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.     

Monitoring façade soiling as a maintenance strategy for the sensitive built heritage

The color patterns generally found on the façades of architecturally sensitive buildings have an adverse impact on their aesthetics, to the detriment of their identity and potential economic value. A quantitative and qualitative study was conducted of the perception of aesthetic decay in the limestone on a heritage building. The study assessed building aesthetics between two façade cleaning operations, conducted in 1984–1986 and 2006–2008. Based on the calculation of the final or total soiling index, by means of in situ lightness measurement and three architectural design variables, the color distribution of the façades was quantified in 2006 and a model was developed to monitor façade soiling over time. The proposed model, a tool for planning preventive façade maintenance on architecturally sensitive buildings, advocates for sustainable cleaning operations. Its premise that periodic cleaning should only be conducted in areas where the limestone is affected by aesthetic decay redounds to minimised intervention and lower building management costs.     

New Developments in the Use of Spatial Technology in Archaeology

Spatial technology is integral to how archaeologists collect, store, analyze, and represent information in digital data sets. Recent advances have improved our ability to look for and identify archaeological remains and have increased the size and complexity of our data sets. In this review we outline trends in visualization, data management, archaeological prospecting, modeling, and spatial analysis, as well as key advances in hardware and software. Due to developments in education, information technology, and landscape archaeology, the implementation of spatial technology has begun to move beyond superficial applications and is no longer limited to environmental deterministic approaches. In the future, spatial technology will increasingly change archaeology in ways that will enable us to become better practitioners, scholars, and stewards.