GIS: An Array of Tools for Archaeology
Among the rich array of tools available in GIS, we review a useful subset of tools for archaeological applications and describe how they can be used to integrate spatial data from a variety of sources.
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GIS: An Array of Tools for Archaeology
Preamble A geographic information system (GIS) is a software system that provides a framework for gathering, integrating, managing, and analysing spatial data. As we have noted earlier, it is often useful to look at multiple satellite images for a given site. These could be images taken by the same sensor on different dates (see Sect. 2.3.6), or from different sensors (see Sect. 3.2.1). GIS software organizes information into layers based on geospatial location, allowing the analyst to integrate data from multiple images, as well as spatial data from other sources such as ground truthing,1 field observations, old maps, and other historical spatial records. In order to integrate spatial data, it is obviously necessary to ensure that all this data is georeferenced (i.e. it is expressed in a common geospatial coordinate system) so that features in one layer are as accurately aligned as possible to their footprint in other layers (Fig. 4.1). Thus, any geospatial analyst must be proficient in georeferencing. In the first part of this chapter (Sect. 4.1), we will discuss why georeferencing can greatly benefit archaeological and cultural heritage research. In the second part, we will discuss how to georeference the type of spatial data we typically encounter in this domain. We will split this discussion into three parts: georeferencing satellite images (Sect. 4.2), georeferencing historical spatial records (Sect. 4.3), and discussing other kinds of spatial analysis that adds value to research in cultural landscapes (Sects. 4.4, 4.5 and 4.6).
1 By
ground truthing we mean making direct observation to verify a feature already detected in satellite imagery, whereas field observation includes observing features afresh on the ground (not necessarily as an act of verifying a predetermined feature).
© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021 M. B. Rajani, Patterns in Past Settlements: Geospatial Analysis of Imprints of Cultural Heritage on Landscapes, Springer Remote Sensing/Photogrammetry, https://doi.org/10.1007/978-981-15-7466-5_4
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4 GIS: An Array of Tools for Archaeology
Fig. 4.1 Georeferenced Survey of India map overlaid over a satellite image. The spatial alignment between the two layers can be seen in the shape of the river
4.1 Why Is Georeferencing Useful? An immediate benefit of georeferencing spatial data is that it facilitates precision measurements. However, the accuracy of these measurements depends on the accuracy of georeferencing and the spatial resolution of the images being used. In the context of studying past settlement patterns, typical measurements of interest include: the latitude and longitude of a specific point of interest (e.g. one that has been or will be investigated at ground level during a site visit), the dimensions of a linear or curvilinear feature (e.g. length of a wall or a street), the area of a feature with well-defined boundaries (e.g. a fort or a tank), and the or
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