Session 1: Digital Cartography

Prepared by Sean Murphy Stone, U.S. Geological Survey, Menlo Park, California

The digital cartography session, convened by Bob Davie (Ontario Geological Survey, Sudbury, Ontario), covered a full range of issues--collection of digital data in the field, production of digital maps using a GIS system, and print-on-demand of digital maps. Cost and timely production of geologic maps are of such interest and relevancy that a special one-day registration was permitted for this session.

Geological Map Production Using ARC/INFO

Vic Dohar, Cartographer, Earth Sciences Sector, Natural Resources Canada, Ottawa

Vic started off the session by describing how the Geological Survey of Canada (GSC) produces digital geologic maps using ARC/INFO (A/I), a GIS system from Environmental Systems Research Institute (ESRI). Development of the A/I-based system in the cartography section at the GSC started in 1989, production mode was reached in 1993 (first map printed), and all staff were trained for map production in 1994. Further refinements have included additional training, hardware acquisition, and implementation of an automatic backup system.

The system now includes 21 networked SPARC workstations, 3 SYNERGY and 1 Calcomp electrostatic plotters, digital graphics for figures (PCs), photomechanical production of figures (Macs), and an AutoCAD workstation (PC). What is needed to maintain the system is a dedicated, well-trained staff; an applications specialist to streamline the production process; a backup system for data integrity; continued training; technical support to keep up with changes in technology; and a healthy working environment.

The production process involves converting (digital or hard-copy data) geologic map and base data into a systematic GIS format, followed by editing of the data and attributing all features. The map data and marginalia, such as figures and a correlation, are placed in an overall layout with surrounding information. Once the map exists in the database, output can be on-demand plotter printing, film output for offset printing, a CD-ROM, or WWW/Internet release for GIS applications. The database features standard naming conventions, a standard data structure, a symbol library, and an archiving procedure. The data are readily understood, expandable to other data sets, and portable to other systems. Map production at the GSC has grown significantly since 1993. In 1996, the ratio between maps published on-demand versus using offset printing is 50:50, but is expected to change to 80:20 as plotter technology improves or if offset printing costs become prohibitive.

Future goals for digital map production include more user-friendly production processes and applications; a generic symbol designer portable across various software applications; Internet applications; and faster, cheaper hardware. The WWW homepage is being developed to make available sample digital data sets; a symbol library; production and training manuals; files and programs for production; and FAQ.

CARIS as a Field-Based Geological Mapping and Map Publication System:
The Verde Basin Project, Arizona, USA

H. Wouter van de Poll, Co-Director, GIS Laboratory, Department of Geology, University of New Brunswick

The second speaker, H. Wouter van de Poll, described how he and colleague Paul F. Williams set up their GIS Lab and, in cooperation with Universal Systems Ltd. of Fredericton, New Brunswick (developers and vendors of CARIS GIS), developed the CARIS GEMM (Computer Aided Resources System Geological Mapping Module). The purpose was to design and implement a field-based geologic mapping system capable of producing full-color, GIS-ready, geological maps available for on-demand publication immediately after completion of the fieldwork. Because they, like most applied geologists, did not come from a technical computer background, Wouter and Paul wanted an easy-to-use, low-cost system, which means PC DOS/Windows based. As a result, there are now two fully compatible CARIS systems available--CARIS for the PC and CARIS for UNIX. For field work, Wouter uses a laptop PC with the GEMM software. The system is spatially rather than database driven to facilitate data input and to mimic time-proven conventional geologic map-making procedures.

To test the system, Wouter initiated in 1993 a geological mapping project in the Verde Basin, Arizona. This required a digital base map, preferably at a scale of around 1:125,000, which was apparently not available. In addition, only about half of the fourteen 1:24,000-scale U.S. Geological Survey (USGS) topographic maps needed to cover the Verde Basin were available at the time, so a U.S. Forest Service map for the area was used as a hard-copy base map. By the end of the 4-month mapping project, Wouter had produced a hand-drawn and hand-colored lithofacies map subdividing the Verde Formation into seven lithofacies. In the meantime, the computer had crashed and the test of the GEMM software was postponed.

Because of redesign of the software and other constraints, Wouter did not get back to the project until the fall of 1995. By then, the need for an accurate digital base map was solved quickly and efficiently in the GIS Lab by using USGS digital elevation data for the fourteen 1:24,000-scale topographic maps and combining the derived elevation contours with digital line data (e.g., roads, streams, etc.) obtained from the Arizona State Lands Bureau. Although the 11 million elevation points took CARIS several days to process, the time was significantly less than the 115 days it would have taken to hand-digitize the 14 maps. The resulting map is comparable in accuracy to the 1:24,000-scale topographic maps from which the CARIS-produced base map was derived. After the base was prepared, the preliminary digital geologic map for the Verde Basin was created in December 1995 by adding the geology from two sources: (1) an existing 1963 geological map by F.R. Twenter and D.G. Metzger and (2) the lithofacies map produced by Wouter in 1993.

In early 1996 Wouter returned to Arizona to field-check the accuracy of the map and submit the preliminary geologic map to the Arizona Geological Survey (AGS). The significantly improved quality and readability of the base map enabled Wouter to re-map certain areas for greater detail and accuracy, which was done in March and April. During this period, geologic revisions were added to the map on a daily basis with the aid of the computer. After completion of the revisions, the topology was rebuilt to enable colors to be added and to make the geologic map GIS-ready again. From the field, Wouter forwarded the revised map file, complete with colors, via the Internet to his GIS Lab for printing on an HP InkJet color plotter. Printing at a scale of 1:75,000 took a few minutes at a cost of approximately $3.00 per running foot ($7.00 for the map). A few days later the completed map was returned to Wouter in the field and hand-delivered by him to the AGS for editorial review. This process took 8 days from completion of the fieldwork.

Wouter pointed out that creating and/or updating a geologic map digitally in the field not only enables the geologist to be more productive, thereby reducing the cost of producing a geologic map, but, more importantly, it dramatically speeds up release of the most recent geologic data. Using the right software, GIS-ready geologic maps can be readily produced in full color for improved visualization and for overlay analysis. Also, once in digital format, geologic maps can be easily revised or updated and reproduced on demand.

The full CARIS requires approximately 260 MB of disk space and 16 MB of RAM, although approximately 45 MB of disk space will suffice for the CARIS GEMM only, to add the geology in the field. A portable generator can be used to power the computer in areas where electricity is not available.

The Evolution of Digital Print-on-Demand Maps in the Ontario Geological Survey

Tom Watkins, Senior Cartographer, Publication Services Section, Ontario Geological Survey, Sudbury, Ontario

Tom discussed how color map production in the Ontario Geological Survey evolved from manually produced maps in 1984 through semi-automated map production, introduced in the late 1980s, to completely automated digital production that began in 1992 and was fully operational by 1995. Manually prepared maps took about 6 to 8 months to prepare and cost about $20,000 to be ready for printing. Semi-automated techniques took only slightly less time but saved about $5,000 in production costs. Today, fully digital maps can take as little as 1 month to prepare at a cost of about $2,000 for production. As of April 1995, map printing switched from primarily offset printing to exclusively print-on-demand using an electrostatic plotter.

The solution for entirely digital map production was a turn-key system from Intergraph. The system consists of a configuration of 4 workstations with 64 MB of RAM, 3 GB of disk space, and a file server using a Clix-based operating system from UNIX; a Versatec 44-in electrostatic plotter; and a MapSetter 4000 Scanner/Film recorder. Intergraph software includes MicroStation, Map Publisher, and Modular GIS Environment. Key elements for implementation of the new system were classroom training and on-site workshops.

Maps submitted for publication consist of three separate digital components--geologic vector data, base-map vector data, and marginal or legend ASCII data. Geologic vector data are created in-house by the geologists, who use AutoCAD or MicroStation (CAD) software, or inked linework is sent to outside contractors for digitizing. Early testing and conversion of data revealed problems that had to be resolved, such as poor-quality digitizing, inconsistent layering conventions, unstructured base-map vector data, and software incompatibility. Furthermore, these problems identified the critical need to define standards for all aspects of the digital process.

To define standards, several small working groups were formed. For base-map data, less than 100 (out of more than 1,000) features were identified as necessary. For geological features, more than 1,600 point symbols (Open-File Report 5909) and nearly 1,000 linear features (draft report) were identified for the features library. Standards for capturing data and establishing layers when digitizing were also developed, and a manual for digitizing was prepared. A standard format and coding for marginal data was also established. Once all the features on the map were identified and coded, the digital cartographic symbology was created; this symbology matches that used in offset printing as closely as possible.

The map production process for a color print-on-demand map can be summarized in the following steps:

  1. Import or convert geologic and base-map data into MicroStation to ensure that all standards are met; if not, return report to the geologist for modification.
  2. Strip base-map data into one MicroStation file and the geology data into another.
  3. Import ASCII marginal material or surround data into a third MicroStation vector file where it is formatted and added to the overall layout.
  4. Using Intergraph's GIS software, feature-code all vector elements in each of the three files. Data are now GIS ready.
  5. Create a fourth vector file that contains color polygons identifying geologic units.
  6. Symbolize all features in the four files, including coloring polygons, assigning line styles, and changing text fonts and sizes.
  7. Plot a copy of the map and send it out for review.
  8. After review by the author and editor, incorporate all corrections and changes.
  9. Merge all four corrected production files into a final composite file.
  10. Print 40 paper copies and send to Sales Facility. More copies are printed as needed.
  11. Send the composite vector file to the digital map database in ERLIS (Earth Resources Land Information System).

In addition to the print-on-demand paper copy of the map, a digital version, either in native MicroStation or DXF format, is available through ERLIS.