Contour map showing elevation

UNIVERSITY OFWISCONSIN

EAU CLAIRE

UNIVERSITY OFWISCONSIN

EAU CLAIRE Mark D. Aurit, Amy D. Landis, Garry L. Running IV, Department of Geography, University of Wisconsin-Eau Claire, Eau Claire WI 54702-4004 E-mail: auritmd@uwec.edu,

and Tim D. Morrell, Department of Geology, University of Wisconsin-Eau Claire, Eau Claire WI 54702-4004.

Using GPS, GIS, and Computer Cartography to Improve Archaeological Site Mapping: A Case-Study from Southwestern Manitoba

The purpose of this paper is to present research designed to determine if computer-generated topographic maps can replace hand-drafted maps generated by field archaeologists. Preparation of detailed topographic maps is a routine part of archaeological fieldwork in North America. Archeologists in the field survey points, and then maps are painstakingly hand-drafted in the laboratory "after the fact". Considerable time and effort better allocated to archaeological research is directed toward mapping production, and the maps are not available in a timely manner. We compared a hand-drafted topographic map with a computer-generated map. The computer-generated map was produced using Surfer. Map comparison was conducted in a GIS. Polygons of ".5 meter contour slices" were delineated from both maps, compared, and the percentage of polygon non-overlap was calculated. Though analysis is ongoing, the following can be reported: 1) computer-generated maps a far less time-consuming to produce; 2) archaeologists indicate both map adequately address their needs, but the hand-drafted map is more detailed; 3) discrepancies between maps do not reflect limitations inherent in computer cartography. Rather, they reveal a need for improvements in survey methods. We recommend: surveying more points, using more accurate range finders, and adding a GPS/GIS-trained geographer to archaeological research teams.

Abstract

GIS-ready Archeological Field Cartography of Tomorrow: An Example from the University of Wisconsin-Eau Claire

Mapping ProjectOriginally, we intended to use the surveyed points collected in the "traditional" manner described previously to generate a DEM using Surfer 3-D mapping software, generate a topographic map from there using ArcView, and compare the accuracy of the two maps. We found retrofitting surveyed point data so collected to a GIS-ready format was not possible. Instead, we provide this example of a field mapping technique that will produce GIS-ready topographic maps of archaeological sites . *NOTE - Below is a locational map of the site-specific topgraphic map study area at the University of Wisconsin-Eau Claire

This project is part of a larger interdisciplinary archaeological project entitled, "Changing Opportunities and Challenges: Local-Scale Human-Environment Interaction Within the Canadian Prairies Ecozone." Four localities across the prairie province will be under study. One of the main objectives is to develop a consistent GIS based spatial data set for the four localities, including the Lauder Sandhills area, within which is located the Flint Stone Hill site. GIS spatial databases must include mapped cultural and physical elements at the local and site-specific scale. A major component of the GIS spatial data set will be detailed, topographic maps of archaeological sites.

The purpose of this poster is to address the following research question:

"How can detailed topographic maps of archaeological sites be prepared in a manner that serves the needs of archaeologists in the field AND can

be included in the unified GIS spatial database?"

Step 1: Select your survey site Step 2: Create a grid to overlay on an aerial photograph of your site.Step 3: Using a dGPS, collect a minimum of 100 points per square on the grid. Step 4: Download your data and manually digitize features such as rivers for visual appeal. Step 5: Export your data into ArcView and run script to calculate your elevation (Z) data. This will allow you to create a DEM of the site.

Color Digital Elevation Model (DEM)

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Surfer Contour and 3D Elevation Maps

3D Elevation models with different aspect

Conclusions"Traditionally" prepared topographic maps of archaeological sites provide acceptable map accuracy for archaeological purposes but have some significant disadvantages associated with them, notably: *They are far too time-consuming to make *Changes and additions cannot be made easily *They produce maps that cannot be directly inputted into a GIS database

Topographic maps of archaeological sites offer signifigant advantages: *dGPS technology is sufficiently accurate for this purpose (certainly as accurate as traditional survey methods we describe) and error is systematic and quantifiable.

*Additional point data can be easily incorporated into the GIS database and new maps can be created easily

*dGPS based GIS-ready topographic maps can be produced in the field. Input from archaeologists can be incorporated yet archaeologists can concentrate their efforts on archaeological research and not on field cartography.

Additional spatial data can be added to the GIS

Recommendations*We recommend dGPS technology and specialists be included in archaeological research teams.

*Moreover, we recommend ALL archaeological site mapping be conducted in a GIS-ready format.

Acknowledgements

*The UWEC Office of University Research and Geography Department for the funding.*The UWEC Deparment of Geography for the use of equipment.*Dr. Sean Hartnett, Department of Geography (UWEC) for his GPS wisdom and help with this project.*Dr. Garry Running, Department of Geography (UWEC), for his guidance and knowledge.*Dr. Scott Hamilton, Lake Head University (Canada) for letting me use his hand-made contour map of the Flintstone Hill Site.*My friends Justin Valeri and Matt Demuth, for their help gathering the GPS data in Eau Claire and the organization of my poster.*The 1999 Archeological Field crew, Dr. Matt Boyd, Amy Landis, and Tim Morrell for the great time in Lauder!

Purpose

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Archaeological Field Cartography Today: A Case Study from Flintstone Hill

*Establishing a 'relative datum"

*Survey points with: laser level (Z axes), Brunton compass (bearing along ray from known point), laser range finder (distance along bearing from known point) to survey X,Y, Z for points within the site.

*Establish secondary instrument positions with X, Y, and Z values known, relative to the 'relative datum", survey more points.

*Plot points on graph paper, generate contour lines by hand.

Disadvantages of The Tradtional Method

TIME. Very time-consuming to prepare! Trained archaeologists are taken from excavation and primary research for considerable periods of the field season.

ACCURACY. Accuracy limited by the resolution of the survey equipment. Laser level is accurate to within a few cm in the Z axis. Brunton compass bearings are accurate to within a degree if care is taken. Laser range finder accuracy is +/- cm across short distances but up to +/- 100 cm in distances over ~ 75 meters). Plotting points on graph paper by hand adds an additional error source. All error is difficult to quantify.

NON-DYNAMIC. Once generated from

After the field work is completed the archaeologist must analyze an overwhelming amount of tabular data to create a topographic map. Hundreds of pages of documentation must be compiled.

Advantages of "Traditional" Method

*Survey technique and instruments are simple in design, problems are easy to identify and correct in the field.

*Archaeologists can identify areas within the site where varying degrees of accuracy are required and collect X, Y, and Z data for more or less points as needed.

Archaeologists have used traditional methods of surveying to create detailed topographic maps of their sites. As seen in the photos above, a laser level or theadolite are used to gather topographic information from sites. After this field data is collected the archaeologist spends time plotting point data in order to begin extrapolating contour lines.

This is an example of the meticulus work invoved in manually creating a topographic map of the Flintstone Hill study site.

To make this map more visually appealing, the map has been redrawn using Adobe Illustrator 8.0

*Location: Lauder Sand Hills in Southwestern Manitoba, Canada*Physiography: Saskatchewan Till Plains; low-relief outwash and moraines; interconnected meltwater channels and proglacial lake basins *Climate: Subhumid continental, warm summer and cold winters, extreme annual variability

Physical Setting

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Visual Representation of GPS Data

ArcView Maps

Triangulated Irregular Network (TIN) Model