Commission VI, WG VI/4KEY WORDS: Cultural Heritage, close range photogrammetry, RPAS, MicMac, Photoscan, multi-image matching. ABSTRACT:3D detailed models derived from digital survey techniques have increasingly developed and focused in many field of application. The high detailed content and accuracy of such models make them so attractive and usable for large sets of purposes in Cultural Heritage. The present paper focuses on one of the main techniques used nowadays for Cultural Heritage survey and documentation: the image matching approach or Structure from Motion (SfM) technique. According to the low cost nature and the rich content of derivable information, these techniques are extremely strategic in poor available resources sectors such as Cultural Heritage documentation. After an overview of the employed algorithms and used approaches of SfM computer vision based techniques, the paper is focused in a critical analysis of the strategy used by two common employed software: the commercial suite Agisoft Photoscan and the open source tool MicMac realized by IGN France. The experimental section is focused on the description of applied tests (from RPAS data to terrestrial acquisitions), purposed to compare different solutions in various featured study cases. Finally, the accuracy assessment of the achieved products is compared and analyzed according to the strategy employed by the studied software.

ABSTRACT:Recognizing the various advantages offered by 3D new metric survey technologies in the Cultural Heritage documentation phase, this paper presents some tests of 3D model generation, using different methods, and their possible fusion. With the aim to define potentialities and problems deriving from integration or fusion of metric data acquired with different survey techniques, the elected test case is an outstanding Cultural Heritage item, presenting both widespread and specific complexities connected to the conservation of historical buildings. The site is the Staffarda Abbey, the most relevant evidence of medieval architecture in Piedmont. This application faced one of the most topical architectural issues consisting in the opportunity to study and analyze an object as a whole, from twice location of acquisition sensors, both the terrestrial and the aerial one. In particular, the work consists in the evaluation of chances deriving from a simple union or from the fusion of different 3D cloudmodels of the abbey, achieved by multi-sensor techniques. The aerial survey is based on a photogrammetric RPAS (Remotely piloted aircraft system) flight while the terrestrial acquisition have been fulfilled by laser scanning survey. Both techniques allowed to extract and process different point clouds and to generate consequent 3D continuous models which are characterized by different scale, that is to say different resolutions and diverse contents of details and precisions. Starting from these models, the proposed process, applied to a sample area of the building, aimed to test the generation of a unique 3Dmodel thorough a fusion of different sensor point clouds. Surely, the describing potential and the metric and thematic gains feasible by the final model exceeded those offered by the two detached models.

ABSTRACT:The paper presents the workflow and the results of an ultrasonic 3D investigation and a 3D survey application aimed at the assessment of the internal integrity of an ancient sculpture. The work aimed at highlighting the ability of methods devoted to the 3D geometry acquisition of small objects when applied to diagnosis performed by geophysical investigation. In particular, two methods widely applied for small objects modelling are considered and compared, the digital Photogrammetry with the Structure from Motion (SFM) technique and hand-held 3D scanners. The study concludes with the aim to enhance the final graphical representation of the tomographic results and to subject the obtained results to a quantitative analysis. The survey is applied to the Egyptian naophorous statue of Amenmes and Reshpu, which dates to the reign of Ramses II (1279-1213 BC) or later and is now preserved in the Civic Archaeological Museum in Bologna. In order to evaluate the internal persistency of fractures and visible damages, a 3D Ultrasonic Tomographic Imaging (UTI) test has been performed and a multi-sensor survey (image and range based) was conducted, in order to evaluate the locations of the source and receiver points as accurate as possible The presented test allowed to evaluate the material characteristics, its porosity and degradation state, which particularly affect the lower part of the statue. More in general, the project demonstrated how solution coming from the field of 3D modelling of Cultural Heritage allow the application of 3D ultrasonic tomography also on objects with complex shapes, in addition to the improved representation of the obtained results.

No abstract

No abstract