University of Maryland

Poster in the HCIL: A Million Item Treemap

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This poster shows a 2002 treemap created by Jean-Daniel Fekete (then a visitor in sabbatical in the HCIL, working with Catherine Plaisant).

The treemap gives an overview of the 970,000 files on a 1600×1200 display. The large hierarchical file structure came from a Unix server of the CS department. The size of each rectangle is determined by the file’s size. Color represents file type. Green is for images, blue for text (so websites are a mix of blue and green), yellow is source code and red executable. The rest is gray, including the big gray area at the top right which was the result of a bug in a program not releasing temporary files, which accumulated over several years. It was discovered using the visualization and lots of space could be freed on the server.
We also see duplicates of large directories, or code saved in odd places. Files are grouped by directories, Deeply nested directories appear darker. The interactive interface displayed label and path information, and zooming would reveal more details.


Here is the project page associated with this poster, the paper and a video.

Did you know that treemaps were invented in the HCIL?
A treemap is a space-constrained visualization of hierarchical structures. It is very effective in showing attributes of leaf nodes using size and color coding. Treemaps enable users to compare nodes and sub-trees even at varying depth in the tree, and help them spot patterns and exceptions.
See Treemap 4 (our last prototype) and the Treemap history page.