developments. We validate our method through quantitative experiments, case studies informed by real-world urban challenges, and feedback from domain experts. Results show its effectiveness in finding desirable viewpoints, analyzing building facade visibility, and evaluating views from outdoor spaces. Code and data are publicly available at urbantk.org/neural-3d.

Analyzing the impact of socioeconomic and urban variables on crime is a complex data analysis problem. Exploring synthetic, correlation-based scenarios using changes in a set of variables could alter a region’s definition from unsafe to safe (known counterfactual explanation), which can aid decision-makers in interpreting crime in that region and define public policies to mitigate criminal activity. We propose CounterCrime, a visual analytics tool for crime analysis that uses counterfactual explanations to add insights for this problem. This tool employs various interactive visual metaphors to explore the counterfactual explorations generated in each region. To facilitate exploration, we organize our analysis at three levels: the whole city, the region group, and the regional level. This work proposes a new perspective in crime analysis by creating “what-if” scenarios and allowing decision-makers to anticipate changes that would make a region safer. The tool guides the user in selecting variables with the most significant effect in all city regions. Using a greedy strategy, the system recommends the best variables that may influence crime in unsafe regions as the user explores. Our tool allows for identifying the most appropriate counterfactual explorations at the regional level by grouping them by similarity and determining their feasibility by comparing them with existing examples in other regions. Using crime data from Sao Paulo, Brazil, we validated our results with case studies.

This paper presents a generalization of the Wasserstein distance for both 0th persistence diagrams and merge trees (Edelsbrunner and Harer 2009), (Pont et al. 2022) that takes advantage of the regions of their topological features in the input domain. Specifically, we redefine the comparison of topological features as a distance between the values of their extrema-aligned regions. It results in a more discriminative metric than the classical Wasserstein distance and generalizes it through an input parameter adjusting the impact of the region properties in the distance. We present two strategies to control both computation time and memory storage of our method by respectively enabling the use of subsets of the regions in the computation, and by compressing the regions’ properties to obtain low-memory representations. Extensive experiments on openly available ensemble data demonstrate the efficiency of our method, with running times on the orders of minutes on average. We show the utility of our contributions with two applications. First, we use the assignments between topological features provided by our method to track their evolution in time-varying ensembles and propose the temporal persistence curves to facilitate the understanding of how these features appear, disappear and change over time. Second, our method allows to compute a distance matrix of an ensemble that can be used for dimensionality reduction purposes and visually represent in 2D all its members, we show that such distance matrices also allow to detect key phases in the ensemble. Finally, we provide a C++ implementation that can be used to reproduce our results.

In this paper, we present SIGMA, a declarative spatial interaction grammar for multiple displays and devices. SIGMA specifies (1) display entities in a display ecology, (2) spatial predicates that capture relevant spatial conditions among displays and devices, and (3) mapping rules that translate satisfied predicates into interaction semantics and corresponding visualization updates. By providing a small set of reusable primitives that can be logically composed into richer spatial conditions, SIGMA enables concise specifications over a wide range of spatial relationships and cross-display interactions. The grammar is informed by a literature review of 34 multi-display papers that met our inclusion criteria, from which we extracted 96 spatial interaction techniques to iteratively refine it. To enable declarative SIGMA specifications to work in a real multi-display system, we developed a runtime engine that interprets them by continuously processing 6DoF pose data, evaluating predicates, and triggering the corresponding visualization updates across displays. We further present three use cases showing how SIGMA supports diverse display configurations and categories of spatial interaction in real-world multi-display visual analytics scenarios.