Digital topographic data are a critical information component for most environmental GIS applications. A recent survey of GIS users engaged in natural resources and environmental management activities indicated that topographic information is used by 83.2% of the respondents. (Geographic Technology Markets, Vol. 1, No. 1, GIS World, Inc.) Digital Elevation Models (DEM) are available from the US Geological Survey (USGS) for the entire US at a horizontal resolution of approximately 100 meters (3 arc-seconds); 30 meter resolution data are available for about one-half of the US. Digital Terrain Elevation Data (DTED), similar to the 3 arc-second DEMs, are available for large regions of the world from the Defense Mapping Agency (DMA)-for military users and contractors only. For those areas, however, where digital elevation data have not been produced or are not publicly available, the only practical alternative is the creation of a digital elevation database from existing hardcopy topographic maps-a very labor intensive prospect. Traditional photogrammetric techniques, or even newer satellite-based elevation extraction methods, would be prohibitively expensive and time consuming for all but small-sized areas. Starting with activities on a United Nations Food and Agricultural Organization (UN/FAO)-sponsored project to identify and map poppy cultivation in Afghanistan (ERIM Final Report 250800-1-F, August, 1993) and proceeding through EAGLE VISION support activities for Operation SUPPORT HOPE in Rwanda, ERIM has developed and refined procedures for preparing Digital Elevation Models from scanned topographic map sources. The process is technologically challenging-involving raster scanning, image processing, semi-automated feature extraction, raster-to-vector conversion, coordinate transformation, and surface generation technologies. This paper explores, through a series of application projects, the evolution of ERIMs DEM-from-Topo process. Initial efforts relied extensively on operator knowledge of ARC, ARCEDIT and ARCPLOT environments as well as the DEM production process. Subsequent projects built upon this base by developing ARC Macro Language (AML) programs and menus to simplify labor intensive steps in the process. Recently, these AMLs have been reengineered to provide a more user-effective interface for all phases of the map-to-DEM process. The resulting AML application, DTED/Topo, supports the development of DMA DTED-formatted DEMs from hardcopy topographic maps in a production environment. A main menu guides the user through the DEM development process and includes appropriately sequenced quality control steps. An underlying database tracks various interim data products from the original scanned map through the creation of the final DTED cell, recording data creation and quality control information. As a final step, an accuracy assessment, compliant with DMA standard procedures, is conducted. The resulting DEMs may be converted from ArcInfo's GRID structure to either a generic raster image format (.BIL) or to DMA's DTED format. For regions of the world where no suitable DEM exists, hardcopy topographic maps can be used to cost-effectively develop a digital elevation database. Terrain features generally do not change, so virtually any vintage topographic map is a potential candidate. DTED/Topo provides a production environment for efficiently producing DEMs from scanned map sources - exploiting information previously created and mapped at only a fraction of the original map preparation cost. It achieves a significant reduction in labor over manual digitizing methods. Through integrated QC steps, operator errors can be detected and corrected-or even eliminated-early in the DEM production process. Developed with AMLs, DTED/Topo integrates into existing workstation ArcInfo settings.
A key problem for users of information systems--information analysts, decision makers, planners--is the magnitude of data that has become available as a result of improvements in the acquisition of machine-readable text and the dissemination of textual documents across proliferating networks. It is estimated that the total amount of textual data in the world is doubling every 12 to 15 months. The rapidly growing breadth of information sources makes it increasingly difficult to distill information for analysis. Tools are needed to mine information on an ongoing basis to bring out key, relevant facts for analysis, and to support interfaces to analytical tools. Assisting a user to rapidly filter and assimilate useful information from a variety of data sources is a major way to leverage the individual's productivity, and meet the mission-critical objectives and deadlines of the organization. Data Extraction provides a method for having the computer read vast quantities of textual information and identify components of information that are pertinent to the user's interests. This information can be presented as attributes (e.g., Buyer, Seller, Date), and used to populate databases. Capabilities currently exist that can read several months of a daily newspaper, identify topics of interest, extract relevant information, and present it to the user within seconds. Additionally, the extracted information can populate database tables with relevant attributes. This data then becomes a repository of information available to the organization. Data Extraction can also be used to glean spatial information (countries, cities, landmarks, etc.) which can then be used in conjunction with a GIS to display spatial constructs. These constructs may involve activities between countries (e.g., trade between the U.S. and Mexico), cities, or regions, and can be displayed spatially for easy understanding. Combining Data Extraction with spatial tools used for data visualization and presentation provides substantial assistance in allowing users to formulate, explore, and evaluate textual content using visual characteristics.
A prototype command and control software project providing battle management functions for the British Army using Windows NT and ArcView products in a client-server architecture. Presentation and lessons learned by the project using rapid application development techniques will be given.
Jeppesen Sanderson, Inc. (Jeppesen), stands alone as the world's premier aeronautical chart publisher. Over the years the complexity and amount of flight information matched the growth of aviation, and Jeppesen kept ahead of these changing needs by assuming a strong leadership position both in the private and the governmental sectors. As aviation's leading supplier of flight information, Jeppesen pioneered the publication of enroute charts and approach charts beginning in 1934. In addition to being instrumental in the establishment of the National Flight Data Center, Jeppesen also published the first standard arrival (STAR), standard departure (SID), and profile descent charts in the early 1960s. High demands on an existing chart compilation system and development of a new corporate database prompted Jeppesen to review commercially available software suitable for chart generation and maintenance. Jeppesen organized a team of experts that began the software evaluation in early 1995. The team set out to determine if Jeppesen could improve chart production efficiencies by integrating a new database concept with the latest chart production hardware and software technologies. Jeppesen sent a request for information, containing over 100 questions regarding potential vendors' interest and technical capabilities to 28 companies. Ultimately, Esri's ArcInfo software was selected for a proof-of-concept and a follow-on pilot project. Potential aeronautical chart production efficiencies were demonstrated by a small prototype version of the new corporate database and an ArcInfo-based chart production system. Esri and Jeppesen completed an implementation plan in February of 1996 and are currently developing a detailed system design. The first phase of the new charting system is expected to be operational in the first quarter of 1997.