3D virtual reconstructions at the service of computer assisted archaeological measurements

Technological advances have enabled photogrammetric and surveying methods to produce recording materials surpassing the traditional line drawings in accuracy and completeness. These methodologies may offer products not possible in the past. This paper relates the difficult experience of collecting, archiving, processing, combining, visualizing and exploiting data from a multitude of sources to make accurate geometric records of monuments, implementing the most contemporary, innovative and technologically advanced methods. Issues analysed include collecting and processing field data from a variety of sources and their respective properties, but also the production of different end products, vector and raster, with the main emphasis on complex 3D visualizations. Different approaches are assessed for their usefulness and potential accuracy. Examples covering a variety of Greek and Cypriot monuments are presented, which are acquired from the rich experience of the archaeological surveys of the Laboratory of Photogrammetry of NTUA

DEVELOPMENT OF A GEOREFERENCED ARCHAEOLOGICAL INFORMATION DATA BASE FOR ELEUTHERNA IN CRETE

[EN] Cultural Heritage Information Management Systems (CHIMS) have been developed in order to achieve the georeference of the items in the Cultural Heritage database. Eleutherna in Crete is one of the most significant archaeological sites in Greece, with. many buildings constructed and destroyed during its long life. Hence, it is easily understandable that this vast archaeological site is complicated and difficult to understand, even by experts. In this paper the development of a Cultural Heritage Management System, called ARCHAEOsystem, is described and analyzed. The system has as geographic base a recent orthophoto of the area and for its design several parameters were taken into account. The conceptual design of the data base with the Entity-Relational (E-R) model preceded the development of this object oriented system. This E-R model is described and evaluated for its operability. After the initial experimental operation of the system, eventual practical problems will be identified and confronted. Finally, presentation of future prospects is being attempted and eventual uses of such a system are proposed.Tapinaki, SI.; Georgopoulos, A.; Ioannidis, C.; Frentzos, E.; Stampolidis, N.; Maragoudakis, N. (2016). DEVELOPMENT OF A GEOREFERENCED ARCHAEOLOGICAL INFORMATION DATA BASE FOR ELEUTHERNA IN CRETE. En 8th International congress on archaeology, computer graphics, cultural heritage and innovation. Editorial Universitat Politècnica de València. 333-336. https://doi.org/10.4995/arqueologica8.2015.3558OCS33333

An Overview on Image-Based and Scanner-Based 3D Modeling Technologies

Advances in the scientific fields of photogrammetry and computer vision have led to the development of automated multi-image methods that solve the problem of 3D reconstruction. Simultaneously, 3D scanners have become a common source of data acquisition for 3D modeling of real objects/scenes/human bodies. This article presents a comprehensive overview of different 3D modeling technologies that may be used to generate 3D reconstructions of outer or inner surfaces of different kinds of targets. In this context, it covers the topics of 3D modeling using images via different methods, it provides a detailed classification of 3D scanners by additionally presenting the basic operating principles of each type of scanner, and it discusses the problem of generating 3D models from scans. Finally, it outlines some applications of 3D modeling, beyond well-established topographic ones

3D virtual reconstructions at the service of computer assisted archaeological measurements

Technological advances have enabled photogrammetric and surveying methods to produce recording materials surpassing the traditional line drawings in accuracy and completeness. These methodologies may offer products not possible in the past. This paper relates the difficult experience of collecting, archiving, processing, combining, visualizing and exploiting data from a multitude of sources to make accurate geometric records of monuments, implementing the most contemporary, innovative and technologically advanced methods. Issues analysed include collecting and processing field data from a variety of sources and their respective properties, but also the production of different end products, vector and raster, with the main emphasis on complex 3D visualizations. Different approaches are assessed for their usefulness and potential accuracy. Examples covering a variety of Greek and Cypriot monuments are presented, which are acquired from the rich experience of the archaeological surveys of the Laboratory of Photogrammetry of NTUA

An Integrated Approach to 3D Web Visualization of Cultural Heritage Heterogeneous Datasets

The evolution of the high-quality 3D archaeological representations from niche products to integrated online media has not yet been completed. Digital archives of the field often lack multimodal data interoperability, user interaction and intelligibility. A web-based cultural heritage archive that compensates for these issues is presented in this paper. The multi-resolution 3D models constitute the core of the visualization on top of which supportive documentation data and multimedia content are spatial and logical connected. Our holistic approach focuses on the dynamic manipulation of the 3D scene through the development of advanced navigation mechanisms and information retrieval tools. Users parse the multi-modal content in a geo-referenced way through interactive annotation systems over cultural points of interest and automatic narrative tours. Multiple 3D and 2D viewpoints are enabled in real-time to support data inspection. The implementation exploits front-end programming languages, 3D graphic libraries and visualization frameworks to handle efficiently the asynchronous operations and preserve the initial assets’ accuracy. The choice of Greece’s Meteora, UNESCO world site, as a case study accounts for the platform’s applicability to complex geometries and large-scale historical environments

Mobile Augmented Reality for Low-End Devices Based on Planar Surface Recognition and Optimized Vertex Data Rendering

Mobile Augmented Reality (MAR) is designed to keep pace with high-end mobile computing and their powerful sensors. This evolution excludes users with low-end devices and network constraints. This article presents ModAR, a hybrid Android prototype that expands the MAR experience to the aforementioned target group. It combines feature-based image matching and pose estimation with fast rendering of 3D textured models. Planar objects of the real environment are used as pattern images for overlaying users’ meshes or the app’s default ones. Since ModAR is based on the OpenCV C++ library at Android NDK and OpenGL ES 2.0 graphics API, there are no dependencies on additional software, operating system version or model-specific hardware. The developed 3D graphics engine implements optimized vertex-data rendering with a combination of data grouping, synchronization, sub-texture compression and instancing for limited CPU/GPU resources and a single-threaded approach. It achieves up to 3× speed-up compared to standard index rendering, and AR overlay of a 50 K vertices 3D model in less than 30 s. Several deployment scenarios on pose estimation demonstrate that the oriented FAST detector with an upper threshold of features per frame combined with the ORB descriptor yield best results in terms of robustness and efficiency, achieving a 90% reduction of image matching time compared to the time required by the AGAST detector and the BRISK descriptor, corresponding to pattern recognition accuracy of above 90% for a wide range of scale changes, regardless of any in-plane rotations and partial occlusions of the pattern

Development of a 3D Information System for the Old City Centre of Athens

The representation of three dimensional city models has been gaining ground increasingly in many scientific fields in the recent years. 3D City Modelling is a scale representation of natural and artificial objects in order to present the spatial data and highlight the social development of the city. Depending on its importance or the purpose of use, an object can be represented in various levels of detail. An increasing tendency to 3D city models is their integration into GIS, which proves to be an effective tool for managing, analyzing and planning in order to make decisions about technical, administrative and financial matters. A combination of digital photogrammetric techniques and laser scanning data contribute greatly to this, since a variety of data, such as aerial, satellite and terrestrial images, point clouds from airborne and terrestrial laser systems, and also a variety of photogrammetric and mobile mapping methods are available. The objective of this paper is the development of a 3D Information System (IS) for the three-dimensional geometric documentation of the buildings owned by the Ministry of Culture in the old city centre of Athens, Greece, named “Plaka”. The area has been inhabited continuously since the prehistoric era, it has a special architectural style and includes a number of unique cultural heritage monuments. The data used for the reconstruction of the 3D model of Plaka consisted of aerial and terrestrial images, while raster, vector and descriptive data were used for the creation of a 2D GIS, which served as the background for the development of the 3D GIS. The latter includes all of the qualitative and quantitative information related to the 3D building models owned by the Ministry of Culture according to users’ needs. Each building in the vicinity of Plaka was depicted in one of the four different levels of detail created for the purpose of the study, according to their ownership status and other criteria. The building models, depicted in the highest level of detail, were owned by the Greek Ministry of Culture whereas the other buildings (of a lower level of detail) were depicted in a more subtractive way. Therefor an integrated IS was developed that combines descriptive information, e.g., use, legal status, images, drawings, etc, with the spatial information and geometric documentation in three dimensions

A digital atlas for the Byzantine and Post Byzantine Churches of Troodos region (central Cyprus)

This paper presents the results produced during an interstate research project between universities of Greece and Cyprus using Web technologies. The main aim of the Digital Atlas is to create a unique product for the visualization of the cultural heritage of Cyprus, while at the same time to be able to provide information to the end-users. The region of Mountain Troodos is characterized by one of the largest groups of churches and monasteries of the former Byzantine Empire. The complex of 10 monuments – churches, which are all richly decorated with murals, provides an overview of Byzantine and post-Byzantine painting (frescoes religious paintings) on Cyprus. These churches – monuments where inscribed to the UNESCO list of World Heritage Monuments and attract a large number of tourists every year (over 1 million). The above application consists of a WebGIS tool, using the ArcGIS Server software. The WebGIS includes a detail 3D reconstruction of the surrounding area of the monuments using grayscale high resolution orthophotos and 3D digital “light” models of the monuments, produced in Google SketchUp software, using non-rigorous topometric methods. Moreover the application includes no-spatial information about the monuments, such as relevant bibliography, photos of the interior and exterior of the monuments and also audiovisual data. Finally this digital tool provides to the end-users a brief, time-stamped, historical background information about the Byzantine and postByzantine monuments

The Geometric Documentation of the Asinou Church in Cyprus

The Asinou Church, devoted to the Virgin Mary, is a wonderful 11th c. Byzantine Church built up in Troodos Mountain on the island of Cyprus. This Church has been recognised as a World Heritage Monument by UNESCO. A joint effort between the Laboratory of Photogrammetry of NTUA and HTI had as main goal the geometric documentation of this monument, using a combination of modern digital techniques for data acquisition and methodologies for data processing. Digital surveying and photogrammetric instrumentation, as well as a laser scanner were employed, in order to collect the necessary data for producing digital colour orthophotographs for the four exterior facades and six interior crossections of the church. The methodology is briefly described and assessed for its adaptability to the special requirements of this monument. The results of the data processing are presented and evaluated for their usefulness. Moreover a 3D visualisation of the church is attempted based on the accurate measurements performed. The paper concludes with an appraisal of the products in view of their inclusion in a Monument Information System, which could include all monuments of the particular area of Cyprus