tree graphs – vialab | Dr. Christopher Collins

Balancing Clutter and Information in Large Hierarchical Visualizations

Contributors:

In this paper, we propose a new approach for adjusting the level of abstraction of hierarchical visualizations as a function of display size and dataset. Using the Minimum Description Length (MDL) principle, we efficiently select tree cuts that feature a good balance between clutter and information. We present MDL formulae for selecting tree cuts tailored to treemap and sunburst diagrams and discuss how the approach can be extended to other types of multilevel visualizations. In addition, we demonstrate how such tree cuts can be used to enhance drill-down interaction in hierarchical visualizations by enabling quick exposure of important outliers. The paper features applications of the proposed technique on treemaps of the Directory Mozilla (DMOZ) dataset (over 500,000 nodes), and on the Docuburst text visualization tool (over 100,000 nodes).

Validation is done with the feature congestion measure of clutter in views of a subset of the current DMOZ web directory. The results show that MDL views achieve near-constant clutter levels across display resolutions. We also present the results of a crowdsourced user study where participants were asked to find targets in views of DMOZ generated by our approach and a set of baseline aggregation methods. The results suggest that, in some conditions, participants are able to locate targets (in particular, outliers) faster using the proposed approach.

Check out our GitHub Repository for source code related to this project.

The slides from our VIS 16 presentation are available here.

Publications

Acknowledgements

DAViewer: Facilitating Discourse Analysis with Interactive Visualization

Contributors:

Jian Zhao, Fanny Chevalier, Christopher Collins, and Ravin Balakrishnan

A discourse parser is a natural language processing system that can represent the organization of a document based on a rhetorical structure tree—one of the key data structures enabling applications such as text summarization, question answering and dialogue generation. Computational linguistics researchers currently rely on manually exploring and comparing the discourse structures to get intuitions for improving parsing algorithms. In this paper, we present DAViewer, an interactive visualization system for assisting computational linguistics researchers to explore, compare, evaluate and annotate the results of discourse parsers. An iterative user-centred design process with domain experts was conducted in the development of DAViewer. We report the results of an informal formative study of the system to better understand how the proposed visualization and interaction techniques are used in the real research environment.

Resources

Publications

Acknowledgements

Bubble Sets

Contributors:

Christopher Collins, Gerald Penn, and Sheelagh Carpendale

While many data sets contain multiple relationships, depicting more than one data relationship within a single visualization is challenging. We introduce Bubble Sets as a visualization technique for data that has both a primary data relation with a semantically significant spatial organization and a significant set membership relation in which members of the same set are not necessarily adjacent in the primary layout. In order to maintain the spatial rights of the primary data relation, we avoid layout adjustment techniques that improve set cluster continuity and density. Instead, we use a continuous, possibly concave, isocontour to delineate set membership, without disrupting the primary layout. Optimizations minimize cluster overlap and provide for the calculation of the isocontours at interactive speeds. Case studies show how this technique can be used to indicate multiple sets on a variety of common visualizations.

[Download mp4]

Software

Using prefuse

Source code as an Eclipse project (requires prefuse; I recommend the latest prefuse from the CVS repository, but the beta release will also work.) [v.3 updated 24 November 2010]

Also, you can now download the code for the papers timeline explorer. It is somewhat messy and depends on the BubbleSets code (above) as well as prefuse and the two jar libraries included in the archive.

As a stand-alone Java library

Bubble Sets library on GitHub (thanks Josua Krause for creating a testing application)!

Javascript version of the library