Multiple-view geospatial comparison using web-based virtual globes

摘要

Existing virtual globes, including both unique platforms and associated visualization applications, often present geospatial information with a single-view mode that restricts the user to a single dataset. Due to the absence of the functionality and user interface for coordinating multiple virtual-globe views, it is either hard or impossible to explore multiple different geospatial datasets simultaneously only using the existing virtual globes, especially when the datasets come in multiple sources, multiple spatial resolutions or multiple temporal scales. Here we present a general visualization framework that supports the exploration and comparison of various datasets with multiple coordinated views in the web-based virtual globe environment. This framework not only comprehensively considers the dynamic master/slave relationship between multiple virtual globes, but also effectively handles the coordination mechanism for diverse views to respond to users' manipulations. We also implement a prototype application (termed MultiGlobe) and demonstrate its effectiveness over three typical application scenarios. The first case addresses the comparison of diverse imagery layers derived from different providers. A second case is examining multiple digital maps for a specific region or theme, such as time-varying LUCC datasets. As a final example, we compare and evaluate the accuracy of multiple DEMs generated from diverse data sources with different resolutions. Our informal evaluation with experts in exploratory visualization and spatial analysis confirms that the multiple-view-enhanced virtual globe can bring many benefits including focusing on spatial awareness, reducing cognitive efforts, coordinating interaction strategies, increasing browsing speed and enhancing comparison capabilities. Therefore, it can be incorporated into a variety of geospatial visualizations to replace or supplement the fixed single-view interfaces of the traditional virtual globe applications, empowering users with the ability to explore and compare multiple different datasets across the same geospatial area synchronously.