Integrating Multiband Photogrammetry, Scanning, and GPR for Built Heritage Surveys: The Façades of Castello Del Valentino

Abstract

Abstract. The conservation of built heritage is a complex process that necessitates co-operative efforts. Holistic, integrated documentation constitutes a crucial step towards conservation by contributing to diagnosis and by extension to the effective decision-making about the required preventive and restorative interventions. It involves the recording of interdisciplinary data to produce objective diagnostical conclusions concerning the state of preservation. Although the developments in close-range sensing techniques allow increasingly accurate and rich data recording for heritage building condition surveys, the problem of combining them (to allow integrated processing) often remains unsolved. This is particularly true when surveys include vastly heterogenous documentation data. This work aims to discuss methodologies and implications of such integrations through a monumental heritage survey case – the Castello del Valentino in Turin (Italy). Visible-spectrum and infrared imagery is combined with photogrammetric techniques, terrestrial LiDAR, and microwave measurements conducted on the historical façades’ surfaces, to examine the comprehensiveness of the data fusion results, as well as conclusions that can be drawn regarding previous interventions and the current condition of the monument.

Condition Assessment of Heritage Buildings via Photogrammetry: A Scoping Review from the Perspective of Decision Makers

“…In the case of multispectral imaging, as presented in Section 3.3.1, a direct comparison is enabled between CRP surface colorimetric/metric data and TIR, NIR and/or UV surface data, which might be useful to assess the position and quantitative extent of non-visible anomalies, such as material inhomogeneity [129,130,134], energy losses [131], cracks and mechanical damage [132,136], moist areas [133,135] and weathering patterns [53,60]. Differently, in the case of multisensory data collection, as reported in Section 3.3.2, an indirect comparison is enabled between CRP surface colorimetric/metric data and measurements of constructional discontinuities and pathologies across the components; this comparison is detected as variations in radar reflection from underground structures [143][144][145]147,148]; moist areas [142,146]; or variations in ultrasonic velocities in walls [148,150,151], columns [92,152,153] and pillars [154]. In a few applications, the employment of CRP models to accurately set up onsite tests and equipment is also documented [155][156][157].…”

“…In the work by Abate et al [145], the photogrammetric reconstruction of a "Painted Church" in Cyprus was used to develop an interactive environment, where 2D radargrams of the underground structures were rendered into the 3D space as flat 3D objects textured with the GPR image which could be interrogated and displayed interactively. Differently, Adamopoulos et al [146], within a comprehensive investigation of an Italian castle where multispectral survey was also applied, tested the data fusion of the point clouds with GPR reflection amplitude values. In detail, the values were displayed as horizontal circular sections of a column, leading to the assumption that the bottom part had undergone mortar replacement from a previous intervention, and as isosurfaces of high echo for a portion of the monumental façade, supporting the diagnosis of high moisture content from water that had permeated the damaged structure's surface layers.…”

Management Properties and Procedures in the Information Model of the Historic Building Hbim on Building Facades

“…Although there are very advanced techniques in the area of thermography to detect humidity problems for the purpose of controlling characteristics and pathologies in buildings (Fino et al, 2019), in photogrammetry, you can observe the colour changes in the facing. Holistic documentation constitutes one of the essential steps in the detection of alterations in the façade (Adamopoulos et al, 2021). Durability problems in coatings are an important factor determining the characteristics of the material properties.…”

A practical workflow for the 3D reconstruction of complex historic sites and their decorative interiors: Florence As It Was and the church of Orsanmichele

“…Since 2005, pipelines have been established to create accurate point cloud models of important sites such as the basilica of S. Francesco in Assisi, the Medieval wall of Avila, the Roman Forum in Pompeii, and multiple structures produced during the early modern period in Florence, to name but a few [12][13][14][15]. More recently, specialists have combined photogrammetric models with point clouds for research purposes, layering the former over the latter in order to place textured surfaces on top of spatially accurate models produced with LiDAR equipment [16][17][18][19]. An important aspect of the traditional model construction workflow has been the time-consuming process of editing collected scans and images to eliminate tangential data that interferes with the model construction and the combining of individual point clouds to create an accurate representation of the structure.…”