<acronym>USGS</acronym> OFR 01-223: Conclusions From Four Years Collecting Digital Map Data Using a PDA

Digital Mapping Techniques '01 -- Workshop Proceedings
U.S. Geological Survey Open-File Report 01-223

Conclusions From Four Years Collecting Digital Map Data Using a PDA

By Van S. Williams

U.S. Geological Survey
Box 25046, MS 913
Denver Federal Center
Denver, CO 80225-0046
Telephone: (303) 236-1289
Fax: (303) 236-0214
e-mail: vwilliam@usgs.gov

INTRODUCTION

Recording geological field observations on a personal digital assistant (PDA) is a practical and effective first step toward digital map compilation in the field. A small investment in equipment and time can increase productivity substantially. Advantages include elimination of digitizing of attitude symbols and of double entry of numeric data; notes and photos linked directly to the draft geologic map onscreen, quick search of notes for key phrases; reduced risk of data loss, more compact and portable note archives, and more legible and better organized notes that can be shared across a mapping team. Disadvantages are the cost of the PDA, time investment to become skillful at hand writing intelligible to the PDA, and hand writing recognition that is generally slightly slower than pen on paper. Advantages of a PDA are multiplied when used in conjunction with GPS, a laptop computer, and a digital camera. In addition to holding traditional field notes, PDAs support sketches, data entry forms with check boxes and pull down lists, drill hole databases, and even topographic base maps and orthophotos.

DISCUSSION

Field geologists engaged in geologic mapping are pressed by ever increasing expectations on the rate of production while at the same time they are given the additional task of delivering the data in digital form. One response has been to try to increase efficiency by developing and adopting practical techniques to collect points and lines in digital format during the course of field work, rather than collecting analog data by traditional methods and converting it to digital format in the office. The Canadian Geological Survey (Brodaric, 1997) pioneered digital field compilation using the original PDA, the Apple Newton. USGS field mappers have followed and now have several years of experience using later generation PDAs such as Palm Pilots or Pocket PCs (Walsh, 1999a, 1999b, Williams, 1999). In this brave new world the rapidograph, greenline, and field notebook are becoming superfluous.

To date, PDAs at the USGS have been used primarily to record point attributes, either on customized data entry forms or as freeform notes and sketches. The recent introduction by ESRI of ArcPad software running on some Pocket PCs has allowed some users to begin also collecting lines drawn over map or orthophoto images. Previously, methods of line collection in the field described by Kramer (1998) required much heavier and more expensive specially constructed ruggedized laptop PCs.

Methods used for collecting field notes on Palm Pilot PDAs at the USGS fall into two main categories. One uses a system of forms with text boxes, check boxes, and pick lists to populate a database. These forms can be designed fairly easily using the Pilot Forms program from PenDragon, a Visual Basic addin from AppForge, or other programs. Forms for Windows CE PDAs can be designed using Microsoft Embedded Visual Basic, which is a free program that requires some programming skills. To a limited degree they can also be designed within ESRI's ArcPad application.

A form-based system may be the best choice to ensure complete data collection to populate a highly structured database, but it may not be the best approach to entice beginning users. Perhaps for that reason, some USGS geologists prefer to use freeform notes. From these geologist's perspective, forms are slower, a little more complicated to learn to use, and may be perceived as stifling individuality. Few field geologists collect their data on paper forms, and most will be more receptive to recording data digitally if not required to change their familiar format. Later, they may come to see some convenience in customizing forms to fit their own preferences.

Numeric attitude data recorded in freeform notes entered using the Palm "Memopad" or the Pocket PC "Notes" applications can still be extracted automatically to generate attributed point databases if the numeric portion is flagged (Williams, 1999). This requires more programming support than a forms-based approach, but appears simpler to the geologist in the field. Digital field photos and sketches drawn in PDA paint programs can be linked to the notes and database on a laptop PC or even on a pocket PC-type PDA.

In addition to generating digital field notes, PDAs offer the geologist quick reference to large graphical databases while in the field. For example, a geologist in the field drawing contacts between glacial geologic units may have to rely excessively on landform interpretation in areas of poor exposure. Referring to a database of water well drillers' logs stored on the PDA may provides a peek into the subsurface and improve the interpretation.

REFERENCES

Brodaric, Boyan, 1997, Field Data Capture and Manipulation Using GSC Field log v.3.0, in D.R. Soller, ed., Proceedings of a Workshop on Digital Mapping Techniques: Methods for Geologic Map Data Capture, Management, and Publication U.S. Geological Survey, Open-file Report 97-269, p. 77-81, https://pubs.usgs.gov/openfile/of97-269/brodaric.html.

Kramer, J.H., 1998, Advances in Digital Field Mapping: Geological Society of America Annual Meeting, Abstracts with Programs v.30(7), p. A-256, http://www.geosociety.org/.

Williams, V.S., 1999, Simple Techniques Used at the USGS for Compiling Digital Geologic Maps in the Field: Geological Society of America Annual Meeting Abstracts with Program, v.31(7), p A-191, http://www.geosociety.org/.

Walsh, G.L, Reddy, J.E., Armstrong, T.R., Burton, W.C., 1999a, Geologic mapping with a GPS Receiver and a Personal Digital Assistant Computer Streamlines Production of Geologic Maps: Geological Society of America Annual Meeting Abstracts with Program, v.31(7), p. A-192, http://www.geosociety.org/.

Walsh, G.J., Reddy, J.E., and Armstrong, T.R., 1999b, Geologic Mapping and Collection of Geologic Structure Data with a GPS Receiver and a Personal Digital Assistant PDA Computer, in D.R. Soller, ed, Digital Mapping Techniques '99 -- Workshop Proceedings: U.S. Geological Survey Open-file Report 99-386, p. 127-131, https://pubs.usgs.gov/openfile/of99-386/walsh.html.

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