Connected 2d and 3d Visualizations for the Interactive Exploration of Spatial Information

This paper describes the concepts and the successful prototypal implementation of interactively connected 2D information visualizations and data displays in 3D virtual environments for the interactive exploration of spatial data and information. Virtual globes or earth viewers such as Google Earth have become very popular over the last few years. They are used for looking at holiday destinations but more importantly also for scientific visualizations. From a geovisualization point of view we might regard 3D data or information displays as yet another representation type that adds to the multitude of information visualization methods. Combining 3D views of data sets with traditional 2D displays offers the advantage of being able to use 3D if and when this type of representation is considered useful or effective for finding new insights into a data set. The traditional and newer displays of mainly 2D information visualization may be enhanced and new insights into the data may be generated by displays of the data in a 3D virtual environment. On the other hand, data in 3D displays might be better understood by simultaneously reading and querying connected 2D representations. The paper presents a prototypal implementation of the interactively connected visualizations of spatial information in 2D views and 3D virtual environments using the brushing technique. The prototype is implemented using the virtual globe technology i3D, a 3D geovisualization engine developed at the University of Applied Sciences Northwestern Switzerland (FHNW). SVG is used to realise the 2D graphics and diagrams of the information. The connection between the views, the interactive querying and brushing is implemented employing the scripting languages Lua and ECMAScript. This prototype implementation is applied to and tested with two different data sets: slope stability data from Brienz and statistical data of the canton of Baselland in Switzerland. Technically, the combination and interactive linking of 2D data displays and 3D visualizations as implemented in the prototype is feasible. It seems that connecting 2D data displays to the 3D views and updating or changing them dynamically allows overcoming some of the shortcomings of using stand-alone 3D views of information. The combined use of the virtual globe technology i3D and the scripting language Lua for the 3D displays and the interaction with 2D representations (SVG and ECMAScript) bears a considerable potential for enhancing the explorative analysis of spatial information. Such combined 2D and 3D displays open up new possibilities for the explorative evaluation and analysis of spatial information in the context of the landscape. Additionally, they allow using each type of 2D and 3D representations when it is deemed appropriate and when it may be able to play out its respective strengths. * Corresponding author.