Visualization tab

Visualization algorithms change the graphical appearance of the network; they are accesible via the visualization tab. Basic illustrations of how to layout networks or display attribute values are provided in the two trails on visualization and analysis and advanced attribute management.

visone distinguishes between three major visualization categories

• layout to recompute the positions (coordinates) or nodes, links-bends, or labels to optimize readability or other specified layout criteria;
• mapping to specify how attribute values (such as node centrality, tie strength, or class membership) are encoded in grapical variables (such as size, width, or color);
• geometry to apply geometric transformations such as rotation, reflection, or scaling to the network or parts of the network;

layout

Layout refers to the task of obtaining positions for the elements of a network visualization, where arranging positions of nodes is of primary interest. Other tasks are (re-)routing the links of a visualization, e.g. to avoid overlap between link and node representations, or to automatically arrange label positions for better readability.

node layout

The methods in this section deal with the computation of node positions for one or more networks. Generally, nodes are considered to be geometric points (or objects that are described by a single point), and links are represented as straight lines between their incident nodes. Thus most methods produce so called straight-line drawings (also referred to as node-link diagrams or sociograms).

There are several general objectives that most methods try to optimize, such as:

uniform link length

links should have more or less the same length.

node distribution

nodes should be distributed well over the drawing area.

minimal crossings

the number of meaningless link crossings should be kept small.

symmetries

structural symmetries in the network should be represented well.

Additionally, some methods are constrained by additional or different objectives:

• node placement is restricted with respect to a given scalar node attribute, e.g., such that nodes lie on concentric circles or verical layers corresponding to the attributes values.
• the layout should ease comparison with respect to the previous layout, given a sequence of networks.
• the layout should reveal the properties of a network's spectrum.

link routing

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label placement

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geometry

affine transformations

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procrustes analysis

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