The Nevada Bureau of Mines and Geology (NBMG) is a research and public service unit of the University of Nevada and is the state geological survey. Our scientists conduct research and publish reports on mineral resources, engineering geology, environmental geology, hydrogeology, and geologic mapping. Our public service responsibilities include earth science education projects, geologic and geographic information collection and dissemination, development of statewide geographic information systems, maintenance of core and cuttings facilities, rock and mineral collections, aerial photographic imagery, and extensive files on Nevada geology.
Before 1986, we were scribing all the line work, using wax-backed custom-ordered typography, peeling windows for color separation, and printing several thousand copies of every publication with Williams & Heintz in Washington D.C. In October of 1986, the cartography section of NBMG acquired an IBM AT for our first attempt at digital cartography. Those first years saw our efforts limited to page-size figures. We experimented with GS Draw, Generic Cadd, and finally AutoCad. Our output device was a small format HP pen plotter.
With these first attempts at digital cartography we initiated the struggle that we are still coping with today. Geologists and other authors want their published maps looking as published geologic maps have looked for the last 50 years. Our Director felt our role as a support group within a state survey was to keep our authors happy while at the same time adhering to the highest possible cartographic standards. So we began what has become an ongoing challenge to produce published digital cartography that looks like traditional cartography.
With our first attempts came the immediate recognition that our authors were not pleased with the coarse line patterns available on pen plotters. The stick-like fonts and crude symbols also left them less than impressed. For a few years we used computer-generated linework but supplemented it with stick-on type generated on IBM Composers and Zip-a-Tone type patterns. The fonts available on IBM Composers were proportionally spaced and available in either serif or sans serif faces, regular, bold or italic. The Zip-a-Tone type patterns allowed use of fine screens and detailed patterns. Using this combination of techniques allowed us to produce maps that were as acceptable to our authors as traditionally drafted maps.
In October of 1989, we ordered out first Apple Macintosh and laser printer. From what we had heard, the Macintosh and laser printer would solve many of our problems. We could have fine patterns and nice fonts and eliminate the time-consuming tasks of modifying the computer line work with traditional hand drafting. For graphic software we chose to go with Adobe Illustrator because Adobe had the foresight to provide packages of patterns that included standard US Geologic Survey's topographic and geologic patterns. We now had a functioning system that allowed computer generation of page-size illustrations which had the appearance of traditional published geologic maps.
Our next assignment was to design a process to produce large-format geologic maps that would maintain the author-pleasing traditional appearance. In 1991, we met with Joe Vigil (USGS). He had developed many custom patterns and fonts specifically for geologic applications for the Macintosh, which he shared with us. His opinion was that Arc/Info was a great analytical tool but was weak in cartographic presentation.
ESRI (Environmental Systems Research Institute) also recommended output from Arc/Info to Adobe Illustrator for final cartographic presentation. Another factor that contributed to the Macintosh solution was our final product. At that time we published all of our geologic maps as commercially printed maps. The printers we dealt with had never heard of Arc/Info and were not able to suggest any way to get color separation negatives from Arc/Info. The conclusion at this point was that if we wanted the highest quality graphic output we needed to be communicating in Adobe PostScript, the printing industry standard.
Our first large-format, full-color printed maps were digitized in Arc/Info. While still in ARC, the line work was cleaned and edited; polygons were built and filled. This file was then exported into Adobe Illustrator. We quickly learned some tricks that made the process easier. Lines should never be exported with a wide line symbol, nor with decorations, because these import as multiple lines in Illustrator. However, if lines are exported with attributes shown as color only, they can be easily separated into layers and formatted in Illustrator. For example, solid contacts could be red, dashed contacts blue, dotted contacts green, etc. When opened in Illustrator a layer for each symbol is created. Select all red lines, drag to the "solid contact" layer, and format all at one time by designating format specifications.
The cartographic finishing was all done in Illustrator. Marginal type, large text blocks, cross sections, index maps, scales, correlation charts, lists of symbols, etc. are all easily prepared in Illustrator with the click-and-drag ease of a graphics design program. The final output was color separation negatives generated by a service bureau directly from the Illustrator files. The printer used these negatives to print the final maps.
The shortcoming with this procedure was the digitizing. At NBMG, digitizing is done by student employees. Student employees by their very nature are temporary and lack a depth of experience. Since our primary task is turning author's field sketches into printed maps, a degree of geologic and cartographic experience is required to make the decisions that are necessary to interpret these sketches. We tried explaining to the students about the cartographic representation of geologic contacts and faults. Often the students did not have the background or interest to incorporate this theory into their digitizing. When one student would grasp the implications and start producing acceptable geologic line work, he would graduate and leave. Because the students do not work full time, digitizing is also exceedingly slow. Many repetitions of author proofing and revision were necessary. Budget constraints eliminated the possibility of hiring permanent digitizing employees.
Next we tried scanning the author's field maps and having them vectorized. We published several geologic maps using this procedure. This approach eliminated the use of low-priced, inexperienced employees to perform the labor-intensive job of digitizing. The vectorized files were cleaned and edited in Illustrator by experienced geologic cartographers. However, the process is time-consuming and as is true everywhere, there was always pressure to produce the maps with the same quality but faster. Being a relatively small state survey with an extremely limited budget, owning our own large-format scanner and vectorization software was not a viable option. That meant that we were at the mercy of the scheduling of the vendor providing the vectorized files. At times, weeks were wasted waiting for delivery of files.
We worked to develop a procedure that did not depend upon circumstances beyond our control. We are currently dividing each map into small segments and scanning them in-house on a page-sized scanner. We place 2.5' quad tics on our 7.5' quads and 7.5' quad tics on our 30' x 60' quads. We generate a grid of these tics in Arc/Info and export it to Illustrator. The tic grid from Arc/Info gives us a scale-true grid with which to register the small segments. The small segments also allow us to use high resolution scans and yet keep each file to a manageable size. Illustrator has the capability of rectifying any distortion in the scan to match the true tic grid from Arc/Info. We generate transparent scans so that they can be overlapped as they are placed in Illustrator This insures smooth transitions from one small segment scan to the adjacent scan.
Once a small segment scan is placed in Illustrator, the geologic linework is drawn. Illustrator provides great flexibility in its curve drawing capabilities. On tight, curvy contacts, you can use the freehand tool. This produces lines very much like a scriber or a technical pen. On gentle, flowing curves, the pen tool is recommended. This produces smooth, generalized curves, similar to those drawn with a flexible curve or French curve. This type of line (e.g., long, regional dashed faults) was always very difficult to digitize smoothly enough to please our authors. To make tracing these curves even easier, we have a pencil-like stylus that feels and handles like a traditional drafting instrument.
Since we began capturing lines in Illustrator with the curve tools, we have received many favorable comments from geologists. Since the tracing of the scan can be done at any level of magnification, it is also much easier to exactly duplicate the author's positioning and conformation of lines. This technique is also extremely quick. When we used student digitizers, most 7.5' quads took an average of two months to generate acceptable line work. The current procedure of capturing lines from a 7.5' quad takes 8 to 12 hours. Our authors also spend significantly fewer hours of their time with repetitive proofing and fine tuning of digitized lines.
After the lines are generated, they are output to a HP DesignJet 755CM and proofed by both a cartographer and the author. Lines are then separated, by type, into different layers in Illustrator. These lines are then exported to Arc/Info for creation of polygons. Currently we use Deneba's Canvas as a translation bridge between Illustrator and DXF. The resulting file can then be imported into Arc/Info. Each layer plus the border is exported separately. As they are translated into Arc/Info a "select all" can help to attribute all lines of a particular type very easily and quickly. As the layers are converted into coverages and globally attributed, they are appended together. After some minor editing, polygons are then built. Printing colors are selected following USGS suggestions for geologic units by age. A shadeset is created using these selected colors. The filled polygons are then exported back to Illustrator. In the current version of Arc/Info (ver. 7.0.4), we use EPS export rather than Illustrator export. This change has eliminated the earlier problem of "tie-lines" within the polygons that had to be mitigated in Illustrator.
In Illustrator, each layer is then formatted, basically following the USGS "Cartographic and Digital Standard for Geologic Map Information" (Open-File Report 95-525). After all formatting is finished, filled polygons from Arc/Info are merged with the file and marginal information is added. After author's modifications are addressed, the file is ready for our vendor to create color separation printing negatives. If modifications have been made by the author and if the geologic map is to be released as a digital product, then the Illustrator layers are again exported to Arc/Info. Again the layers are globally attributed and appended together into a single coverage with attributes.
These techniques evolve quickly. We have many aspects that need improvement and we are currently working on better solutions to most of the problems. With developing computer technology and opportunities for sharing such as the AASG-USGS Workshop on Digital Mapping Techniques, we can continue to progress toward the better-faster-cheaper, while maintaining high quality geologic maps. One avenue we are currently investigating is Avenza's MAPublisher, a bridge between Arc/Info and Illustrator. As a plug-in that allows Illustrator to retain GIS functionality, MAPublisher should make the transition from geologist's sketch to published map even more efficient.
Last year it was decided that Nevada needed to print more geologic maps than our budget could support . We have adopted a couple of responses to this situation. Most of our geologic maps are still traditionally printed in full color. Some, especially those of more limited interest, are printed in black and white. These black and white printed maps go through all the same steps for production as the full-color maps. After printing in black and white, custom plotted full-color copies are available as a "on-demand" publication. Some, especially those with a very limited audience, are released only as "on-demand" publications. Nearly all of our geologic maps published in the last year are available as digital files. These are released as Arc/Info coverages, as Arc/Info .e00 export files, and as Portable Document Format (PDF) files. Currently our digital Arc/Info releases do not carry marginal information, topographic base information, nor point symbol notation. The PDF files contain all components of the published map with the exception of the topographic base, which at NBMG is still composited photographically by the printer.
During the last few years, we have been contacted by individuals and organizations desiring a high quality, traditional, cartographic publication. They have line work in Arc/Info and are not satisfied with the quality of hardcopy output from that software. Because of our experience in this aspect of geologic cartography, we have assisted others by taking their Arc/Info coverages and reformatting them in Illustrator, replacing type and symbols, designing layouts and creating geologic publications of traditional appearance. Our most ambitious undertaking to date has been the formatting of the Rhode Island State Geologic Map. We are also currently working on two projects of reformatting Arc/Info files as Illustrator publications for the USGS. We are still fulfilling that instruction from our Director of many years ago, "...make those geologists happy."
Computer, Purchase Date, Hard Drive (in mb)/Memory (in mb):
Quadra 900 (with PowerPro Accelerator), 11-91, 160/54
Quadra 800 (with PowerPro Accelerator), 2-93, 1430/40 (used mostly for desktop publishing)
Centris 650 (with PowerPro Accelerator), 8-93, 230/90
PowerMac 7100, 7-95, 680/80
PowerMac 7500, 10-95, 518/114
Sun SPARC Station, 9-92. 1000/32
HP DesignJet 755CM large format ink jet plotter
Tektronix Phaser III phase-change tabloid printer
PrePRESS VT1200, tabloid, 1200 dpi laser printer
LaserWriter Pro 630, page-size 600 dpi laser printer
LaserWriter II NT, page-size 300 dpi laser printer
GTCO 24x36 digitizing tablet
Agfa Argus II color page-size scanner
Canon page-size scanner
Datacopy 730 GS page-size scanner
Wacom ArtZ II Tablet with Stylus