JASPER: Just A new Space-filling and Pixel-oriented layout for large graph ovERview

Abstract

When analysing data and handling a visualisation, users mainly spend their cognitive resources making sense of the graph-ical representation and mapping it back to the data and domain. This task becomes even more critical when dealing with larger data sets. Therefore, a valuable visualisation design strategy is to couple graphical representations and user tasks to better support the sense making process. This paper focuses on a particular task where users must make sense of state changes occurring on nodes of a graph. To this end, we propose JASPER, a new layout algorithm focusing on the visualisation of nodes inspired from pixel-oriented layouts, relying on node clustering to identify and represent existing connections through spatial adjacency. JASPER can layout moderate size graphs in real-time and is able to tackle large graphs with up to 2 million nodes and 5 million edges in reasonable time (about half a minute). Furthermore, although JASPER has been designed around a specific application , the underlying methodology can be employed to draw quick overviews of any type of graphs. The paper lays down the underlying principles of JASPER, and reports it performances (execution times) on increasingly large graphs. JASPER is then used and showcased to visualise network propagation phenomenon in large graphs.