Graphics Reference
In-Depth Information
Chapter 13
Spatial Networks
Spatial networks are a unique form of graph. Unlike in community analysis,
where layout is instrumental in revealing how nodes are connected, nodes
in a spatial network have pre-existing physical characteristics that are
preserved, relying on link visualization alone to convey connections.
Spatial networks occur in nature, and graphs can be useful in understanding
complex networks of this kind. Neuroscientists use graph visualization and
analysis to learn more about how our brains are wired. In the business
world, however, spatial networks are often equated with infrastructure. For
example, supply chains have a spatial component that may be highly relevant
to supply optimization. Oil pipelines, electrical power networks,
transportation infrastructure, and computer networks are a few of the many
other examples of spatial networks where graph visualization and analysis
are of value.
Seeing how elements are connected physically and logically provides insight
into the structure of a system. It also provides important context in
understandingthehealthandperformanceofasystem,theimpactoffailures,
and how to plan for and mitigate them.
System routes and flows are often of central interest in spatial networks.
One of the primary challenges of visualizing spatial networks is the limited
number of links that can be successfully displayed at once. Links that cross
each other or other nodes in their path introduce perceptual confusion. So,
when node locations are fixed and cannot be arranged to mitigate this,
connections can quickly become difficult to follow. This can be a significant
issue, given that link visualization is critical to conveying a spatial network.
This chapter discusses strategies for effective visualization of spatial
networks, including route aggregation, schematic representations, grouping
of small worlds, and alternative representations for links.
Schematic Layout
WhenHarryBeckbeganworkingforLondonTransportasayoungdraftsman
in the 1920s, the London Underground was in a state of rapid evolution.
