And as more people use the technology, future GIS packages will have virtual reality models embedded within them. ASI used ESRI Inc.'s ArcView 3D Analyst software to drape the orthophotography across highly detailed 3-D models. In traditional digital orthophotography, above-ground objects like buildings and bridges aren't modeled in a DEM and are radially displaced in photography, distorted from their true location. A tall building may lean over a street, hiding information like manholes, fire hydrants and utility poles. There are several approaches to solving these problems through aerial photographic methods, such as a denser photography grid or longer focal-length camera.
Attribute information includes items such as street names and building elevations.
All features are added as themes to an ArcView 3D Analyst scene and displayed in a perspective view along with the orthophoto. During a fly through, for example, users can point to a building top and obtain its elevation, or point to a street centerline and view the street name. 3-D models also are used to evaluate potential locations for setting antennas and other communication devices as well as to view corridors. Observing the view from all sides in a 3-D model brings planning to a higher level. Planners may see the impact of new buildings or other structures and how they aesthetically fit into the environment.