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June 2004 |
Geomatics in archaeology High tech for old digs
Geographic Information System
The heart of Geomatics is the Geographic Information System. GIS provides for the integration and analysis of disparate data; such as surveyed areas, archaeological site locations, scanned aerial photos, satellite images, scanned historic maps, and GPS field data; along with more traditional GIS data such as soils and geology maps, hydrology, and elevation. Raster, vector, and point data now are routinely combined into an integrated GIS system, along with a relational database. The GIS provides a more flexible and accessible storage environment for excavation and survey data, and allows us to put our archaeological data in its correct environmental, social, and political context. The ability to produce custom hardcopy maps is very important, again because archaeologists routinely work in remote areas that are poorly mapped. The cumulative nature of the GIS database is particularly important. Before GIS, each field season produced a unique set of paper maps and photo prints that were difficult to integrate with each other, or with other data. Now with GIS, all of our data, as it becomes available, are entered into a single, integrated database where we can analyze the data at any scale, from a single excavation to regional analysis of the patterns of many sites across the landscape. Having easy access to the data the analysis by multiple disciplinary specialists becomes possible and we all benefit from this interaction.
The Angkor Zoning and Environment Management Plan, successfully used GIS to integrate data from the fields of achaeology, geology, hydrology, climatology, environmental science and demography together with plans being prepared for the development of agriculture, irrigation, road construction and tourism.
Image courtesy UNESCO
Spatial Analysis
The real heart of the GIS for archaeologists is our ability to conduct spatial analysis on the patterns and relationships between archaeological sites, and between sites and their environmental context. We want to understand the patterns and relationships between sites and natural resources, between sites and sites of the same time periods, and how those patterns change over time.
We conduct spatial statistical analysis, including advanced exploratory data analysis (EDA) techniques, to discover the changing patterns of settlement and land use over time. Archaeologists can now quantitatively test theories of political, economic, and environmental patterns that were not possible without these powerful tools.
We routinely create predictive models of archaeological site distribution, based on combinations of environmental (elevation, slope, distance to water, and soil types, for example) and cultural data (such as political boundaries, religious and economic centers). We can also look at how these patterns have changed over time. We can then ask the GIS to find certain combinations of environmental parameters that could signify higher likelihood of containing cultural resources. These GIS-based predictive models can then be tested against our theories, or in the field against real data. They can be further verified with new field surveys using GPS, or we can look at our imagery for sites in particular areas. Models can be created that show the relationship of sites with intervisibility of other sites or features on the landscape such as ritual or defensive centers, and we can create new models of where roads should likely be found to connect these sites. As theories change and develop, we can go back to our data and test new ideas and refine existing concepts. All of this work can be conducted between field seasons at the archaeologists' home institution, and can be used to plan the next round of fieldwork. Conducting field work in distant lands is a very expensive and complex undertaking, and GIS assists the archaeologist in being more efficient with his precious time on the ground.
Visualization and simulation are also rapidly becoming parts of the archaeologists' toolkit. We can create CAD models of what we believe a structure looked like, based on excavation results, and then can place it into the modern landscape or a recreation of how we think the ancient landscape looked. Interactive visualization tools let us fly through our study areas and virtually visit remote or destroyed archaeological sites on the internet, allowing for improved education and bringing the value of these cultural resources to the public and decision makers.
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