Prof Mark Aldenderfer
Director, Office of Information Technology
Department of Anthropology
University of California, Santa Barbara
Santa Barbara, CA 93106
Email: [email protected]
- Tell us something about the current activities involving GIS and Remote Sensing in Archaeology?
This is a very exciting time in the application of GIS and remote sensing in archaeology. Although GIS has been used in the field since the 1980s, and aerial photography has had a long history of use, it has only been within the past decade that these two technologies have matured substantially in archaeology. Remotely sensed data are currently used for exploration and discovery, and there have been numerous successful attempts to use them to identify landscape or cultural features, such as stone quarries, structural remains, and ancient river courses. Remotely sensed data are increasingly valuable as basic components of predictive models, which seek to classify landscape or other features as to their probabilities of possessing archaeological sites of particular ages or cultural affiliations. Although RS is increasingly important to archaeology, GIS is rapidly becoming indispensable. Archaeological data are inherently spatial, and archaeologists are naturally concerned with the distribution of archaeological sites across the landscape. From these distributions, described as settlement patterns, we can infer a great deal about the social and political complexity of the ancient people’s we study, the size of their domains, aspects of resource procurement, and much more. Here GIS can be used as a database management tool of great flexibility. New information can be generated by the GIS, and it in turn can be subjected to a variety of analytic methods that seek to discover patterning in the data. GIS-based modeling approaches to the analysis of regional-scale data include the estimation of cost-surfaces, network models of trade and cultural interaction, predictive models of site location, viewshed analysis, in which the intervisibility of archaeological sites is assessed, as well as a number of other models derived from geography and spatial analysis. GIS has also proven to be an effective management tool for the large number of archaeologists who work for governmental agencies. Here, it serves as a means by which managers of sites can quickly identify potential threats to sites by land-modifying activities, and can more easily coordinate with other agencies and managers.
An area that promises to see explosive growth in the use of GIS is in the integration of near-surface sensing and intra-site analysis at archaeological sites. Near-surface sensing refers to a suite of geophysical sensing techniques, including ground-penetrating radar, electrical resistivity, proton magnetometry, fluxgate and cesium gradiometry and other methods. These technologies are used to get a picture of what may lay below the ground surface before an excavation begins. They are, in a sense, a kind of remote sensing, but in this case, they are usually limited in scope to a single archaeological site. Intra-site analysis refers to the examination of how artifacts and cultural features are distributed within a single site. GIS has seen limited application in intrasite studies because excavations are of course three dimensional, and current GIS technology only allows for 3D visualisation, but not querying. However, a number of work-arounds that permit the analysis of 3D data are now available, and new generations of GIS packages will allow limited 3D functionality with the promise of even more useful tools in the future. The combination of these 3D GIS with near-surface sensing data means that archaeologists will be able to visualise their sites as never before possible, and this in turn will allow them to excavate more efficiently and effectively, thus saving resources and time. It will also allow them to pinpoint their excavations to answer very specific research questions, thereby preserving much of the site for the future. Finally, governmental managers of sites under threat of destruction will be better able to determine if the threats to the site require extensive excavation, testing, or nothing at all.
- What are the problems that you have faced while using GIS and Remote Sensing for Archaeology purposes?
Archaeologists in general face two kinds of problems in their use of GIS and remote sensing technologies. The first is concerned with data and data quality, and the second is concerned with training, infrastructure, and support. Although remotely sensed images of all kinds are readily available, they are not often useful for many kinds of archaeological applications, especially when these images have been taken with low spatial resolution. For the many archaeologists working outside the developed world, basic data for generating GIS coverages, for soils, geology, vegetation, etc. are either wholly unavailable or are inaccurate. A DEM generated from a topographic map with faulty contouring is often of little value when used for analytical purposes, such as the computation of least-cost paths, for example. Although the numbers of GIS-savvy archaeologists is increasing, it remains the case that we have relatively few expert users in the field, and therefore, we often look to geography and related fields for training. And while this helps us with the basics of GIS, it does not prepare us well for the special problems we always encounter with archaeological data. We also have serious infrastructure and support problems. Many archaeologists lack access to state-of-the art computers and GIS/RS software, and even when we have the best available, it is often a problem to find competent support staff to assist us with our projects. As more students are trained in GIS/RS technologies, though, this problem should diminish.
- What level of expertise an archaeologist should have to use GIS and Remote Sensing?
We have found that in order to really use GIS/RS technologies effectively, students should have university-level courses in both the theory and practice of GIS as well as have some practical experience in its application to a real-world problem. At my university, for example, we encourage archaeology students to take a three-course sequence of GIS from the Geography department followed by a course I teach on archaeology and GIS. We also encourage them to apprentice themselves to faculty or advanced graduate students who seek assistance in the development of their GIS-related projects. An alternative is to pursue certification in GIS, and which is offered by smaller colleges, university extension programs, private companies, or professional organisations such as the American Society for Photogrammetry and RS. It is essential, however, that students obtain some understanding of the specific problems they are likely to encounter in their use of GIS in archaeology, and this can only be accomplished by specific courses or direct and intensive involvement with active research projects.
- Do you feel that there is a need for customised software for Archaeology?
There is no question that many aspects of archaeological research using GIS and remote sensing techniques would benefit from the development of customised software. Although off-the-shelf applications such as ArcView, for example, are fundamental to our research, we have found that we must always write scripts that extend the basic functionality of the software to meet our needs. Similarly, there are circumstances unique to archaeology that demand novel software solutions. For example, within the context of an archaeological excavation, there is currently no simple way to link 2D or 2.5D GIS representations of the horizontal surfaces of a site to a stratigraphic profile of the levels of a site and at the same time maintain the functionality of the GIS. And while the promise of a true 3D GIS remains bright, archaeologists will still need to be able to transform any “plain vanilla” GIS package into something useful for their ends. Our problem, of course, is that we are a relatively small field and lack sufficient resources to do the many things our research demands of us when it comes to the development of customised software.
- In archaeology, which sphere of application is most benefited by the use of GIS and Remote Sensing technologies?
GIS/RS technologies have been applied with greatest success to regional-scale archaeological survey, which is the systematic search for archaeological sites on the landscape. Remotely sensed data are often used as guides to survey, and GIS is most frequently used as a data management and analysis tool to examine the spatial patterning of archaeological sites in relationship to natural features and inferred social and political landscapes. RS data is also used as a discovery and exploration tool. For example, radar imaging, the Landsat Thematic Mapper, and SPOT satellite images were all used in the search for the ancient city of Ubar, once a thriving trade center in the southern Arabian peninsula that is now buried below deep sand dunes. Although the city itself was not discovered, the combined images did reveal caravan routes which converged at a central location. Subsequent excavation discovered the city. Similar data have been used to find sites and agricultural features of the ancient Maya, fortifications in Britain, and roadways in Burgundy. However, archaeologists have begun to adapt both GIS and RS technologies to the investigation of individual archaeological sites, and it is here that both show great promise for the future.
- Being an academician, could you suggest the future prospects of “GIS/RS in Archaeology” as a specialised discipline of study?
I have noticed over the past decade that universities and colleges in the United States are more frequently indicating that knowledge of GIS and related technologies is a desirable quality for any candidate. My university, for example, has had great success in placing students into faculty positions because of their GIS background. The federal government has been quite active as well in hiring archaeologists with GIS skills, although these positions tend to be entry at level and often temporary. All of this suggests to me that there will be a steady demand for archaeologists with intensive GIS training over the next decade. Meeting this level of demand, however, may be difficult, because there are at present relatively few universities that provide comprehensive training in GIS and remote sensing technologies that is specifically designed for archaeologists. Notable exceptions include the University of Arkansas, the University of California, Santa Barbara, Boston University, Rutgers University, University College, London, University of Sydney.