Computer-based data acquisition and visualization systems in field geology; results from 12 years of experimentation and future potential
Computer-based data acquisition and visualization systems in field geology; results from 12 years of experimentation and future potential (in LASI III; magma pulses and sheets in tabular intrusions, Sergio Rocchi (prefacer), Andrea Dini (prefacer), Francesco Mazzarini (prefacer) and David S. Westerman (prefacer))
Geosphere (Boulder, CO) (June 2010) 6 (3): 275-294
Paper-based geologic mapping is now archaic, and it is essential that geologists transition out of paper-based field work and embrace new field geographic information system (GIS) technology. Based on approximately 12 yr of experience with using handheld computers and a variety of field GIS software, we have developed a working model for using field GIS systems. Currently this system uses software products from ESRI (Environmental Systems Research Institute, Inc.) (ArcGIS and ArcPad), but the data model could be applied to any GIS system. This field data model is aimed at simultaneously increasing the efficiency of field work while adding the attributing capability of GIS to develop field data products that are more data rich than any paper map could ever achieve. We emphasize three basic rules in the development of this data structure. (1) A field GIS map should emphasize line and point objects, avoiding polygons, objects that can easily be constructed outside of the field environment. (2) Keep it simple stupid (KISS) is a critical rule for setting up data structures to avoid field GIS systems that are less efficient than paper. (3) Data structures need to develop a compromise between display and data entry, with display always trumping data entry because geologic insight is the primary goal. This paper contains two sample blank databases that illustrate these approaches for two applications: (1) generic bedrock geologic mapping, and (2) metamorphic geology mapping multiple generations of fabrics. Key features in our approach are to use display as a first-order attribute, sorting point objects into four basic types (station, orientation, sample, photo) and lines into the four basic contact types (depositional contact, unconformity, intrusive contact, fault), plus other specialized data layers where needed. Individual GIS objects are further attributed, but attributing is limited to critical information with all objects carrying a special "note" field for input of nonstandard information. We suggest that when field GIS systems become the norm, field geology should enjoy a revolution both in the attitude of the field geologist toward his or her data and the ability to address problems using the field information. However, field geologists will need to adjust to the changing technology, and many long-established field paradigms should be reevaluated. One example is the rule that all linework on geologic maps needs to be perfected in the field setting. Our experience suggests that with modern high-resolution imagery (aerial photography and topographic shaded reliefs) and digital elevation models, field work should evolve into an iterative process where map linework is roughed out in the field, refined during evening field sessions, then potentially revisited if problems arise. This procedure is particularly efficient when three-dimensional visualization is added to the system, a feature that will soon become the norm rather than the exception. We note that using these systems is particularly important for future developments in metamorphic geology, sedimentary geology, and astrogeology, but other applications are clearly also possible. For geoscience instructors who teach field geology classes, we note that it is critical that these systems be incorporated into all geoscience field programs, but research is needed on the best teaching approaches in the use of the technology.