TECHNOTES
True Ortho
Overcoming building lean, tilt and other distortions using a fully automated process
By Peggy Ammerman

From one local government to another, what falls under the heading "public works" varies widely. The American Public Works Association based in Kansas City, Missouri, says, "Public works is a generic term broadly defined as: The physical structures and facilities developed or acquired by public agencies to house government functions and that provide water, waste disposal, power, transportation, and similar services." One theme is consistent though when it comes to how a GIS relates to public works functions: Geospatial data that falls under the public works heading is the undercarriage of many main GIS applications at local governments, helping to ensure that the infrastructure and associated programs-the very framework on a which a community is built-are kept in good repair.
    The mix of GIS, mapping, imagery, and other technologies that capture and serve up the data are as varied as the uses of the public works data and applications at local governments across the nation. Each of the following municipalities uses GIS public works data and technologies for different purposes; from real-time analysis with natural disaster emergency response and keeping tabs on the sign inventory, to modeling infrastructure systems and forecasting the impact of land use scenarios. While public works often operates behind the scenes, the contributions that GIS public works data and applications make to the well-being of the community are significant.

Cambridge GIS City of Cambridge, Massachusetts
For a community of just 95,000 that is home to 5 colleges and universities and surrounded by another dozen, the City of Cambridge, Massachusetts, is well schooled in GIS. Considering this densely literate setting, it only makes sense that the city's GIS includes a "smart parcel" application for complex land analysis and for infrastructure planning, a high-level data sharing process between a CAD and GIS environment.
    Planning for the Cambridge GIS began in 1995 when the city manager formed a task force and conducted a users' needs analysis. Before that time, Peter Bujwid, GIS manager, says that several departments throughout the city government were already using GIS data and technology to do specific tasks. The efforts were not integrated though, says Bujwid with "each department making its own effort at getting GIS data and software." The GIS originally took roughly $1.5 million for consulting, data conversion, hardware, software, and implementation of a fiber optic network for high-speed data transfer throughout the city. The funding formula included $700,000 total in equal amounts from the sewer and the water fund, $200,000 in parking funds and $600,000 in free cash.
    After the task force determined there was a need for a cohesive GIS program that could be networked to user departments citywide, the GIS was launched in earnest with the production of aerial photography for the 6.43 square-mile land area. Colorado Springs, Colorado-based ASI Technologies Inc. (ASIT), a customer service center of Analytical Surveys, Inc., (ASI) was contracted for mapping services. The city was flown for color photography at 1" = 400' scale for production of 1" = 100' scale planimetric land base data. The products delivered included color digital ortho imagery at 1', 2' and 4'resolutions. Bujwid says, as compared to black-and-white imagery, "Color adds a lot in terms of context." Bujwid notes that "for infrequent users of GIS data, lines, points, and various symbols are not easily interpreted." Secondly, Bujwid adds, "The color imagery provides a lot of information such as seasonal water coverage or vegetation features that are not captured with the other data." In summing up, Bujwid says that the color imagery "basically makes the GIS data more digestible."
    Planimetric features from imagery were converted into digital format. ASI also delivered 2' interval contour, a very dense spot-height database, and a digital terrain model (DTM). In addition, ASI converted documents such as sewer, water, and 1940 vintage linen tax maps. Converted digital data was then tied to the planimetric base. Overall, Bujwid says, "We were very satisfied with the digital ortho imagery and tax map conversion which helps determine how we can use the data." For example, Bujwid offered, the GIS can be integrated with other databases.
    While ASIT was making data deliveries, the city was installing high-end UNIX workstations in four core departments-Management Information Systems (MIS), water, community development, and the assessor. At the time, a small server stored all of the GIS data. Next, map query and display were written. While ARC/INFO GIS software is the "main workhorse for data maintenance and development, and for some application development as well," Bujwid says, for basic map query and analysis ArcView is being used.
    The department of public works uses an application that originated in the assessor's office called EZParcel for accessing data on the city's more than 13,000 parcels. Built using ArcView Avenue programming language, EZParcel acts as a bridge to the GIS and was designed for users of all computer skill levels. After zooming in on a particular parcel and retrieving the owner's name, address, and other information, a map can be printed. For new construction planning, the department of public works uses GIS data with ArcCAD, which sits on top of AutoCAD. This application is particularly useful for infrastructure planning within a CAD environment. Bujwid says that part of the new data maintenance suite will include "a two-way process where the GIS data is used within CAD and then updated data is imported back into the GIS." Bujwid goes on to say that this is the type of GIS data maintenance program that is being implemented on an individual department basis. With data maintenance, the MIS would be involved strictly in an oversight role to ensure data quality and integrity.
    Maps have also been converted into Acrobat Reader PDF file format for viewing and downloading purposes and published on the city's web site under the Map Library. The Tax Atlas was compiled from 291 assessor's tax maps. Under the Parcel Map Library, about 14,887 color land parcel maps with boundaries, dimensions, footprints, edge-of-pavement, parking lots, driveways, and other features are available. The city is also looking at making thematic maps available through the web site.
     Next on the drawing board is an integrated infrastructure management system (IMS). Along with a comprehensive inventory of infrastructure features, the IMS would be integrated with the GIS. In explaining the process, Bujwid says, "The IMS could be queried and the results manifested in the GIS and vice versa." Data would be maintained in the GIS and then the IMS would be repopulated with updated data. In keeping with the city's tradition of incorporating dynamic information-sharing protocols and "smart" applications, Bujwid says of the next planned development, "This would be a dovetailed situation with communication between two software packages and a sewer data modeling component."
    Today, there are 23 UNIX and PC access points throughout the city. One of the core functions of the GIS is map making, so there is a series of stock maps that users can print on demand from a number of access points. There is also an interactive map making function that allows users to view and seamlessly pan the map display for the city. A customized map showing certain features for a specific portion of the city can then be printed. This map query and making function is a "friendly application," notes Bujwid, adding, "Users are only four mouse clicks away from any map."

Knoxville GIS City of Knoxville and Knox County, Tennessee, and Knoxville Utilities Board
Back in 1985, when life was breathed into the Knoxville GIS (KGIS), it was one of the first systems developed through a consortium of municipal government, the City of Knoxville/Knox County, and a public utilities organization, the Knoxville Utilities Board (KUB). KGIS Director John Lutz, who has been with the program, which serves the City of Knoxville and a population of 335,000, since its inception, says, "If you mention that our GIS was originally based on a VAX, you will probably have to explain what that is."
    When the KGIS first started out, the city was in the process of turning over operation of the sewer system to KUB, which together with the City of Knoxville funds the GIS. The system first managed water, electric, and gas data and has since added wastewater. On the utility side of the GIS, Intergraph FRAMME GIS software is now used and Intergraph MGE is being used for the land base. Original utilities data conversion and, currently, migration services for KGIS and its utilities applications to Windows NT, are being provided by MSE Corporation, an Indianapolis, Indiana, customer service center of ASI. Most recently, ASI/MSE has been contracted for sewer data conversion and application development.
    Just 4 years ago, digital ortho imagery was added to KGIS. Every year for the past 4 years ASI, through ASIT, has provided new aerial photography updates to the original vector database, and digital ortho imagery for 25% of the KGIS county-wide land area. With this year's flight information, KGIS will have a complete digital ortho base map that covers 525 square miles and started with 135,000 parcels in 1985, and is now topping 160,000. Recently, KGIS contracted with ASIT for 4 additional years of the same services.
    Black-and-white aerial photography at 1" = 800' and 1" = 1600' scales is being produced. The 1" = 800' scale stereomodels observed during aerial triangulation were used to produce 1" = 100' scale mapping products. Lutz says that ASI has demonstrated "a high level of expertise" with digital ortho imagery, which has helped make the data a valuable component of KGIS. In the urban areas, data is scanned at 1/2' pixels with the production of 2' interval contours, and for rural areas scanning is at 1' pixels with 4' interval contours. KGIS uses a land-base viewing application developed in-house called LandViewer, which will operate on various Windows platforms.
    Many of KGIS public works applications are under the city engineering department. The storm water mapping application tracks and maps all of the features of the storm water management system and performs tasks required by the Environmental Protection Agency. The sign inventory program, also handled through city engineering, maintains sign location, materials, and other information through graphic symbols as well as in a database.
    Main applications of a GIS, such as appraisal and zoning district maps, have a trickle down effect on public works GIS data and applications for infrastructure and other community assets. For example, Lutz notes that land development and rezoning affects the design of roadways, delivery of wastewater and other utility services, and changes in property valuation. KGIS is working towards direct input into the GIS from the land development review and approval process. Currently, a land developer submits a digital plat, which goes through an entire evaluation process. Lutz says, "Anyone can see at anytime what is under consideration." Then once the plat is approved and recorded, the information is merged with the property assessor's database. As a result, Lutz says, "The property map reflects current property ownership" as a real-time portrait capturing changes as they occur. Prior to the real-time application, the property map reflected 6-month old information.
    A large segment of the population that uses public works data from the KGIS is the public. Lutz says that $1.1 million worth of data is distributed every year, both on a complimentary basis to contractors and engineers doing work for the city and to the public through sales that amount to $60,000 annually. Generating and distributing GIS is labor intensive, notes Lutz, and therefore comes with a hefty price tag. Lutz is currently looking at alternative solutions for publishing and distributing KGIS data, including ASI's IDS digital map publishing service that publishes GIS data including digital ortho imagery on CD-ROM. IDS takes GIS data and packages it on a CD-ROM along with IDS Windows software for viewing. Typically, local government organizations and utility companies distribute the IDS CDs to internal users, and in the case of local governments, make the IDS CDs available for purchase to the public. To illustrate the public demand for readily accessible and easy-to-use GIS data, sales of the City of Indianapolis IDS CD-ROM have totaled over $100,000 in the inaugural year. Those purchasing IDS CDs for the most part have been land use attorneys, contractors, consulting engineers, and Realtors.
    In looking back over the 15 years that KGIS has been in existence, Lutz points out "we are still here, still funded and that is success." With an annual budget at roughly $1 million, Lutz says, "KGIS has been maintained in a rather vigorous mode." Lutz is finding today that as the older technology goes by the wayside, maintenance costs actually go down. For KGIS technology maintenance costs have dropped $80,000 over the last year.
    Today, with the range of technologies available, potentially "anyone with a desktop PC can access KGIS data," Lutz points out. "The pay back of advancing technology," Lutz says, "is making the data directly available to a lot more people." Until recently, "The people who needed the data had to go to the people who knew about the data management system in order to gain access to the data," Lutz notes. He adds, "Now the people who need the data are the direct users of the system." Lutz says the middleman is being eliminated and his expertise is being put to use in a different way. Lutz says technology development is going through a revolutionary process. He says, "Implementing technology is an evolutionary process, and it takes a lot longer for evolution than a revolution to take place."

DeKalb County GIS DeKalb County, Georgia
Typically, the public works department of a city or county is one of the heaviest users of GIS data and maps. When an emergency situation or natural disaster occurs though in Dekalb County, Georgia, both the Public Works department and the GIS are put to the test. On April 9, 1998, when a tornado and storm hit heavily wooded DeKalb County just northeast of downtown Atlanta, the value of the county's GIS really stood out.
    In this county of a little over 580,000, a 4 square-mile area was hardest hit with substantial damage to both the tree cover and structures. "Fortunately," says DeKalb County GIS Director Denise Finley, "we were able to equip crews from public works and public safety with map sets immediately." The GIS department, which was established in 1994, had received just a few months earlier, delivery of planimetric, topographic, and digital ortho imagery mapping products for the hardest hit DeKalb County area from ASI.
    Finley says many of those on the public works and public safety crews had been with the county for over 20 years and were very familiar with the "look" of the area. Because the storm destroyed many of the natural landmarks like groves of trees and littered the roadways with debris and, in certain instances, totally obscured major thoroughfares, crews were faced with the task of getting reoriented with their surroundings. Finley says that's where the maps played a crucial role as an orienting tool. The planimetric data of the GIS was based on a highly accurate mapping scale of 1" = 100', so maps produced by the GIS were key to defining in precise terms the scope of the affected area and quantifying damage.
    Through the responsive action of the GIS department, recovery efforts were put on a fast-track time frame. Public works and public safety personnel were armed with maps during their field inspections. While in the field assessing the damage, crews noted on the maps the extent of damage and locations requiring debris removal and recovery assistance. These notes were then digitized and used with GIS data on acreage, square miles, and miles of roadway in calculating the size of affected areas. This information then served as the basis for defining the scope of work and prioritizing work efforts for debris removal, demolition, and clean-up contracts.
    In constructing the DeKalb County GIS, over a period of 3 years, ASI provided a range of land-base and digital ortho imagery services for a countywide base map. The company's Colorado Springs, Colorado, customer service center, ASI Technologies, specializes in softcopy photogrammetry and advanced digital ortho imagery processes and was able to provide a highly accurate digital ortho imagery base map. According to Finley, DeKalb County was among the first municipalities to use airborne GPS in the construction of a GIS digital ortho base map. Among the services ASI Technologies performed were airborne GPS control and the production of aerial photography (using 6' focal length cameras) at 1" = 600' scale. Next, ASI Technologies began production of land base and digital ortho imagery products at 1/2' pixel resolution using the 1" = 600' photography. The land base products included 1" = 100' maps with planimetric and road centerline details on over 1,360 map sheets. Contour data with 2' intervals as well as DEM data is also being produced. ASI Technologies is also providing DeKalb County with its Image DataBase, which is a format or structure for storing imagery. IDB is a highly efficient method for accessing and displaying imagery at any resolution. The DeKalb County GIS uses an Oracle database and MGE GIS software on a mix of UNIX and Windows NT operating environments, with the GIS undergoing migration to a single operating system using Windows NT.
    Right now within DeKalb County government, about eight departments and 90 PCs are on-line with the GIS. The heaviest demand for GIS data comes from the public works department, which is divided into component units of water and sewer, roads, drainage, sanitation, fleet maintenance, economic development, and development that handles building permits. All units report to a "super" department of public works.
    Since the idea for a GIS was first presented, the DeKalb County GIS has received a lot of support mainly from the administration, the county commissioners and within the county government ranks as well, says Finley. About $1.6 million was originally slated for development and implementation of the DeKalb County GIS. Back when the budget for the GIS was being put together, the public works department offered to pay the difference for increased accuracy, Finley notes. After the events of April 1998, this investment has proved to be money very well spent.

About the Author:
Peggy Ammerman is a writer with the Indianapolis, Indiana, office of Analytical Surveys, Inc. (ASI) and specializes in GIS and geospatial information technology issues. She can be reached at 317-634-1000, ext. 285 or by e-mail at [email protected].

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