Trees shows link between nodes and its sub nodes and one common way to do this is by drawing connecting lines between nodes and its sub-nodes, for example we show family tree using this technique. Space is wasted in visually organizing the nodes. As trees get large they may require an extreme aspect ratio that makes it difficult to display. The treemap visualization technique, developed by Ben Shneiderman at HCIL, University of Maryland College Park, presents a novel method to respond to visualizing hierarchical information. In this method nodes, whose attributes are of more importance are given more display area.
Users have the choice to define the leaf node attribute that determines space allocation.
This is illustrated in the case of statistics for 50 US states. On initialization the Treemap program allocates equal space to all nodes. Figure 2 shows the initialized Treemap. Initialized treemap-'Size by' criteria set to null so equal space allocation to all nodes. Now say, the top three densest states need to be known.