DH2013 - Track 1

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

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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.
Dense Image Matching: comparisons and analyses
(The Eurographics Association, 2013) Remondino, Fabio; Nocerino, Erica; Menna, Fabio; Nex, Francesco; Spera, Maria Grazia; Gonizzi-Barsanti, Sara; -
The paper presents a critical review and analysis of dense image matching algorithms. The analyzed algorithms stay in the commercial as well open-source domains. The employed datasets include scenes pictured in terrestrial and aerial blocks, acquired with convergent and parallel-axis images and different scales. Geometric analyses are reported, comparing the dense point clouds with ground truth data.
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.
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
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.
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.
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.
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.
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.
Temporal Terrestrial Laser Scanning to Visualize the Archaeological Excavation Process
(The Eurographics Association, 2013) Srour, David; Richter, Ashley; Levy, Thomas; Kuester, Falko; -
Archaeology is a destructive science. Photographs and videos preserve some aspects of the sequence of events inherent within the archaeological excavation process, but cannot replicate the spatiality and detail of the downward progression of the digging entailed through excavation. Time lapse sequences of properly adapted and employed terrestrial laser scanning to create a temporal sequence of point clouds of the archaeological methodologies can, however, serve as an innovative step towards accurate documentation of crucial data for future archaeologists interested in the site. Over the course of the National Science Foundation Integrative Graduate Education and Research Traineeship funded Sediment Intervals and Site Deformation Processes: Exploring Time Lapse Laser Scanning Capabilities and Methodologies for Archaeology, temporal scanning was tested on the beaches of San Diego to establish a baseline capability for data capture. Subsequently, the methodologies for data collection were utilized as a part of the excavation workflow at the University of California, San Diego's Edom Lowlands Regional Archaeological Project's excavation of a Roman era section of tell Khirbat Faynan in southern Jordan. With the data collected from the excavation as the impetus for new system development, original visualization processing designed with the archaeological problems and end-goals in mind is being created at the University of California, San Diego Center of Interdisciplinary Science for Art, Architecture, and Archaeology in order to meaningful display the shifting data sets in real time and exhibit not just the archaeological data, but the archaeological process.
Quick textured mesh generation for massive 3D digitization of museum artifacts
(The Eurographics Association, 2013) Gonizzi, Sara; Micoli, Laura L.; Guidi, Gabriele; -
The goal of the "3D Icons" European Project, is to provide Europeana with accurate 3D models of Cultural Heritage artifacts. The purpose of this paper is to describe the specific optimized processing pipeline that has been set-up for digitizing a significant part of the Civic Archaeological Museum in Milan (Italy). Many technical and logistic issues for capturing 3D models in a Museum environment are addressed. In such framework the main problem is generating a good result by the technical point of view, minimizing the impact on the usual Museum activity during 3D capture operations, while shortening the processing time to the minimal allowed by the different applicable techniques. This condition led to precise choices related to the 3D acquisition techniques to be used (SfM), and the related data processing. This paper illustrates the aforementioned systematic aspects through three practical examples, showing good practices for image capturing and some 3D processing optimizations that allowed to speed the 3D models production at a level compliant to the final goal of more than 500 models in 36 months.
Monitoring and conservation of archaeological wooden elements from ship wrecks using 3D digital imaging
(The Eurographics Association, 2013) Bandiera, Adriana; Alfonso, Cristiano; Auriemma, Rita; Bartolo, Maurizio Di; -
In marine archaeology, many artifacts made of metallic or organic material are found in different state of conservation depending of the environment in which they are discovered. Once brought to the surface for study or display purposes, the artifacts need to be treated properly otherwise they deteriorate in a short lapse of time. The fragility of organic artifacts and the volumetric variation caused by the marine life on or surrounding them and water lead to the need for measuring the physical dimensions soon after an artifact is extracted from the sea. In an ideal context, it would be appropriate to preserve and restore the archaeological elements rapidly and with the latest methods but due to the large number of artifacts, the cost of complete restoration activities becomes prohibitive for the funding available in public institutions. For this reason, many public laboratories are resorting to digital technologies for documentation, restoration, display and conservation. In this paper, we illustrate the experience of the University of Salento in this area of archaeology using 3D imaging technology. The interest sprang from the need to develop a protocol for documentation and digital restoration of archaeological finds discovered along the coast of Torre S. Sabina (BR) Italy.
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.
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.
3D Laser Scanning in Cave Environment: the Case of Las Cuevas, Belize. Acquisition of the Cave System and Excavation Area
(The Eurographics Association, 2013) Lindgren, Stefan; Galeazzi, Fabrizio; -
The Las Cuevas site is a Maya administrative and ceremonial center active during the latter part of the Late Classic period (700 900 AD) in Western Belize. It is of particular interest because a large cave resides directly beneath the largest temple in the site core. This paper presents the use of phase shift variation laser scanning technology (Faro Focus 3D) for the acquisition of the cave's network of galleries (9 chambers) and a large excavation area (8×5 m) investigated in the entrance chamber in the summer of 2012. More than 300 scans were made to acquire the entire cave and the amount of 3D data collected was more than 400 GB. The creation of different level of details allowed the alignment and triangulation of the 3D models of the different chambers and units. The dimension (24×20×10 cm; 5 kg) and accuracy (' 2 mm at 10 25 m) of the laser scanner allowed complete documentation of the cave and units in just three weeks of work. The importance of this work relies on the possibility to use the processed data to systematically improve the archaeological understanding of Las Cuevas' complex cave system, favoring the interpretation of socio-cultural dynamics linked to cave environments during the Late Classic. The use of 3D technologies can, in fact, help the understanding of how the space in the cave was used in the past for rituals and ceremonies. Moreover, the 3D millimetric reproduction of the excavation process linked to the 3D survey of the entire cave will be instrumental for the archaeological record's preservation. Future scholars will have the opportunity to retrace the work made by archaeologists at Las Cuevas, starting new discussion and interpretations of the same 3D archaeological context.
Underwater photogrammetry for archaeology and marine biology.40 years of experience in Marseille, France
(The Eurographics Association, 2013) Drap, Pierre; Merad, Djamel; Seinturier, Julien; Mahiddine, Amine; Peloso, Daniela; Boi, Jean-Marc; Long, Luc; Garrabou, Joaquim; -
Since 1973 archeology and computer science have developed close ties in Marseille. Two departments (computer science and archaeology) from the French National Centre for Scientific Research (CNRS) in Marseille started working together and laid the cornerstone of the Computer Applications and Quantitative Methods in Archaeology (CAA) community. Marseille also has the advantage of being located in a very interesting place on the Mediterranean Sea and being the home to several famous laboratories, such as the French Cultural Heritage Department (DRASSM) or private companies like COMEX. In 1980 they performed a series of explorations of a deep-sea wreck with the help of COMEX and DRASSM. More recently, ten years ago, the Centre d'Océanologie de Marseille (COM) started using underwater photogrammetry to survey and monitor red coral populations in situ. In this paper we present new advances in underwater photogrammetry for archaeology and marine biology based on forty years of experience. The survey described in this article does not only discuss the acquisition of 3D points in difficult conditions but also linking archaeological knowledge to the surveyed geometry. This approach needed to combine automatic data processing and offered the opportunity to experts, archaeologists or biologists, to insert knowledge in the process. After an introduction to the history of computer science and archaeology, we will present related work in underwater archaeology and marine biology. The last section is dedicated to two recent experiments in Marseille, based on recent developments in automatic photogrammetry: a World War II plane wreck, surveyed using both acoustic and optical sensors, and a survey used to monitor red coral growth over several years.
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.
Multi-scalar 3D digitization of Cultural Heritage using a low-cost integrated approach
(The Eurographics Association, 2013) Manferdini, Anna Maria; Russo, Michele; -
In the architectural survey field, one of the main aspects to consider during a 3D digitization is the multi-scalar geometrical complexity of the artifact to acquire, besides other fundamental factors connected with the different aims of communication. Since the widespread of range-sensors has provided extremely versatile instruments able to easily acquire huge amount of data that can be processed for different uses and users and changing communication aims, the possibility to survey and restore high-quality 3D multi-resolution models has become an urgent need. Despite these developments, these technologies are still very expensive, need expertise and present persistent bottlenecks both in the reverse modeling process and in time consuming. In order to overcome these critical aspects and taking advantage of recent improvements of automated image-based technologies based on the Structure from Motion approach, this contribution presents some first results of investigations on the reliability of these low-cost technologies for the 3D digitization of Cultural Heritage. One of the main aims of these investigations rely on developing a procedure that could ease the work of surveyors called to represent artifacts at an architectural scale using fast and low-cost technologies. 3D models derived using the selected low-cost image-based technologies were compared among each other and with a 3D laser scanner gold standard acquisition. These investigations led to qualitative and quantitative evaluations and to considerations on times and skills required by all tested technologies. Strengths and weaknesses are highlighted, suggesting the best solution with respect to the optimization of all considered aspects. Finally, integration of different technologies are presented, as it represents the best solution in multi-scalar contexts.
Comparing 3D digitising technologies: where are the differences?
(The Eurographics Association, 2013) Mathys, Aurore; Brecko, Jonathan; Semal, Patrick; -
We tested five 3D digitization systems and one method of 2D+ recording on one object: a human skull from the Royal Belgian Institute of Natural Sciences collection (RBINS). We chose a skull because it has both simple and complex structures and different materials such as bone and enamel within the same object. The results obtained with the different technologies were compared for 3D shape accuracy, texture quality, digitization and processing time and finally price. Our results show that the structured light scanner provided the best results to record external structures, CT was found to be the best to record internal structures and is also the best for recording reflecting material such as enamel. Photogrammetry is a very good compromise between portability, price and quality. RTI is a method of 2D+ recording and is a complementary technique, using the same equipment than photogrammetry, which can capture small morphological features that are not easily digitized with the 3D techniques.

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