Digital Mapping Techniques '97
U.S. Geological Survey Open-File Report 97-269

Introduction

By David R. Soller

U.S. Geological Survey

908 National Center

Reston, VA 20192

Telephone: (703) 648-6907

Fax: (703) 648-6937

e-mail: drsoller@usgs.gov



From June 2-5, 1997, selected technical representatives of the USGS and State geological surveys participated in the "AASG/USGS Digital Mapping Techniques" workshop in Lawrence, Kansas. The workshop was initiated by the AASG/USGS Data Capture Working Group, and was hosted by the Kansas Geological Survey (KGS). With a focus on methods for data capture and digital map production, the goal was to help move the state surveys and the USGS toward development of more cost-effective, flexible, and useful systems for digital mapping and GIS analysis. In this Introduction, I describe the workshop content and the context in which the workshop arose.

BACKGROUND

More than three decades ago, computer technology began to be adapted to cartography and mapping sciences, with the vision of capturing thematic map information in digital form to use for spatial analysis and the production of maps. Since then, many agencies that conduct geologic mapping have begun to evaluate the potential uses of computers and software for assisting with the process of mapping and publishing. For example, in 1988 the USGS held informal discussions about digital mapping methods currently under development by Geologic Division projects, and published in a special issue of their internal publication "The Cross Section" a summary of those projects. I participated in that forum, and was concerned about the general lack of available guidance for newcomers to the field of digital mapping (which here includes digital map data capture, data management, and the publishing or on-line release of digital maps). Lack of guidance or standards was to be expected, as the field was evolving rapidly. Interesting and useful work was already underway at that time by various investigators, and I was impressed by the value of forums that summarized the level of knowledge at the time. In response, I coauthored a users manual on the methods we developed (Soller and others, 1990). I also looked forward with anticipation to a time when a forum of wider scope could be organized.

Within just the past few years, the evalution and adoption of digital mapping methods has accelerated markedly. As documented by the papers in this volume, many agencies now rely on digital mapping to support their scientific studies and the delivery of information to the public. This recent rapid adoption of digital mapping techniques is due in part to the increased functionality and decreasing costs for geographic information system (GIS) and map production software, and for computers that are capable of supporting these software.

More importantly, however, digital mapping is a logical response to the public's evolving demand for the rapid delivery of information, especially in forms that are amenable to spatial and statistical analysis. In the past, when information was available only in paper form, the public's expectation for information delivery was tempered by the time-consuming process of conventional printing and distribution. Further, when the information became available, its analytic utility was generally somewhat limited because a high level of expertise and/or resources was needed to extract its full value. In contrast, information in digital form, available quickly and in many cases without cost across the Internet, has changed the public's expectations for information delivery -- they have learned to expect access to information soon after it is gathered.

Access across the Internet to rapidly-produced information is a new paradigm for industry and government. It has spawned in industry a rapid evolution in software designed to exploit the Internet, from the home as well as the office. Government is responding to this new paradigm by encouraging the public's electronic access to information. Perhaps the most visible response has been the establishment of the National Spatial Data Infrastructure, or NSDI (in 1994, by Executive Order 12906). The NSDI is designed to promote access to spatial data produced by government, and to encourage efficiency by minimizing the gathering of redundant digital data. These goals are addressed through the National Geospatial Data Clearinghouse, which is a network of computers each containing a library of descriptive information, or metadata, about spatial data holdings. Because the computers are linked and supported by a standard seach/query software protocol, the user can perform a national search for information. Clearinghouse "nodes," or entities participating in the NSDI, are being developed by various agencies at the State and National level. More information about the Clearinghouse and NSDI can be found on the Web at the FGDC's home page http://www.fgdc.gov.

In the geoscience community, there is another, more specific response to the public's need for information. The National Geologic Mapping Act of 1992 mandates the construction of a National Geologic Map Database (NGMDB), to contain the following map themes: geology, geophysics, geochemistry, geochronology, and paleontology. The NGMDB is designed to be a distributed system of computers and State and Federal agency holdings of both digital and paper maps that is accessed through the search and query of metadata at a central site. Planning for the NGMDB began in mid-1995, through discussions between the USGS and the State geological surveys -- in this venture, I represent the USGS, and Tom Berg (Ohio State Geologist) coordinates the state's involvement as Chair of the Association of American State Geologists' (AASG) Digital Geologic Mapping Committee. The general plan for the Database was written by Soller and Berg (1995). This plan developed into the National Geologic Map Database project, which is funded under the USGS/AASG National Cooperative Geologic Mapping Program. The NGMDB project Web site (http://ncgmp.usgs.gov/ngmdbproject) contains project plans and other pertinent information. The Database's central site is http://ngmdb.usgs.gov.

Standards and guidelines are essential to the success of large, cooperatively-built databases such as the NSDI and NGMDB. For example, without standards for metadata content and format, a user's query of the Clearinghouse or the NGMDB would yield little useful information because the database query software would not be able to identify the appropriate metadata records. Without a standard data model for geologic maps, users would need to interpret the content of each map and, if feasible, translate it into the form they need; they also might need to reformat a collection of adjoining maps of disparate data structure so they could perform spatial analysis and produce derivative maps. The geoscience community recognizes the importance of standards. The difficulty has been the lack of organizational structure and committment needed to develop those standards. Functioning at a broad National level, the Federal Geographic Data Committee (FGDC) was formed to support functions like the NSDI by coordinating the development of both the Clearinghouse and various standards among the participating Federal agencies. Within the FGDC, each spatial theme is represented by a Subcommittee responsible for coordinating NSDI implementation at the Federal level within that theme (e.g., the Geologic Data Subcommittee). Especially because mapping within the geologic community is distributed among many State and Federal agencies, standards should first be developed through close State/Federal cooperation, before they are proposed as Federal standards.

The coordinating role of the National Geologic Map Database is critical to development of needed standards. After preliminary meetings including USGS, AASG, the Geological Society of America, and the Geological Survey of Canada, the NGMDB project and the AASG convened a meeting in St. Louis, Missouri, in August, 1996. At this meeting, various guidelines and standards were noted to be important to both the NGMDB and the development of digital mapping capabilities in the States and USGS. Six Working Groups were chartered, as follows:

  1. Cartographic standards -- Review and revise the USGS draft cartographic standard for geologic maps, prepare a digital version of cartographic elements, and submit to FGDC as a draft Federal standard (as Executive Secretary of FGDC Geologic Data Subcommittee, Dave Soller (USGS) is responsible for this).
  2. Data Capture -- Through workshops and technical evaluations, help to promote more efficient and useful methods for digital mapping through the coordination and sharing of expertise and information among the State geological surveys, the USGS, and others (Chair -- Dave Soller, USGS).
  3. Metadata -- Evaluate the FGDC metadata content standard for applicability to geologic map information, and develop tools and guidance that lead to greater expertise in writing metadata (Chair -- Peter Schweitzer, USGS).
  4. Data Information Exchange (also referred to as "Guidelines for digital geologic map publications") -- Produce a guideline stipulating the types of files (e.g., Readme file, FGDC-compliant metadata, graphics file) that need to be contained in digital geologic map publications, to enhance their utility (Chair -- Todd Fitzgibbon, USGS).
  5. Spatial Accuracy -- Produce a general-interest publication that explains the accuracy of geologic maps, and investigate methods for evaluating the spatial accuracy of maps (Chair -- Richard Berg, Illinois State Geological Survey).
  6. Geologic Data Model -- Develop a standard data model that represents in computer files the spatial relations among geologic map elements and fully captures the complex information contained in the map legend, to permit standard queries and creation of derivative maps, from source maps produced by various agencies (Chair -- Gary Raines, USGS).

The deliberations and results of each Working Group are posted for public inspection at the NGMDB project Web site. This Proceedings volume is an outcome of the Data Capture Working Group.

THE WORKSHOP

Despite a relatively short period of announcement before the workshop, it was very well attended. In fact, the level of interest exceeded our expectations: 70 persons attended, from 30 state geological surveys, the USGS, and the Geological Survey of Canada (see Appendix A). As befitting a technical meeting of this type, the KGS provided a Web site for attendees and interested parties (Appendix B and, for a limited duration, http://www.kgs.ukans.edu/DMT97).

Acknowledgments

The Kansas Geological Survey has earned our gratitude for hosting a productive and enjoyable meeting. I especially thank Jorgina Ross, who coordinated the meeting for the KGS and who provided all attendees with excellent support. Gina was vital to the meeting's success. Other KGS personnel who helped with the workshop were: Dana Adkins-Hieljeson, Nick Callaghan, John Charlton, LingYuan Cao, David Collins, Elizabeth Crouse, John Davis, Jim Deputy, Winston Heng, Scott Highby, Pat Moore, Jennifer Mouser, Joel Rotert, Robert Sampson, Lynn Watney, and David Williams. Gina also provided the attendees with an overview ("Digital geologic map production using the GIMMAP (Geodata Interactive Management Map Analysis and Production) system") and informal tour of the KGS digital mapping capabilities. I also note with gratitude the contributions of the following individuals: Tom Berg (Chair, AASG Digital Geologic Mapping Committee) for his help in conducting the meeting and for his continued support of AASG/USGS efforts to collaborate on the NGMDB; the members of the Data Capture Working Group (Warren Anderson, Kentucky Geological Survey; Rick Berquist and Elizabeth Campbell, Virginia Division of Mines and Geology; Rob Krumm and Barb Stiff, Illinois State Geological Survey; Scott McCulloch, West Virginia Geological and Economic Survey; Gina Ross, Kansas Geological Survey; Dave Wagner, California Division of Mines and Geology; and Tom Whitfield, Pennsylvania Geological Survey) for advice in planning the workshop's content and the suggestions to authors; John Davis (KGS) for an entertaining and enlightening keynote address; Connie Schafer (USGS) for typesetting the manuscripts; and Patricia Packard (USGS) for help with Appendix C.

Presentations

The workshop began with the keynote address delivered by John Davis (KGS). His remarks provided an interesting perspective on early development of digital mapping, and especially at the KGS beginning in the early 1970's, that lent perspective to the specific issues addressed during the workshop. His address was followed by 23 oral presentations, and various additional posters and computer demonstrations of software and digital mapping techniques. Each presentation was supported by a short paper contained in these Proceedings. These papers represent approaches that currently meet some or all needs for digital mapping at the respective agency. There is not a single "solution" or approach to digital mapping that will work for each agency or for each program or group within an agency -- personnel and funding levels, and the schedule, data format, and manner in which information is delivered to the public requires that each agency design its own approach. However, the value of this workshop, and other forums like it, is through their role in helping to design or refine these agency-specific approaches to digital mapping, and to find approaches used by other agencies that are applicable. In other words, communication helps us to avoid "reinventing the wheel." Further, workshops such as this also contribute to the evolution of GIS technolgoy and its convergence towards accepted methods and standards.

Most presentations ranged across a number of issues, so I make little attempt to organize the papers by topic. With my apologies to authors whose work I may not adequately describe, I provide here a brief description of each paper. For the sake of brevity, the presenting author only is listed. Further information about the software and hardware referred to below and elsewhere in these Proceedings is provided in Appendix C.

  1. Robert Krumm (Illinois State Geological Survey) -- overview of their GIS facilities, with an emphasis on digital map publication and print-on-demand.
  2. Warren Anderson (Kentucky Geological Survey) -- method for converting 1:24,000-scale published maps to digital format, and compilation of a 1:100,000-scale map from those files.
  3. David Viljoen (Geological Survey of Canada) -- advantages of structuring or organizing map data, beginning with data capture, to increase efficiency for storage, revision, and query.
  4. Barbara Stiff (Illinois State Geological Survey) -- specific techniques in Arc/Info for incorporating raster imagery into a geologic mapping project, to assist in the preparation of vector geologic maps.
  5. Susan Tingley (Nevada Bureau of Mines and Geology) -- cartographic preparation of printed geologic maps using Arc/Info and Adobe Illustrator.
  6. Loudon Stanford (Idaho Geological Survey) -- overview of digital map production, from author copy to plotting.
  7. David Wagner (California Division of Mines and Geology) -- methods and costs of developing 1:24,000-scale geologic map data in complex terranes, and of compiling it into 1:100,000-scale maps.
  8. Ronald Pristas (New Jersey Geological Survey) -- overview of methods, including data capture, incorporation of tabular data on rock structure, and metadata.
  9. Gary Raines (U.S. Geological Survey) -- progress report of the AASG/USGS Data Model Working Group.
  10. David Collins (Kansas Geological Survey) -- general concepts in a KGS methodology for adapting the outcrop and contact information on older geologic maps to modern topographic bases, to create new geologic maps.
  11. Jorgina Ross (Kansas Geological Survey) -- specifics of the KGS methodology introduced by Collins.
  12. Jonathan Arthur (Florida Geological Survey) -- methods used in the preparation of a Statewide map, and preparation of a three-dimensional database to support mapping in southwest Florida.
  13. Berry Tew (Geological Survey of Alabama) -- overview of methods, including preparatory steps for data capture and database development.
  14. Paul Staub (Oregon Department of Geology and Mineral Industries) -- overview of methods, with discussion of conversion of 1:100,000-scale maps to digital format.
  15. Richard Lively (Minnesota Geological Survey) -- overview of methods for data capture and release of map data.
  16. Jim Giglierano (Iowa Geological Survey) -- details of digital mapping techniques for a 1:24,000-scale, a county, and a 1:100,000-scale mapping project, using ArcView software.
  17. Rick Berquist (Virginia Division of Mineral Resources) -- description of an integrated system for field data collection and map preparation, using Abicas software.
  18. Neil Rogers, speaking on behalf of Boyan Brodaric (Geological Survey of Canada) -- description of an integrated system for field data collection and map production, and of a geologic data model, using Fieldlog software.
  19. Van Williams (U.S. Geological Survey) -- description of field data capture and preparation of GIS coverages using GSMCAD software.
  20. Tim Cowman (South Dakota Geological Survey) -- overview of methods, with discussion of a state lithologic log database and production of aquifer maps at different scales.
  21. Ron Wahl (U.S. Geological Survey) -- data capture by scanning and photogrammetric methods.
  22. Grant Willis (Utah Geological Survey) -- data capture using soft-copy photogrammetry.
  23. Eric Schuster (Washington Division of Geology and Earth Resources) -- database design and progress toward a Statewide 1:100,000-scale geologic map (this paper was submitted, but the author was unable to attend the workshop).

Resources, both people and money, are required to create digital map data from either field sheets or printed maps. Generally, agency personnel perform this activity. In some cases, sufficient personnel are not available to complete the job quickly enough. A workshop poster described the use of contracting services to perform the needed work. That information is summarized in Appendix D, which also includes the contract specifications used many times by the author to obtain fully attributed and geographically registered digital data from existing maps.

Conclusions

The workshop ended with a general discussion and suggestions for topics of future workshops. Attendees noted that the workshop had provided them with valuable information, personal contacts, and insight into the general problems facing all of us. It was the consensus that a similar workshop should be held again next year. Further, certain aspects of digital mapping were raised, and it was suggested that these topics could be the focus of separate workshops. The two topics receiving the most discussion were: 1) print-on-demand technology, including problems with available topographic map digital raster graphic (DRG) files and development of methods for plotting color geologic maps on DRG base maps that produce a graphic similar to a conventionally-printed map; and 2) automated methods for line generalization to assist, for example, in converting 1:24,000-scale maps to 1:100,000-scale.

REFERENCES

Soller, D.R., and Berg, T.M., 1995, Developing the National Geologic Map Database: Geotimes, v. 40, no. 6, p. 16-18.

Soller, D.R., Stettner, W.R., Lanfear, K.J., and Aitken, D.S., 1990, A user's manual for a method of map scanning and digital editing for thematic map production and data-base construction: U.S. Geological Survey Circular 1054, 38 p.



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