Visualizing Populated Ontologies with OntoTrix

Most tools for visualizing Semantic Web data structure the representation according to the concept definitions and interrelations that constitute the ontology’s vocabulary. Instances are often treated as somewhat peripheral information, when considered at all. The visualization of instance-level data poses different but significant challenges as instances will often be orders of magnitude more numerous than the concept definitions that give them machine-processable meaning. We present a visualization technique designed to visualize large instance sets and the relations that connect them. This visualization uses both nodelink and adjacency matrix representations of graphs to visualize different parts of the data depending on their semantic and local structural properties, exploiting ontological knowledge to drive the layout of, and navigation in, the visualization.