| Virtual Reconnaissance of Geospatial Data Using Flight Simulators
By Micha Pazner, Matthew Ross and Neil Ripley Introduction
The concept of virtual aerial reconnaissance of geospatial data combines RS and GIS, enhanced 3D cartographic visualization, and PC-based flight simulation. Geospatial data is first subjected to RS/GIS modeling. This is followed by a processing stage that focuses on cartographic visualization. The results are then transformed into scenery for a flight simulator. Use of flight-simulation software for geospatial applications offers significant visualization potential. The ability to fly over 3D scenery is also available using software called "fly-by" modules, and less widely available in Virtual Reality Modeling Language (VRML) applications.
On the technological side, flight simulators have strong, realistic multi-component simulation capabilities. This allows users to experience virtual travel as their "aircraft" moves through a richly represented environment. Flight simulators offer flexible multiple views and extensive navigation support that includes moving map displays, virtual GPS, automatic pilots, and mission- and flight-planning aids.
There are also economic reasons to use a flight simulator loaded with processed geodata scenery. The cost of PC-based flight simulator software is in the double-digit range. This can translate into substantial savings for commercial firms and institutions in multi-user applications. In addition, virtual visits cost less money, time and effort than do actual, physical visits to hard-to-reach study sites. Virtual aerial reconnaissance can be an alternative to or an augmentation of field expeditions, whether performed before, during, or after.  Low-level flight over Lake Ontario facing Toronto and the "Golden Horseshoe," with Detroit visible further west. Chicago is the GIS generated "hill-of-light" on the horizon.
From Cartographic Visualization to Flight Simulation
The most important way that humans interpret data is through sight. Visual representations of information assist humans in generating ideas and hypotheses about observed data. A report titled "Geomatics Technology Road Map," published by Industry Canada in 1998, described the need for - and the trend toward - enhanced cartographic visualization this way. "As geographic information systems become more flexible, powerful, sophisticated, and more closely integrated with modeling software, the interface between the GIS and the user needs to become more interactive and complex."
One of the next steps taken in GIS evolution was the transition from 2D representations through 3D GIS, to dynamic and interactive 3D virtual worlds. GIS users find a virtual-reality paradigm an aid to interpretation, idea generation, and problem solving. Using flight simulators for dynamic visualization of geo-spatial data is a form of interactive cartographic animation. One type of map that lends itself to animated viewing is the very large spatial data set. The oblique perspective view - looking at a 45-degree angle - can augment the orthogonal map view as an efficient viewing mechanism for extremely large spatial search spaces. This is due to the fact that perspective views can extend to great distances, albeit at the cost of varying the scale of objects depending on their distance from the viewing position. Close-in objects conveniently come into sharper focus, while distant landscape features are progressively generalized as their distance from the viewer increases. Oblique viewing angles may become increasingly essential for roaming vast digital landscapes, for many of the same reasons that aircraft cockpit windows afford oblique views.
Only recently, however, has computer processing power approached the point where it is feasible to run interactive massive cartographic animations. Powerful yet relatively inexpensive, modern personal computers are capable of generating highly realistic 3D renderings in real time. This allows a growing number of professionals the opportunity to interactively explore spatial databases in 3D. Flight simulators offer a rich suite of instruments and tools within the virtual reality (VR) environment. The virtual pilot can accurately navigate about in the environment with the aid of maps and instruments, including GPS and radio navigation systems.
Flight simulators make maps such as aeronautical charts and navigational vector charts available to the virtual pilot. In modern flight simulators, these take the form of moving map displays that auto-scroll the map and track the movement of the aircraft. Map support is important for augmenting oblique perspective views with orthogonal representations of the landscape at various scales, along with providing symbolic information. From Geospatial Data to Flight Simulation Scenery
The geospatial data is initially processed and developed within a RS/GIS/Cartographic system, and then exported and processed into flight simulator scenery. Scenery is composed of two main components, an elevation model that forms the terrain, and an image that is draped over that terrain. This scenery development is a three-stage process.
A number of different cartographic, remote sensing and GIS data scenery prototypes accompany this article. These prototypes exemplify different kinds of GIS-processed scenery that can be created for any part of the world. The GIS software used to prepare this scenery was Mfworks, and the flight simulator used was Fly!2K. From Geospatial Applications to Virtual Geo-Reconnaissance
Virtual aerial reconnaissance of geospatial data has a wide range of applications. Some of these application areas include the following:
• Resource extraction - mining, gas and petroleum industries
• Renewable resources - forestry, agriculture, fisheries
• Environmental modeling - coastal sea level changes, desertification
• Environmental monitoring, planning and management - flooding, damage to forests, water pollution • Utility planning and management - energy transmission, telecommunications
• Civil engineering - road development, highway maintenance
• Aerospace - Visual Flight Rules (VFR) training and briefing, aviation facilities planning and management, cockpit control design for actual aircraft
• Military - mission planning, aerial reconnaissance
• Insurance - risk assessment, catastrophic loss reduction, response planning for natural catastrophes
• Flight-simulator users - hobbyists, flight simulator developers, third-party scenery developers
• Tourism - virtual tourism, atlases for trip and vacation planning
• Archaeology - virtual exploration for locating viable sites
• History - virtual visits to back-in-time scenery using old photos, maps, or reconstructive modeling of ancient landscapes
• Marine applications - sea-floor map exploration for geological applications, navigational hazards, shipwrecks
• Entertainment/Media - scenery development for computer games, movies, documentaries, news programs, and web media
• Education - teaching aids such as virtual site exploration and 3D digital atlases
In applications developed in an office setting, this technology can be used to help solve problems and stimulate ideas for corporate decision makers, researchers, instructors, and publishers. In applications involving fieldwork, virtual geo-reconnaissance may offer substantially lower costs without the risks associated with exploring large or remote geographic areas. Flight simulation acts as a substitute for some or all of the need to go out into the field, and can also support efficient pre-trip real-world mission planning. There are broad applications that can benefit from the highly dynamic and interactive nature of virtual, flight-simulator reconnaissance of geospatial data. It appears this is yet another case where the only limit to the scope of potential applications is one's imagination.
About the Authors:
Micha I. Pazner is the president of SymVista Inc., a high-tech company located in London, Ontario, Canada. He is also an associate professor of Geography at the University of Western Ontario (London).
Matthew Ross is vice president of business development at SymVista Inc.
Neil Ripley is vice president of research and development at SymVista Inc. For more information, please visit the company's web site at www.symvista.com. Editors Note: This material was originally published in the GIS 2001 conference proceedings published by GeoTec Media, www.gisconference.com Back |
