Marinos Ioannides

Progress in Cultural Heritage Preservation

In most cases archaeological finds and objects remain in the country of origin. Thus, for potential users away from that location, 3D models of archaeological finds and objects form an increasingly important resource since they can be analysed and visualised in efficient databases using web-based tools over the Internet. Since typical 3D recording technologies for archaeological objects, such as terrestrial laser scanning or fringe projection systems, are still expensive, cumbersome, inconvenient, and often require expert knowledge, camera-based systems offer a cost-effective, simple and flexible alternative that can be immediately implemented. This paper will demonstrate how the geometry and texture of archaeological finds and objects can be automatically constructed, modelled and visualized from digital imagery using freelyavailable open-source software or web services. The results of several objects derived from different tested software packages and/or services are compared with reference data in order to analyse the accuracy and reliability of such objects.

4D Reconstruction of Tangible Cultural Heritage Objects from Web-Retrieved Images

The number of digital images that are available online today has reached unprecedented levels. Recent statistics showed that by the end of 2013 there were over 250 billion photographs stored in just one of the major social media sites, with a daily average upload of 300 million photos. These photos, apart from documenting personal lives, often relate to experiences in well-known places of cultural interest, throughout several periods of time. Thus from the viewpoint of Cultural Heritage professionals, they constitute valuable and freely available digital cultural content. Advances in the fields of Photogrammetry and Computer Vision have led to significant breakthroughs such as the Structure from Motion algorithm which creates 3D models of objects using their 2D photographs. The existence of powerful and affordable computational machinery enables the reconstruction not only of single structures such as artefacts, but also of entire cities. This paper presents an overview of our methodology for producing co...

In the wild image retrieval and clustering for 3D cultural heritage landmarks reconstruction

One of the main characteristics of Internet era is the free and online availability of extremely large collections of images located on distributed and heterogeneous platforms over the web. The proliferation of millions of shared photographs spurred the emergence of new image retrieval techniques based not only on images’ visual information, but on geo-location tags and camera exif data. These huge visual collections provide a unique opportunity for cultural heritage documentation and 3D reconstruction. The main difficulty, however, is that the internet image datasets are unstructured containing many outliers. For this reason, in this paper a new content-based image filtering is proposed to discard image outliers that either confuse or significantly delay the followed e-documentation tools, such as 3D reconstruction of a cultural heritage object. The presented approach exploits and fuses two unsupervised clustering techniques: DBSCAN and spectral clustering. DBSCAN algorithm is used to remove outliers from the initially retrieved dataset and spectral clustering discriminate the noise free image dataset into different categories each representing characteristic geometric views of cultural heritage objects. To discard the image outliers, we consider images as points onto a multi-dimensional manifold and the multi-dimensional scaling algorithm is adopted to relate the space of the image distances with the space of Gram matrices through which we are able to compute the image coordinates. Finally, structure from motion is utilized for 3D reconstruction of cultural heritage landmarks. Evaluation on a dataset of about 31,000 cultural heritage images being retrieved from internet collections with many outliers indicate the robustness and cost effectiveness of the proposed method towards a reliable and just-in-time 3D reconstruction than existing state-of-the-art techniques.

4D reconstruction of the past

One of the main characteristics of the Internet era we are living in, is the free and online availability of a huge amount of data. This data is of varied reliability and accuracy and exists in various forms and formats. Often, it is cross-referenced and linked to other data, forming a nexus of text, images, animation and audio enabled by hypertext and, recently, by the Web3.0 standard. Search engines can search text for keywords using algorithms of varied intelligence and with limited success. Searching images is a much more complex and computationally intensive task but some initial steps have already been made in this direction, mainly in face recognition. This paper aims to describe our proposed pipeline for integrating data available on Internet repositories and social media, such as photographs, animation and text to produce 3D models of archaeological monuments as well as enriching multimedia of cultural / archaeological interest with metadata and harvesting the end products to EUROPEANA. Our main goal is to enable historians, architects, archaeologists, urban planners and affiliated professionals to reconstruct views of historical monuments from thousands of images floating around the web.

Digital Heritage. Progress in Cultural Heritage: Documentation, Preservation, and Protection

This paper presents an automatic methodology capable of registering non-overlapping laser scans based on a bundle block adjustment for the orientation estimation of synthetic images generated from the 3D data and camera images using a Structure-from-Motion (SfM) method. Adding camera images to the registration of the generated images can improve the block geometry. The SfM process provides accurate image orientations and sparse point clouds, initially in an arbitrary model space. This enables an implicit determination of the 3D-to-3D correspondences between the sparse points and the laser data then, the Helmert transformation is introduced and its parameters are computed. This results in registering the non-overlapping scans, since the relative orientations between the generated images are determined at the SfM step and transformed to the absolute coordinate system directly. The proposed approach was tested on real case studies and experimental results are shown to demonstrate the effectiveness of the presented method.

Documenting a Unesco Wh Site in Cyprus with Complementary Techniques

According to UNESCO directives, the documentation of monuments is a complex task, which both terrestrial laser scanning (TLS) and photogrammetry can decisively support. Today, these techniques are considered complementary, as they demonstrate clear advantages and disadvantages to each other, with regard to representation, texture application, data gathering, acquisition and processing time, practicality, accuracy, data density, surface reflectivity and absorption. In an effort to clarify which part should be acquired with which technique, as well as to understand whether one technique has a clear advantage over the other in some specific task of the documentation process, the Church of the Holy Cross in Pelendri, Cyprus, which is a UNESCO World Heritage monument, was selected as a test site. The deliverables are orthophotos, sections, plots and a complete and accurate 3D model of the monument. The whole documentation process has been carried out independently using an image based technique with Mencis ZS...

Content-Based Filtering for Fast 3D Reconstruction from Unstructured Web-Based Image Data

The huge amount of visual collections provides a unique opportunity for cultural heritage e-documentation and 3D reconstruction. The main difficulty, however, is its unstructured nature. In this paper a new content-based image filtering is proposed to discard image outliers that either confuse or significantly delay the 3D reconstruction process. The presented approach exploits a dense-based unsupervised paradigm applied on multi-dimensional manifolds where images are represented as image points. The multidimensional scaling algorithm is adopted to relate the space of the image distances with the space of Gram matrices to compute the image coordinates. Evaluation on a dataset of about 31,000 cultural heritage images being retrieved from internet collections with many outliers indicate the robustness and cost effectiveness of the proposed method towards an affordable 3D reconstruction.

Educational use of 3D models and photogrammetry content: the Europeana space project for Cypriot UNESCO monuments

Digital heritage data are now more accessible through crowdsourcing platforms, social media and blogs. At the same time, evolving technology on 3D modelling, laser scanning and 3D reconstruction is constantly upgrading and multiplying the information that we can use from heritage digitalisation. The question of reusing the information in different aspects rises. Educators and students are potential users of the digital content; developing for them an adaptable environment for applications and services is our challenge. One of the main objective of the EU Europeana Space project is the development of a holistic approach for educating people (grown ups and kids) on Monuments that are listed at UNESCO world heritage list, in Cyprus. The challenge was the use of Europeana Data (Pictures and the 3D objects) in a way that the information on the platform would be comprehensible by the users. Most of the data have little metadata information and they lack history and cultural value description (semantics). The proposed model ction is based on the cross cultural approach which responds to the multicultural features of present era but at the same time to the contemporary pedagogical and methodological directions. The system uses all innovative digital heritage resources, in order to help the user, in a UX friendly way, to learn about the different phases of the monument, the history, the pathology state, the architectural value and the conservation stage. The result is a responsive platform, accessible through smart devices and desktop computers, (in the frame of “Bring Your Own Device” a.k.a. BYOD) where every Monument is a different course and every course is addressed to different age groups (from elementary level to adults’ vocational training).

Modelling of Static and Moving Objects: Digitizing Tangible and Intangible Cultural Heritage

From the ancient library of Alexandria 2300 years ago, cultural collections have a common fundamental base; to gather, preserve and promote knowledge helping the intellectual and cognitive evolution of humanity. Nowadays the information revolution has given scientists, educators, researchers and individuals the ability not only to use a variety of digital libraries as a source of information but also to contribute to these libraries by uploading data that they create, leading to a massive production of digital data that we need to verify, manage, archive, preserve and reuse. Cultural heritage (CH) data is a category in digital libraries that needs our attention the most, because of their crucial role in helping us to interact with the past and learn, promote and preserve our cultural assets. Digital documentation of tangible and intangible heritage, data formats and standards, metadata and semantics, linked data, crowdsourcing and cloud, the use and reuse of data and copyright issues are the rising challenges that we try to address in this chapter, through literature research and best practice examples. At the end of this analysis, this chapter tries to predict the future of Digital Heritage Libraries, where 3D digital assets will be part of augmented, virtual and mixed reality experiences.

4D reconstruction of the past: the image retrieval and 3D model construction pipeline

One of the main characteristics of the Internet era we are living in, is the free and online availability of a huge amount of data. This data is of varied reliability and accuracy and exists in various forms and formats. Often, it is cross-referenced and linked to other data, forming a nexus of text, images, animation and audio enabled by hypertext and, recently, by the Web3.0 standard. Our main goal is to enable historians, architects, archaeolo- gists, urban planners and affiliated professionals to reconstruct views of historical monuments from thousands of images floating around the web. This paper aims to provide an update of our progress in designing and imple- menting a pipeline for searching, filtering and retrieving photographs from Open Access Image Repositories and social media sites and using these images to build accurate 3D models of archaeological monuments as well as enriching multimedia of cultural / archaeological interest with metadata and harvesting the end products to EU- ROPEANA. We provide details of how our implemented software searches and retrieves images of archaeological sites from Flickr and Picasa repositories as well as strategies on how to filter the results, on two levels; a) based on their built-in metadata including geo-location information and b) based on image processing and clustering techniques. We also describe our implementation of a Structure from Motion pipeline designed for producing 3D models using the large collection of 2D input images (>1000) retrieved from Internet Repositories.