The treemap chart displays file system data as a set of nested rectangles. Each folder is given a rectangle, which is then tiled with smaller rectangles representing subfolders or files. A rectangle has an area proportional to a specified dimension of the folder or file that it represents. When coupled with color and various display properties treemaps provide a method to display patterns that would be difficult to visualize in other ways. Treemaps also makes excellent use of display space and can legibly display thousands of items simultaneously.
DiskFerret uses color and highlighting to enhance the visualization of the data in the treemap. Each rectangle at the smallest level represents a folder or file, and each base color represents the contents of a top level folder, with a top level folder being defined as a subfolder of the currently selected folder. To the extent possible a label is displayed for individual items in the treemap, but as seen it Figure 1 below the labeling can be very limited when many items are displayed in the chart. When the mouse cursor is moved over a folder or a file in the chart, the rectangle is highlighted and a tooltip is displayed for the object with its path and size (see Figure 2).
The treemap chart allows for “drilling down” to subfolders in the Size data view. The drilldown capability is indicate by a finger cursor as shown in Figure 2. The finger cursor is displayed when the mouse is positioned over any subfolder of the currently displayed folder, the folder is outlined with a yellow rectangle, and a single click will “drill down” and update the display to the directory under the mouse.
Unlike the pie chart and bar chart which display only top level folders, the treemap chart attempts to display all children of the selected folder (in the Size data view only). This provides a very quick method to visualize the space used for an entire disk or folder, however the display can be overwhelming on volumes that contain many thousands of folders and files. Options are available in Tools > Options > Treemap to specify the number of nested subfolders that the treemap view will traverse before displaying summary folder information.
If you would like to learn more about Treemaps and their origins check out this website.