Photo Scanner 3D Survey for Monitoring Historical Monuments. the Case History of Porta Praetoria in Aosta


  • Paolo Salonia CNR, Institute for Technologies Applied to Cultural Heritage, Rome Research Area, Via Salaria, km 29.300, 00016 Monterotondo St. (Rome) ITALY
  • Tommaso Leti Messina CNR, Institute for Technologies Applied to Cultural Heritage, Rome Research Area, Via Salaria, km 29.300, 00016 Monterotondo St. (Rome) ITALY
  • Andrea Marcolongo CNR, Institute for Technologies Applied to Cultural Heritage, Rome Research Area, Via Salaria, km 29.300, 00016 Monterotondo St. (Rome) ITALY
  • Lorenzo Appolonia Direzione ricerca e progetti cofinanziati - Dipartimento soprintendenza per i beni e le attività culturali - Assessorato istruzione e cultura - Regione Autonoma Valle d'Aosta



Terrestrial Photo Scanner 3D, UAV, Image processing, Points clouds RGB, Multiscale, GIS Monitoring Cultural Heritage.


Accessibility to cultural heritage is one of the most important factors in cultural heritage preservation, as it assures knowledge, monitoring, Public Administration management and a wide interest on cultural heritage sites. Nowdays 3D surveys give the geometric basis for an effective artefact reconstruction but most of the times 3D data are not completely and deeply investigated to extract other useful information on historical monuments for their conservation and safeguard. The Cultural Heritage Superintendence of Aosta decided to run a time continual project of monitoring of the Praetorian Roman Gate with the collaboration of the ITABC, CNR of Italy. The Praetorian Roman Gate in Aosta, Italy, of Augustus ages, is one of the most well-known roman monumental gates, it is a double gate with three arches each side, 12 meters high, 20 meters wide, made of pudding stone ashlars, Badoglio, travertine, marble blocks and other stone insertion due to restorations between 1600 and 1950. In years 2000 a final restoration intervention brought the gate at the present state of art, within the frame of a restoration and conservation building site with the purpose of treat the different decay pathologies and conditions. A complete 3D geometric survey campaign has been the first step for the monitoring of the gate morphologic changes and decay progress in time. The main purpose is to collect both quantitative data, related to the geometry of the gate, and the qualitative data, related to the chromatic change on the surface due to the stone decay. The geometric data with colour information permits to associate materials and stone pathologies to chemical or mechanical actions and to understand and analyse superficial decay kinetics. The colours survey will also permit to directly locate on the 3D model areas of different stratigraphic units. The project aims to build a rigorous quantitative-qualitative database so to be uploaded into a GIS. The GIS will become the monitoring main means. Considering the huge dimension of the gate and its urban location a multi-scale approach has been considered. Controlled and free images have been taken from the ground and the top of the gate so to reconstruct all the walls and the upper cover. A topographic survey has been done so to be able to control and relate all the different acquisitions. It has been chosen a Photo Scanner 3D system. It is a photogrammetry-based survey technology for point clouds acquisition and 3D models configuration, from digital images processing. This technology allows to obtain point clouds (xyz coordinates) with RGB information and geometries at different levels of complexity by processing a number of images taken with a limited set of constraints, with the use of a simple acquisition equipment and through an image matching algorithm (ZScan, by Menci Software). Due to the high walls of the arch gates, the higher part has been surveyed with a remote controlled drone (UAV Unmanned Aerial Vehicle) with a digital camera on it, so to take pictures up to the maximum altitude and with different shooting angles ( 90 and 45 degree). This is a new technology which permits to survey inaccessible parts of a high monument with ease and accuracy, by collecting redundant pictures later bound together by an image block algorithm. This paper aims to present the survey experience architectural monuments trough the application of a trifocal quick photogrammetric system, in surveying at different scales and for different purposes.


Promis, C., 1862. Le antichità di Aosta, Capo VII, § 1. Porta Pretoria nello stato presente, Stamperia Reale, Torino, 1862, 142-156.

Drap, P., Sgrenzaroli, M., Canciani, M., Cannata, G., Seinturier, J., 2003. Laser Scanning and close range photogrammetry: Towards a single measuring tool dedicated to architecture and archaeology, in Proceeding ISPRS symposium.

Salonia, P., Scolastico, S., Bellucci, V., 2006. Laser scanner, quick stereo-photogrammetric system, 3D modelling: new tools for the analysis and the documentation of cultural archaeological heritage, in Proceedings of 2nd international conference on remote sensing in archaeology, Rome.

Salonia, P., Bellucci, V., Scolastico, S., Marcolongo, M., Leti Messina, T., 2007. 3D survey technologies for reconstruction, analysis and diagnosis in the conservation process of cultural heritage, in Proceedings of Cipa 2007 – XXI International Symposium. Anticipating the future of the cultural past, 1-6 October 2007, Athens, Greece.

Salonia, P., Leti Messina, T., Marcolongo, A., Scolastico, S., 2009. Three focal photogrammetry application for multi-scale and multi-level Cultural Heritage survey, documentation and 3D reconstruction, in Proceedings of The 22nd CIPA Symposium 2009, Kyoto.

Menci Software Homepage. .

Salonia, P., Leti Messina, T., Marcolongo, A., Scolastico, S., 2009. Survey and 3D reconstruction of the St. Orso capitals in Aosta, through three-focal photogrammetry, in Proceedings of The 10th International Symposium on Virtual Reality, Archaeology and Cultural Heritage VAST 2009.

The CENOBIUM Project's Homepage 2009. index.php.

Salonia, P., 2003. Strumenti informatici innovativi di ausilio alla conservazione del patrimonio storico architettonico: problemi di organizzazione, diffusione e gestione dati, in Rossi M., Salonia P., a cura di, , Comunicazione Multimediale per i Beni Culturali, Addison-Wesley, Milano 2003.

Martinelli, M., 2006. Passato e futuro del 3D archeologico, dalle foto stereoscopiche al computer per l'architettura antica, Arkos, 16, pp. 18-23.