A metrological approach for multispectral photogrammetry

<p>This paper presents the design and development of a three-dimensional reference object for the metrological quality assessment of photogrammetry-based techniques, for application in the cultural heritage field. The reference object was 3D printed, with nominal manufacturing uncertainty of the order of 0.01 mm. The object was realized as a dodecahedron, and in each face, a different pictorial preparation was inserted. The preparations include several pigments, binders, and varnishes, to be representative of the materials and techniques used historically by artists.</p><p>Since the reference object’s shape, size and uncertainty are known, it is possible to use this object as a reference to evaluate the quality of a 3D model from the metric point of view. In particular, verification of dimensional precision and accuracy are performed using the standard deviation on measurements acquired on the reference object and the final 3D model. In addition, the object can be used as a reference for UV-induced Visible Luminescence (UVL) acquisition, being the materials employed UV-fluorescent. Results obtained with visible-reflected and UVL images are presented and discussed.</p>

3D Reconstruction of a Roman Bridge in Canosa di Puglia (Italy)

The Roman bridge near Canosa di Puglia (Southern Italy) currently has a very different morphology from the one planned by its builders in the second century AD as part of the program for the construction of the Via Traiana. Although the piers, the abutments and the foundation platea are still preserved from the Roman age, the changes made over the centuries have altered its aspect, forgetting the traces of its monumental past. Starting from the surviving elements and the few available sources, an investigation has been carried out to reconstruct its original structure, thanks to a multidisciplinary and metrological approach and the combined use of aerophotogrammetry and 3D modeling. The usage of these technologies proved to be an essential tool, since they made it possible to carry out a survey otherwise hampered by the bulk of the artifact and the presence of the Ofanto River flowing below. The outcome of this research has led to a reconstruction hypothesis that returns a majestic monument that deserves an adequate place in the panorama of Roman architecture.

Measurements of N2, CO2, Ar, O2 and Air Pressure Broadening Coefficients of the HCl P(5) Line in the 1–0 Band Using an Interband Cascade Laser

We determine the CO2, N2, Ar, O2 and air pressure broadening coefficients of the H35Cl P(5) absorption line at 2775.77 cm−1 in the fundamental (1←0) band using a newly developed direct tunable diode laser absorption spectroscopy (dTDLAS)-based spectrometer employing a mid-IR interband cascade laser (ICL). For the first time, a reliable and consistent set of five different foreign pressure broadening coefficients for the same HCl P(5) line has been measured by a consistent metrological approach covering pressures from 100 to 600 hPa at temperatures of 294 and 295 K. The relative uncertainties of the stated CO2, N2, Ar, O2 and Air pressure broadening coefficients are in 1–3% range. The results are compared to previously available literature data—two broadening coefficients have been improved in accuracy and two have been determined for the first time in the sub 1000 hPa pressure range.