Earlier this year, GITA hosted an Emergency Response Symposium (ERS), organized by Talbot Brooks of Delta State University, as part of GITA's 2008 annual conference. Doug Eberhard, Tim Case, Dan Campbell, and I were part of a panel that discussed the convergence of BIM, CAD, GIS, and 3D simulation, digital cities, and some of the implications for emergency response. Joe Francica of Directions Magazine was in the audience, and asked a very important question which I will paraphrase. Where does the data come from ? Afterward Joe wrote an insightful article about this discussion. Recently, I discussed the same issue with Kenneth Wong of Cadalyst magazine.
When we talk about modeling cities digitally, we are talking about modeling the infrastructure of a modern
city including buildings and other structures, transportation networks, and utility and communications networks. We need to be able to visualize the city photorealistically, and we also need to be able to analyze how it works, and simulate how it would might work under different conditions.
Data Sources: Visualization
The relatively recent introduction of new technologies has dramatically improved our ability to efficiently image cities digitally in 3d. Advances in aerial photogrammetry and the widespread application of laser scanning are making 3D imagery available for many of the cities of the world. For example, Vexcel, now part of Microsoft, has developed cameras that enable the efficient creation 3D building models, rectangular solids with textures draped on the exterior walls, with a precision on the order of centimeters. Other technologies such as LIDAR and mobile terrestrial laser scanning are also being applied to create high resolution 3D cityscapes. To image the inside of buildings and structures such as electrical sub-stations, terrestrial laser scanning can generate imagery with sub-centimeter precision. Technology even exists for subterranean imaging of utility and communications networks.
Data Sources: Analysis and Simulation
In addition to being able to visualize cities, it is also important to be able to analyze how cities 
behave and to simulate how they might behave under different circumstances. Analysis and simulation is easier to do when the infrastructure data has intelligence. For example, capturing connectivity enables tracing an electrical network from a failed transformer to determine the customers affected so they can be contacted. Similarly, an intelligent transportation network model facilitates determining possible evacuation routes.
Utility, Communications, and Transportation networks
In the 1980's utilities and communications companies, realizing that their paper-based business processes were inefficient and were hindering their ability to provide new services to a growing, more affluent population and with the example of the successful replacement of paper and ink engineering drafting by CAD technology, began converting their paper engineering drawings into digital form. The conversion process required an expensive, multi-year effort, but the result is that for many cities intelligent digital utility and communications network models are available. Most of these models include not only location and properties, such as rated voltage and installation date, of each item of network infrastructure, but also connectivity, for example, which electrical networks are connected to which transformers. Similarly, topological network models also exist for rail networks and other transportation networks including roads and highways.
Buildings and Other Urban Structures
In a similar vein, intelligent digital models are required for buildings and other structures. For example, it may be necessary to model the propagation
of smoke or a noxious gas through the heating and ventilation system of a building, conduct a finite element analysis to determine the structural stability of an impaired structure, or determine evacuation routes form the upper floors of a high rise.
The data required to model buildings often already exists because it was created when the building was designed. It may be in the possession of the owner and designer, an engineer or architect. But it also may be at city hall or the town council, because most municipalities' permitting process requires the submission of engineering or architectural drawings. The permitting process usually requires that these drawings be made available for public inspection at city hall or the town council offices. After the public review process is completed and a decision rendered on the permit application, these drawings are archived, either in their paper form, on microfiche, or using a digital document management system.
For older buildings, these drawings are paper. For buildings designed since the widespread adoption of CAD, they may be available in both paper and digital form, as a DWG or DGN file. For very new structures, it may be possible to find both paper and an electronic building information model (BIM). Some municipalities, such as the St Johns River Water Management District in Florida, are actively encouraging electronic submissions.
It is interesting to what extent municipal governments make use of these drawings after the permit has been issued and the structure built. In some municipalities, it appears that they are archived, and no further use is made of them. But in some municipalities the value of these drawings is recognized, and they are being used for a variety of purposes, among them, emergency planning and first response. For example, the fire marshal may find that the drawings are invaluable for emergency preplanning or the police may find the drawings reduce risk to personnel responding to an an emergency situation in a bank or at an airport.
Some of the questions that this raises and that I hear people asking are,
1) How should municipalities be encouraging the submission of intelligent, digital designs, for example BIM models, as part of the permitting process ? At the federal level the GSA in the US requires BIM models for federal projects. The analogous organization in Singapore recommends BIM models.
2) How do we overcome issues of intellectual property rights and security that hinder reuse of this data ?
3) Can we expect to see the conversion of paper drawings to digital form and the capture of critical infrastructure intelligence for buildings and other urban structures analogously to what happened beginning in the 1980's at utilties and communications firms ?
Gary is an economist who focuses on creating new markets.
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