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Now showing 1 - 10 of 13
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    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.
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    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.
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    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.
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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.
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    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.
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    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
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    Global refinement of image-to-geometry registration for color projection on 3D models
    (The Eurographics Association, 2013) Dellepiane, Matteo; Scopigno, Roberto; -
    The management, processing and visualization of color information is a critical subject in the context of the acquisition and visualization of real objects. Especially in the context of Cultural Heritage, artifacts are so complex or hard-to-handle that the appearance information has to be extracted from a set of images. The images usually have to be registered to the 3D model of the objects, in order to transfer the needed information. Hence, the problem of image-to-geometry registration has been thoroughly studied by the Computer Graphics and Computer Vision community. Several methods have been proposed, but a fully automatic and generic solution is still missing. Moreover, small misalignments often lead to visible artifacts in the final colored 3D models. In this paper, we propose a method to refine the alignment of a group of images which has been already registered to a 3D model. Taking advantage of the overlapping among the images, and applying a statistical global method based on Mutual Information, the registration error is distributed among all the elements of the dataset. Hence, the quality of color projection is improved, especially when dealing with small details. The method was tested on a number of heterogeneous Cultural Heritage objects, bringing to a visible improvement in the rendering quality. The method is fully automatic, and it does not need powerful hardware or long processing time. Hence, it represents a valid solution for a wide application on CH artifacts.
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    Orthophoto mapping and digital surface modeling for archaeological excavations. An image-based 3D modeling approach
    (The Eurographics Association, 2013) Reu, Jeroen De; Clercq, Wim De; Laloo, Pieter; -
    We have examined image-based 3D modeling for the generation of orthophotos and digital surface models of archaeological surfaces and features. Our results suggest that image-based 3D modeling can be both a time-efficient and cost-effective as well as a scientific valuable method to document archaeological excavations. Although there are limitations, these are greatly surpassed by the possibilities. We believe that image-based 3D modeling can cause a(n) (r)evolution in archaeological excavation practice.
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    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.
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    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.