Virtual Reality and Distributed GIS

Virtual Reality and GIS : Two Sides of a Coin
The concept of merging Geographic Information Systems and Virtual Reality into Virtual Geographic Information Systems (VGIS) has enjoyed increasing attention in the recent past. Virtual GIS has been defined as a highly integrated, efficient real time 3 D GIS for visualizing geographic data. In the journey from a 2D map to a more interactive 3D, GIS has no doubt served the user community well, but there is an increasing demand for better data handling and visualization using the recent developments such as Virtual Reality. On the other hand, Virtual Reality applications are also looking for potential applications, and since GIS captures and stores spatial data, it is not surprising that GIS is used as a test case.

Such a marriage between these two powerful technologies has its own share of problems even suggesting immediate divorce. The 3D GIS, which has come into play with decidedly more interactive rates for high resolution display than a 2D GIS, has large amounts of data that can be expected to grow by a factor of 100 (3D textures, photo textures, etc.). This makes visualization of data more difficult; the rendering algorithms have to be optimized to load only data that is actually visible. Due to the performance demands, the increased complexity and hierarchical organization of data, relational databases are no longer suitable to manage a 3D GIS database. VGIS manages its huge, complex terrain and GIS data sets at real time rates in an efficient manner by using hierarchical spatial data structures. Virtual Reality adds an important freedom for the user to visualize and interpret spatial data more effectively. A real time visual simulation in VGIS supports the accurate depiction of terrain elevation and imagery, in addition to features such as ground cover and trees, buildings, and static objects, roads, and atmospheric effects, thus adding new dimensions to the concept of simulation of real life situations. It adds a new dimension in the visualization of abstract variables (e.g., environmental variables such as pollution level) by reducing the level of abstraction. Virtual Reality improves the communication of ideas and concepts in a collaborative process. In the GIS realm, the goal is to support users who are “overwhelmingly map illiterate”. Here, VRGIS acts as a mediator and transmitter of ideas between participants. Thus, the marriage of the two technologies promises the much-needed relief for the demanding user. So researchers around the world, both at academic and industry levels, are feverishly working towards trying to integrate these two technologies together.

Work Being Done
This emerging technology, which has redefined the users concept of visualizing data, has been a hot topic of research. Successful attempts have been and are being made to merge GIS and Virtual Reality for a more interactive and user-friendly interface. The various research areas where VRGIS is being incorporated are Urban Planning, Environmental Planning & Impact Assessment, Scientific Visualization, Education (Virtual Field Course) and Military Simulation and Intelligent Application. The following pie chart shows the amount of work being done in various fields

Figure 2. [http://www.casa.ucl.ac.uk/virgin/cat/vrgisentfrm.htm]
There are a lot of working models of VRGIS with varying levels of complexity that have been developed. We can generally classify the research in VRGIS at two levels:

High End Virtual Reality Interfaces
Low End Virtual Reality Interfaces