GCH 2016 - Eurographics Workshop on Graphics and Cultural Heritage

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https://diglib.eg.org/handle/10.2312/2630933

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3D Object Spatial- consistent Texture Maps Appropriate for 2D Image Processing
(The Eurographics Association, 2016) Ioannakis, George; Koutsoudis, Anestis; Chamzas, Christos; Chiara Eva Catalano and Livio De Luca
The aim of this work is to generate a spatial-consistent UV maps of a 3D object's texture suitable for 2D image processing algorithms. An approach to produce such a fully spatially consistent UV mapping suitable for image processing based on the planar parameterisation of the mesh is presented. The mesh of a 3D model is parametrised onto a unit square 2D plane using computational conformal geometry techniques. The proposed method is genus independent, due to an iterative 3D mesh cutting procedure. The selection of the initial seed vertex for the mesh-cut is not essential for the parameterisation of the geometry, however it affects heavily the appearance of the obtained texture map. In this work we attempt to determine such a seed vertex, in order the UV map to be suitable for image processing. Having the texture of a 3D model depicted on a spatially continuous two dimensional structure enables us to efficiently apply well known image processing based techniques and algorithms. Our method is applied on a 3D digital replica of an ancient Greek Lekythos vessel.
A Framework for Compact and Improved Panoramic VR Dissemination
(The Eurographics Association, 2016) Fanini, Bruno; D'Annibale, Enzo; Chiara Eva Catalano and Livio De Luca
Panoramic capture devices in Cultural Heritage are becoming widely available to consumer market, also due to comfortable interactive online dissemination and to the growth of VR segment. VR fruition through an HMD although, requires a virtual 3D representation to provide consistency in terms of experience, scale and spatial perception, overcoming limitations of standard approaches in orientation+positional HMD tracking model. However, modeling of 3D scenes and especially optimization of acquired dataset, are often time-consuming tasks: these are further stressed when dealing with latency-free demands of latest HMDs. In this paper, we propose a novel framework for panoramic acquisition and an improved data model for VR dissemination: spherical panoramas, omnidirectional depth-maps and semantic annotations are encoded into a compact, coherent representation that suits modern HMD needs and low-cost VR devices. We describe advantages of our approach in terms of acquisition pipeline, presence and depth perception in HMDs fruition, discussing also visualization efficiency in online contexts. We present a few case studies where we applied the methodology and the workflow we adopted, comparing results. We discuss integration of existing desktop toolkits into the pipeline, dissemination capabilities through recent WebVR API and framework advantages for immersive VR panoramic video streaming.
2D/3D Semantic Annotation of Spatialized Images for the Documentation and Analysis of Cultural Heritage
(The Eurographics Association, 2016) Manuel, Adeline; Véron, Philippe; Luca, Livio De; Chiara Eva Catalano and Livio De Luca
The introduction of digital technologies in the documentation methods for cultural heritage has helped to design new tools for the acquisition and management of information collected for multidisciplinary studies. These tools are beginning to emerge as the preferred media for describing, analyzing and understanding the objects of study. Existing solutions for semantic annotation on images, on 3D models or with 2D/3D hybrid methods still reveal themselves today insufficient to tackle the complex problem of annotating heritage artifacts. In this field, the semantic description of the studied objects must be able to rely on a rich and structured representation by on one hand making explicit the morphological complexity of the object and on the other hand by reflecting all aspects conveyed by the acquisitions of scientific imaging. This paper introduces an approach for conducting semantic annotations on 2D images (photography, scientific imaging ...) while facilitating the annotation work with an automatic propagation of these annotations between other correlated representations (2D or 3D) of the object. It is based on a spatial referencing method aiming at the establishment of a continuous 2D/3D projective relationship. The goal of the approach is to define an informative continuum between all phases of observation and description processes ranging from the acquisition of images and spatial data up to the building of semantically-enriched 3D representations. The idea is to insert semantics at all phases of 2D/3D data processing while ensuring a continuous correlation of annotations from a spatial, temporal and morphological point of view.
A Soft Union based Method for Virtual Restoration and 3D Printing of Cultural Heritage Objects
(The Eurographics Association, 2016) Gregor, Robert; Mavridis, Pavlos; Wiltsche, Albert; Schreck, Tobias; Chiara Eva Catalano and Livio De Luca
Recent improvements in 3D acquisition and shape processing methods lead to increased digitization of 3D Cultural Heritage (CH) objects. Beyond the mere digital archival of CH artifacts, there is an emerging research area dedicated to digital restoration of 3D Cultural Heritage artifacts. In particular several methods have been published recently that, from a digitized set of fragments, enable their reassembly or even the synthesis of missing or eroded parts. Usually the result of such methods is a set of aligned but disconnected parts. However, it is often desirable to produce a single, watertight mesh that can be easily 3D printed. We propose a method based on a volumetric soft union operation that can be used to combine such sets of aligned fragments to a single manifold mesh while producing smooth and plausible geometry at the seams. We assess its visual quality and efficiency in comparison to an adaption of the well-known Poisson Reconstruction method. Finally, we provide practical insights on printing the results produced by our method on digitized fragments of real CH objects.
CHER-Ob: A Tool for Shared Analysis in Cultural Heritage
(The Eurographics Association, 2016) Shi, Weiqi; Kotoula, Eleni; Akoglu, Kiraz; Yang, Ying; Rushmeier, Holly; Chiara Eva Catalano and Livio De Luca
The study of cultural heritage involves many different activities, including digital data visualization, information analysis and sharing results. Current technologies focus on providing better tools for data representation and processing, neglecting the importance of analysis and sharing. In this paper, we present a software system, CHER-Ob, which offers powerful tools for evaluation and publication of the results of cultural heritage research, and at the same time supports visualization of various data formats. CHER-Ob also introduces the concept of Cultural Heritage Entity, which serves as a template for cultural heritage research and a model to manage projects. We use typical case studies of cultural heritage research to evaluate the system and demonstrate how it works.
Web-based Exploration of Semantically Rich 3D Decorative Ornament
(The Eurographics Association, 2016) Echavarria, Karina Rodriguez; Few, Dean; Song, Ran; Chiara Eva Catalano and Livio De Luca
The aim of this research is to document and provide easy access and exploration to 3D decorative ornament, in order to support its preservation and reuse in future products. The research focuses on the Regency style of ornamentation used to decorate different type of objects such as furniture, and, for example, in architecture. The ambition of the project is to bring this decorative art into the 21st Century by conducting research using the latest 3D access technologies as well as applying additive manufacturing technologies to its reproduction. Therefore, this paper will contribute information about the development of an accessible, web based, digital repository with semantically rich 3D ornamental shapes. This repository has the potential to make the content available to a variety of users, including art historians and designers.
A Practical Reflectance Transformation Imaging Pipeline for Surface Characterization in Cultural Heritage
(The Eurographics Association, 2016) Ciortan, Irina Mihaela; Pintus, Ruggero; Marchioro, Giacomo; Daffara, Claudia; Giachetti, Andrea; Gobbetti, Enrico; Chiara Eva Catalano and Livio De Luca
We present a practical acquisition and processing pipeline to characterize the surface structure of cultural heritage objects. Using a free-form Reflectance Transformation Imaging (RTI) approach, we acquire multiple digital photographs of the studied object shot from a stationary camera. In each photograph, a light is freely positioned around the object in order to cover a wide variety of illumination directions. Multiple reflective spheres and white Lambertian surfaces are added to the scene to automatically recover light positions and to compensate for non-uniform illumination. An estimation of geometry and reflectance parameters (e.g., albedo, normals, polynomial texture maps coefficients) is then performed to locally characterize surface properties. The resulting object description is stable and representative enough of surface features to reliably provide a characterization of measured surfaces. We validate our approach by comparing RTI-acquired data with data acquired with a high-resolution microprofilometer.
Digital Epigraphic Heritage Made Simple: an Android App for Exploring 3D Roman Inscriptions
(The Eurographics Association, 2016) Ramírez, Manuel; Suárez, Jose Pablo; Trujillo, Agustín; Fernández, Pablo; Santana, Jose Miguel; Ortega, Sebastián; Chiara Eva Catalano and Livio De Luca
Spain keeps an exceptional epigraphic heritage, dated from the Roman civilization, that integrates thousands of Latin inscriptions nowadays disseminated along the Iberian peninsula. For many purposes such as education, innovation, cataloging, study and dissemination of this type of historical documentation, a clear demand of placing all this epigraphic heritage into modern 3D graphics, internet and mobile devices is increasing. We present the novel 'Epigraphia 3D' for handheld devices, a native Android app for exploring a total of 60 Roman inscriptions from the National Museum of Roman Art (Mérida, Badajoz). The work emphasizes the 3D nature feature for navigating through the inscriptions, by using Glob3 Mobile, an open source GIS framework for visualizing the 3D inscriptions. Besides, an error analysis of the simplified models is tackled.
Representation and Visualization of Urban Fabric through Historical Documents
(The Eurographics Association, 2016) Samuel, John; Périnaud, Clémentine; Servigne, Sylvie; Gay, Georges; Gesquière, Gilles; Chiara Eva Catalano and Livio De Luca
Documents serve an important role in understanding change in urban fabric. The available multidimensional (spatial, temporal and thematic) information in these documents narrate not only the various features of the elements of the urban fabric but also notifies their changes during time. CityGML standard is used to spatially and temporally represent the city objects. But it misses features to represent city lifecycle and its linked documents. The first part has been addressed recently. In this article, we propose an extension to CityGML standard to integrate city objects and relevant associated documents. Proposing a solution based on standards permits data interoperability. We also briefly describe how these documents are visualized in our current 3D urban environment prototype built over CityGML.
Multi-View Ambient Occlusion for Enhancing Visualization of Raw Scanning Data
(The Eurographics Association, 2016) Sabbadin, Manuele; Palma, Gianpaolo; Cignoni, Paolo; Scopigno, Roberto; Chiara Eva Catalano and Livio De Luca
The correct understanding of the 3D shape is a crucial aspect to improve the 3D scanning process, especially in order to perform high quality and as complete as possible 3D acquisitions on the field. The paper proposes a new technique to enhance the visualization of raw scanning data based on the definition in device space of a Multi-View Ambient Occlusion (MVAO). The approach allows improving the comprehension of the 3D shape of the input geometry and, requiring almost no preprocessing, it can be directly applied to raw captured point clouds. The algorithm has been tested on different datasets: high resolution Time-of-Flight scans and streams of low quality range maps from a depth camera. The results enhance the details perception in the 3D geometry using the multi-view information to make more robust the ambient occlusion estimation.
Using Flash Photography and Image-Based Rendering to Document Cultural Heritage Artifacts
(The Eurographics Association, 2016) Tetzlaff, Michael; Meyer, Gary; Chiara Eva Catalano and Livio De Luca
A novel image-based rendering system is proposed for documenting cultural heritage artifacts. The system utilizes backscattering photography to acquire the initial pictures and derives estimates for the object's diffuse albedo, surface normals, and the specular reflectivity from the images. A projective texture mapping technique is used to create a novel view of the artifact by blending the original photographs and projecting them onto a mesh that is also derived from the photos. By weighting the images according to how they best depict the manner in which a virtual light source illuminates the artifact's surface, object relighting is also achieved.
Reflecting on European History with the Help of Technology: The CrossCult Project
(The Eurographics Association, 2016) Lykourentzou, Ioanna; Naudet, Yannick; Vandenabeele, Luc; Chiara Eva Catalano and Livio De Luca
History, and in particular European history, is not merely a collection of unconnected events, but rather a complex mesh of interrelated facts, events and concepts, taking place within a wider context of previous and contemporary situations. Unfortunately when addressing the wider public, like in schools, museums and cultural spaces, history is often presented in a simplistic, siloed and localistic manner that promotes memorizing rather than understanding, does not account for cross-border cultural aspects and prevents historical events from being viewed as a shared, global experience. The goal of the CrossCult H2020 project, comprising 11 partners from 7 European countries, is to spur a change in the way European citizens appraise, interpret and access history, by enabling new and highlighting existing cross-border connections among pieces of cultural heritage, other citizens' viewpoints and physical venues. Facilitated by technology and mobile applications, with a strong background in social sciences, the project focuses on developing pilot experiences that build narratives of cross-border connections and crosscutting topics, to help visitors gain insight into how the same facts may be interpreted differently from different social realities and by different individuals. In this paper we introduce the CrossCult project and its goals, provide an overview of its four project pilots and discuss the technologies it employs to connect cultural heritage venues, repositories and people's viewpoints.
Automatic Selection of Video Frames for Path Regularization and 3D Reconstruction
(The Eurographics Association, 2016) Pavoni, Gaia; Dellepiane, Matteo; Callieri, Marco; Scopigno, Roberto; Chiara Eva Catalano and Livio De Luca
Video sequences can be a valuable source to document the state of objects and sites. They are easy to acquire and they usually ensure a complete coverage of the object of interest. One of their possible uses is to recover the acquisition path, or the 3D shape of the scene. This can be done by applying structurefrom- motion techniques to a representative set of frames extracted from the video. This paper presents an automatic method for the extraction of a predefined number of representative frames that ensures an accurate reconstruction of the sequence path, and possibly enhances the 3D reconstruction of the scene. The automatic extraction is obtained by analyzing adjacent frames in a starting subset, and adding/removing frames so that the distance between them remains constant. This ensures the reconstruction of a regularized path and an optimized coverage of all the scene. Finally, more frames are added in the portions of the sequence when more detailed objects are framed. This ensures a better description of the sequence, and a more accurate dense reconstruction. The method is automatic, fast and independent from any assumption about the acquired object or the acquisition strategy. It was tested on a variety of different video sequences, showing that a satisfying result can be obtained regardless of the length and quality of the input.
Wall Painting Reconstruction Using a Genetic Algorithm
(The Eurographics Association, 2016) Sizikova, Elena; Funkhouser, Thomas; Chiara Eva Catalano and Livio De Luca
Global reconstruction of two-dimensional wall paintings (frescoes) from fragments is an important problem for many archaeological sites. The goal is to find the global position and rotation for each fragment so that all fragments jointly "reconstruct" the original surface (i.e., solve the puzzle). Manual fragment placement is difficult and time-consuming, especially when fragments are irregularly shaped and uncolored. Systems have been proposed to first acquire 3D surface scans of the fragments and then use computer algorithms to solve the reconstruction problem. These systems work well for small test cases and for puzzles with distinctive features, but fail for larger reconstructions of real wall paintings with eroded and missing fragments due to the complexity of the reconstruction search space. We address the search problem with an unsupervised genetic algorithm (GA): we evolve a pool of partial reconstructions that grow through recombination and selection over the course of generations. We introduce a novel algorithm for combining partial reconstructions that is robust to noise and outliers, and we provide a new selection procedure that balances fitness and diversity in the population. In experiments with a benchmark dataset our algorithm is able to achieve larger and more accurate global reconstructions than previous automatic algorithms.
Color Restoration of Scanned Archaeological Artifacts with Repetitive Patterns
(The Eurographics Association, 2016) Gilad-Glickman, Danit; Shimshoni, Ilan; Chiara Eva Catalano and Livio De Luca
Our work addresses the problem of virtually restoring archaeological artifacts. Virtual restoration is the process of creating a noise-free model of a degraded object, to visualize its original appearance. Our work focuses on restoring the coloring of the object. We considered both 2D and 3D objects, including scans of ancient texts and 3D models of decorated pottery. Our denoising method exploits typical characteristics of archaeological artifacts, such as repetitive decoration motifs and a limited palette of colors. Our classification method is based on minimization of an energy function, which includes a correspondence term, to encourage consistent labeling of similar regions. The energy function is minimized using the Graph-Cuts algorithm.
3-D Digital Preservation of At-Risk Global Cultural Heritage
(The Eurographics Association, 2016) Lercari, Nicola; Shulze, Jurgen; Wendrich, Willeke; Porter, Benjamin; Burton, Margie; Levy, Thomas E.; Chiara Eva Catalano and Livio De Luca
Recent current events have dramatically highlighted the vulnerability of the world's material cultural heritage. The 3-D Digital Preservation of At-Risk Global Cultural Heritage project, led by Thomas Levy at UC San Diego, catalyzes a collaborative research effort by four University of California campuses (San Diego, Berkeley, Los Angeles and Merced) to use cyberarchaeology and computer graphics for cultural heritage to document and safeguard virtually some of the most at-risk heritage objects and places. Faculty and students involved in this project are conducting path-breaking archaeological research - covering more than 10,000 years of culture and architecture - in Cyprus, Greece, Egypt, Ethiopia, Israel, Jordan, Morocco, Turkey, and the United States. This project uses the 3-D archaeological data collected in numerous at-risk heritage places to study, forecast, and model the effects of human conflict, climate change, natural disasters and technological and cultural changes on these sites and landscapes. The greater challenge undertaken by this project is to integrate archaeological heritage data and digital heritage data using the recently-announced Pacific Research Platform (PRP) and its 10-100Gb/s network as well as virtual reality kiosks installed in each participating UC campus. Our aim is to link UC San Diego and the San Diego Supercomputer Center to other labs, libraries and museums at the other UC campuses to form a highly-networked collaborative platform for curation, analysis, and visualization of 3D archaeological heritage data.
The Missing Scholarship Behind Virtual Heritage Infrastructures
(The Eurographics Association, 2016) Champion, Erik Malcolm; Chiara Eva Catalano and Livio De Luca
This theoretical position paper outlines four key issues blocking the development of effective 3D models that would be suitable for the aims and objectives of virtual heritage infrastructures. It suggests that a real-time game environment which composes levels at runtime from streaming multimédia components would offer advantages in terms of editing, customisation and personalisation. The paper concludes with three recommendations for virtual heritage infrastructures.
Interdisciplinary Dialogue Towards an Enhanced Understanding of Optical Techniques for Recording Material Cultural Heritage - Results of a COST Action
(The Eurographics Association, 2016) Boochs, Frank; Bentkowska-Kafel, Anna; Wefers, Stefanie; Chiara Eva Catalano and Livio De Luca
The COST Transdomain Action TD1201, Colour and Space in Cultural Heritage [COSb], 2012-2016, contributes to the conservation and preservation of cultural heritage (CH) by enhancing shared understanding, between experts from various disciplines, of the spectral and spatial recording of physical CH objects. Optimal recording, adapted to the requirements of a CH application, should involve experts from multiple disciplines and industries. Such an interdisciplinary approach is necessary "in order to protect, preserve, analyze, understand, model, virtually reproduce, document and publish important CH in Europe and beyond" [COSa]. In order to fulfil this goal, experts from 28 European countries entered into a multidisciplinary dialogue trying to establish a common understanding of spatial and spectral recording techniques best suited for particular CH applications. Several COSCH groups worked on the characterisation of spatial and spectral recording techniques; the use of algorithms and processing chains; and requirements of analysis, restoration and visualisation of CH surfaces and objects. A range of possible applications of optical techniques, now available to recording and examination of CH objects, have been tested through six COSCH case studies [BKM17]. These projects have exposed the challenges of common understanding of the processes involved, and differences in disciplinary research needs and methods. A number of issues have been identified, sometimes as basic as lack of common specialist terminology and relevant technical standards. The complexity of the field became apparent in the course of designing COSCHKR, ontological knowledge representation, which employs semantic technologies. After four years of interdisciplinary dialogue, COSCH leaves a legacy that will help the dialogue to continue, technology to develop, and specialist training to better respond to the actual needs of the interdisciplinary CH research communities.
Semantic Structuring and 3D Modeling of Masonry Structure
(The Eurographics Association, 2016) Jacquot, Kévin; Luca, Livio De; Chiara Eva Catalano and Livio De Luca
Studies of architectural heritage require tight control over spatial data. It is an prerequisite for the representation, analysis, conservation and structural restoration of architectural heritage. As regards the morphology of architectural works, the challenge is to move from 3D survey raw data to semantic 3D models. The objective of our project is to develop and experiment a process for the treatment of point clouds in order to create a computational model dedicated to mechanic behavior analysis. Thus, the modeling and semantic structuring is achieved through a knowledge-based approach. Semantic dimension and topological constraints are identified and explicated through the creation of a knowledge model of masonry works. This knowledge is used to implement a set of tools for the reverse engineering of digitized masonry structures.
Harvesting Dynamic 3D Worlds from Commodity Sensor Clouds
(The Eurographics Association, 2016) Boubekeur, Tamy; Cignoni, Paolo; Eisemann, Elmar; Goesele, Michael; Klein, Reinhard; Roth, Stefan; Weinmann, Michael; Wimmer, Michael; Chiara Eva Catalano and Livio De Luca
The EU FP7 FET-Open project ''Harvest4D: Harvesting Dynamic 3D Worlds from Commodity Sensor Clouds'' deals with the acquisition, processing, and display of dynamic 3D data. Technological progress is offering us a wide-spread availability of sensing devices that deliver different data streams, which can be easily deployed in the real world and produce streams of sampled data with increased density and easier iteration of the sampling process. These data need to be processed and displayed in a new way. The Harvest4D project proposes a radical change in acquisition and processing technology: instead of a goaldriven acquisition that determines the devices and sensors, its methods let the sensors and resulting available data determine the acquisition process. A variety of challenging problems need to be solved: huge data amounts, different modalities, varying scales, dynamic, noisy and colorful data. This short contribution presents a selection of the many scientific results produced by Harvest4D. We will focus on those results that could bring a major impact to the Cultural Heritage domain, namely facilitating the acquisition of the sampled data or providing advanced visual analysis capabilities.

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