Wednesday, November 16, 2011

Treemaps: a space-filling approach

The paper addresses the classic problem of visualizing the Hierarchical information structures. If you check out any of the directory/hierarchy there are two components mainly : The structural information associated with the hierarchy, and content information associated with each node.

Treemaps are able to depict both the structure and content of the hierarchy. The focus in on hierarchies in which the content of the leaf nodes and the structure of the hierarchy are of primary importance, and the content information associated with internal nodes is largely derived from their children.

The unix ls command or the tree tree structure as we all know have its own problems. Even thought the venn diagram approach is close to utilize space and provide better visualization but when there is lot of nesting , this is no answer the problem.

The treemap does address the problem and utilizes the space 100%. It is kind of a knapsack with weights allocating the space in the confined area. The one problem that i feel when observing the tree map is the consistency either on the horizontal or vertical axis that is missing, it hard to compare the rectangular shapes that are vertically aligned to that which are vertically. The nesting is handled by boundaries but with lot of hierarchies this could be a difficult problem to address.

The properties of weight directly proportional to the area and further parent/ancestor having area equal to the sum of their children provide correctness but visually identifying this is still a problem.

Also 3D is still an option that is not discovered and there is definitely lot of scope with treemaps.