Historic images as spatiotemporal archives: Historical 3D data as a form of archaeological source criticism?

Abstract

This paper will discuss the use of historic digital elevation models generated form archival aerial imagery for historic landscape analysis and heritage management. Using images from a number of case studies in Western Europe, the physical process of landscape change is reconstructed at discrete points in time, and these datasets are used to calculate geomorphic change in the environment and its impact on archaeological resources. Such datasets offer us the opportunity to evaluate the bias that the process of modern, large-scale physical modification of the landscape may impart to our interpretation of preceding human activity. Stacking a series of historical digital elevation models together provides a 4-dimensional spatiotemporal ‘terrain data cube’ that can act as a form of source criticism for a given landscape, with each discrete period of activity acting as an independent event that can be compared to its preceding and subsequent counterparts and juxtaposed with other data sources. Thus, this allows us to evaluate the processes that contributed to the shape of the landscape as we see it today from multiple temporal perspectives and compare these with what we see in the present. From this, we can attempt to understand and deconstruct the process of modern landscape formation and its impact on prior activity, rather than simply viewing the present as a result of past activity. The aim of this paper, therefore, is not to discuss the process of creating geospatial information from historic imagery, but how these data may be useful for us from an analytical perspective, including evaluating their merits and limitations. In short, this paper will examine the following question: What information do we gain from observing the process of landscape change via historical elevation models that we cannot understand from other sources, or by simply viewing the result?