17,698 research outputs found
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Automated Layout of Origin-destination Flow Maps : U.S. County-to-county Migration 2009-2013
Visualizing large movement datasets with flow maps is difficult because overlapping flows create significant graphical conflicts that make accurate interpretation difficult or impossible. Interactive flow mapping applications allow users to explore large movement datasets by automatically generating flow maps from subsets of the data in response to queries by the user. However, even a small number of flows can overlap and cross each other in a way that impedes accurate interpretation. We introduce an interactive flow map of migration in the United States from 2009 to 2013 that uses a force-directed method to automatically lay out county-to-county migration. This is the first interactive map for web browsers that automatically creates origin-destination flow map layouts according to identified cartographic design principles. Adhering to these principles improves the readability of origin-destination flow maps. Map users explore high-level state-to-state migration patterns as well as detailed county-to-county movements through a custom user interface and interactive map features. We show migration flows between counties of different states by representing other states as nodes with a circular arrangement around the selected state, and connect county flows to those nodes. This constrains the map layout to a smaller area, reducing clutter and the amount of interaction required to view flows
Visualizing the dynamics of London's bicycle hire scheme
Visualizing flows between origins and destinations can be straightforward when dealing with small numbers of journeys or simple geographies. Representing flows as lines embedded in geographic space has commonly been used to map transport flows, especially when geographic patterns are important as they are when characterising cities or managing transportation. However, for larger numbers of flows, this approach requires careful design to avoid problems of occlusion, salience bias and information overload. Driven by the requirements identified by users and managers of the London Bicycle Hire scheme we present three methods of representation of bicycle hire use and travel patterns. Flow maps with curved flow symbols are used to show overviews in flow structures. Gridded views of docking station location that preserve geographic relationships are used to explore docking station status over space and time in a graphically efficient manner. Origin-Destination maps that visualise the OD matrix directly while maintaining geographic context are used to provide visual details on demand. We use these approaches to identify changes in travel behaviour over space and time, to aid station rebalancing and to provide a framework for incorporating travel modelling and simulation
FlowMapper.org: A web-based framework for designing origin-destination flow maps
FlowMapper.org is a web-based framework for automated production and design
of origin-destination flow maps (https://flowmapper.org). FlowMapper has four
major features that contribute to the advancement of existing flow mapping
systems. First, users can upload and process their own data to design and share
customized flow maps. The ability to save data, cartographic design and map
elements in a project file allows users to easily share their data and
cartographic design with others. Second, users can customize the flow line
symbology by including options to change the flow line style, width, and
coloring. FlowMapper includes algorithms for drawing curved line styles with
varying thickness along a flow line, which reduces the visual cluttering and
overlapping by tapering flow lines at origin and destination points. The
ability to customize flow symbology supports different flow map reading tasks
such as comparing flow magnitudes and directions and identifying flow and
location clusters that are strongly connected with each other. Third,
FlowMapper supports supplementary layers such as node symbol, choropleth, and
base maps to contextualize flow patterns with location references and
characteristics such as net-flow, gross flow, net-flow ratio, or a locational
attribute such as population density. FlowMapper also supports user
interactions to zoom, filter, and obtain details-on-demand functions to support
visual information seeking about nodes, flows and regions. Finally, the
web-based architecture of FlowMapper supports server side computational
capabilities to process, normalize and summarize large flow data to reveal
natural patterns of flows
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Visualisation of Origins, Destinations and Flows with OD Maps
We present a new technique for the visual exploration of origins (O) and destinations (D) arranged in geographic space. Previous attempts to map the flows between origins and destinations have suffered from problems of occlusion usually requiring some form of generalisation, such as aggregation or flow density estimation before they can be visualized. This can lead to loss of detail or the introduction of arbitrary artefacts in the visual representation. Here, we propose mapping OD vectors as cells rather than lines, comparable with the process of constructing OD matrices, but unlike the OD matrix, we preserve the spatial layout of all origin and destination locations by constructing a gridded two‐level spatial treemap. The result is a set of spatially ordered small multiples upon which any arbitrary geographic data may be projected. Using a hash grid spatial data structure, we explore the characteristics of the technique through a software prototype that allows interactive query and visualisation of 105‐106 simulated and recorded OD vectors. The technique is illustrated using US county to county migration and commuting statistics
Visualizing and Interacting with Geospatial Networks:A Survey and Design Space
This paper surveys visualization and interaction techniques for geospatial
networks from a total of 95 papers. Geospatial networks are graphs where nodes
and links can be associated with geographic locations. Examples can include
social networks, trade and migration, as well as traffic and transport
networks. Visualizing geospatial networks poses numerous challenges around the
integration of both network and geographical information as well as additional
information such as node and link attributes, time, and uncertainty. Our
overview analyzes existing techniques along four dimensions: i) the
representation of geographical information, ii) the representation of network
information, iii) the visual integration of both, and iv) the use of
interaction. These four dimensions allow us to discuss techniques with respect
to the trade-offs they make between showing information across all these
dimensions and how they solve the problem of showing as much information as
necessary while maintaining readability of the visualization.
https://geonetworks.github.io.Comment: To be published in the Computer Graphics Forum (CGF) journa
Exploring geo-genealogy using internet surname search histories
We present an interactive flow map to visualize aspects of the ways in which surnames have dispersed and migrated around the globe. This work utilizes Internet search queries from the Worldnames Project and uses the density of search locations to determine the node and leaf structures of a flow map. The mapping technique utilized in this work is a variant of geometric minimal Steiner arborescences called the spiral tree. Our implementation is developed in JavaScript to allow for interactive online exploration. Nodes and flow lines can be interactively modified to allow for esthetic changes of color and layout. The results can provide interesting insight into the geography of amateur genealogy
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