Multi-image photogrammetry can in favorable conditions even under water generate large clouds of 3D points which can be used for visualization of sunken heritage. For analysis of under-water ...archeological sites and comparison of artifacts, more compact shape models must be reconstructed from 3D points, where each object or a part of it is modeled individually. Volumetric models and superquadric models in particular are good candidates for such modeling since automated methods for their reconstruction and segmentation from 3D points exist. For the study case we use an underwater wreck site of a Roman ship from 2nd/3rd century AD located near Sutivan on island Brač in Croatia. We demonstrate how superquadric models of sarcophagi and other stone blocks can be reconstructed from an unsegmented cloud of 3D points obtained by multi-image photogrammetry. We compare the dimensions of stone objects measured directly on the corresponding 3D point cloud with dimensions of the reconstructed superquadric models and discuss other advantages of these volumetric models. The average difference between point-to-point measurements of stone blocks and the dimensions of the corresponding superquadric model is on the order of few centimeters.
•Multi-image photogrammetry is becoming the most accurate and cost effective method of documentation in underwater archeology.•The result of multi-image photogrammetry is a dense 3D point cloud that can be covered with photographic texture.•A 3D point cloud is difficult to use directly for analysis and comparison of object shapes.•Volumetric models address such difficulties. Superquadric models can be automatically reconstructed from a 3D point cloud.•Superquadric models offer an abstraction level suitable for reasoning about a scene (i.e. size and shape of the ship).
The National Park Service (NPS) Submerged Resources Center (SRC) documented the East Key Construction Wreck in Dry Tortugas National Park using Structure from Motion photogrammetry, traditional ...archaeological hand mapping, and real time kinematic GPS (Global Positioning System) survey to test the accuracy of and establish a baseline “worst case scenario” for 3D models created with NPS SRC’s tri-camera photogrammetry system, SeaArray. The data sets were compared using statistical analysis to determine accuracy and precision. Additionally, the team evaluated the amount of time and resources necessary to produce an acceptably accurate photogrammetry model that can be used for a variety of archaeological functions, including site monitoring and interpretation. Through statistical analysis, the team determined that, in the worst case scenario, in its current iteration, photogrammetry models created with SeaArray have a margin of error of 5.29 cm at a site over 84 m in length and 65 m in width. This paper discusses the design of the survey, acquisition and processing of data, analysis, issues encountered, and plans to improve the accuracy of the SeaArray photogrammetry system.
The last few years have marked an exponential growth in the use of electronic and computing technologies that opened new possibilities and new scenarios in the Geomatic field. This evolution of tools ...and methods has led to new ways of approaching survey. For what concerns architecture, the new tools for survey acquisition and 3D modelling allow the representation of an object through a digital model, combining the visual potentials of images, normally used for documentation, with the precision of a metric survey. This research focuses on the application of these new technologies and methodologies on sensitive areas, such as portions of the cities affected by earthquakes. In this field the survey is intended to provide a useful support for other structural analysis, in conservation as well as for restoration studies. However, survey in architecture is still a very complex operation both from a methodological and a practical point of view: it requires a critical interpretation of the artefacts and a deep knowledge of the existing techniques and technologies, which often are very different but need to be integrated within a single general framework. This paper describes the first results of the survey conducted on the church of San Geminiano in San Felice sul Panaro (Modena). Here, different tools and methods were used, in order to create a new system that integrates the most recent and cutting-edge technologies in the Geomatic field. The methodologies used were laser scanning, UAV photogrammetry and topography for the definition of the reference system. The present work will focus on the data acquisition and processing whit these techniques and their integration.
Digital survey techniques are well established in the cultural and archaeological heritage fields and they have been used by us to document, study and promote knowledge on ancient ships and wooden ...boats. In this paper, we want to show four case studies with different peculiarity on which digital techniques have been applied: (1) ‘Comacchio sewn boat’, discovered in a land excavation site. (2) ‘Ercolano boat’, restored and exposed in a museum. (3) ‘Trabaccolo Nuovo Trionfo’, historical carriage boat of High-Adriatic sea. (4) Wooden scaled model of ‘brick Cygne’. These represent a peculiar application, complicated by the specific nature of the material of the boats, due to the structural stability and the shape of the wood that could be compromised in an aerobic environment. The archaeologists have the responsibility to employ a fast documentation, but with the correct precision and accuracy for the nominal scale of the survey; the use of digital imaging and survey techniques supports the researchers, such as video and photograph recording, multi-image photogrammetry and laser scanning, and the subsequent elaboration of a virtual 3D model of the real surveyed artefact. This allows scrupulous study of ancient naval construction from both a scientific and disseminative point of view to take place, permitting to increase the knowledge and perception by the general public of this important archaeological and historical heritage.
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