EVAT: Environment for Visualization and Analysis of Trees

Abstract

Exploration of trees is an important domain for information visualization. EVAT is designed for exploring one tree or comparing two or more trees, keeping a view on each tree analyzed within the session. Three sets of data were proposed and for each of them, EVAT helps answering user’s questions. Help means that it shows, using colors, similarity or allows filtering on value in order to extract a selection view. In this filtering process, the focus+context technique is applied in relation with the drawing. It means that the coordinate are recomputed taking in account the selected data. EVAT allows importation of XML files and also direct importation of a file system. The whole session can be saved in EVAT format. It runs under Linux Redhat 9.1 using QT library. It is useful but not mandatory to have 512MB memory and a graphic card Open GL 3D with acceleration. EVAT manages trees up to 550 000 nodes using 140MB memory. Thus it is possible to deal during the same session with several huge trees. In the following sections, hhis note presents the background tools, the menus and ergonomic feel, the main tools for filtering. Some examples are shown. Then in a last paragraph some strong and weak points of the software are discussed.