Local relief models (LRM) are proposed as a new tool for archaeological prospection. A data processing approach is presented which produces LRM from LiDAR-derived high-resolution digital elevation models (DEMs). The LRM represents local, small-scale elevation differences after removing the large-scale landscape forms from the data. The LRM greatly enhances the visibility of small-scale, shallow topographic features irrespective of the illumination angle and allows their relative elevations as well as their volumes to be measured directly. This makes the LRM an improved basis for spatially extensive archaeological prospection over a wide range of landscapes. The LRM raster map of local positive and negative relief variations can be used for the mapping and prospection of archaeological features such as burial mounds, linear and circular earthworks, sunken roads, agricultural terraces, ridge and furrow fields, kiln podia and mining/quarrying sites. This approach is currently being used in a project aimed at the complete archaeological mapping and prospection of the state Baden-Wurttemberg (Germany), covering an area of 35 751 km(2). The goal of the project is the verification and extension of the existing archaeological data base. An object-based local relief vector layer is produced as a by-product; however, due to the common amalgamation of natural and anthropogenic features this cannot be used efficiently for archaeological prospection at present. Copyright (C) 2010 John Wiley & Sons, Ltd.
Object‐based image analysis (OBIA) is a method of assessing remote sensing data that uses morphometric and spectral parameters simultaneously to identify features in remote sensing imagery. Over the past 10–15 years, OBIA methods have been introduced to detect archaeological features. Improvements in accuracy have been attained by using a greater number of morphometric variables and multiple scales of analysis. This article highlights the developments that have occurred in the application of OBIA within archaeology and argues that OBIA is both a useful and necessary tool for archaeological research. Additionally, I discuss future research paths using this method. Some of the suggestions put forth here include: pushing for multifaceted research designs utilizing OBIA and manual interpretation, using OBIA methods for directly studying landscape settlement patterns, and increasing data sharing of methods between researchers.
This article presents results of a case study within a project that seeks to develop heavily automated analysis of digital topographic data to extract archaeological information and to expedite large area mapping. Drawing on developments in computer vision and machine learning, this has the potential to fundamentally recast the capacity of archaeological prospection to cover large areas and deal with mass data, breaking a dependency on human resource. Without such developments, the potential of the vast amount of archaeological information embedded in large topographic and image‐based datasets cannot be realized. The purpose of the case study reported on here is to assess existing developments in a Norwegian study against digital topographic data for the island of Arran, Scotland, examining the transferability of the approach and providing a proof of concept in a Scottish context. For Arran, three monument classes were assessed – prehistoric roundhouses, shieling huts of medieval or post‐medieval date, and small clearance cairns. These present different challenges to detection, with preliminary results ranging from a manageable mix of false positives and true identifications to the chaotic. The influence of variable morphology and the occurrence of other, largely natural, objects of confusion in the landscape is discussed, highlighting the potential improvements in automated detection routines offered by adding anthropogenic and natural false positives to additional confusion classes.
Diminishing returns of archaeological crop marks in lowland areas from traditional observer‐directed visible spectrum aerial survey with standard photographic cameras highlights a need to explore alternative approaches to maintain the effectiveness of survey programmes. Developments in low‐cost multispectral remote sensing have in part been driven by the growth of precision agriculture and, whilst contributing to the intensification of land use, these technologies may offer new spectral and temporal capacities for detecting, recording and monitoring historic landscapes. However, there are significant challenges to the deployment of such approaches, not least the costs of data acquisition and uncertainty about the best conditions for data collection. This study assesses the effectiveness of the Parrot Sequoia, a relatively low‐cost multispectral sensor recently developed for agricultural applications, for the detection of crop marks to inform archaeological survey. A series of observations were taken with the sensor mounted on an unmanned aerial vehicle (UAV) at Ravenshall, Fife, Scotland, between April and July 2017. The resulting reflectance maps are compared to red, green and blue (RGB) photographs taken with a Nikon D800E digital camera during seven light aircraft surveys, with the aim of testing the sensors' comparative ability to record crop mark developments over time. The contrast in reflectance between vegetation samples growing over buried archaeological remains and the surrounding field was assessed through separability in regional histogram values across different image band combinations. Separable values indicative of crop marks were found in both the multispectral and RGB results from June 2017 onwards. Several vegetation index (VI) maps, particularly the Simple Ratio (SR) and Normalised Difference Vegetation Index (NDVI), were found to be effective for distinguishing crop marks in the multispectral results. The Sequoia is a cost‐effective sensor offering improved spectral resolution over the RGB photographs, showing potential for subtle crop mark detection across compact study areas.
This article focuses on a significant parameter associated with the interpretation of cropmarks of three‐aisled longhouses on aerial photographs of western Jutland, Denmark. Between 2008 and 2013, during the first part of the project ‘An aerial view of the past – aerial archaeology in Denmark’, 672 three‐aisled longhouses were discovered. These longhouses have been dated typologically, identifying only four houses from the Early Bronze Age (ca 1700–1100 bc ) and showing no recorded examples from the Late Bronze Age (1100–500 bc ). The remaining longhouses fall primarily within the period from the Early Iron Age to the Viking Age (ca 500 bc – ad 1050). The absence of longhouses from the Bronze Age is presently explained as a consequence of age and dimensions. Two factors that revolve around the possibilities of cropmark occurrence. In this article, it is suggested that the method of classification used to interpret longhouses on aerial photographs is of crucial significance with respect to the virtual absence of Bronze Age examples. The typological problems associated with visual classification are outlined, after which the possible latent presence of Bronze Age longhouses in the aerial photograph database is investigated. The problems are addressed via a series of principal component analyses (PCAs), employed as a classification tool. The PCA classification of the longhouses is based exclusively on the arrangement of the internal roof‐bearing posts. The analysis uses data from 203 excavated longhouses, which are compared with 120 longhouses recorded on aerial photographs. The analysis identified 14 longhouses that could potentially be from the Late Bronze Age, both with respect to internal roof‐bearing construction and visual appearance on aerial photographs. This leads on to a discussion of the typological problems associated with identifying longhouses from the Late Bronze Age and Early Pre‐Roman Iron Age, together with a weighting of the factors: age, dimensions and classification.
Three‐dimensional (3D) documenting and rubbing of rock art is aimed to produce descriptive and analytic graphic documentation with metric scale and geospatial information for archaeological analysis. Although the integrated surveying technologies of aerial photogrammetry, close‐range photogrammetry, and laser scanning have been widely used to generate the 3D models of archaeological sites, the implementation of these technologies in complex surroundings with steep terrain, such as riverside cliffs, remains challenging. In this study, we present an unmanned aerial vehicle (UAV)‐based structure‐from‐motion (SfM) photogrammetry approach to obtain the 3D geospatial data of rock paintings. A field data collection approach for high‐resolution multiperspective images using UAV equipped with a high‐resolution camera is implemented together with high accuracy ground control points (GCPs). An appropriate flowchart of multi‐view stereo (MVS) photogrammetry processing is designed including multi‐view dense matching, bundle adjustment (BA) and metric rectification for the orthoimages production of the rock paintings. A digital rubbing approach based on the orthoimages is proposed to obtain the geometry contents, including symbols and characters, of the rock paintings. The Huashan rock paintings, which are located on the vertical faces of the cliffs that line the course of Zuo River, is taken as a case study. Our proposed approach can obtain orthoimages of the Huashan rock paintings with 2 mm resolution. The reality‐based 3D model can reach the absolute accuracy of 5 mm. Clear, exact, and blur‐free metric rubbing images of the Huashan rock paintings are produced, which are useful for the research and preservation of Zhuang culture.
Santa Elena, located on Parris Island along the coast of South Carolina, was the first capital, and northernmost permanent settlement, of Spanish La Florida . Over two decades of occupation ( ad 1566–1587), five forts were successively built while by ad 1569 a burgeoning Spanish settlement of over 200 people, complete with artisans, farmers, and Jesuit missionaries, flourished. Here, we articulate the results of recent, full‐coverage ground‐penetrating radar and magnetic gradiometry surveys with over 40 years of extant archaeological data to elucidate organizational characteristics of the Spanish settlement at Santa Elena. In particular, we use geophysical data to identify the potential locations of buried Spanish wells across the site. We identify roughly 200 potential well locations and compare these locations to the distribution of Spanish artifacts across the site yielded through a full‐coverage shovel test survey, the arrangement of Spanish structures known from large‐scale block excavations, and the likely position of roadways and house lots. This new data is used to contextualize and refine extant understandings of Santa Elena's town plan while also contributing to a broader research program devoted to exploring Spanish colonial life and settlement in 16 th ‐century North America (The Santa Elena Landscape Project). As Santa Elena is a National Historic Landmark currently threatened by rising sea levels, this work contributes to an efficient, minimally invasive research program devoted to exploring the Spanish settlement at Santa Elena and to documenting the range of cultural resources present at the site for the purposes of protection and remediation in the context of significant, ongoing shoreline erosion.
The year 2015 marked the millennium of the first documentary evidence of the city of Leipzig as urbs Libzi . Inspired by this event the first digital elevation model (DEM 1015) from the palaeorelief at the time of the first settlement is modelled in two/three‐dimensions by applying geographic information system (GIS)‐technology. The article focuses on innovative multiproxy ideas to reconstruct the palaeorelief for a city centre. Thus, the topic of the project combines various scientific disciplines such as geomorphology and statistics. Qualitative data, mainly from archaeological excavations and geological drills, are linked by using GIS through surveying techniques. By applying the same method as for the DEM 1015, a recent DEM (DEM Today) is created. Furthermore, a comparison is conducted between this DEM Today and another recent DEM, which was generated with LiDAR data provided by the Staatsbetrieb Geobasisinformation und Vermessung Sachsen (GeoSN, State Operation Geobasisinformation and Surveying Saxony). A regression analysis and the descriptive comparison validate a close connection between the two recent DEMs. This supports the proposed methodology as being well suited to generate a visualization of the palaeorelief. However, models represent only a limited picture of reality. Undoubtedly, strong anthropogenic influences in the entire study area result in limiting factors which are hard to quantify. Therefore, the DEM 1015 shows the highest possible approximation of the ancient relief at the time of the first settlement. Nevertheless, the project supports further research on the landscape and settlement genesis at the study area. The DEM 1015 allows the investigation of the palaeorelief concerning geomorphological conditions during the Holocene. Furthermore, it is possible to draw inferences about how the environment has been shaped and structured by anthropogenic influences in this area over the last 1000 years. The research has the character of a case study that subsequently will open up opportunities to other areas.
Thermal infrared imaging, or thermography, is the remote sensing technique of detecting variations in ground temperature caused by exposed or subsurface archaeological remains either absorbing or radiating heat. Despite its conception in the 1970s, the practice has to date been rarely utilized, as a result of the high cost of the technology and the complex interplay of environmental variables. However, recent studies have demonstrated the effectiveness of the technique, especially when combining modern thermal cameras with unmanned aerial vehicles (UAV). Yet these papers often focus on mid‐ to high‐altitude flights, where the technique is only effective at detecting larger thermal anomalies. This article presents a new method for terrestrial thermography, developed for the Zagora Infrared Photogrammetry Project (The University of Sydney and the Australian Archaeological Institute at Athens). The project undertook a six week thermal investigation of the Early Iron Age site of Zagora and the surrounding hinterland utilizing the newest commercial thermal cameras and UAVs. The method of terrestrial thermography involves using photographic poles and photogrammetry to create high‐resolution thermal orthophotographs, which allow the detection of smaller thermal anomalies, providing significantly more detail than aerial thermography. Several features were discovered using this method, including a possible kiln, which would be the first ever identified at the site.
We present a new three‐dimensional (3D) marine seismic data acquisition system, named PingPong , developed for archaeological prospection in shallow water. Prospection targets for the system are ancient harbour sites and sedimented remains of shipwrecks. The prospection of such targets often means working at the transition from land to water, in areas of only a few meters of water depth and hardly accessible waters. An acquisition system for such environments needs to meet specific demands, especially low draught and marginal weight besides the requirements of archaeological prospection, meaning decimetre resolution and 3D imaging capabilities, together with fast multichannel acquisition to be able to cover large areas. We explain the properties of the PingPong system and show its imaging capabilities using the case study of a sedimented medieval shipwreck. The study area is located at the innermost part of the Baltic fjord Schlei, Germany. In 2014, divers found a wreck in this area, mostly covered by mud. Findings and two timbers, dated by dendrochronology, indicated that the wreck is a Scandinavian transport ship dating to the middle of the twelfth century and related to Schleswig, which is located 2 km northwest of the study area. We show that the PingPong system is able to image the major remains of the wooden wreck at the seafloor and underneath. The acquired seismic datacube has a resolution of 0.15 m. It shows a number of distinct reflections that can clearly be assigned to the shipwreck, helping to understand the overall condition of the wreck. The reflections originate from one half the ship's hull, which is tilted to the side. The reflections concentrate in the first metre below the seafloor and correlate well with the results from the diving prospection.
The megalithic sites from southwest Iberia represent one of the largest clusters of prehistoric monuments in Europe from the Neolithic and Copper Age (fifth and third millennia cal bc ). Unlike other regions from western Europe, there has not been a recent effort to map the distribution of these kinds of burials across this vast territory. Therefore, this article aims to collect geographic information from three regions of southwest Iberia (Alentejo and Beira Baixa from Portugal and Extremadura from Spain) and to compare the archaeological evidence between different landscape units. We have mapped already known megaliths ( ca 2000) and settlements ( ca 1500) in this area. Moreover, through the interpretation of light detection and ranging (LiDAR) datasets, we have identified new walled enclosures and megaliths in the Extremadura region (Spain), the only one of the three where LiDAR data are available. The new data reveals new connections between settlements, burials and other archaeological evidence. Finally, we discuss the impact that these new data have on a new overall interpretation of megalithic landscapes from the Iberian Peninsula, stressing also the potential risks that the massive application of remote sensing can have in the production of archaeological knowledge.
Traditionally, ground‐penetrating radar (GPR) measurements for near‐surface geophysical archaeological prospection are conducted with single‐channel systems using GPR antennae mounted in a cart similar to a pushchair, or towed like a sledge behind the operator. The spatial data sampling of such GPR devices for the non‐invasive detection and investigation of buried cultural heritage was, with very few exceptions, at best 25 cm in cross‐line direction of the measurement. With two or three persons participating in the fieldwork, coverage rates between a quarter hectare and half a hectare per day are common, while frequently considerably smaller survey areas at often coarse measurement spacing have been reported. Over the past years, the advent of novel multi‐channel GPR antenna array systems has permitted an enormous increase in survey efficiency and spatial sampling resolution. Using GPR antenna arrays with up to 16 channels operating in parallel, in combination with automatic positioning solutions based on real‐time kinematic global navigation satellite systems or robotic total‐stations, it has become possible to map several hectares per day with as little as 8 cm cross‐line and 4 cm in‐line GPR trace spacing. While this dramatic increase in coverage rate has a positive effect on the reduction of costs of GPR surveys, and thus its more widespread use in archaeology, the increased spatial sampling for the first time allows for the high‐resolution imaging of relatively small archaeological structures, such as for example 25 cm wide post‐holes of Iron Age buildings or the brick pillars of Roman floor heating systems, permitting much improved archaeological interpretations of the collected data. We present the state‐of‐the‐art in large‐scale high‐resolution archaeological GPR prospection, covering hardware and software technology and fieldwork methodology as well as the closely related issues of processing and interpretation of the huge data sets. Application examples from selected European archaeological sites illustrate the progress made.
One of the major problems in the forward modelling of magnetic anomalies is the assessment of a minimum level of acceptable accuracy in the fit between observed and theoretical anomalies. We present a new approach to the analysis and interpretation of archaeological magnetic anomalies, based on classical algorithms of forward modelling and a new technique of error assessment. This approach allows us to determine geometry, physical properties, and location of buried archaeological features, as well as the occurrence of fires or other historical events that may have affected the observed magnetic signal. Our method starts from the acquisition of total field data, usually in a regular grid arrangement, and proceeds through their reduction to archaeological magnetic anomalies. This reduction is performed subtracting from the observed total field data a polynomial representation of the regional field, on the basis of a rigorous criterion that tries to separate archaeological anomalies from geological (crustal) contributions. At the next step, a map of the maximum allowed misfit is built, which depends from the estimated uncertainty at each point of the magnetic anomaly field. This map specifies the maximum allowed deviation of theoretical anomalies from the observed values. The last step is the analysis of these anomalies through a new forward modelling tool, with the objective to reconstruct the three‐dimensional arrangement of buried features and possibly obtain some information about the history.
The nature of earth mounds and their function over time in northern Australia is of ongoing academic debate. Here we present how the integration of ground‐penetrating radar (GPR) and magnetic data, after being adjusted for surface elevation changes, was used to analyse the interior features and objects within six earth mounds in Mapoon, western Cape York, Australia. These geophysical techniques were merged and interpreted jointly to produce images of the stratigraphic units and objects within the mounds to determine their extent and composition. It was found that some mounds were built over burned areas that contain large objects on the original ground surface. Those modified areas were then converted into substantial earth mounds, which reach a maximum height of about 4 m. Other mounds nearby show no evidence of pre‐construction burning. In one mound cluster the western three mounds contain human burials that were visualized using GPR profile interpretation. The nearby eastern three mounds were devoid of human burials, but contained many of the pre‐mound burned features seen in those just a few hundred metres to the west. The close proximity of these six mounds, with very different associated features and internal objects suggests that they are related in some way, but differed in their function. It is also possible that they were constructed at different times by different people. The data analysis techniques presented in this article assists with further opportunities to undertake non‐destructive investigations of these earth mounds that are culturally appropriate to living Aboriginal people. They will also help to resolve the function and possible importance of these constructed features over time.
An annual series of lectures and field exercises has provided training in the archaeological application of geophysical, aerial and other remote sensing methods; this week‐long workshop has been coordinated by the US National Park Service (NPS) since 1991. Volunteer instructors have trained nearly 900 attendees at a variety of prehistoric, protohistoric, and historic sites across the United States. This NPS workshop is the longest‐standing training course in archaeological prospection and it is also responsible for training the greatest number within the archaeological community. Participants have benefited from their interactions with the large number of experienced instructors and from field exercises with a diverse array of modern equipment. The course has emphasized practical techniques for archaeologists and the development of research and commercial strategies; it has not trained archaeologists to be geophysicists. Above and beyond its role in training, the NPS workshop has created a community of practitioners, providing myriad opportunities for professional development, mentoring and collaboration, and it has played a major role in the acceptance of geophysics by archaeologists in the United States.