DH2013 - Track 1

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https://diglib.eg.org/handle/10.2312/12322

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3D Reconstruction of an outdoor archaeological site through a multi-view stereo technique
(The Eurographics Association, 2013) Muzzupappa, Maurizio; Gallo, Alessandro; Spadafora, Francesco; Manfredi, Felix; Bruno, Fabio; Marca, Antonio La; -
This paper describes the experimentation of a common multi-view stereo technique on a particularly complex test case: the ''Via Colonnata'' in the archaeological site of Kyme Eolica in Turkey. The study demonstrates that it is possible to create a detailed 3D model of an area sized tens of square meters without the need to use any dedicated device like laser scanners, drones or helium balloons, but just employing a digital camera and open source software. The reconstruction process implemented in this study addresses and solves some of the most relevant problems related to the reconstruction of large areas and the subsequent mapping of a texture on the geometrical model. In particular, we suggest some guidelines for the acquisition phase that help to reduce the subsequent problems related both to 3D geometry creation and texture mapping. In the pre-processing phase, we propose an automated technique for filtering of unimportant areas, based on the analysis of the disparity maps related to each image pair (the farther areas from the current point of view are masked out, in order to obtain a 3D model free of artifacts/defects). For the texture mapping process, in order to reduce the blur resulting from averaging and blending operations in overlapping areas, we propose a method that automatically identifies the most appropriate subset of images to be projected on the 3D model.
3D Reconstruction of the Cave of the Great Pyramid from Video Footage
(The Eurographics Association, 2013) Kawae, Yukinori; Yasumuro, Yoshihiro; Kanaya, Ichiroh; Chiba, Fumito; -
Studies on the great pyramid of King Khufu (2509-2483 BCE '25) in Egypt are numerous, but only a few surveys, which are the basis of any hypotheses on the construction of a pyramid, have been conducted. In particular, since no observation of the core of the pyramid has been made, theories about the structure are still hypothetical. In 2013, a Japanese TV production company had the opportunity to climb the northeast corner of the pyramid to shoot a crevice that led to an open space (named ''cave'') inside the pyramid, located about 80m from the ground. The authors are fortunate to be allowed to use this video footage for academic research. We employed a ''structure from motion'' (SfM) technique using Microsoft Photosynth to reconstruct the 3D point cloud of the surface of the cave. Twenty minutes of footage was split into thirty thousand image frames, out of which we selected three hundred images shot using several smooth motions of the camera and used these for the SfM process. SfM tracks the ''feature points'' in the image sequence to estimate the camera motion and then triangulates these feature points to produce the point clouds. As a result, the static feature points from the overall surface of the cave were effectively collected and reconstructed as point clouds, whereas inconsistent points from a moving person are automatically eliminated through the SfM process. Thus we have produced, albeit in a small area, the first record of the actual structure of the great pyramid's core. The production of a 3D model from existing video footage is a rather new methodology in the field of archaeology. This set of techniques can be applied to not only academic investigation but also to the restoration and conservation of damaged heritage and artifacts.
On the 3D Documentation of the Igel Column Original and Copy. Structured 3D Survey and Analytical 3D Information System
(The Eurographics Association, 2013) Schaich, Martin; Jahnke, Peter; Knechtel, Sebastian; Rahrig, Max; -
The Igel Column, 23 m high, is one of the best known Roman column monuments in Germany and is part of the UNESCO World Heritage 'Roman Structures, Cathedral and Church of Our Lady' in Trier. The list also includes a faithfully reconstructed and colored one-to-one copy of the column monument from the early 20th century, which is located at the Rheinisches Landesmuseum Trier. Both original and copy are in danger of decay and require comprehensive restoration. Commissioned by the LBB Trier, ArcTron3D GmbH documented both monuments with combined terrestrial and airborne high-resolution 3D scanning technologies. Apart from terrestrial laser scanning and structured light scanning, SFM-photogrammetry was carried out from a lifting platform and a camera copter (MAV Micro Aerial Vehicle). The data fusion and processing resulted in photorealistic high-resolution 3D models. These models were managed and prepared in ArcTron3D's database-supported 3D information system aSPECT3D, which is able to handle large data amounts. For further use during the restoration process, the database allows systematic access to all project data, which was structured according to archaeological and restoration questions.
Cultural heritage documentation using geomatic techniques; Case study: San Basilio s monastery
(The Eurographics Association, 2013) Dominici, Donatella; Rosciano, Elisa; Alicandro, Maria; Elaiopoulos, Michail; Trigliozzi, Serena; Massimi, Vincenzo; -
Each community, passing through its history and its collective memories, has the duty to conserve, identify and properly manage its own heritage that, unfortunately, is often susceptible to transformations due to time, anthropogenic factors or damages caused by natural phenomena. For this reason, heritage artifacts are being extensively documented in order to be maintained in the very best way and bestowed for the benefit of future generations. Geomatic techniques (total stations, GNSS receivers and laser scanners), when integrated among them in an appropriate surveying methodology, data management and processing, can provide dedicated methodologies able to detect and survey the particular characteristics of such complicated structures. In this way, 3D geometric models of the building can be created and enriched with a wide range of information, results of the combination between the visual potential of the images with the high accuracy of the geometric survey. Thus, the use of geomatics represents an interesting tool both for the visualization and the metric evaluation of the structure itself providing an efficient support for professionals and public bodies. The survey of the old monastery of San Basilio, a 16th century building in L'Aquila, central Italy, is presented in this paper.
3D documentation and monitoring of the experimental cleaning operations in the underwater archaeological site of Baia (Italy)
(The Eurographics Association, 2013) Bruno, Fabio; Gallo, Alessandro; Filippo, Francesco De; Muzzupappa, Maurizio; Davidde, Barbara; Caputo, Paolo; -
The CoMAS project aims to develop new methodologies and tools for the restoration and conservation of submerged archaeological artefacts. One of the project goals is to study the cleaning operations that are intended to remove the living organisms (algae, sponges, molluscs, etc.). These organisms cause severe deteriorations of the artefacts and their removal is crucial for the subsequent phases of consolidation and protection. In particular, the Unit of Underwater Archaeology of the Istituto Superiore per la Conservazione ed il Restauro is experimenting and comparing different cleaning techniques and tools developed in the context of the CoMAS project. This comparison requires also a precise documentation of the test cases and a quantitative measurement of the effectiveness of the cleaning procedures. This paper describes the process that has been defined in order to document and monitor the results obtained through different cleaning experiments, conducted with different tools and utensils over various types of surfaces (marble, bricks, mortar, etc.) affected by several types of biological colonization. The process includes: 1) the 3D mapping of the experimental site; 2) the planning of the tests and the choice of the areas to be cleaned; 3) the 3D reconstruction of the selected areas; 4) the execution of cleaning operations; 5) the 3D acquisition of the cleaned areas; 6) the comparison of the 3D model of the areas before and after the cleaning; 7) the analysis of the data about the cleaning effectiveness. This process has been implemented during an experimentation carried out in the ''Villa dei Pisoni'', located within the underwater archaeological site of Baia near Naples.
Faithful, Compact and Complete Digitization of Cultural Heritage using a Full-Spherical Scanner
(The Eurographics Association, 2013) Nöll, Tobias; Köhler, Johannes; Reis, Gerd; Stricker, Didier; -
Effective documentation and display of ancient objects is an essential task in the field of cultural heritage conservation. Digitization plays an important role for the process of creating, preserving and accessing objects in digital space. Up to the present day, industrial scanners are used for this task that focus mainly on the detailed reconstruction of the object's geometry only. However, important for a faithful digital presentation of the object is in particular the appearance information, i.e. a description of the used materials and how they interact with incident light. Using the worlds first full-spherical scanner, we propose a user friendly reconstruction process that is specifically tailored to the needs for digitizing and representing cultural heritage artifacts. More precisely, our hardware specifically addresses the problem that invaluable or fragile artifacts may not be turned over during acquisition. Nevertheless, we can digitize the object completely including its bottom. Further, by integrating appearance information into our digitization we achieve a far more faithful digital replica with a quality comparable to a real picture of the object. But in contrast to a static picture, our representation allows to interactively change the viewing and lighting directions freely. In addition, the results are very memory efficient, consuming only several MB per scanned object and hence are suited to be accessed and visualized interactively in a web browser. In cooperation with museums and a private collector, we digitized several cultural heritage artifacts in order to demonstrate the feasibility of the proposed process.
On-the-fly automatic alignment and global registration of free path collected 3D scans
(The Eurographics Association, 2013) Signoroni, Alberto; Bonarrigo, Francesco; Pezzotti, Nicola; -
We present a complete geometry processing pipeline for multiple 3D scans alignment, composed by a fast, automated feature-based coarse alignment and an efficient global registration, with the aim to enable high-quality and high-throughput cultural heritage digitization. Salient features of our pipeline consist in the capability to provide low-latency, on-the-fly coarse alignment regardless to the number of scans, the capacity to handle interruptions of a continuous acquisition path, as well as an improved implementation of a robust state-of-the-art global alignment technique.
Improving the digitization of shape and color of 3D artworks in a cluttered environment
(The Eurographics Association, 2013) Bettio, Fabio; Gobbetti, Enrico; Merella, Emilio; Pintus, Ruggero; -
We propose an approach for improving the digitization of shape and color of 3D artworks in a cluttered environment using 3D laser scanning and flash photography. In order to separate clutter from acquired material, semi-automated methods are employed to generate masks for segment the 2D range maps and the color photographs, removing unwanted 3D and color data prior to 3D integration. Sharp shadows generated by flash acquisition are trivially handled by this masking process, and color deviations introduced by the flash light are corrected at color blending time by taking into account the object geometry. The approach has been applied to, and evaluated on, a large scale acquisition campaign of the Mont'e Prama complex, an extraordinary collection of stone fragments from the Nuragic era, depicting larger-than-life archers, warriors, boxers, as well as small models of prehistoric nuraghe (cone-shaped stone towers). The acquisition campaign has covered 36 statues mounted on metallic supports, acquired at 0.25mm resolution, resulting in over 6200 range scans (over 1.3G valid samples) and 3426 10Mpixel photographs.
A Methodology for Updating 3D Solid Models of Complex Monumental Structures Based on Local Point-based Meshes
(The Eurographics Association, 2013) Zvietcovich, Fernando; Castaneda, Benjamin; Perucchio, Renato; Morales, Ricardo; Uceda, Santiago; -
Structural changes introduced during the life of monuments contribute to produce complex geometrical configurations that cannot be properly represented in standard solid modeling systems designed for current engineering applications such as finite element analysis (FEA). Likewise, point-based 3D meshes laser-scanner or photogrammetric , although capable of constructing detailed representation of surfaces, cannot be used for direct application in structural analysis because they do not produce complete and unambiguous solid models. To tackle this issue, we merged these two approaches into a unified methodology capable of updating a 3D solid model, representing the entire monument as reconstructed in its presumed original configuration, with information from a 3D mesh model containing a detailed geometrical description of the recent structural state of a specific sector of the same monument. The methodology is based on a series of functions that operate in the Mesh and Solid Modeling Space. The mesh model is aligned via 3D registration and, subsequently, segmented for its conversion to a solid model. Finally, this solid updates the solid representation of the entire monument via Boolean operations. We test the procedure on the Main Platform of the Huaca de la Luna, Trujillo, Peru, one of the most important massive earthen structures of the Moche civilization. Solid models are defined in AutoCAD while 3D meshes are constructed via the photogrammetric program Agisoft PhotoScan. The results indicate that the proposed methodology is effective at transferring complex geometrical and topological features from the mesh to the solid modeling space. The updated solid model can be represented and visualized in any standard CAD software, and utilized for FEA and augmented reality applications.
Replicating perishable artefacts. A project for analysis and exhibition of Early Medieval objects from the Byzantine village at Scorpo (Supersano, Italy)
(The Eurographics Association, 2013) Bandiera, Adriana; Arthur, Paul; Imperiale, Marco Leo; Maffezzoli, Alfonso; Frigione, Mariaenrica; Montagna, Francesco; Signore, Grazia Maria; -
Artefacts found in an archaeological excavation are sometimes made of perishable or fragile material like wood, iron, or leather. These present obvious conservation problems. This is the case of various artefacts from the Byzantine village of Scorpo (Supersano, southern Italy) that has been the object of excavations by archaeologists from the University of Salento (Italy) since 1999. In 2007 a number of wooden objects were discovered in a well, while in 2012 a hoard of ferrous objects was found near a drystone wall that perhaps enclosed the settlement. Given the highly fragile and perishable nature of the objects, the questions arise as to how to study these artefacts, preserve them for the future and display them to the public. In this paper we will illustrate the methodology developed at the University of Salento to give an answer to all these questions and we will describe the entire process ranging from the discovery of the artefacts, to their 3D digital acquisition and modeling, the eventual digital restoration, the realization of one or more physical copies using a rapid prototyping apparatus (RP), to their display in a museum. Digital models of artefacts and ancient contexts are increasingly used in museums in order to improve communication, also for the disabled. Furthermore, the resin replica of an object, created from its digital 3D model, can also be useful for its preservation and fruition, especially if it is fragile or in poor condition.
Anomaly Detection using Remote Sensing for the Archaeological Heritage Registration
(The Eurographics Association, 2013) Rejas, Juan Gregorio; Burillo, Francisco; Bonatti, Javier; Martínez, Rubén; -
The aim of this work is an approach using multisensor remote sensing techniques to recognize the potential remains and recreate the original landscape of three archaeological sites. We investigate the spectral characteristics of the reflectance parameter and emissivity in the pattern recognition of archaeological materials in several hyperspectral scenes of the prehispanic site in Palmar Sur (Costa Rica), the Jarama Valley site and the celtiberian city of Segeda in Spain. Spectral ranges of the visible-near infrared (VNIR), shortwave infrared (SWIR) and thermal infrared (TIR) from hyperspectral data cubes of HyMAP, AHS, MASTER and ATM have been used. Several experiments on natural scenarios of Costa Rica and Spain of different complexity, have been designed. Spectral patterns and thermal anomalies have been calculated as evidences of buried remains and change detection. First results, land cover change analyses and their consequences in the digital heritage registration are discussed.
Measuring Changes in Cultural Heritage Objects with Reflectance Transform Imaging
(The Eurographics Association, 2013) Manfredi, Marcello; Williamson, Greg; Kronkright, Dale; Doehne, Eric; Bearman, Gregory; Jacobs, Megan; Marengo, Emilio; -
Sites and objects of cultural heritage from art to ancient inscriptions to ruins are under constant attack by time and the environment. While much is known about how material components change from laboratory-based artificial aging, very little is known about the process or rates of change of actual objects and sites in situ. Reflectance Transformation Imaging (RTI) is a quantitative method that captures surface normals. In our case, it provides detailed information on the geometry of the object surface. We show that RTI can be quantified for use as a method for measuring change in cultural heritage objects. The past decade has seen the rapid evolution and application of computational photography methods to document important works of human heritage, from art and architecture to archives and archaeology. The next logical step involves defining just how reproducible and precise these methods can be to use them to measure rates of change for important works of cultural heritage. The need is to move to calibrated, quantitative image datasets for reproducible imaging. We measure the precision of computed surface normals, which define the basic repeatability of RTI. Our results show that the average included solid angle for RTI sensitivity fitted to the Hemispherical Harmonics (HSH) polynomial function is 0.003 steradians (3 sigma), while the older Polynomial texture map (PTM) method is much less sensitive (0.5 steradians). The absolute sensitivity of the method is the minimum variation of the normal that can be statistically considered a change of the object. It is calculated considering the average value of the normal of each single pixel. The solid angle of the cone of variation represents the statistical limit (3 *s). Analysis of multiple RTI data sets from objects that have changed between image capture sessions results in a map of change that can easily be evaluated by conservators.
Realistic Virtual Reproductions. Image-based modelling of geometry and appearance
(The Eurographics Association, 2013) Martos, Antonio; Ruiz, Bernardino; -
Existing technologies for contact-less 3D scanning and Image Based Modelling (IBM) methods are being extensively used nowadays to digitize cultural heritage elements. With a convenient degree of automation these methods can properly capture and reproduce shape and basic colour textures. However, there is usually a quite evident lack of fidelity in the resulting appearance of the virtual reproductions when compared with the original items. Even when properly photo-textured, the reproduced surfaces often resemble either plaster or plastic, regardless of the properties of the original materials. What is neither captured nor modelled is the natural dynamic response of the actual materials with respect to changes in observation angle and/or the lighting arrangement. The methodology introduced in this paper tries to improve the three-dimensional digitalization and visualization of cultural heritage elements, by extending the present capabilities of IBM with additional capture and modelling of surface appearance. We show that it is possible to automatically reproduce realistic-looking virtual objects and scenes, even with photographs taken with an uncalibrated single moving camera and while under uncontrolled and intentionally variable lighting conditions. This is achieved not only by reconstructing the shape and projecting colour texture maps from photographs, but also modelling and mapping the apparent optical response of the surfaces to light changes, while also determining the variable distribution of environmental illumination of the original scene. This novel approach integrates Physically Based Render (PBR) concepts in a processing loop that combines capture and visualization. Using the information contained in different photographs, where the appearance of the object surface changes with environmental light variations, we show that it is possible to enhance the information contained in the usual colour texture maps with additional layers. This enables the reproduc- ion of finer details of surface normals and relief, as well as effective approximations of the Bi-directional Reflectance Distribution Function (BRDF). The appearance of the surfaces can then be reproduced with a dedicated render engine providing unusual levels of detail and realism due to enriched multi-layer texture maps and custom shading functions. This methodology will be introduced with a real case-study, to illustrate its practical applicability and flexibility; The virtual reproduction of the Lady of Elche was performed only from archived photographs taken at the museum for different documentation purposes, using uncalibrated optics and an uncontrolled studio light arrangement. We discuss the capture on larger architectural elements as well, with uncontrolled (yet still variable) illumination in outdoor environments and challenging items with difficult to capture surfaces such as the brass sculpture of La Regenta, where proper reproduction of surface reflection and environmental lights are fundamental steps to provide a good visualization experience. These cases will show the feasibility of working with field calibration and initial approximations for the camera model and light-maps, addressing thus the flexibility required for practical field documentation in museum environments or outdoors. The potential for diffusion will be shown with the use of open source software tools for enhanced visualization. The presented capture methods are integrated with the specific adaptation of open-source GPU-based (Graphics Processing Unit) render engines to produce two flavours of 3D inspection/visualization tools with proper relighting capabilities, able to reveal very subtle details: A quasi-real time realistic engine (Blender Cycles), which is also the basis for the capture process and is focused on realistic reproduction, and a real-time version based on customized pixel shaders, for the real-time visualization of lightweight models on web browsers and other interac
Cutting-edge technologies for the survey and documentation of cultural heritage: the case study of the architectural-archaeological area of Aruch in Armenia
(The Eurographics Association, 2013) Versaci, Antonella; Cardaci, Alessio; -
One of the most important finalities of survey is the architecture's comprehension. To the end of cultural heritage conservation, it is furthermore necessary to communicate the acquired knowledge. In the recent years, this need has resulted in a radical change in cataloging and digitization systems, as well as in telematics networking. Moreover, the use of 3D laser scanner has transformed not only the approaches related to metrics data acquisition and graphic rendering but has also afforded the opportunity to share important information on the web. This paper focuses on the usefulness of state-of-the-art technologies for documentation, presenting a case study related to the architectural-archeological area of Aruch in Armenia.
Characterization of European Lacquers by terahertz (THz) reflectometric imaging
(The Eurographics Association, 2013) Dandolo, Corinna Ludovica Koch; Jepsen, Peter Uhd; -
In this study a European lacquerware replica has been investigated by terahertz (THz) reflectometric imaging. The inspected lacquerware is a wooden panel covered by multiple complex layers of lacquers and plaster. Utilizing pulsed Terahertz Time-Domain Imaging (THz-TDI) in reflection mode, we observe non-invasively buried layers of the lacquerware replica, including the internal structure of the wooden panel itself. We find that non-invasive terahertz reflectometric imaging analysis of lacquerware is can provide conservators with important information about the condition of the compositional layers, potentially aiding in the development of appropriate conservation treatments. With the same technique we have performed a surface material mapping. The material distribution has been enhanced through reflected THz composite RGB false color rendering, where RGB mapping allows distinction between different materials and textures on the surface of the lacquerware. The contrast between different textures is enabled by wavelength-dependent scattering from the surface, as well as differences in the composition of the surface layer.
Digital Production of Traditional Costumes
(The Eurographics Association, 2013) Kang, Yeonkyung; Wu, Sehee; Ko, Young-A; Martin, Kathi; Ko, Hyeong-Seok; -
The role of the museum has changed from a "onesided information delivery" system focusing on exhibition and education to ''community as culture''. Creating richly detailed digitized reproductions of museum holdings can stimulate the social media dialogue between museum and visitor. The purpose of this study is to determine the feasibility of reproducing traditional costumes using digital technology. For this experiment, we selected a woman's robe and a man's ensemble of the Rococo era of the 18th century. Using historical reference material we first analyzed the design features of the silhouette, and the fabrics, hairdos and accessories of the period. This paper details the application of 3D technologies, DC Suite and Maya Qualoth, to reconstruct them.
3D documentation of Cultural Heritage artefacts: from data acquisition to virtual conservation and restoration
(The Eurographics Association, 2013) Athanasiou, Eleni; Faka, Marina; Hermon, Sorin; Vassallo, Valentina; Yakoupi, Kyriaki; -
This paper focuses on the development of a procedure for 3D documentation of Cultural Heritage assets and describes all the steps from the 3D data acquisition of the real object, the post processing the raw data and finally the digital recording, documentation and virtual preservation of the 3D data. It will also describe the experiences, carried out during the digital process, of some virtual restoration cases.
Design and implement a reality-based 3D digitisation and modelling project
(The Eurographics Association, 2013) Remondino, Fabio; Menna, Fabio; Koutsoudis, Anestis; Chamzas, Christos; El-Hakim, Sabry; -
3D digitisation denotes the process of describing parts of our physical world through finite measurements and representations that can be processed and visualised with a compute r system. Reality-based 3D digiti sation is essential for the documentation, conservation and preservation of our Cultural Heritage. This article composes a critical review of the digitisation pipeline, ranging from sensor selection and planning to data acquisition, processing and visualisation.
A Low-Cost Portable 3D Laser Scanning System with Aptness from Acquisition to Visualization
(The Eurographics Association, 2013) Banerjee, Sumandeep; Biswas, Prabir Kumar; Bhowmick, Partha; Dutta, Somnath; -
This paper presents the design perspectives of a low-cost portable 3D laser scanning mechanism. The hardware is simple in design, easy to fabricate, and costs much less compared to the cheapest ones available in the market. Moreover, it is noninvasive and able to generate high-quality data sets. We present the complete design pipeline and discuss how to implement and put together the most recent algorithms. We propose this design for its wide applications to virtual reality simulation, 3D modeling, digitization of archaeological artifacts, automated defect inspection, object recognition etc.
Reverse Engineering of Scale Models Using Dataflow Programming: Application to the fortification of plans-reliefs
(The Eurographics Association, 2013) Jacquot, Kevin; Chevrier, Christine; Gilles, Halin; -
Despite the progress in three-dimensional scanning, some architectural artifacts remain a digitizing challenge. Scale models and more especially the plans-reliefs of Louis XIV of France have specific characteristics such as size, scale, number, etc. A knowledge-based modeling approach is developed to address the limitations of digitizing tools. Our study deals with the fortified areas of the scale models. Bastioned fortification works extend over wide areas but they are built according to design rules. Once studied and organized, fortification knowledge has been used to create a library of parametric components. Implemented in Grasshopper, the components were manually adjusted to different practical cases. The library was then validated and we are now focusing on the automation of the adjustments of the components. Thereupon a reverse-engineering approach has been set up. Semantic segmentation algorithms have been defined and implemented in Grasshopper to automatically extract fortification features from 3D surveys based on the knowledge of fortification design rules. Along with the three-dimensional modeling of fortification, an automatic reconstruction of the city parts of the scale models is underway. Both these studies are part of a project aimed at valorizing and diffusing a very unique cultural heritage collection. As such, knowledge models are precious assets both the digitizing and the semantic enhancements of the final application.

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