Circular (concentric) & Temporal Hudson Bay Food Web Source: http://www.itk.ca/environment/tek-ecological-foodweb-image.php
Temporal Layout Source:  Garfield, “Historiographic mapping of knowledge…”
Clustering Source: www.visualcomplexity.com (85)www.visualcomplexity.com Vizster, Heer et al.
Hierarchical Clustering Source:  Schaffer, et al.
Matrix-based Layout Ex: VisAdj (Ghoniem, et al.) Ex: VisAdj (Ghoniem, et al.) –column: source vertex –row: target vertex Source:  Ghoniem et al., IEEE 0-7803-8779-1/04 VisAdj, Ghoniem et al.
Challenges of Network Visualization C1) Basic networks: nodes and links C1) Basic networks: nodes and links C2) Node labels C2) Node labels –e.g. article title, book author, animal name C3) Link labels C3) Link labels –e.g. Strength of connection, type of link C4) Directed networks C4) Directed networks C5) Node attributes C5) Node attributes –Categorical (e.g. mammal/reptile/bird/fish/insect) –Ordinal(e.g. small/medium/large) –Numerical (e.g. age/weight) C6) Link Attributes C6) Link Attributes –Categorical (e.g. car/train/boat/plane) –Ordinal(e.g. weak/normal/strong) –Numerical (e.g. probability/length/time to traverse/strength)
C1) Basic Networks (nodes & links) Power Law Graph Power Law Graph –5000 nodes –Uniformly distributed Power Law Graph, Linyuan Lu Source: www.visualcomplexity.com (135)www.visualcomplexity.com
C1) Basic Networks (continued) Social friendship network Social friendship network –3 degrees from Heer – 47,471 people –432,430 relations Vizster, Heer et al. Source: www.visualcomplexity.com (97)www.visualcomplexity.com
C2) Node Labels Adding labels Adding labels –Nodes overlap with other nodes –Nodes overlap with links Internet Industry Partnerships, Valdis Krebs Source: www.visualcomplexity.com (168)www.visualcomplexity.com250 nodes
C3) Link Labels Challenges: Challenges: –Length –Space –Belongingness –Distinction from other labels & other types of labels Netscan, Marc Smith Source: www.visualcomplexity.com (127)www.visualcomplexity.com
C4) Directed Networks Direction Direction –arrows –labels –Thickness –color Source: www.visualcomplexity.com (127)www.visualcomplexity.com Yeast Protein Interaction SeeNet, Becker et al. Source:  Becker et al.
C5 & C6) Node & Link Attributes Value of node attribute indicated by node shape Value of node attribute indicated by node shape Value of link attribute indicated by a letter Value of link attribute indicated by a letter CIA World Factbook Visualization, Moritz Stefaner Source: www.visualcomplexity.com (192)www.visualcomplexity.com
Semantic Substrates Group nodes into regions Group nodes into regions –according to one attribute Categorical, ordinal, or binned numerical Categorical, ordinal, or binned numerical In each region: In each region: –place nodes according to other attribute(s) Advantages Advantages –Location conveys meaning, interpretable –Instant perception of different types of nodes different types of nodes their relative number their relative number connections between different groups of nodes connections between different groups of nodes Limitations Limitations –Beyond 5 regions becomes challenging –Constraint on nodes interferes with aesthetics
Using a third attribute in regions 13 circuits for both Circuit and District Courts 13 circuits for both Circuit and District Courts Horizontally separated Horizontally separated Reveals that links remain mostly within a circuit although there are some across (lateral citations) Reveals that links remain mostly within a circuit although there are some across (lateral citations)