While cities around the world are looking for smart ways to use new advances
in data collection, management, and analysis to address their problems, the
complex nature of urban issues and the overwhelming amount of available data
have posed significant challenges in translating these efforts into actionable
insights. In the past few years, urban visual analytics tools have
significantly helped tackle these challenges. When analyzing a feature of
interest, an urban expert must transform, integrate, and visualize different
thematic (e.g., sunlight access, demographic) and physical (e.g., buildings,
street networks) data layers, oftentimes across multiple spatial and temporal
scales. However, integrating and analyzing these layers require expertise in
different fields, increasing development time and effort. This makes the entire
visual data exploration and system implementation difficult for programmers and
also sets a high entry barrier for urban experts outside of computer science.
With this in mind, in this paper, we present the Urban Toolkit (UTK), a
flexible and extensible visualization framework that enables the easy authoring
of web-based visualizations through a new high-level grammar specifically built
with common urban use cases in mind. In order to facilitate the integration and
visualization of different urban data, we also propose the concept of knots to
merge thematic and physical urban layers. We evaluate our approach through use
cases and a series of interviews with experts and practitioners from different
domains, including urban accessibility, urban planning, architecture, and
climate science. UTK is available at urbantk.org.Comment: Accepted at IEEE VIS 2023. UTK is available at http://urbantk.or