Hobbies And Interests
Determining Viewshed
The term "viewshed" refers to the area visible from a site. Archaeologists are far from the only ones who perform viewshed analysis. It also plays an important role in building structures such as communication stations, roads and homes. Modern geographic information system (GIS) software allows the creation of computer models of elevation. Planners, archaeologists and others can use these digital elevation models (DEM) to determine the viewshed of any given point in the landscape.
Cumulative Viewshed Analysis
Archaeologists use statistical analysis of viewshed information, called cumulative viewshed analysis, to determine the relationship between sites in the landscape. This analysis derives the area of a site's viewshed from a DEM. Cumulative viewshed analysis can determine whether the size of the viewshed of a particular type of site is greater or lesser than would be suggested by chance, as well as whether other monuments are more or less visible. Archaeologists use these connections to identify networks of sites.
Examples of Viewshed Analysis
British archaeologist David Wheatley developed cumulative viewshed analysis to study the Neolithic long-barrows of Wessex in western England. By studying the viewsheds of these sites, Wheatley determined that the barrows near Stonehenge had a high degree of visibility with each other, while barrows in another region, near Avebury, did not, possibly suggesting different social structures. Other examples of viewshed analysis have demonstrated the relationships between ancient sites, which may have served as watchtowers or signalling stations.
Challenges of Viewshed Analysis
When engineers carry out viewshed analysis, they are studying the landscape as it exists in the modern day. However, when archaeologists perform viewshed analysis, they are using elevation data gathered in the modern landscape, but trying to study the historical or prehistoric landscape. This poses some challenges that are absent in other forms of viewshed analysis. One of the largest problems is the question of ancient woodland. Many areas in Europe, North America and elsewhere have undergone significant deforestation over their history. Archaeologists must estimate the position of ancient woodland in order to analyze visibility.