Using dense stereo matching techniques in survey

In recent years there has been an enormous increase in the dissemination of modelling techniques known as dense stereo matching (DSM) or image-based modelling (IBM) using free, low cost, open source software, especially applications involving the survey of cultural heritage (architecture, archaeology, and town planning). The algorithms used by these software programmes process photographic datasets and provide a 3D model of the scene in question. During complex survey and 3D restitution procedures, these techniques save time (processing) and money: these advantages Can he useful to any professional. This is why it is important to identify the real potential and limits of these software programmes and how they should be used to produce the best possible results. We carried out parallel tests to verify how to use the two software packages: 123D Catch by Autodesk and VisualSfM+CMVS/PMVS2 by Changchang Wu. The photographic dataset was the most critical part of the procedure involving DSM or IBM techniques. The article illustrates three case studies in which only the third study, provides an optimal dataset capable of generating a reliable model. The tests were carried out on three different architectural objects, ranging from a small to large scale; terrestrial laser scansions were used for the metric comparisons of the ensuing models

123D Catch: efficiency, accuracy, constraints and limitations in architectural heritage field

Today, the accurate and detailed reconstruction of geometric models of real objects has become a common process. The diffusion of Image-based 3D modeling techniques, through image-based free, low cost and open source software, have increased drastically in the past few years, especially in the sector of Cultural Heritage (Architecture, Archeology, Urban planning). Nevertheless, web based software (ARC3D, 123D Catch, Hyp3D, my3Dscanner) offer another opportunity respect the desktop systems: they use the power of cloud computing to carry out a semi-automatic data processing. In this way is overcome the considerably slowing-down of the computer of hardware-heavy approaches. Our research investigates the limits and potentialities of 3D models obtained by using Autodesk 123D Catch in Architectural Heritage field, in order to verify the applicability of the method for the practitioner purpose. Our goal is to evaluate Catch efficiency, accuracy, constraints and limitations in order to provide insight into the current state of 3D modeling products. Our methodology forecasts the comparison between 123D Catch models and terrestrial laser scanner 3D acquisition in order to verify metric accuracy. Therefore, we propose a lot of interesting examples applied in architectural heritage field from the detail to the large scale

Moving towards a new life cycle analysis approach by implementing low cost structural 3d monitoring of historic building safety by means of image based modelling.

Abstract A building’s structural safety is often remit to human life fatalities and the measures of social protection and security often used following the collapse of a portion of the building. It is quite clear that, if it were possible to monitor the increase of static deterioration, it would be easier to prevent the collapse. There are two fundamental aspects closely linked to the building’s collapse: the first concerns the security of lives and the second concerns the well-being and quality of life when it is considered in relation to Cultural Heritage survival. Unfortunately, the high cost of a 3D survey does not usually permit a constant monitoring of the visible instability. The paper aims to carry out a low-cost workflow for structural 3D monitoring of historical buildings based on Image Based Modeling (IBM) techniques. IBM techniques create a 3D model of the sample by taking a structured dataset of images according to photogrammetric rules. In recent years, the experimentation of several research teams demonstrated the affordability of these techniques, which are able to ascertain data with accuracy within a millimeter (according to the size of the sample and the camera resolution)

VIRTUAL MUSEUMS AS A MEANS FOR PROMOTION AND ENHANCEMENT OF CULTURAL HERITAGE

Abstract. The use of virtual reality and ICT in the museum context provides a new key to understand and promote Cultural Heritage: thanks to these technologies the user has the opportunity to experience without the need to come into contact with the real objects. For the museum institutions VR and ICT are a valuable tool that allows them to perform different cultural tasks, addressing the public in a much more effective way than has previously been possible. Especially through VR, it is possible to reconstruct the original context of the artworks through the interconnection of contents: the virtual visitor, while viewing the artwork, can consult useful contents for the learning process. Another revolutionary element introduced by the new technologies is linked to the possibility of creating virtual exhibitions through which it is possible to exhibit works that are not accessible or not visible. These reflections and these theoretical principles were the basis for the development of the project proposal presented in these pages, that was born as a collaboration between the R3D Lab of the Museo della Rappresentazione of University of Catania and the CIMS Lab of Carleton University, Ottawa. It consists in the creation of a virtual museum, the Timeless Museum, in order to create an educational experience, able to make the users reflect on topics such as the value of history, the sense of beauty, the relationship with our past and our future, the protection and transmission to future generations of the artistic heritage we have.</p

Heritage and technology: novel approaches to 3D documentation and communication of architectural heritage

In the past few years we have seen a drastic increasing of image-based modeling (IBM) techniques to get high quality reality-based 3D models. The low costs of these techniques as well as their attractive visual quality have lead many researchers and professionals to invest their energies and resources in several tests. The use of IMB in the field of cultural heritage is mostly exploited in applications such as documentation, digital restoration, visualization, inspection, planning, AR/VR, conservation and design. One of the strengthen of multi-view stereo techniques is the possibility to capture millions of points in a very short time and to get a 3D textured polygonal model that can be easily used for visualizing and communicating digital assets. Currently, we can distinguish between desktop and web based packages. If the first one needs a high performance computer for data processing, the second one use the power of cloud computing to carry out a semi-automatic data processing instead of considerably slowing-down the computer. The aim of this study is to compare two of the most known IBM packages (Agisoft Photoscan and Autodesk Recap) in applications dealing with architectural heritage. The comparison among the chosen packages are typical user-oriented parameters such as: visual completeness/detail of the 3D model; ratio between images resolution/number of images/time processing; number of used/discharged images (useful to optimize the images network); metric accuracy; learning curve/usability

IMAGE-BASED MODELING TECHNIQUES FOR ARCHITECTURAL HERITAGE 3D DIGITALIZATION: LIMITS AND POTENTIALITIES

3D reconstruction from images has undergone a revolution in the last few years. Computer vision techniques use photographs from data set collection to rapidly build detailed 3D models. The simultaneous applications of different algorithms (MVS), the different techniques of image matching, feature extracting and mesh optimization are inside an active field of research in computer vision. The results are promising: the obtained models are beginning to challenge the precision of laser-based reconstructions. Among all the possibilities we can mainly distinguish desktop and web-based packages. Those last ones offer the opportunity to exploit the power of cloud computing in order to carry out a semi-automatic data processing, thus allowing the user to fulfill other tasks on its computer; whereas desktop systems employ too much processing time and hard heavy approaches. Computer vision researchers have explored many applications to verify the visual accuracy of 3D model but the approaches to verify metric accuracy are few and no one is on Autodesk 123D Catch applied on Architectural Heritage Documentation. Our approach to this challenging problem is to compare the 3Dmodels by Autodesk 123D Catch and 3D models by terrestrial LIDAR considering different object size, from the detail (capitals, moldings, bases) to large scale buildings for practitioner purpose

Reconstructing urban scene 3D using VisualSfM

New computer vision techniques use photo dataset to rapidly build detailed 3D models. Computer- vision researchers have explored many approaches to city-scale 3D reconstruc on. Among these systems stands out VisualSfM developed by the University of Washington & Google Inc. It is a open source GUI applica on of a Structure from Mo on (SfM) so! ware that uses a feature extractor called Si! GPU and the Mul core Bundle Adjustment. In addi on it embeds the CMVS/ PMVS2 able to reconstruct dense 3D point cloud. Our goal is to demonstrate the metric accuracy of VisualSfM+CMVS/PMVS2 and that to get run it, you can use an unstructured photo dataset but the result improves if you use a structured photo dataset. The approach has been tested on several large datasets with structured images

3D #DigitalInvasions: a crowdsourcing project for mobile user generated content

This paper introduces the #InvasioniDigitali project which is an online crowdsourcing initiative started in Italy in 2013 with the aim to promote the value of and engagement with local heritage. The paper focuses on two case studies of pilot ‘invasions’ using 3D data capture by students at museums and heritage sites in Sicily

Microscopic cluster model for the description of (18O,16O) two-neutron transfer reactions

Excitation energy spectra and absolute cross-section angular distributions were measured for the 13C(18O,16O)15C two-neutron transfer reaction at 84 MeV incident energy. Exact finite-range coupled reaction channel calculations are used to analyse the data considering both the direct two-neutron transfer and the two-step sequential mechanism. For the direct calculations, two approaches are discussed: The extreme cluster and the newly introduced microscopic cluster. The latter makes use of spectroscopic amplitudes in the centre-of-mass reference frame, derived from shell-model calculations. The results describe well the experimental cross sections

HBIM FOR THE SURVEYING, ANALYSIS AND RESTORATION OF THE SAINT JOHN THE THEOLOGIAN CATHEDRAL IN NICOSIA (CYPRUS)

Abstract. The present study illustrates the results of an interdisciplinary collaboration between the Mediterranean Laboratory of Survey and Diagnostics for Architecture (RDA) of the Department of Civil Engineering and Architecture (DICAR) of the University of Catania in Italy and the Andreas Pittas Laboratories for Art Characterisation (APAC) of the Science and Technology in Archaeology Research Center (STARC) of the Cyprus Institute in Cyprus. The research focused on the application of an H-BIM approach in the study of a Mediterranean iconic heritage asset, the St. John Cathedral of Nicosia, built in 1662 on the remains of a monastery from the 15th century. The adopted methodology has provided the framework for a dynamic investigation, constantly evolving along several dimensions: historical, geometric spatial, architectural-constructive identification and mapping of degrade, interpretation of degenerative causes and design proposals.</p