Enhanced knowledge of archaeological residues is important for the long-term curation and understanding of a diminishing heritage. There are certain geologies and soils which can complicate the collection and interpretation of heritage remote sensing data. In some of these 'difficult' areas traditional detection techniques have been unresponsive. DART will develop a deeper understanding of the contrast factors and detection dynamics within 'difficult' areas. This will allow the identification of appropriate sensors and conditions for feature detection. the successful detection of features in 'difficult' areas will provide a more complete understanding of the heritage resource which will impact on research, management and development control.
In aerial prospection archaeological features are detected by the contrast between a feature and its surroundings. These contrasts are dynamic, and change over time with variations in local conditions. For example, vegetation marks are caused by changes in soil affecting the growth of the plants on the surface. These are only visible under certain conditions and appropriate stages of vegetation development. The Detection of Archaeological Residues using Remote sensing Techniques (DART) project seeks to model how parameters such as weather, landuse and soils influence these contrasts. Gaining this understanding will both enable us to identify timings, sensors and methodologies that are optimal for detecting archaeological features in different contexts and conditions. This will enable the acquisition of better quality images and facilitate the identification of images suitable for prospection from the ever-growing archives of aerial and satellite imagery. This presentation will provide an overview of how DART is using regular ground-based observations in conjunction with multi-temporal aerial hyperspectral and photographic imagery to investigate how archaeological features interact with their and surroundings and how this changes in relation to precipitation, soil properties and vegetation. The main focus of this work is on repeated ground-based spectroradiometry that allow us to investigate contrast both within and outside the visible spectrum and provide information about the influence of the archaeology on the biophysical properties of the surface. Results from 2011 demonstrate that high spectral resolution data has the potential to discriminate archaeological features more effectively and with a broader window of detection than visible wavelength or multi-spectral imaging. This will be demonstrated using specific examples from our data. The aerial data include EAGLE, HAWK and CASI hyperspectral surveys, oblique photography, and ortho-phototgrapy. The ground-based measurements, both captured concurrently with the flights and on a more regular basis include vegetation properties, weather data and spectro-radiometry
Satellite surveys in Syria have made use of imagery recorded some 30 years apart. By comparing the earlier pictures (Corona) with the later (Ikonos), sites captured on the former can be accurately located by the latter. The comparison also reveals the stark implications for archaeology as large parts of west Asian landscape change from a state of ‘benign neglect’ to active redevelopment. Based on their experience in the Homs survey, the authors have important advice to offer in the design and costing of surveys using satellite imagery.
This report presents a summary of the methods and some preliminary results of fieldwork by an interdisciplinary research team studying the landscape history of the upper Orontes Valley near Homs in western Syria. The particular focus of the project is to document long-term interrelationships between settlement and landscape in two adjacent but divergent regions. Geomorphological fieldwork on the Pleistocene and Holocene environments is considered first, with discussions focusing on the terraces of the River Orontes and the associated artefact material. Next, the geo-correction of satellite imagery and its profitable use in conducting fieldwork is outlined. What follows are some initial thoughts and results obtained for each region through three seasons of extensive and intensive fieldwork survey as guided by remote sensing methods. For the Southern Area these results are revealing differences in the densities of 'off- site' surface material. In the basalt region of the Northern Area satellite imagery has simplified methods of site detection. The report concludes with some preliminary observations on the main trends of settlement history that are emerging from the data.
The DART Project is examining four specific locations in great detail to that we can identify how environmental changes impact soil conditions. Such aspects greatly affect the success of archaeological prospection (both geophysical and optical techniques). The project has collected in-situ measured water content, electrical conductivity, temperature and weather readings and will compare these values with results from monthly geophysical and spectrometry surveys. This paper will examine the effects of differing buried archaeological ditch sediments and the adjacent undisturbed soils and changes in water content (derived from apparent permittivity measurements) on the changing geophysical response, recorded throughout the survey period (June 2011-Sept 2012).
In arable landscapes, the airborne detection of archaeological features is often reliant on using the properties of the vegetation cover as a proxy for sub-surface features in the soil. Under the right conditions, the formation of vegetation marks allows archaeologists to identify and interpret archaeological features. Using airborne Laser Scanning, based on the principles of Light Detection and Ranging (LiDAR) to detect these marks is challenging, particularly given the difficulties of resolving subtle changes in a low and homogeneous crop with these sensors. In this paper, an experimental approach is adopted to explore how these marks could be detected as variations in canopy biomass using both range and full waveform LiDAR data. Although some detection was achieved using metrics of the full waveform data, it is the novel multi-temporal method of using discrete return data to detect and characterise archaeological vegetation marks that is offered for further consideration. This method was demonstrated to be applicable over a range of capture conditions, including soils deemed as difficult (i.e., clays and other heavy soils), and should increase the certainty of detection when employed in the increasingly multi-sensor approaches to heritage prospection and management.
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