Modeling and deterioration mapping of façades in historical urban context by close-range ultra-lightweight UAVs photogrammetry

Deterioration mapping of façades may be a challenging task in historical urban contexts, often characterized by narrow streets and tall buildings. In these situations, the application of Terrestrial Laser Scanning or Terrestrial Photogrammetry does not provide satisfactory results. Furthermore, the use of Unmanned Aerial Vehicles, the so-called “drones”, is generally forbidden in crowded places for safety reasons unless they are lighter than a weight imposed by the regulations in force in each country. This article presents the application of a very small and ultra-lightweight drone (less than 300 g) equipped with a low-cost camera, particularly suitable for operating in very narrow spaces. A close range photogrammetric survey performed to analyze a huge historical building façade in Bologna (Italy) pointed out a good accuracy level, confirmed by the validation of the results carried out by a 3D laser scanner survey. Moreover, a map of the degradation has been realized to support further restoration analysis, demonstrating that this low-cost, fast, and easy-to-use survey technique can be applied to other similar urban contexts at the same time.     

3D model of the Can Sadurní cave

Graphic and metric information about the site and its environment and about the different structures and artefacts located are indispensable for the optimal management of an archaeological excavation. A Geographic Information System (GIS) proves useful in managing and analysing information and data obtained from different sources. Two techniques of data capture, Terrestrial Laser Scanning (TLS) and close range photogrammetry, are used to generate accurate and high-resolution 3D models of a cave, the silos and a combustion structure at the Can Sadurní site (Begues, NE Spain). This site is especially noteworthy on account of its complete stratigraphy of the Catalonian Holocene. The capture and processing of the photogrammetric and TLS data used to generate 3D models are discussed in detail. These models cannot be obtained by classic archaeological techniques since the record is made layer by layer, approximately one decimetre apart, with the result that the information between the layers is lost. Our findings highlight the potential of these techniques for obtaining accurate and photorealistic models that facilitate a complete analysis of the available information at an archaeological site.     

Towards a Risk Management and Conservation Plan for the Djin Blocks at the World Heritage Site of Petra,Jordan: The Case of Djin Block No. 9

Cultural heritage is subjected to many pressures and risks. Over the past few years, the use of digital technologies has significantly changed the approaches to cultural heritage documentation for the purpose of condition assessment and conservation. The integration of novel approaches and techniques has permitted a detailed examination and assessment of damage, deterioration due to weathering and erosion, and their mechanisms. This study seeks to contribute to the preservation and conservation of the significant heritage of the so-called Djin Blocks at the World Heritage Site of Petra in Jordan. While these three dimensional cuboid rock-cut monuments have been subject to extensive conservation studies, this is the first time they have been subjected to 3D recording and multispectral photography, with the aim of recording damage caused by the ravages of time.

This study presents the results of the documentation of the case study Djin Block No. 9. A variety of systematic documentation techniques were used, including 3D recording with terrestrial laser scanning (TLS), close-range photogrammetry, multispectral imaging, and thermography records. In addition, pathological studies of the erosion from various causes and an analysis of the effect of weathering on Djin Block No. 9 are performed. Based on this data, the paper presents recommendations for developing risk management and conservation planning of Djin Block No. 9.     

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.     

Flint and Quartzite: Distinguishing Raw Material Through Bone Cut Marks

Since the 1980s, several experimental analyses have been able to differentiate some lithic tool types and some of their raw materials according to the morphology of cut marks imprinted by such tools when used for butchering activities. Thus, metal tool use has been differentiated in contexts with an abundance of lithic tools, or even the use of hand axes has been documented in carcass processing, in contrast with simple unretouched or retouched flakes. As important as this information is, there are still other important aspects to be analysed. Can cut marks produced with different lithic raw material types be differentiated? Can cut marks made with different types of the same raw material type be characterized and differentiated? The objective of this study is to evaluate if cut marks resulting from the use of different flints and different quartzites are distinguishable from each other. In the present work, an experimental analysis of hundreds of cut marks produced by five types of flint and five varieties of quartzite was carried out. Microphotogrammetry and geometric–morphometric techniques were applied to analyse these cut marks. The results show that flint cut marks and quartzite cut marks can be characterized at the assemblage level. Different types of flint produced cut marks that were not significantly different from each other. Cut marks made with Olduvai Gorge quartzite were significantly different from those produced with a set comprising several other types of quartzites. Crystal size, which is larger in Olduvai Gorge quartzites (0.5 mm) than Spanish quartzites (177–250 μm), is discussed as being the main reason for these statistically significant differences. This documented intra‐sample and inter‐sample variance does not hinder the resolution of the approach to differentiate between these two generic raw material types and opens the door for the application of this method in archaeological contexts.     

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.     

Report on the first research campaign on the Napoleonic brick, Mercure, wrecked off Lignano, Udine, Italy in 1812

During 2001, the NAUSICAA office organized a research campaign on the site where two carronades had been retrieved by a fishing boat. Side-scan sonar research led to the discovery of a mound and six more carronades. The mound was composed of iron ingots, cannon balls, and tools reused as ballast. After the cleaning of a carronade, it was possible to read the name of the foundry, Du Creusot , and the date, 1806. This evidence was sufficient to identify this as the wreck of the Napoleonic brick, Mercure , lost during the Battle of Grado, fought between an English and French fleet in February 1812.     

Classical Temples and Industrial Stores: Survey Analysis of Historic Unreinforced Masonry (URM) Precincts to Inform Urban Seismic Risk Mitigation

ABSTRACT

Oamaru, Winton, and Invercargill feature some of New Zealand’s most intact heritage precincts that are confronted by ongoing threats of seismic activity. The 2010/2011 Canterbury earthquake sequence and Canterbury Earthquakes Royal Commission of 2012, identified a nationwide trend through the proportion of deaths that occurred in public places as a result of the prevalent historic unreinforced masonry (URM) building stock. The reported study was undertaken to address urban safety and seismic risk mitigation through the lens of heritage conservation. The range of classically designed public buildings and industrial warehouses in the South Island of New Zealand were often produced by singular architectural practices, using locally sourced materials and construction techniques. It is vital to incorporate an examination of unique architectural qualities within urban seismic risk assessment and mitigation. Historic urban layout, architectural deployment of masonry, and extent of retrofits were recorded through onsite visual surveys via Geographical Information Systems and three-dimensional representation technologies. Extending the scope of information collected for engineering seismic risk assessment by focusing on the historical architectural context informs the selection of future mitigation measures. Oamaru, Winton, and Invercargill present intriguing case studies for multidisciplinary analysis, prior to testing urban-scale survey approaches within comparable historic centers across New Zealand.     

Multi-temporal archaeological analyses of alluvial landscapes using the photogrammetric restitution of historical flights: a case study of Medellin (Badajoz,Spain)

One of the main challenges affecting the archaeological study of alluvial landscapes is the intensity of change these environments experience over time. Quick and dramatic alterations in geomorphological dynamics and land exploitation determine the visibility and conservation of the archaeological record. This study proposes an approach to the problem of studying these evolving environments based on the analysis and treatment of a series aerial photographs taken between the 1950s and the present day. This paper is particularly interested in looking at the process of photogrammetric restitution and in validating and comparing the digital terrain models and orthoimages produced. The quantitative analysis and visual interpretation of these results can provide valuable information about the transformation of landscapes and factors affecting surface evidence. The intended final result is to develop the ability to map the most problematic or best preserved areas. Nevertheless, it is considered in terms of a relative measure of change magnitude, rather than trying to provide absolute figures.     

A Roman shipwreck with a cargo of Apuan marble (marmor lunense) at Punta del Francese (Stintino-Sassari,Sardinia)

The wreck-site of Punta del Francese (Stintino-Sassari) off the island of Sardinia (Italy) is composed of 14 roughly cubic blocks and slabs of marble lying in an almost coherent arrangement. Archaeometric analyses indicate a provenance of the entire cargo of marble from the Apuan Alps (marmor lunense) of north Italy. Fragments of amphoras confirm its dating to the Flavian period (first century ce ). The dimensions of the cargo, and especially of the single blocks, suggest it would have been destined for the building of an important public monument in western Hispania or southern Gallia. A first hypothesis for the ship's sailing route, and a comparison with the other cargoes of marble from Luna, are proposed.