GCH 2018 - Eurographics Workshop on Graphics and Cultural Heritage

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A Configurable Design Approach for Virtual Museums
(The Eurographics Association, 2018) Tsita, Christina; Sinanis, Anastasis; Dimitriou, Nikolaos; Papachristou, Kostas; Karageorgopoulou, Anastasia; Drosou, Anastasios; Tzovaras, Dimitrios; Sablatnig, Robert and Wimmer, Michael
Virtual Museums (VM) are widely used to preserve and to disseminate cultural heritage to the audience, due to the existing evidence that they can enhance the interest on cultural heritage content, while reinforcing motivation for a real museum visit. A variety of technologies are being used including Virtual Reality (VR), to display cultural heritage objects (CHOs) and related information, in order to offer enjoyable and immersive experiences to the visitors. Additionally, educational aspects of VMs are being explored, due to their inheritance from physical museums, which are educational institutions, among their other roles. Innovative approaches such as authoring tools for the creation of VMs have been introduced in order to fulfil the variant needs of field specialist, audience and educators. The diversity of contexts where a VM can be used, require the creation of open access tools to form customizable VMs for every need. This study aims to present a configurable design approach for the creation of VR museums. The goal is to disseminate the virtual artefacts and introduce them in an appealing way to the audience, the field experts and conservators, through VR experiences. The current version of the VM, allows the curators to dynamically insert objects in the virtual space along with their metadata and measurements derived from various scanning processes. The proposed design approach can support the structure of an open access platform for the creation of immersive VM exhibitions.
CultArc3D_mini: Fully Automatic Zero-Button 3D Replicator
(The Eurographics Association, 2018) Ritz, Martin; Knuth, Martin; Santos, Pedro; Fellner, Dieter W.; Sablatnig, Robert and Wimmer, Michael
3D scanning and 3D printing are two rapidly evolving domains, both generating results with a huge and growing spectrum of applications. Especially in Cultural Heritage, a massive and increasing amount of objects awaits digitization for various purposes, one of them being replication. Yet, current approaches to optical 3D digitization are semi-automatic at best and require great user effort whenever high quality is desired. With our solution we provide the missing link between both domains, and present a fully automatic 3D object replicator which does not require user interaction. The system consists of our photogrammetric 3D scanner CultArc3D_mini that captures an optimal image set for 3D geometry and texture reconstruction and even optical material properties of objects in only minutes, a conveyor system for automatic object feed-in and -out, a 3D printer, and our sensor-based process flow software that handles every single process step of the complex sequence from image acquisition, sensor-based object transportation, 3D reconstruction involving different kinds of calibrations, to 3D printing of the resulting virtual replica immediately after 3D reconstruction. Typically, one-button machines require the user to start the process by interacting over a user interface. Since positioning and pickup of objects is automatically registered, the only thing left for the user to do is placing an object at the entry and retrieving it from the exit after scanning. Shortly after, the 3D replica can be picked up from the 3D printer. Technically, we created a zero-button 3D replicator that provides high throughput digitization in 3D, requiring only minutes per object, and it is publicly showcased in action at 3IT Berlin.
Virtual Reality (VR) Interactions With Multiple Interpretations of Archaeological Artefacts
(The Eurographics Association, 2018) Gaugne, Ronan; Samaroudi, Myrsini; Nicolas, Théophane; Barreau, Jean-Baptiste; Garnier, Laurent; Echavarria, Karina Rodriguez; Gouranton, Valérie; Sablatnig, Robert and Wimmer, Michael
Increasingly, the incorporation of 3D printed artefacts into Virtual Reality (VR) and Augmented Reality (AR) experiences is of interest to Cultural Heritage professionals. This is because virtual environments, by themselves, cannot convey information such as the physical properties of artefacts within the environments. This paper presents a methodology for the development of VR experiences which incorporate 3D replicas of artefacts as user interfaces. The methodology is applied on the development of an experience to present various interpretations of an urn which was found at the edge of a cliff on the south east coastal area of the United Kingdom in 1910. In order to support the understanding of the multiple interpretations of this artefact, the system deploys a virtual environment and a physical replica to allow users to interact with the artefacts and the environment. Feedback from heritage users suggests VR technologies along with digitally fabricated replicas can meaningfully engage audiences with multiple interpretations of cultural heritage artefacts.
3D Reconstruction and Transparent Visualization of Indonesian Cultural Heritage from a Single Image
(The Eurographics Association, 2018) Pan, Jiao; Li, Liang; Yamaguchi, Hiroshi; Hasegawa, Kyoko; Thufail, Fadjar I.; Mantara, Bra; Tanaka, Satoshi; Sablatnig, Robert and Wimmer, Michael
Herein, we propose a method for three-dimensional (3D) reconstruction of cultural heritage based on deep learning, which we apply to the reliefs of the Buddhist temple heritage of Borobudur Temple, in Indonesia. Some parts of the Borobudur reliefs have been hidden by stone walls and are not visible following the reinforcements during the Dutch rule. Today, only gray-scale photos of those hidden parts are displayed in the Borobudur Museum. First, we reconstruct 3D point clouds of the hidden reliefs from these photos and predict the pixel-wise depth information for each of them using a deep neural network model. We then apply our stochastic point-based rendering mechanism to produce a high-quality visualization of the reconstructed point clouds. We have achieved promising visualization results that provide us with an intuitive understanding of the valuable relief heritage that is no longer visible to ordinary visitors.
Integrated Spatio-temporal Documentation and Analysis of Archaeological Stratifications Using the Harris Matrix
(The Eurographics Association, 2018) Neubauer, Wolfgang; Traxler, Christoph; Lenzhofer, Andreas; Kucera, Matthias; Sablatnig, Robert and Wimmer, Michael
The Harris Matrix (HM) is the fundamental diagrammatic representation of relative time for an archaeological site and the de facto standard for the representation of a stratigraphic sequence - the backbone for archaeological stratigraphy. It displays all uniquely identified units of stratification in a sequential diagram representing their relative temporal succession. The Harris Matrix Composer is a widely used application in the archaeological community to efficiently create and analyse HMs. However, it does not support explicit dating of HM units, which is an important information for post-excavation investigations of an archaeological site. In this paper we describe an integrated approach for a combination of stratigraphic and chronologic relations. The implicit, chronologic sequence given by the HM becomes explicit as scientists are enabled to define a hierarchical time model and assign units of the HM to temporal intervals or provide exact dating. The system maintains a consistent visual representation, which means that a correct stratigraphic layout is preserved while units are aligned to intervals of the time model. Evaluation of a real-world use case showed that this combined visualisation makes the scientific analysis and interpretation more efficient and reliable.
VR Video Storytelling for Intangible Cultural Heritage Preservation
(The Eurographics Association, 2018) Selmanovic, Elmedin; Rizvic, Selma; Harvey, Carlo; Boskovic, Dusanka; Hulusic, Vedad; Chahin, Malek; Sljivo, Sanda; Sablatnig, Robert and Wimmer, Michael
Interactive digital storytelling has become a popular method for virtual cultural heritage presentations. Combinations of stories and 3D virtual reconstructions are attractive for the audience and have high edutainment values. In this paper we investigate if 360 degrees VR videos further contribute to user immersion in the preservation of intangible cultural heritage. It describes a case study of the Mostar bridge diving project, aimed to present and preserve the bridge diving tradition from the Old Bridge in Mostar, Bosnia and Herzegovina. It is a virtual reality application which enables the user to virtually jump off the bridge after watching 360 degrees video stories about its history and the bridge diving tradition and upon successfully completing the quiz evaluation of the knowledge gained from the stories. The user experience evaluation study shows that our method was successful in preserving a form of intangible heritage and posits suggestions that can be used in developing an intangible heritage preservation framework.
Development of a High Resolution Topography and Color Scanner to Capture Crack Patterns of Paintings
(The Eurographics Association, 2018) Hengstum, Mathijs J. W. van; Essers, Tessa T. W.; Elkhuizen, Willemijn S.; Dodou, Dimitra; Song, Yu; Geraedts, Jo M. P.; Dik, Joris; Sablatnig, Robert and Wimmer, Michael
The aging of paintings is inevitable and over the years degradation occurs due to exposure to a variety of environmental influences. One of these degradations is craquelure, fracture patterns in the paint. 3D imaging techniques offer opportunities to capture the surface of a painting and these patterns at high resolution. In this paper we present a 3D scanner that is able to capture surface topography and color of oil paintings at high resolution utilizing fringe-encoded stereo imaging scanning system. The scanner is capable of automated capture of an area of 1x1m2, capturing a painting at a spatial resolution of 7 micron and a depth accuracy of 34 microns. Scanning at this resolution creates potential research opportunities for documentation and monitoring oil paintings under its environmental influences. A scan was made of 'Girl with a Pearl Earring' (c.1665), painted by Johannes Vermeer, which exhibits fine craquelure patterns. The scanner is able to capture the painting of 39x44.5 cm within 2 hours with a tile overlap of 25%. The results showed that the craquelure has more often a ridge-shaped profile instead of the expected inward valleys. The documentation of these variations in crack profiles create interesting paths for future research.
Multi-Light Energy Map
(The Eurographics Association, 2018) Lardeux, Florian; Marchand, Sylvain; Gomez-Krämer, Petra; Sablatnig, Robert and Wimmer, Michael
We propose a model to represent quasi-flat objects, such as coins or amphora stamps. These objects are flat surfaces, meaning their length and their width largely exceed their height, and feature a distinctive relief. This relief characterizes the object and its perception is directly influenced by the position of the object, the light direction and the viewer's direction. Our model is a single image representation containing the underlying structural variations of the object. This model, that we call 'Multi-Light Energy Map', is constructed out of several classic images taken with several illumination directions without computing the object's surface normals. We found a way to extract useful information out of this sequence of images and compile it into our map. We eventually explain how we can use this model in the case of image registration of ancient coins.
Browsing Spatial Photography for Dissemination of Cultural Heritage Research Results using Augmented Models
(The Eurographics Association, 2018) Niebling, Florian; Bruschke, Jonas; Latoschik, Marc Erich; Sablatnig, Robert and Wimmer, Michael
Both digital and physical 3D models of buildings as well as historical photographs of architecture are used for a wide range of needs, from research in humanities and information technologies, museum contexts and library studies, to touristic applications. Spatially oriented photographs play an important role in visualizing and browsing contemporary as well as historical architecture, starting with the ground-breaking Photo Tourism project [SSS06]. We present a technique to combine physical, 3D-printed models of buildings with spatially registered historical photographic documents in a hand-held Augmented Reality (AR) environment. Users are enabled to spatially explore historical views of architecture by selecting photos from a collection of images, which are then utilized as textures for the physical model rendered on their respective mobile device. We compare different methods to spatially select photos registered to a physical model in hand-held AR.
Frontmatter: Eurographics Workshop on Graphics and Cultural Heritage
(The Eurographics Association, 2018) Sablatnig, Robert; Wimmer, Michael; Sablatnig, Robert and Wimmer, Michael
Visualizing Networks of Maya Glyphs by Clustering Subglyphs
(The Eurographics Association, 2018) Bogacz, Bartosz; Feldmann, Felix; Prager, Christian; Mara, Hubert; Sablatnig, Robert and Wimmer, Michael
Deciphering the Maya writing is an ongoing process that has already started in the early 19th century. Among the reasons why Maya hieroglyphic script and language are still undeciphered are inexpertly-created drawings of Maya writing systems resulting in a large number of misinterpretations concerning the contents of these glyphs. As a consequence, the decipherment of Maya writing systems has experienced several setbacks. Modern research in the domain of cultural heritage requires a maximum amount of precision in capturing and analyzing artifacts so that scholars can work on - preferably - unmodified data as much as possible. This work presents an approach to visualize similar Maya glyphs and parts thereof and enable discovering novel connections between glyphs based on a machine learning pipeline. The algorithm is demonstrated on 3D scans from sculptured monuments, which have been filtered using a Multiscale Integral Invariant Filter (MSII) and then projected as a 2D image. Maya glyphs are segmented from 2D images using projection profiles to generate a grid of columns and rows. Then, the glyphs themselves are segmented using the random walker approach, where background and foreground is separated based on the surface curvature of the original 3D surface. The retrieved subglyphs are first clustered by their sizes into a set of common sizes. For each glyph a feature vector based on Histogram of Gradients (HOG) is computed and used for a subsequent hierarchical clustering. The resultant clusters of glyph parts are used to discover and visualize connections between glyphs using a force directed network layout.
Towards an Automatic 3D Patterns Classification: the GRAVITATE Use Case
(The Eurographics Association, 2018) Thompson, Elia Moscoso; Biasotti, Silvia; Sorrentino, Giusi; Polig, Martina; Hermon, Sorin; Sablatnig, Robert and Wimmer, Michael
When cataloging archaeological fragments, decorative patterns are an indicator of the stylistic canon an object belongs to. In this paper we address a quantitative classification of the decorative pattern elements that characterize the models in the GRAVITATE use case, discussing the performance of a recent algorithm for pattern recognition over triangle meshes.
Objective and Subjective Evaluation of Virtual Relighting from Reflectance Transformation Imaging Data
(The Eurographics Association, 2018) Pintus, Ruggero; Dulecha, Tinsae; Jaspe, Alberto; Giachetti, Andrea; Ciortan, Irina; Gobbetti, Enrico; Sablatnig, Robert and Wimmer, Michael
Reflectance Transformation Imaging (RTI) is widely used to produce relightable models from multi-light image collections. These models are used for a variety of tasks in the Cultural Heritage field. In this work, we carry out an objective and subjective evaluation of RTI data visualization. We start from the acquisition of a series of objects with different geometry and appearance characteristics using a common dome-based configuration. We then transform the acquired data into relightable representations using different approaches: PTM, HSH, and RBF. We then perform an objective error estimation by comparing ground truth images with relighted ones in a leave-one-out framework using PSNR and SSIM error metrics. Moreover, we carry out a subjective investigation through perceptual experiments involving end users with a variety of backgrounds. Objective and subjective tests are shown to behave consistently, and significant differences are found between the various methods. While the proposed analysis has been performed on three common and state-of-the-art RTI visualization methods, our approach is general enough to be extended and applied in the future to new developed multi-light processing pipelines and rendering solutions, to assess their numerical precision and accuracy, and their perceptual visual quality.
Data Visualization of Decoration Occurrence and Distribution. A Comparative Study of Late Egyptian Funerary Decoration in Thebes
(The Eurographics Association, 2018) Wutte, Anja; Sablatnig, Robert and Wimmer, Michael
Decoration in Ancient Egyptian funerary monuments represents an important part of the monuments layout. Beside scenes displaying the owner, scenes of daily life, fabrication, offerings and hieroglyphic texts are found. Not only topics of self-presentation but also decoration for the translation to the afterlife were predominant. Therefore, this paper suggests approaches to analyze distribution and occurrence of decorations of several ancient monuments of the same style, with data visualization and quantitative methods. As a case study ancient Egyptian funerary monuments of High Officials from the Late Period, twenty-fifth to twenty-sixth dynasty, were studied. The decorative scenes were categorized and tagged in terms of their content. The positions in the monument were highlighted and included in abstracted 3-dimensional models. This computational implementation offers users to search for decoration categories, highlight, locate and finally compare the position of a scene between the monuments. The visualized data include the position and orientation of a categorized scene in the monument, their occurrence and distribution among the analyzed monuments. In a further step the analysis data was studied statistically in order to be able to query detailed results of the prevalence, distribution and preservation of decorations and specific scenes. Both introduced solutions provide a user friendly information interface to visualize, compare and request quantitative data.
Aging Prediction of Cultural Heritage Samples Based on Surface Microgeometry
(The Eurographics Association, 2018) Ciortan, Irina Mihaela; Marchioro, Giacomo; Daffara, Claudia; Pintus, Ruggero; Gobbetti, Enrico; Giachetti, Andrea; Sablatnig, Robert and Wimmer, Michael
A critical and challenging aspect for the study of Cultural Heritage (CH) assets is related to the characterization of the materials that compose them and to the variation of these materials with time. In this paper, we exploit a realistic dataset of artificially aged metallic samples treated with different coatings commonly used for artworks' protection in order to evaluate different approaches to extract material features from high-resolution depth maps. In particular, we estimated, on microprofilometric surface acquisitions of the samples, performed at different aging steps, standard roughness descriptors used in materials science as well as classical and recent image texture descriptors. We analyzed the ability of the features to discriminate different aging steps and performed supervised classification tests showing the feasibility of a texture-based aging analysis and the effectiveness of coatings in reducing the surfaces' change with time.
On Combining Epigraphy, TLS, Photogrammetry, and Interactive Media for Heritage Documentation: The Case Study of Djehutihotep's Tomb in Dayr al-Barsha
(The Eurographics Association, 2018) Lima, Roberto de; Sykora, Toon; Meyer, Marleen De; Willems, Harco; Vergauwen, Maarten; Sablatnig, Robert and Wimmer, Michael
The governors' tombs located at Dayr al-Barsha are considered among the most important monuments of the Egyptian Middle Kingdom. Unfortunately, due to quarrying activities, looting, and natural catastrophes, the archaeological remains are now in a dilapidated state. Their documentation therefore becomes a necessary task towards the preservation and research of this provincial elite cemetery. Traditional geomatics-based heritage recording methods and sensors are, however, not sufficient to yield a full and comprehensive documentation. Inspired by emergent technologies, this paper proposes a symbiosis of digital epigraphy, Terrestrial Laser Scanning (TLS), image-based digitalization techniques, and 3D visualization platforms, to provide experts with a digital tool able to yield high-level information in terms of accurate digital drawings of decorated sections and dense 3D mesh models. Results show that the proposed approach provides a reliable alternative to answer research questions, especially in the context of ancient Egyptian heritage, as the level of detail captured enables the academic community to further explore decoration techniques, damage recognition, and digital reconstruction.
Virtual Restoration of Wooden Artifacts by Non-Rigid 3D Shape Assembly: A Case of the First Solar Boat of King Khufu
(The Eurographics Association, 2018) Nemoto, Takashi; Kobayashi, Tetsuya; Oishi, Takeshi; Kagesawa, Masataka; Kurokochi, Hiromasa; Yoshimura, Sakuji; Ziddan, Eissa; Taha, Mamdouh; Sablatnig, Robert and Wimmer, Michael
In this paper, we present a method to digitally reassemble an object to its original form given the 3D data of its component which are assumed to be non-rigidly deformed. Targeting wooden artifacts, we developed an algorithm to deform the components parametrically, and constraints based on the physical properties of wood are imposed on the deformation. We apply our method to a deformed cultural asset, specifically the first solar boat of King Khufu which is made of wood.
Gloss Calibration and Gloss Gamut Mapping for Material Appearance Reproduction of Paintings
(The Eurographics Association, 2018) Elkhuizen, Willemijn S.; Essers, Tessa T. W.; Song, Yu; Pont, Sylvia C.; Geraedts, Jo M. P.; Dik, Joris; Sablatnig, Robert and Wimmer, Michael
Being able to link captured material characteristics and fabricable material appearance attributes is important for creating life-like reproductions. In this paper we propose a method for gloss calibration, and an approach for gloss gamut mapping, as part of an integrated approach for color, topography and gloss reproduction. For gloss calibration, gloss calibration targets were printed in the primary printing colors (CMYK and White), with uniform gloss in equal distant gloss levels. These targets were scanned using the proposed gloss scanner. To create the gloss gamut map, a monotonic curve was fitted to the mean gloss scan values at different gloss levels. Analysis of fitted curves indicated that the gloss mapping is independent of the diffuse colors. As a case study, the painting 'Fruit Still Life' by Cornelis de Heem was scanned, and the measured gloss was mapped to printable gloss levels using the relation described by the fitted curve. The printed result shows good correspondence to the painting's appearance, with clearly distinguishable gloss features for the in-gamut glass values.
Granitic Recumbent Statue Reproduction by a Seven Axes Robotic Milling Machine
(The Eurographics Association, 2018) Barreau, Jean-Baptiste; Jouneau, Joëlle; Mérelle, Johnny; Maillard, Loïc; Bernard, Yann; Quesnel, Laurent; Sablatnig, Robert and Wimmer, Michael
Facing the sea, the rocks sculpted by the "Abbé Fouré" at the "Pointe du Christ" and the "Pointe de la Haie" in Rothéneuf (Brittany, France) attract many visitors. Winds, rains and sea spray erode each day a little more the sculptures carved in granite more than a century ago. In order to preserve the heritage, the "Association des Amis de l'Oeuvre de l'Abbé Fouré" tried to start an innovative project: recreate a statue sculpted by the "Ermite of Rothéneuf" at the end of the 19th century thanks to 3D technologies and robotics. With a first 3D scanning of the sculpture of the "Pointe du Christ", a stonecutters' company was approached to reproduce identically this recumbent statue, identified as John IV, Duke of Brittany. Thanks to a robotic milling machine working on seven axes, by cutting layers in the granite at each passage, the company realized 60% of the work in less than a month. Then, a sculptor of the company was responsible, from documents collected by the association, to give the granite block the features of the original recumbent statue. This replica is currently the centerpiece of several French exhibitions dedicated to the general public.
A Social Platform to Support Citizens Reuse of Open 3D Visualisations: a Citizen Science Approach
(The Eurographics Association, 2018) Donato, Renato De; Santo, Massimo De; Negro, Alberto; Pirozzi, Donato; Rizzolo, Diletta; Santangelo, Gianluca; Scarano, Vittorio; Sablatnig, Robert and Wimmer, Michael
There is a growing interest in the world of Open Data, with many initiatives in the Cultural Heritage field. Platforms like Europeana, archive.org, Open Heritage by Google are only few examples of on-line catalogues full of open artefacts published with various formats. It is a new and promising way to engage public, such as, students, citizens, non-profit organisations. This paper faces the question of how to help audience in reusing Open 3D models and other artefacts available on Open Cultural Heritage repositories. The idea is to provide a Social Platform named SPOD where citizens can visualise artefacts, share and comment with others in a social way to increase understanding, awareness and engagement in cultural heritage. The foundation is the Datalet-Ecosystem Provider (DEEP), an open source, extensible, scalable, and Edge-centric visualisation architecture to support reuse of visualisations of Open Data in Cultural Heritage. It consists of reusable, dynamic and interactive visualizations named datalets. It includes a variety of visualisations, charts, geographical maps and 3D visualisations. Datalets can be generated and embedded in any web-page as well. SPOD exploits the DEEP architecture to support users within the platform in generating visualisations of Open artefacts, reuse and share them within discussions.

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