In recent years, the Minnesota Geological Survey has moved steadily in the direction of creating and publishing maps and other materials using computer-generated digital files instead of traditional cartographic and offset printing methods. The transition from paper to digital-file formats has largely coincided with the availability at reduced cost
of more powerful personal computers, inexpensive random access memory, and numerous improvements to graphics and publishing software. The MGS has created both maps and booklets in digital format and is currently working on several projects for which the end product will be digital. For example, the surficial geology map of Waseca County went from data capture through the making of composite, screened negatives for the printer entirely as a digital file. Other digitally created publications include open-file maps of Houston County, aerial gamma radiation maps of Minnesota, and educational pamphlets on Minnesota geology. A booklet produced for one of Minnesota's state parks was printed from a digital file and made use of text, scanned 35-mm color photographs, and computer-graphic files.
Conversion of data from analog to digital format at MGS is primarily done by scanning at a service bureau, in-house vectorization, in-house digitization of point data, and reading of existing digital data (for example, GPS points). We do not refer all data capture operations to service bureaus because we prefer to keep some control of the data as they are being entered. Geologists enter some map information into database files while in the field, and for one project outcrop locations are being entered by the geologist onto digital USGS base maps, from within Arc/Info. For the present and probably for the near future, initial geologic maps will still be created by hand before being scanned into a digital format. Following the data capture stage, the majority of the MGS map compilation and production is done on Sun workstations using Arc/Info. Ancillary graphics and text are created and compiled on Macintosh PowerPc computers using Adobe Illustrator, Adobe Photoshop and Microsoft Word. Final compilation and page layout is completed using Adobe Pagemaker. These programs generate files that are readily integrated with each other and with software used by printing companies for pre-press preparation and film making.
The evolution to digital map production at MGS began with the purchase of Arc/Info for a DOS personal computer platform, but it was greatly enhanced with the use of Sun workstations and more robust versions of the ARC software. The most recent evolutionary step has been the integration of ARC output into relatively user friendly Macintosh illustration and page layout software for final compilation and publication. Our recent use of personal computers to produce a single composite file from Arc/Info and other graphic and text sources allows us to create higher quality printed text over what is available from the ARC environment. With this integration, we are in the process of transferring the responsibilities for a final product from geographic information system (GIS) operators to editors and graphic artists who are more familiar with the personal computer software, editing, graphics, and publishing. We have also benefited by developing a good working relationship with several printing shops which have allowed us some experimentation with various digital formats and file types to identify which would produce the best product. Most printing shops are also in early stages of accepting and working from digital files and are quite willing to work with us on meeting our requirements.
The evolutionary process has not always been without problems. Static or shrinking budgets have restricted or prevented initial purchase of up-to-date computers, software and networking systems. We, possibly like other organizations, have more than one computer system in-house and certainly have more than one generation of hardware and software. With manufacturers constantly changing hardware and software, end users such as the MGS find it very difficult to keep up. We find that even though most of the computers in the organization are fine for general tasks, they often won't run the newest versions of software. Although not always a problem internally, keeping current with software is important when dealing with those outside organizations such as print shops that may use the latest versions of software. We also have the problem that MGS staff, particularly outside of the GIS area, are not formally trained in much of the software in use, but learn as they go, or as needed. Some of the increased productivity that computers are expected to provide is therefore being lost to learning the current software to do a particular job. That person may be doing an entirely different job when a new publication is ready, and someone else will learn what is needed to complete the job. In small organizations like the MGS, with limited staff, this needs to be factored into timelines for completion of projects.
Map production at MGS is tied in heavily with use of an appropriate geographic base. In the past, we have acquired negatives from the USGS, used Tiger (census) and digital-line-graph (DLG) files and most recently, have begun to use digital raster graphics (DRG) files from the USGS. In the move to digital compilation, digital-base files are useful in putting together a complete product. Although we have used non-digital base maps when printing a geologic map from a digital file, most of the new contracts specify that a final product be provided in digital form, therefore requiring the base also to be digital. The MGS is currently acquiring all topographic maps of Minnesota in DRG format as they become available and is moving away from the Tiger format as a digital base. Base files in DRG format work well because they supply topography and complete annotations and are usually more accurate than Tiger and DLG files. They also are available at standardized 1:24,000, 1:100,000 and 1:250,00 scales. Although we save time by not correcting and annotating the Tiger base files, the DRG files present some new problems that we are just beginning to solve. For example, the DRG files are TIFFs -- bit-mapped images -- rather than vector-line plots. Editing individual components of an image is more difficult and the line quality is poor for fine lines. DRG files are also very large and require substantially more computer memory and disk space than vector files. We are also still looking for a good method to transform DRG basemaps so they will print as screened, transparent grey lines over color.
The primary users of maps and reports from the MGS are the public, county and state officials, state departments, and environmental, mining and public relations organizations. As the availability of digital production formats has increased, so have the options for output to our product users. Within the ARC environment, maps can be sent directly to a plotter, or can be transferred by disk or network, for additional processing or to a printer for making film. Data and maps can also be prepared as ARC export files for transmittal to groups and organizations that wish to use the information for their own purposes. Additional output options include on-demand plotting of maps on a wide-format plotter, laser printing of text and photos, and network accessible electronic formats such as Adobe PDF or Sun TAR files on our FTP site. We presently have several files and reports available via an FTP connection or via links from the MGS Web homepage (http://188.8.131.52/mgs/).
Although our capabilities of creating output have increased, each type of reproduction and output process currently available, including traditional ink drafting, cartography and offset printing, involves trade-offs. Currently no file type is optimal for all types of reproduction. Transfer or printing of electronic files can present problems if networks are slow or unavailable and they may be printable only on certain types of printers or plotters. On the other hand, digital files can be updated, and changes published, without having to make obsolete hundreds of printed copies of an older version. We have recently updated our Geologic Map of Minnesota, Bedrock Geology (S-20). Easy digital updates raises the question of bibliographic tracking. For instance, when and how are the original and subsequent revisions (both major and minor) recorded for citation?
In the move to a digital publication process, the MGS as an organization has begun to re-examine the process of map preparation and production from the geologist conducting field work, to technical review, to data capture and input into the GIS system, to editing, final layout and printing. We view this as an ongoing learning process and, while not without difficulties and drawbacks, is a move in the direction of the future. Given the constraints of limited resources, mysteries of finances, infrastructure, personnel and experience, and the rapidly changing playing field of digital publishing, our results have been satisfying. We are well on our way to achieving our objectives of disseminating geologic maps and other research results in a timely, cost effective, and widely accessible manner through digital as well as non-digital means.