Archaeological Site Information Modelling and Management Based on Close-Range Photogrammetry and GIS

New challenges in management and restoration of archaeological sites require the utilization of advanced technologies and systems to assist in preserving the important legacy of human heritage. These challenges include monitoring and preserving of site landscapes, maintenance and rehabilitation of archaeological structures, and quality and safety management. In this research, an integrated methodology based on photogrammetry and Three-Dimensional (3D) Geographic Information System (GIS) is developed to capture and model essential details needed for the proper management of archaeological sites. Recent advances in digital imagery and modelling utilize photogrammetry as an efficient technique for 3D modelling of archaeological sites to derive accurate measurements of size, shape, position, and texture of objects using two-dimensional digital photographs. Spatial data that include aerial stereo photographs, satellite images, close-range photos, terrestrial surveying and Global Positioning Systems (GPS) are integrated within the design of the proposed model. The approach is validated with a case study of Ajloun Castle, one of the ancient and important preserved structures located in Jordan. Various sequential levels of details have been developed for the castle: Orthophoto, Digital Elevation Model (DEM), structures geometry and site layout and 3D textured model. The suggested methodology is expected to be efficient in modelling and documenting archaeological structures. The developed model is utilized to assess the management of archaeological structures through feasibility analysis, rehabilitation decisions, and safety planning.     

Satellite Remote Sensing of Archaeological Vegetation Signatures in Coastal West Africa

This article discusses how archaeological sites in Sierra Leone, and by extension much of West Africa, can be identified through vegetation patterns (vegetation signatures) detectable in very high-resolution (VHR) multispectral satellite imagery. Settlement sites typically have a differing pattern of vegetation from the surrounding landscape, including concentrations of very large trees with sociocultural and historical significance: cotton (Ceiba pentandra) and baobab (Adansonia digitata). These features are conspicuous elements of the landscape both from the ground and in aerial imagery. Two complementary methods of using VHR multispectral satellite imagery are discussed in this paper: visual interpretation and semi-automated subpixel classification. These techniques are aiding ongoing archaeological survey of the Sierra Leone River Estuary. The impact of recently renewed industrial activity at a site of probable archaeological significance is also assessed through visually interpreted VHR satellite imagery.     

Towards a three-dimensional cost-effective registration of the archaeological heritage

Archaeological practice within the European context of heritage management is facing huge challenges in ways of recording and reproduction of ex-situ preserved sites. As a consequence of the Valletta-treaty, numbers of archived images and drawings of excavated structures as prime sources of past human activity, are exponentially growing. Contrarily to portable remains however, their future study and revision is biased by the two-dimensional character of the recorded data, rendering difficult their future reconstruction for new study or public dissemination. A more realistic three-dimensional (3D) way of recording and archiving should be pursued. In this paper the possibilities for 3D registration of archaeological features are examined in a computer vision-based approach using the PhotoScan software package (Agisoft LCC). It proved to be a scientific and cost-effective improvement compared to traditional documentation methods. Advantages can be found in the high accuracy and straightforwardness of the methodology. The extraction of an orthophoto or a Digital Terrain Model from the 3D model makes it feasible to integrate detailed and accurate information into the digital archaeological excavation plan. The visual character of 3D surface modeling offers enhanced output-possibilities allowing a better documentation of in-situ structures for future research and a higher public participation and awareness for the archaeological heritage.     

Tracing Settlement Patterns and Channel Systems in Southern Mesopotamia Using Remote Sensing

Abstract

The integration of spatial datasets from historical satellite imagery, digital elevation models (DEMs), and past archaeological surveys provides new insights into the nature and remains of past landscape transformations. Using southern Mesopotamia as a case study, this article addresses, both quantitatively and qualitatively, long-held assumptions concerning the nature and relationship of settlement patterns and river channel systems in antiquity. GIS and image analysis are used to fill in gaps in the settlement record and propose a revised location for the Tigris River during most of antiquity. Given that only one-third of the central alluvial plain had been ground surveyed in southern Mesopotamia, how complete was our picture of landscape and settlement? How could gaps in settlement be interpreted? The present work in the area east of Baghdad suggests that archaeologists and historians have underestimated the nature and movements of the Tigris River. Satellite imagery can help reveal the location of the Tigris River prior to its settling into its modern course, shedding light on its potential role in the rise of early Mesopotamian agricultural societies. The work presented here proposes a methodology for unweaving and mapping preserved pieces of ancient landscapes, addressing larger issues of human modification of the landscape.     

Mapping by matching: a computer vision-based approach to fast and accurate georeferencing of archaeological aerial photographs

To date, aerial archaeologists generally apply simple rectification procedures or more expensive and time-consuming orthorectification algorithms to correct their aerial photographs in varying degrees for geometrical deformations induced by the topographical relief, the tilt of the camera axis and the distortion of the optics. Irrespective of the method applied, the georeferencing of the images is commonly determined with ground control points, whose measurement and identification is a time-consuming operation and often limits certain images from being accurately georeferenced. Moreover, specialised software, certain photogrammetric skills, and experience are required. Thanks to the recent advances in the fields of computer vision and photogrammetry as well as the improvements in processing power, it is currently possible to generate orthophotos of large, almost randomly collected aerial photographs in a straightforward and nearly automatic way. This paper presents a computer vision-based approach that is complemented by proven photogrammetric principles to generate orthophotos from a range of uncalibrated oblique and vertical aerial frame images. In a first phase, the method uses algorithms that automatically compute the viewpoint of each photograph as well as a sparse 3D geometric representation of the scene that is imaged. Afterwards, dense reconstruction algorithms are applied to yield a three-dimensional surface model. After georeferencing this model, it can be used to create any kind of orthophoto out of the initial aerial views. To prove the benefits of this approach in comparison to the most common ways of georeferencing aerial imagery, several archaeological case studies are presented. Not only will they showcase the easy workflow and accuracy of the results, but they will also prove that this approach moves beyond current restrictions due to its applicability to datasets that were previously thought to be unsuited for convenient georeferencing.     

Mapping Submerged Archaeological Sites using Stereo‐Vision Photogrammetry

Creating photo‐mosaics and plans of submerged archaeological sites quickly, cost‐effectively and, most importantly, to a high level of geometric accuracy remains a huge challenge in underwater archaeology. This paper describes a system that takes geo‐referenced stereo imagery from a diver‐propelled platform and combines it with mapping techniques widely used in the field of robotic science to create high‐resolution 2D photo‐mosaics and detailed 3D textured models of submerged archaeological features. The system was field tested on the submerged Bronze Age town of Pavlopetri off the coast of Laconia, Greece, in 2010. This paper outlines the equipment used, data collection in the field, image processing and visualization methodology.     

Monitoring Islamic Archaeological Landscapes in Ethiopia Using Open Source Satellite Imagery

The African landscape is set to change dramatically in the coming years, and will have a detrimental impact on the inherent archaeological and cultural heritage elements if not monitored adequately. This paper explores how satellite imagery, in particular open source imagery (Google Earth, multispectral satellite imagery from Landsat and Sentinel-2), can be utilized to monitor and protect sites that are already known with particular reference to Islamic archaeological sites in Ethiopia. The four sites used are in different geographic and geomorphological areas: three on the Somali Plateau (Harlaa, Harar, and Sheikh Hussein), and one on the edge of the Afar Depression (Nora), and have varied histories. The results indicate that open source satellite imagery offers a mechanism for evaluating site status and conservation over time at a large scale, and can be used on data from other areas of Africa by heritage professionals in the African continent at no cost.     

Refining Broad-Scale Vulnerability Assessment of Coastal Archaeological Resources,Lough Foyle,Northern Ireland

Increasing evidence indicates that ongoing and future climate change impacts, such as enhanced coastal erosion driven by intensified storms and sea-level rise, will be destructive or problematic for coastal archaeological heritage. Approaches to this problem range from broad-scale GIS-based vulnerability assessments to site-scale monitoring and survey. In all cases, the approach chosen should be based on the best-available data on the local historic environment and pattern of coastal change. Therefore, this paper will demonstrate how such data can be successively acquired and enhanced using an integrated approach that builds on and refines a previously conducted broad-scale vulnerability assessment. This approach was adopted in the study region (Northern Ireland) owing to a lack of coherent and up-to-date information on shoreline change. This approach incorporated the GIS-based Digital Shoreline Analysis System (DSAS) to quantify and analyze local shoreline change. DSAS is a software extension for ESRI ArcGIS which allows calculation of rate-of-change statistics using past shorelines identified from georeferenced historic maps and vertical aerial imagery. Additionally, a field survey was conducted to assess the condition of recorded sites, and identify unrecorded ones. Results revealed a more complex pattern of shoreline change in the study area (Magilligan Foreland, Lough Foyle) than previously anticipated, with zones of significant erosion interspersed with areas of stability or advance. Fifty-one new sites ranging from the prehistoric period to the Second World War were also identified. The new information was used to develop a priority classification based on site significance, condition and risk level which improved significantly on the uniform classification of the original broad-scale assessment.     

Image‐Based Modelling from Unmanned Aerial Vehicle (UAV) Photogrammetry: An Effective,Low‐Cost Tool for Archaeological Applications

The recording and 3D modelling of complex archaeological sites is usually associated with high capital and logistical costs, because the data acquisition must be performed by specialists using expensive surveying sensors (i.e., terrestrial laser scanners, robotic total stations and/or ground‐penetrating radar). This paper presents a novel, low‐cost, user‐friendly photogrammetric tool for generating high‐resolution and scaled 3D models of complex sites. The results obtained with unmanned aerial vehicle (UAV) photogrammetry of an archaeological site indicate that this approach is semi‐automatic, inexpensive and effective, and that it guarantees quality.     

Analysis of Explorers' Records of Aboriginal Landscape Burning in the Kimberley Region of Western Australia

The accounts of explorers and colonists in the Kimberley region of Western Australia were searched to find records of landscape burning by Aborigines. Analyses of these records provide estimates of the spatial and temporal patterns of fire across the region in historic times. The seasonality of fire varied across the region. In northern parts of the Kimberley landscape fire was recorded from May to October with peak levels in June and September. In southern parts of the region there are records of burning as early as February and March, through to August but no records of fire were made in late dry season months. Modern fire regimes were compared with historic by superimposing the routes taken by five explorers over a modern fire history map derived from satellite imagery. Tallies of the number of modern fires that intersect the explorer's daily and monthly route were compared with actual observations of fire made by the explorers in historic times. The results indicate an increase in early dry season fires and the overall frequency of fires across the region in modern times. Explorers' accounts were also examined to derive further information regarding Aboriginal landscape burning in different environments and to distinguish landscape burning from other uses of fire such as smoke signals and cooking fires.     

Unmanned Aerial Vehicle (UAV) Survey with Commercial-Grade Instruments: A Case Study from the Eastern Ḫabur Archaeological Survey,Iraq

Low-altitude photography in archaeology is now common practice at the scale of excavations; however, landscape-scale applications are a relatively new endeavor with promising analytical potential. From 2014–2016, an unmanned aerial vehicle (UAV) with a mounted camera was used to document sites recorded as part of the Eastern ?abur Archaeological Survey (E?AS), an archaeological reconnaissance project in western Dohuk Province, Iraqi Kurdistan. The E?AS team documented over 70 archaeological sites with the UAV, from single-phase artifact scatters, to archaeological remains with standing architecture, to tells that cover more than 30 hectares. Representative examples from this survey are presented here to outline the project workflow and primary output data layers, including digital orthomosaics and digital elevation models. The quality and utility of results are then assessed in relationship to available satellite-based data. Methods for analysis and interpretation are then considered to demonstrate applications in landscape archaeology. An A) orthomosaic and B) shaded relief model with surface collection area (in red) of site EHAS-C045 created from photographs taken from a UAV.     

Integration of geophysical surveys,ground hyperspectral measurements,aerial and satellite imagery for archaeological prospection of prehistoric sites: the case study of Vésztő-Mágor Tell,Hungary

An integration of geophysical surveys, ground hyperspectral data, aerial photographs and high resolution satellite imagery for supporting archaeological investigations at the multi-component Vészt?-Mágor Tell, located in the southeastern Great Hungarian Plain, is presented in this study. This is one of the first times that all these techniques have been combined and evaluated for retrieving archaeological information. Geophysical explorations, specifically magnetic gradiometry and ground penetrating radar methods, have revealed shallow linear anomalies and curvilinear rings at the Tell. The use of remote sensing images has confirmed the diverse anomalies with respect to geophysics through photointerpretation, radiometric and spatial enhancements. Moreover, several indices from ground hyperspectral data also have revealed stress vegetation anomalies. These integrated results were used to map the main areas of archaeological interest at the Vészt?-Mágor Tell and plan future excavations. It was found that these multiscalar data can be used efficiently for detecting buried archaeological features.     

Mapping ancient chinampa landscapes in the Basin of Mexico: a remote sensing and GIS approach

This paper uses remote sensing data to document a raised field, chinampa system adjacent to the Postclassic kingdom of Xaltocan in the northern Basin of Mexico. Various forms of landscape information; historic records and maps as well as remote sensing; are considered to understand the chinampa system. The remote sensing data examined include 1950s aerial photographs, Landsat 7 data, and Quickbird VHR, multi-spectral imagery. This article evaluates the utility of each of these forms of data to identify buried chinampa features and integrates them in a GIS to produce a map of Xaltocan's chinampa landscape. Canals of various sizes and hydrological positions comprised the chinampas and integrated the system together. Occupying at least 1500–2000 ha, Xaltocan's chinampa system represents the largest pre-Aztec, chinampa system in the Basin of Mexico.     

From conflict archaeology to archaeologies of conflict: remote survey in Kandahar,Afghanistan

ABSTRACT

Emerging from research with the Afghan Heritage Mapping Partnership, a multi-year project using satellite imagery to detect, record and manage archaeological heritage, this paper examines the potentials of remote-sensing to not only monitor archaeological material culture, but also contemporary materiality as it is violently (re)assembled through conflict. Through systematic remote-sensed archaeological survey using diachronic imagery in Kandahar, Afghanistan, this work expands archaeological understanding of an under-surveyed region while exploring the impact of the region’s expansive military infrastructural footprint on cultural heritage. Further, this research considers the long history of landscapes of control and successive military occupations. Remote survey allows for continued generation of archaeological data during conflict, thereby enabling more thorough heritage management. Finally, this survey demonstrates that, although remote aerial technologies have been criticized as tools of violence, surveillance and control, satellite imagery can be used analytically to generate new understandings of and challenges to military infrastructural reach.     

Near-Infrared Aerial Crop Mark Archaeology: From its Historical Use to Current Digital Implementations

Even though most archaeologists are aware of the crop mark phenomenon and its possible archaeological nature, the information on its occurrence and specific character is, in most cases, obtained by imaging in the visible spectrum. After the Second World War, the occasional use of near-infrared (NIR) sensitive emulsions attributed this kind of invisible imaging with a great potential. However, archaeological NIR imaging always remained restricted due to several reasons not, at least, its complicated workflow and uncertain results. This article wants to delve deeper into the subject, looking at the conventional film-based approach of NIR aerial reconnaissance and its historical use in archaeological crop mark research, after which a current straightforward digital approach will be outlined. By explaining the spectral properties of plants and using examples of recently acquired NIR imagery in comparison with visible frames, it should become clear why the detection and interpretation of crop marks can benefit from low-cost digital NIR imaging in certain situations.     

Airborne LiDAR,archaeology, and the ancient Maya landscape at Caracol,Belize

Advances in remote sensing and space-based imaging have led to an increased understanding of past settlements and landscape use, but – until now – the images in tropical regions have not been detailed enough to provide datasets that permitted the computation of digital elevation models for heavily forested and hilly terrain. The application of airborne LiDAR (light detection and ranging) remote sensing provides a detailed raster image that mimics a 3-D view (technically, it is 2.5-D) of a 200 sq km area covering the settlement of Caracol, a long-term occupied (600 BC-A.D. 250–900) Maya archaeological site in Belize, literally “seeing” though gaps in the rainforest canopy. Penetrating the encompassing jungle, LiDAR-derived images accurately portray not only the topography of the landscape, but also, structures, causeways, and agricultural terraces – even those with relatively low relief of 5–30 cm. These data demonstrate the ability of the ancient Maya to modify, radically, their landscape in order to create a sustainable urban environment. Given the time and intensive effort involved in producing traditional large-scale maps, swath mapping LiDAR is a powerful cost-efficient tool to analyze past settlement and landscape modifications in tropical regions as it covers large study areas in a relatively short time. The use of LiDAR technology, as illustrated here, will ultimately replace traditional settlement mapping in tropical rainforest environments, such as the Maya region, although ground verification will continue to be necessary to test its efficacy.     

Historic landscape management: a validation of quantitative soil thin-section analyses

The archaeological interpretation of past land management practices can be greatly enhanced through examination of soil thin sections. Features relating to manuring practice are among those key to interpreting agricultural practices. The sources and the processes leading to the distribution of these manure materials may further improve knowledge of the past landscape utilisation. The use of quantitative analyses to examine soil thin sections opens the possibility of considering these relationships between manured areas in greater detail and to extract more subtle spatial and temporal changes in past management. In this study the validation of this methodology has been tested with quantitative image analysis methods used to examine manure inputs to a well-documented historical landscape of Papa Stour, Shetland, where intensive manuring has been practised until the 1960s. By using both historic and ethnographic evidence to validate the image analysis protocol, differences in spatial and temporal distribution are examined for the practices of manuring with both fuel residues and with turf. The validation of the hypotheses expected from ethnographic and historical data that quantitative soils-based evidence allows the definition of variations in manuring strategies and provides a more secure basis from which to interpret manuring management strategies in archaeological landscapes.     

Methods for the extraction of archaeological features from very high-resolution Ikonos-2 remote sensing imagery,Hisar (southwest Turkey)

Archaeological research in the territory of Sagalassos is a multidisciplinary project covering scientific disciplines traditionally linked to archaeology and also new technologies such as very high-resolution remote sensing with sufficient radiometric and spatial resolution (<2.5 m). This paper focuses on the evaluation of GIS-, pixel- and object-based techniques for automatic extraction of archaeological features from Ikonos-2 satellite imagery, which are then compared to a visual interpretation of ancient structures. The study was carried out on the unexcavated archaeological site of Hisar (southwest Turkey). Although all techniques are able to detect archaeological structures from Ikonos-2 imagery, none of them succeed in extracting features in a unique spectral class. Various landscape elements, including archaeological remains, can be automatically classified when their spectral characteristics are different. However, major difficulties arise when extracting and classifying archaeological features such as wall remnants, which are composed of the same material as the surrounding substrate. Additionally, archaeological structures do not have unique shape or colour characteristics, which can make the extraction more straightforward. In contrast to automatic extraction methods, a simple visual interpretation performs rather well. The methods presented in this paper can be applied with variable success to archaeological structures composed of the same material as the surrounding substrate, which is often the case.