  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.
