Detecting and Mapping Slag Heaps at Ancient Copper Production Sites in Oman

Abstract

This study presents a new approach for detection and mapping of ancient slag heaps using 16-band multispectral satellite imagery. Understanding the distribution of slag (a byproduct of metal production) is of great importance for understanding how metallurgy shaped long-term economic and political change across the ancient Near East. This study presents results of slag mapping in Oman using WorldView-3 (WV3) satellite imagery. A semi-automated target detection routine using a mixed tuned matched filtering (MTMF) algorithm with scene-derived spectral signatures was applied to 16-band WV3 imagery. Associated field mapping at two copper production sites indicates that WorldView-3 satellite data can differentiate slag and background materials with a relatively high (>90%) overall accuracy. Although this method shows promise for future initiatives to discover and map slag deposits, difficulties in dark object spectral differentiation and underestimation of total slag coverage substantially limit its use. Resulting lower estimations of combined user’s (61%) and producer’s (45%) accuracies contextualize these limitations for slag specific classification. Accordingly, we describe potential approaches to address these challenges in future studies. As sites of ancient metallurgy in Oman are often located in areas of modern exploration and mining, detection and mapping of ancient slag heaps via satellite imagery can be helpful for discovery and monitoring of vulnerable cultural heritage sites.

The Innovative Growth of Space Archaeology: A Brief Overview of Concepts and Approaches in Detection, Monitoring, and Promotion of the Archaeological Heritage

“…Cluster 4 comprises methodologies that apply Image Enhancement (IME) to improve spectral and spatial resolution, thereby increasing the possibility of identifying information useful for archaeological purposes. For example, techniques, such as image texture filters, band combinations, and false color are widely used to detect archaeological sites, and are often closely related to visual interpretation [42,44,45,54,[61][62][63][64][65][66][67][68][69][70][71]. The latter is defined as Image Visual Inspection (IVI) and composes cluster 5, indicating the examination of satellite data to identify objects, such as crop/soil marks, morphological and/or geometric features, and the form of site damage, in order to support the analysis of archaeological sites, particularly with respect to their relation to the landscape.…”

A remote sensing-based survey of archaeological/heritage sites near Kandahar, Afghanistan through publicly available satellite imagery

“…Different approaches in the application of satellite imagery for archaeological and cultural heritage studies have been suggested in recent years. There have been attempts to automate the survey process by developing and applying rule-based site detection protocols [ 40 , 69 – 74 ], or by utilizing artificial intelligence and machine learning [ 75 ]. Other researchers have outlined ‘crowd-sourced’ approaches that depend on the contribution of a large number of participants for the detection of archaeological features [ 76 , 77 ].…”

“…Similar methods were applied elsewhere on entirely different research themes: Such as the case of Tripolye mega-sites of the 4 th Millennium BC in the northwestern Pontic Region [ 24 , 25 ], Bronze Age geoglyphs in Kazakhstan [ 26 , 27 ], or the Polynesian geoglyphs in New Zealand and the Pacific which are dated before the European colonization of the islands [ 28 ]. Currently, there is a growing body of literature on the use of satellite data for site detection [ 29 – 32 ], or on obtaining data on past land-use [ 33 ], cultural heritage management [ 34 – 39 ], and more recently on ancient mining and metallurgy [ 40 ]. The number of studies dealing with the archaeology of Afghanistan and cultural heritage management through satellite imagery has also been increasing in recent years [ 6 , 41 – 43 ].…”

Stockpile Volume Estimation in Open and Confined Environments: A Review

“…Satellite imagery (or Earth-observation imagery, spaceborne photography, or simply satellite photo) can be used for earthwork monitoring and stockpile volume estimation [24][25][26][27][28]. This method is useful for monitoring changes in landfills over a long period of time, particularly for large areas.…”