Word clouds provide a simple and effective means to visually communicate the most frequent words of text documents. However, only few word cloud visualizations support the contrastive analysis of multiple texts. This paper introduces ConcentriCloud, a layered word cloud layout that merges the words from several text documents into a single visualization. The weighted words are arranged in a concentric layout, with those representing the individual documents on the outer circle and the merged ones on inner circles. Interaction techniques allow to analyze the word cloud composition and to provide details on demand. The approach has been implemented and tested on several examples. A qualitative evaluation indicates the general value of ConcentriCloud and reveals benefits and limitations.
The visual representation of textual content is difficult. Visualizing texts from multiple documents is an even more challenging problem. But if we are also interested in time-varying changes to multiple text documents we still need advanced analysis and visualization techniques.