Calibrating and evaluating a range camera for Cultural Heritage metric survey

At the last ISPRS Congress in 2008, the first experimental evaluations of range cameras were presented. During the last four years, much research has been done by different research groups and some meetings have allowed a continuous sharing of experiences and results. The research group of the Politecnico di Torino has developed some original methodologies for calibrating range cameras and a set of tests for evaluating the possible use of range cameras for Cultural Heritage metric surveys. Cultural Heritage objects are characterized by complex shapes and different materials (e.g. stones, plasters, etc.). The present paper describes the results achieved in calibrating the SR4000 range camera and it studies the influences of the measuring direction inclination and of the different materials on distance measurements accuracy and completeness. This allows defining which are the possible strategies to be adopted to give affordable and useful point clouds for the metric description of Cultural Heritage objects. Some basic metric survey examples of architectural objects are given to demonstrate the real application of such devices to Cultural Heritage metric documentation, from the acquisition of point clouds up to 2D (elevations) and 3D representations (texturized 3D models). Considering the current development of such devices and their possible future evolutions, the expected possible uses of range cameras in Cultural Heritage metric survey should be advantageous, especially considering the low costs of such devices and the possibility of their making 3D videos which can be acquired in a short tim

Points clouds generation using TLS and dense-matching techniques. A test on approachable accuracies of different tools

3D detailed models derived from digital survey techniques has increasingly developed and focused in many field of application, ranging from the land and urban areas survey, using remote sensed data, to landscape assets and finally to Cultural Heritage items. The high detailed content and accuracy of such models makes them so attractive and usable for large sets of purposes. The present paper is focused on a test aimed to point clouds generation fulfilled by archaeological data; active and passive sensors techniques and related image matching systems have been used in order to evaluate and compare the accuracy of results, achievable using proper TLS and low cost image-matching software and techniques. After a short review of approachable methods some attained results will be discussed; the test area consists of a set of mosaic floorings in a late roman domus located in Aquileia (UD-Italy) requesting a very high level of details and high scale and precision. The experimental section provides the descriptions of the applied tests in order to compare the different software and the employed method

Performance evaluation of cots UAV for Architectural Heritage documentation. A test on S.Giuliano Chapel in Savigliano (CN) - Italy

Even more the use of UAV platforms is a standard for images or videos acquisitions from an aerial point of view. According to the enormous growth of requests, we are assisting to an increasing of the production of COTS (Commercial off the Shelf) platforms and systems to answer to the market requirements. In this last years, different platforms have been developed and sell at low-medium cost and nowadays the offer of interesting systems is very large. One of the most important company that produce UAV and other imaging systems is the DJI (Dà-Jiāng Innovations Science and Technology Co., Ltd) founded in 2006 headquartered in Shenzhen – China. The platforms realized by the company range from low cost systems up to professional equipment, tailored for high resolution acquisitions useful for film maker purposes. According to the characteristics of the last developed low cost DJI platforms, the onboard sensors and the performance of the modern photogrammetric software based on Structure from Motion (SfM) algorithms, those systems are nowadays employed for performing 3D surveys starting from the small up to the large scale. The present paper is aimed to test the characteristic in terms of image quality, flight operations, flight planning and accuracy evaluation of the final products of three COTS platforms realized by DJI: the Mavic Pro, the Phantom 4 and the Phantom 4 PRO. The test site chosen was the Chapel of San Giuliano in the municipality of Savigliano (Cuneo-Italy), a small church with two aisles dating back to the early eleventh century

PHOTOGRAMMETRIC UNDERWATER AND UAS SURVEYS OF ARCHAEOLOGICAL SITES: THE CASE STUDY OF THE ROMAN SHIPWRECK OF TORRE SANTA SABINA

The 2020 underwater archaeological research in the inlet of Torre Santa Sabina – Baia dei Camerini (Municipality of Carovigno, Brindisi, Italy) represented the first phase of the pilot intervention of the Interreg Italia-Croatia UnderwaterMuse project. The project aims to enhance and make accessible the vast underwater heritage of the areas involved; this will be done by creating submerged archaeological parks and using virtual reality's narrative and communicative tools and platforms. During the 2020 campaign, different survey activities were carried out using several techniques and methodology to produce the area's multi-scale documentation. First of all, the entire stretch of coast was mapped with UASs (Uncrewed Aerial Systems) flights to reconstruct the coastal landscape in various phases. Furthermore, an underwater photogrammetric survey carried out by expert scuba divers has been achieved in the wreck's aft area (the site analyzed during the 2020 excavation activities). The fruitful synergy between the various actors involved and the support of the territory and the community has allowed the achievement of this campaign's objectives, preliminary to the broader and more articulated intervention foreseen for the following year

HISTORICAL BUILDINGS MODELS AND THEIR HANDLING VIA 3D SURVEY: FROM POINTS CLOUDS TO USER-ORIENTED HBIM

This paper retraces some research activities and application of 3D survey techniques and Building Information Modelling (BIM) in the environment of Cultural Heritage. It describes the diffusion of as-built BIM approach in the last years in Heritage Assets management, the so-called Built Heritage Information Modelling/Management (BHIMM or HBIM), that is nowadays an important and sustainable perspective in documentation and administration of historic buildings and structures. The work focuses the documentation derived from 3D survey techniques that can be understood like a significant and unavoidable knowledge base for the BIM conception and modelling, in the perspective of a coherent and complete management and valorisation of CH. It deepens potentialities, offered by 3D integrated survey techniques, to acquire productively and quite easilymany 3D information, not only geometrical but also radiometric attributes, helping the recognition, interpretation and characterization of state of conservation and degradation of architectural elements. From these data, they provide more and more high descriptive models corresponding to the geometrical complexity of buildings or aggregates in the well-known 5D (3D + time and cost dimensions). Points clouds derived from 3D survey acquisition (aerial and terrestrial photogrammetry, LiDAR and their integration) are reality-based models that can be use in a semi-automatic way to manage, interpret, and moderately simplify geometrical shapes of historical buildings that are examples, as is well known, of non-regular and complex geometry, instead of modern constructions with simple and regular ones. In the paper, some of these issues are addressed and analyzed through some experiences regarding the creation and the managing of HBIMprojects on historical heritage at different scales, using different platforms and various workflow. The paper focuses on LiDAR data handling with the aim to manage and extract geometrical information; on development and optimization of semi-automatic process of segmentation, recognition and modelling of historical shapes of complex structures; on communication of historical heritage by virtual and augmented reality (VR/AR) in a 3D reconstruction of buildings aggregates from a LiDAR and UAV survey. The HBIM model have been implemented and optimized to be managed and browse by mobile devices for not only touristic or informative scopes, but also to ensure that HBIM platforms will become more easy and valuable tools helping all professionals of AEC involved in the documentation and valorisation process, that nowadays more and more distinguish CH policies

3D Modelling of trompe l’oeil decorated vaults using dense matching techniques

Dense matching techniques, implemented in many software, both commercial or open source, are effective instruments to realize a rapid and detailed survey of complex objects, including many different surfaces and a lot of details. For this reason these tools have been tested for the metric survey of a frescoed ceilings of the hall of honour of a baroque building. These surfaces are densely painted with trompe-l’oeil technique, what, in theory, can offer a very good texture to automatic matching algorithms, but in this case the painting gives problems in reconstructing the correct geometry: in fact, in correspondence with principals architectonic painted details, the models presents some irregularity following the painted drawing. The photogrammetric models have been compared with data deriving from a LIDAR survey of the same object, to evaluate the entity of this blunder: some profiles of selected sections have been extracted, verifying the different behaviours of the software tools

Photogrammetric underwater and UAS surveys of archaeological sites: the case study of the Roman shipwreck of Torre Santa Sabina

The 2020 underwater archaeological research in the inlet of Torre Santa Sabina - Baia dei Camerini (Municipality of Carovigno, Brindisi, Italy) represented the first phase of the pilot intervention of the Interreg Italia-Croatia UnderwaterMuse project. The project aims to enhance and make accessible the vast underwater heritage of the areas involved; this will be done by creating submerged archaeological parks and using virtual reality's narrative and communicative tools and platforms. During the 2020 campaign, different survey activities were carried out using several techniques and methodology to produce the area's multi-scale documentation. First of all, the entire stretch of coast was mapped with UASs (Uncrewed Aerial Systems) flights to reconstruct the coastal landscape in various phases. Furthermore, an underwater photogrammetric survey carried out by expert scuba divers has been achieved in the wreck's aft area (the site analyzed during the 2020 excavation activities). The fruitful synergy between the various actors involved and the support of the territory and the community has allowed the achievement of this campaign's objectives, preliminary to the broader and more articulated intervention foreseen for the following year

OBLIQUE IMAGES and DIRECT PHOTOGRAMMETRY with A FIXED WING PLATFORM: FIRST TEST and RESULTS in HIERAPOLIS of PHRYGIA (TK)

The complex archaeological site documentation benefits for a long time now from the aerial point of view and remote sensing methods. Moreover, the recent research on UAV photogrammetry platform equipment and flight planning actively contribute in this sense for a scaling improvement and cost-benefits balance. Frequently, the experiences on articulated topographic profiles in archaeological excavations require not only a multi-sensor approach but also and above all a multiscale one. According to this line, in a general time-cost ration framework, the geometric content of the generated DSMs should be complete of nadir and oblique point of view for the accurate 3D reconstruction of both upstanding buildings and excavations. In the same way, also the radiometric content closely depends on sensor payload quality and is strictly affected by excavation site condition, related to the site material and light. In this research, carried out in the impressive archaeological site of the ancient city of Hierapolis in Phrygia (Turkey) in the autumn 2019 campaign, the main goal was to evaluate and validate the overall performance of a novel UAV fix-wing ultralight platform with onboard GNSS receiver for RTK/PPK processing of cameras positioning and with the possibility of oblique images capturing. The expected contribute in terms of the acquisition, processing time, radiometric enhancement and geometry 3D reconstruction will be explored with preliminary test and outcomes, and with the results of the high-scale DSM and orthoimage generation of the complete Hierapolis site