GIS DATA STRUCTURE FOR GEOLOGIC MAPPING USING INTEGRATED PRECISION DIGITAL TECHNIQUES

New techniques in digital geologic mapping with multiple survey instruments create many challenges in managing data in GIS. The large amount of data collected must be properly integrated and uniformly named and cataloged to prevent loss of data and repetition of work. The contents and history of each file must also be accessible for later identification. During a month of field work with a nine-person digital mapping team, outcrop surface maps were created to document the deformation associated with the eastern contact of the Late Devonian Waldoboro pluton. With the large amount of data being collected and processed, it was necessary to create a data model in GIS which preserves back-up files at all stages of data formatting, creating a “trail of bread crumbs” for the processing and analysis procedures. The instruments used in the survey included 3 Trimble Geodimeter 608 Series total stations, 3 Trimble 5700 RTK GPS, and 3 GeoXT handheld GPS unts. Georeferenced digital and high resolution analog photography was also utilized. The typical data output of these instruments amounted to 3000-5000 measured points, and 10-20 files per day. Survey work was tied to a single datum when possible and all data was collected in a standard coordinate system (WGS-84; UTM Zone 19N). Each file was exported in a standardized .csv format compatible with the data sets of each instrument. A 9-character coded file name system was used to include the location, date, instrument number, and feature type for the individual data files. Data was processed in the field on Toughbook CF-29 laptops after every half day of work using Excel and ArcMap to convert the raw point files to shape files in GIS. A uniform file hierarchy and naming system was devised to maintain the data structure as the daily files accumulated. Once all shapefiles were finalized in ArcMap, the raw and backup data were archived and a final data file set was created for use in analysis. A standard metadata form was created and attached to each new shapefile with information about the location and date of survey, type of data collected, and the workers who created and processed the files providing easy tracking of data history. The effectiveness of the data model allowed us to successfully maintain a multi-user interactive analytical database that contained approximately 10 gigabytes of geologic data.