Information Visualization, 6, 4 (2007), 281-300.
A semantic substrate is a spatial template for a network, where nodes are
grouped into regions and laid out within each region according to one or more
node attributes. This paper shows how users can be given control in designing
their own substrates and how this ability leads to a different approach to
network data exploration. Users can create a semantic substrate, enter their
data, get feedback from domain experts, edit the semantic substrate, and
iteratively continue this procedure until the domain experts are satisfied
with the insights they have gained. We illustrate this process in two case
studies with domain experts working with legal precedents and food webs.
Guidelines for designing substrates are provided, including how to locate,
size, and align regions in a substrate, which attributes to choose for grouping
nodes into regions, how to select placement methods and which attributes
to set as parameters of the selected placement method. Throughout the
paper, examples are illustrated with NVSS 2.0, the network visualization tool
developed to explore the semantic substrate idea.