In this paper, we introduce a new style of visualization called Situational Visualization, in which the user of a robust, mobile visualization system uses mobile computing resources to enhance the experience and understanding of the surrounding world. Additionally, a Situational Visualization system allows the user to add to the visualization and any underlying simulation by inputting the user's observations of the phenomena of interest, thus improving the quality of visualization for the user and for any other users that may be connected to the same database. Situational Visualization allows many users to collaborate on a common set of data with real-time acquisition and insertion of data. In this paper, we present a Situational Visualization system we are developing called Mobile VGIS, and present two sample applications of Situational Visualization

This paper presents results for real-time visualization of out-of-core collections of 3D objects. This is a significant extension of previous methods and shows the generality of hierarchical paging procedures applied both to global terrain and any objects that reside on it. Applied to buildings, the procedure shows the effectiveness of using a screen-based paging and display criterion within a hierarchical framework. The results demonstrate that the method is scalable since it is able to handle multiple collections of buildings (e.g., cities) placed around the earth with full interactivity and without extensive memory load. Further the method shows efficient handling of culling and is applicable to larger, extended collections of buildings. Finally, the method shows that levels of detail can be incorporated to provide improved detail management.

This paper considers how out-of-core visualization applies to terrain datasets, which are among the largest now presented for interactive visualization and can range to sizes of 20 GB and more. It is found that a combination of out-of-core visualization, which tends to focus on 3D data, and visual simulation, which places an emphasis on visual perception and real-time display of multiresolution data, results in interactive terrain visualization with significantly improved data access and quality of presentation. Further, the visual simulation approach provides qualities that are useful for general data, not just terrain.

We present an algorithm for real-time level of detail reduction and display of high-complexity polygonal surface data. The algorithm uses a compact and efficient regular grid representation, and employs a variable screen-space threshold to bound the maximum error of the projected image. A coarse level of simplification is performed to select discrete levels of detail for blocks of the surface mesh, followed by further simplification through repolygonalization in which individual mesh vertices are considered for removal. These steps compute and generate the appropriate level of detail dynamically in real-time, minimizing the number of rendered polygons and allowing for smooth changes in resolution across areas of the surface. The algorithm has been implemented for approximating and rendering digital terrain models and other height fields, and consistently performs at interactive frame rates with high image quality. 1 INTRODUCTION Modern graphics workstations allow the display of thousa...

Advances in computer graphics hardware and algorithms, visualization, and interactive techniques for analysis offer the components for a highly integrated, efficient real-time 3D Geographic Information System. We have developed "Virtual GIS", a system with truly immersive capability for navigating and understanding complex and dynamic terrain-based databases. The system provides the means for visualizing terrain models consisting of elevation and imagery data, along with GIS raster layers, protruding features, buildings, vehicles, and other objects. We have implemented window-based and virtual reality versions and in both cases provide a direct manipulation, visual interface for accessing the GIS data. Unique terrain data structures and algorithms allow rendering of large, high resolution datasets at interactive rates.