The unmanned aerial vehicle (UAV) photogrammetric survey of an archaeological site has proved itself to be particularly efficient. In order to obtain highly accurate and reliable results, it is necessary to design carefully the flight plan and the geo-referencing, while also evaluating the indicators of the accuracy rate. Using as a test case a UAV photogrammetric survey conducted on the archaeological site of the Roman Amphitheatre of Avella (Italy), in this paper, we propose a pipeline to assess the accuracy of the results according to some quality indicators. The flight configuration and the georeferencing chosen is then be checked via the residuals on the ground control points (GCPs), evenly distributed on the edges and over the entire area. With the aim of appraising the accuracy of the final model, we will suggest a method for the outlier detection, taking into account the statistical distribution (both global and of portion of the study object) of the reprojection errors. A filter to reduce the noise within the model will then be implemented through the detection of the angle formed by homologous rays, in order to reach a compromise between the number of the usable points and the reduction of the noise linked to the definition of the 3D model.

<p class="normal">The main objective of this paper is to analyse the potential as well as the limitations of an action camera (GoPro Hero 3 Black) in photogrammetric application for architectural cultural heritage reconstruction. The investigations were carried out in a site of notable historical interest, “Villa Giulia Felice” in Pompeii, Italy. In order to estimate the work pipeline, the time-consuming processing and the output product accuracy using fisheye camera images, three commercial image processing software packages were tested: Agisoft PhotoScan, Pix4Dmapper and 3DF Zephyr Aerial. Several comparisons among the final 3D models produced have been developed and the results achieved. Despite the problems found related to lens distortion and the small distance from the camera to the object (average distance ~80 cm), the test has provided good results in terms of accuracy (average error 2 - 3.5 cm) and reliability.</p>

<p><strong>Abstract.</strong> The paper reports the results of a photogrammetric survey made using an Unmanned Aerial Vehicle (UAV) in the archaeological site of the Roman Amphitheatre in Avella (Avellino, Italy). The aim of the study is to verify which modality of image acquisition (if only nadiral images or nadiral plus Oblique images), together with the method of Global Positioning Satellite System (GNSS) survey of the Ground Control Points (GCP) is able to produce the better 3D model, in terms of accuracy, in order to extract traditional graphic drawings (plan, elevation and section), suited to the required representation scales (1<span class="thinspace"></span>:<span class="thinspace"></span>100 and 1<span class="thinspace"></span>:<span class="thinspace"></span>50). The accuracy in georeferencing was evaluated analysing the residues on the GCPs; subsequently, a more detailed analysis of the accuracy of the final 3D model was performed analysing the residuals on the image coordinates, also called re-projection error. The method developed is based on the statistical analysis of the different models, built changing the GCPs survey method and the photogrammetric shots acquired. The results of our analysis show that the photogrammetric survey is more ‘stable’ using only nadiral images and that the nRTK technique allows results comparable to those obtained with static measurements, both in precision and in reliability. Moreover, if the GCPs are measured in nRTK mode, taking into consideration the graphical error, the maximum representation scale is 1<span class="thinspace"></span>:<span class="thinspace"></span>100, whereas the use of static technique makes it possible to describe major details, at a scale of 1<span class="thinspace"></span>:<span class="thinspace"></span>50.</p>

This project aimed to systematically investigate the archaeological remains of the imperial Domitian villa in Sabaudia (Italy), using different three-dimensional survey techniques. Particular attention in the research was paid to the identification and documentation of traces that buried structures left on the surface occupied by the villa, which extended for 46 hectares, an area that was fully covered with structures. Since a dense pine forest was planted during the 1940s and is currently covering the site, this contribution investigates particularly the correlation among the presence of cropmarks, identifiable with the processing of multispectral maps and vegetation indices from RGB images, and earthwork anomalies identified in a Digital Terrain Model (DTM) built, by utilizing a light detection and ranging (LiDAR) flight from an Unmanned Aerial Vehicle (UAV). The study demonstrates how the use of vegetation maps—calculated starting from RGB and multispectral aerial photos—can provide a more expeditious preliminary analysis on the position and extension of areas characterized by the presence of buried structures, but also that, in order to investigate in-depth a context in similar conditions, the most effective approach remains the one based on LiDAR technology. The integration between the two techniques may prove fruitful in limiting the extension of the areas to be investigated with terrestrial survey techniques.

The first objective of the work is to test a cost-effective tool for the collection of debris flows (DF) field data such as volumes, peak flow depths and deposit depths. Secondly, we show how these data can be used for the calibration of a depth-averaged propagation model. The case study is a DF of pumiceous sediments, occurred in the Amalfi Coast (Southern Italy) in October 2013. The DF path is a steep channel, ending in a small debris fan delimitated by a gabion wall. The risk is high because DFs, having a return period of just few years, overtop the wall and hit a busy road. Both terrestrial laser scanner (TLS) and photogrammetric techniques were employed to survey the topography, before and after the event under study. The images of the channel were taken from an unmanned aerial vehicle (UAV). Digital terrain models (DTM) were obtained pre and post event while the traces left by the DF along the channel banks allowed the estimation of the peak flow depths.A finite volume two-dimensional numerical code (FLATModel), based on shallow-water equations, was used for modelling the propagation and deposition of the DF under study. Both Voellmy and pure Coulomb friction resistance laws were tested. The numerically predicted deposit was compared to the post event DTM. Such comparisons showed a good agreement in terms of both depths and shape of deposit. The calibrated model could be used to predict the DFs run-out distances in similar contexts.