GeoWorld January 2013

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Imagery Applications BY SATYEN SARHAD Video Games Increasingly Add Geospatial Imagery M apping the Earth has truly come full circle. Originally, geospatial imaging technology was a strictly military affair—a product of the Cold War space race, as the 1950s and 1960s saw the launch of the world's first imaging and spy satellites. Flash forward just one human lifespan, and today you can drive virtual cars and fight zombies on your mobile phone, on top of these same satellite maps. The public now can play combat-simulation games for fun using a previously restricted military technology. Along the way, something else happened: cartography became popular! Navigation systems started appearing in cars and as affordable handheld units, and GPS became a household name. Online maps with integrated satellite/aerial imagery exploded in public popularity in the 1990s and 2000s, and the sudden ubiquity of mobile maps followed. The 3-D Virtual Globe One of the most impressive classes of applications to emerge from the popularization and commercialization of geospatial imaging technology was the "virtual globe," a 3-D graphical rendering of the entire Earth and its topology, with commercially sourced geospatial imagery orthographically draped over the terrain. 14 G E O W O R L D / J A N U A R Y 2 O 1 3 The result is a photorealistic 3-D model of Earth, with some basic camera controls and markup capability. Examples include Google Earth, Microsoft Virtual Earth and WebGL Earth. What people might commonly think of as 2-D imagery, however, actually has a lot of 3-D information, often enough to usefully reconstruct a 3-D model of the photographed environment. Several virtual-globe applications now employ sophisticated photogrammetric techniques to automatically model terrain and other physical features (e.g., buildings and trees) directly from 2-D optical imagery. Improving on the established technique of texturing stretched geospatial imagery over the terrain, these newer image-processing systems can automate the extraction of 3-D information from 2-D photographs, and then appropriately model and texture the resultant 3-D structures. This is part of the evolution of "geospatial imagery," as complex digital image analysis and preprocessing becomes more important prior to rendering. Geospatial Imagery in Entertainment It's no wonder that as mapping technology has gone mainstream, geospatial imagery has found its way into the popular entertainment industry. Imagery from commercial Imagery/LIDAR Special Issue

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