“…Using a variety of visualization techniques, humans can perform effective cognitive analysis, extract knowledge and reveal patterns from data. Visualization and visual analysis have been introduced in different application domains such as in public opinion analysis [23], research hotspot evolution [24], air pollution source analysis [25], financial risk management [26,27] and many others. Usually built on top of the statistical analysis or data mining layers, visual analysis adopts a human-machine interaction methodology to help target users such as decision makers, interactively gain insight into complex problems by combining them with domain knowledge.…”