GCH 2018 - Eurographics Workshop on Graphics and Cultural Heritage

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https://diglib.eg.org/handle/10.2312/2632673

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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.
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.
Atalaya3D: Making Universities' Cultural Heritage Accessible Through 3D Technologies
(The Eurographics Association, 2018) Melero, Francisco Javier; Revelles, Jorge; Bellido, Maria Luisa; Sablatnig, Robert and Wimmer, Michael
This work was carried out over the past eight years through the Atalaya3D project, which aims to make the cultural heritage of the ten public Andalusian universities accessible. Since 2010, the project has been a pioneer in the field of 3D scanning of sculptures and historical sites, opening up restricted areas virtually through 3D web displays. Moreover, in addition to the website, a mobile app allows visitors to browse these institutions' vast heritage and examine it before visiting the campus in a 3D environment. More than 70 artworks and historical buildings have been accurately scanned using the latest 3D scanning technologies, so that we now have the geometry and colour of the pieces documented in detail. QR codes make it easier to reach the relevant information about our universities' heritage via any mobile device (phone or tablet).
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.
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.
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.
Deep Mapping Tarn Hows: Automated Generation of 3D Historic Landscapes
(The Eurographics Association, 2018) Reinhold, Alexander; Gregory, Ian; Rayson, Paul; Sablatnig, Robert and Wimmer, Michael
Changing landscape presents a problem for both conservation and education at heritage sites. We consider the site of Tarn Hows in the English Lake District National Park, a site which has had significant landscape change over the past 200 years, from developing tree coverage, to the merging of three lakes into one. We created an automated process that combines an elevation map and a vegetation map to build a 3D representation of the landscape. We used this tool to create a 3D Deep Map of Tarn Hows, representing the site's landscape at multiple periods over time, allowing them to be viewed side by side and explored in an interactive environment. This 3D Deep Map provides an exploratory resource for site authorities to educate the public about the historic environment, with embedded multimedia in the application to provide additional information to users that might be disruptive or impractical to display on site. The 3D Deep Map also provides a tool for conservators to plan site maintenance to best maintain the integrity of the historic landscape without negatively impacting visitors' experience of the iconic site.
Developing and Maintaining a Web 3D Viewer for the CH Community: an Evaluation of the 3DHOP Framework
(The Eurographics Association, 2018) Potenziani, Marco; Callieri, Marco; Scopigno, Roberto; Sablatnig, Robert and Wimmer, Michael
3DHOP (3D Heritage On-line Presenter) has been released 4 years ago, as an open-source framework for the creation of interactive visualization of 3D content on the web, aimed at the CH field. Transforming a research tool into a software ''product'' usable by the heterogeneous CH community is not a simple task and requires a significant amount of resources plus a specific design. This work presents the evolution of the 3DHOP system, and the complex relationship with its community of users, made of content creators, CH experts and general public. We will discuss the new features introduced, as well as the design and implementation strategy employed to maintain the software and make it usable by developers. We will evaluate the effectiveness of the platform by illustrating some of the applications built with 3DHOP either internally or by external users, as well as by presenting the results of a survey aimed at gathering the opinions and suggestions of the user community.
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.
Digital Workflow for Creating 3D Puzzles to Engage Audiences in the Interpretation of Archaeological Artefacts
(The Eurographics Association, 2018) Echavarria, Karina Rodriguez; Samaroudi, Myrsini; Sablatnig, Robert and Wimmer, Michael
3D physical puzzles are typically used to engage audiences in the interpretation of archaeological artefacts in a museum exhibition. The reason for this is that a puzzle can be seen as a game but also as a complex activity that archaeologists undertake to re-assemble fragments. The contribution of this paper is a novel digital worfklow for the design and fabrication of 3D heritage puzzles. The input to the workflow is an authentic artefact from a heritage collection, which is then digitised using technologies such as 3D scanning and 3D modelling. Thereafter, a puzzle generator produces the 3D puzzle pieces using a cell fracture algorithm and generates a set of puzzle pieces (female) and a single core piece (male) for fabrication. Finally, the pieces are fabricated using 3D printing technology and post-processed to facilitate the puzzle assembly. To demonstrate the workflow, we deploy the proposed method to create a 3D puzzle of an artefact, the Saltdean urn, for the Archaeological Gallery of the Brighton Museum and Art Gallery. The significance of this research is that it eases the task of creating puzzle-like activities and maintaining them within a busy museum gallery.
Earthquake Simulation for Ancient Building Destruction
(The Eurographics Association, 2018) Fita, Josep Lluis; Besuievsky, Gonzalo; Patow, Gustavo; Sablatnig, Robert and Wimmer, Michael
Research on seismic simulations has been focused mainly on methodologies specially tailored for civil engineering. On the other hand, we have detected a certain lack of this kind of tools for interactive cultural heritage applications, where speed and plausibility are the main requirements to satisfy. We have designed a tool that allows to parameterize and recreate real earthquakes in an accurate, but simple way. Furthermore, we have focused our efforts on those users without much technical experience in geology or seismic simulation, such as historians, art historians, museum curators and other similar stakeholders. We have performed a series of tests over a set of ancient masonry buildings such as walls with their respective battlements, houses and a Romanesque church with structural simulation enabled, thus, allowing the coupling between the earthquake being simulated and the objects of interest. We show the feasibility of including earthquake simulations and structural stability into historical studies for helping the professionals to understand better those events of the past where an earthquake took place.
Elastic Flattening of Painted Pottery Surfaces
(The Eurographics Association, 2018) Preiner, Reinhold; Karl, Stephan; Bayer, Paul; Schreck, Tobias; Sablatnig, Robert and Wimmer, Michael
Generating flat images from paintings on curved surfaces is an important task in Archaeological analysis of ancient pottery. It allows comparing styles and painting techniques, e.g, for style and workshop attribution, and serves as basis for domain publications which typically use 2d images. To obtain such flat images from scanned textured 3d models of the pottery objects, current practice is to perform so-called rollouts using approximating shape primitives like cones or spheres, onto which the mesh surfaces are projected. While this process provides in intuitive deformation metaphor for the users, it naturally introduces unwanted distortions in the mapping of the surface, especially for vessels with high-curvature profiles. In this work, we perform an elastic flattening of these projected meshes, where stretch energy is minimized by simulating a physical relaxation process on a damped elastic spring model. We propose an intuitive contraction-directed physical setup which allows for an efficient relaxation while ensuring a controlled convergence. Our work has shown to produce images of significantly improved suitability for domain experts' tasks like interpretation, documentation and attribution of ancient pottery.
Evaluation of Multi-Platform Mobile AR Frameworks for Roman Mosaic Augmentation
(The Eurographics Association, 2018) Cardoso, Jorge C. S.; Belo, André; Sablatnig, Robert and Wimmer, Michael
Augmented Reality (AR) development frameworks have different recognition performance on different kinds of target images. In this work, we studied AR frameworks applied in the context of outdoor Roman mosaic ruins with the final aim of developing a multi-platform mobile AR application. We started by analysing the documented features of existing frameworks to determine the feasible ones. This resulted in the selection of three frameworks: CraftAR, PixLive, and Wikitude. We then experimentally evaluated the performance of the target recognition features against real mosaics by measuring the recognition delay, minimum required target area, visual alignment and visual stability. Results indicate a good recognition rate for CraftAR and a poor recognition rate for Wikitude. CraftAR showed better recognition delay and visual stability, while PixLive showed better minimum required target area and visual alignment.
Frontmatter: Eurographics Workshop on Graphics and Cultural Heritage
(The Eurographics Association, 2018) Sablatnig, Robert; Wimmer, Michael; Sablatnig, Robert and Wimmer, Michael
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.
An Image-based Approach for Detecting Faces Carved in Heritage Monuments
(The Eurographics Association, 2018) Lai, Yu-Kun; Echavarria, Karina Rodriguez; Song, Ran; Rosin, Paul L.; Sablatnig, Robert and Wimmer, Michael
Heritage monuments such as columns, memorials and buildings are typically carved with a variety of visual features, including figural content, illustrating scenes from battles or historical narratives. Understanding such visual features is of interest to heritage professionals as it can facilitate the study of such monuments and their conservation. However, this visual analysis can be challenging due to the large-scale size, the amount of carvings and difficulty of access to monuments across the world. This paper makes a contribution towards this goal by presenting work-in-progress for developing image-based approaches for detecting visual features in 3D models, in particular of human faces. The motivation for focusing on faces is the prominence of human figures throughout monuments in the world. The methods are tested on a 3D model of a section of the Trajan Column cast at the Victoria and Albert (V&A) Museum in London, UK. The initial results suggest that methods based on machine learning can provide useful tools for heritage professionals to deal with the large-scale challenges presented by such large monuments.
Improving Marker-Based Tracking for Augmented Reality in Underwater Environments
(The Eurographics Association, 2018) Cejka, Jan; Zuzi, Marek; Agrafiotis, Panagiotis; Skarlatos, Dimitrios; Bruno, Fabio; Liarokapis, Fotis; Sablatnig, Robert and Wimmer, Michael
Underwater sites are a challenging environment for augmented reality. Images taken under water are degraded in several ways, most importantly they are affected by unbalanced colors due to uneven absorption of light in each color channel, blurring and desaturation caused by turbidity, or noise due to the presence of larger organisms, plants, or bubbles. In this paper, we introduce a new method based on white balancing that enhances underwater images to improve the results of detection of markers. We compare this method with several image enhancement methods, and evaluate their performance when applied to the problem of detecting markers under water. Our results show that our method improves the detection in underwater environments while keeping the computation time low.
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.

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