DOI Artikel:
Perlińska, Marta: The potential of "viewshed" analysis: Risan as a case study
DOI Seite / Zitierlink:https://doi.org/10.11588/diglit.41947#0029
Marta Perlińska
THE POTENTIAL OF “VIEWSHED” ANALYSIS:
RISAN AS A CASE STUDY*
Abstract: Risan is a well-known ancient city, one of the most important centers of the Illyrian kingdom,
the capital of the kingdom in Queen Teuta’s reign. Its location, in the innermost part of the Bay of Kotor,
does not afford easy visibility of the sea, a situation which could have been potentially dangerous for the
town, especially during the Illyrian Wars. The issue can be studied with a “viewshed” analysis using GIS
software, which is particularly suited to conducting analyses of issues related to space.
Key words: Risan, Bay of Kotor, “viewshed” analysis, Geographic Information Systems
Modern technology plays an increasingly important role in contemporary archaeology. Traditional
excavation methods, developed in the nineteenth century, are slowly giving way to modern docu-
mentation techniques and site analyses, which are based on solutions from other environmental
sciences, such as geography and geology. One of the best computer software used for this purpose
today is a package of programs developed by ESRI - ArcGIS, which has been used in this study.
The main objective of this analysis was to designate areas where permanent watch points could
have been located to allow the city’s garrison to stay in visual contact with the main city on one
side and the mouth of the bay where it gave on the open sea on the other.
Eet us start with a clear definition of what “viewshed” analysis is. In their book Geographical
Information Sciences in Archaeology' Conolly and Lake use two categories: “visibility” and “view-
shed”. The first answers the question whether one point is visible from another (“intervisibility”
is when reciprocal visual contact is analyzed) and the analysis is based on the “line-of-sight”
connecting two points. An algorithm then calculates, which sections of the line are obscured by
features, usually higher parts of an elevation model. Analyses of this kind, which are part of spatial
analyses, are conducted mostly in the DEM.2 The output of a “viewshed” analysis is a raster binary
map, where each cell has been coded with either 1 -visible or 0-obscured, dependent on the visibility
from a given point (analogous with “line-of-sight”, but with lines going in all directions). Software
can also provide additional information, such as observation angle for each raster cell.3 The first
uses of these categories in archaeological practice date back to the 1970s.4
* Scientific project of the National Science Centre, Poland,
no. 2011/03/B/HS3/00371.
1 Conolly, Lake 2006, p. 226.
2 DEM (Digital Elevation Model): in this case raster map
of part of Earth’ surface, with each cell standing for dif-
ferent elevation value.
3 E.g. open source software such as GRASS.
4 See Fraser 1983; Renfrew 1979.
THE POTENTIAL OF “VIEWSHED” ANALYSIS:
RISAN AS A CASE STUDY*
Abstract: Risan is a well-known ancient city, one of the most important centers of the Illyrian kingdom,
the capital of the kingdom in Queen Teuta’s reign. Its location, in the innermost part of the Bay of Kotor,
does not afford easy visibility of the sea, a situation which could have been potentially dangerous for the
town, especially during the Illyrian Wars. The issue can be studied with a “viewshed” analysis using GIS
software, which is particularly suited to conducting analyses of issues related to space.
Key words: Risan, Bay of Kotor, “viewshed” analysis, Geographic Information Systems
Modern technology plays an increasingly important role in contemporary archaeology. Traditional
excavation methods, developed in the nineteenth century, are slowly giving way to modern docu-
mentation techniques and site analyses, which are based on solutions from other environmental
sciences, such as geography and geology. One of the best computer software used for this purpose
today is a package of programs developed by ESRI - ArcGIS, which has been used in this study.
The main objective of this analysis was to designate areas where permanent watch points could
have been located to allow the city’s garrison to stay in visual contact with the main city on one
side and the mouth of the bay where it gave on the open sea on the other.
Eet us start with a clear definition of what “viewshed” analysis is. In their book Geographical
Information Sciences in Archaeology' Conolly and Lake use two categories: “visibility” and “view-
shed”. The first answers the question whether one point is visible from another (“intervisibility”
is when reciprocal visual contact is analyzed) and the analysis is based on the “line-of-sight”
connecting two points. An algorithm then calculates, which sections of the line are obscured by
features, usually higher parts of an elevation model. Analyses of this kind, which are part of spatial
analyses, are conducted mostly in the DEM.2 The output of a “viewshed” analysis is a raster binary
map, where each cell has been coded with either 1 -visible or 0-obscured, dependent on the visibility
from a given point (analogous with “line-of-sight”, but with lines going in all directions). Software
can also provide additional information, such as observation angle for each raster cell.3 The first
uses of these categories in archaeological practice date back to the 1970s.4
* Scientific project of the National Science Centre, Poland,
no. 2011/03/B/HS3/00371.
1 Conolly, Lake 2006, p. 226.
2 DEM (Digital Elevation Model): in this case raster map
of part of Earth’ surface, with each cell standing for dif-
ferent elevation value.
3 E.g. open source software such as GRASS.
4 See Fraser 1983; Renfrew 1979.