3D technologies for cultural heritages

Remotely Operated underwater Vehicles (ROVs) play an important role in a number of operations conducted in shallow and deep water (e.g.: exploration, survey, intervention, etc.), in several application fields like marine science, offshore construction, and underwater archeology. In this work we describe the preliminary steps in the development of the set-up of a special ROV addressed to perform the monitoring and the planned maintenance activities required to prevent the biological colonization in an underwater archeological site. In order to perform these operations, the ROV has been equipped with a custom arm and an opto-acoustic camera. To simultaneously satisfy position and force trajectory constraints, the vehicle-manipulator system is also controlled through a hybrid positionforce control scheme.

Keywords: opto-acoustic 3D camera , ROV control , sensorized arm

Blind people are typically excluded from equal access to the world's visual culture, thus being often unable to achieve concrete benefits of art education and enjoyment. This is particularly true when dealing with paintings due to their bi-dimensional nature impossible to be explored using the sense of touch. This may be partially overcome by translating paintings into tactile bas-reliefs. However, evidence from recent studies suggests that the mere tactile exploration is often not sufficient to fully understand and enjoy bas-reliefs. The integration of different sensorial stimuli proves to dramatically enrich the haptic exploration. Moreover, granting blind people the possibility of autonomously accessing and enjoying pictorial works of art, is undoubtedly a good strategy to enrich their exploration. Accordingly, the main aim of the present work is to assess the feasibility of a new system consisting of a physical bas-relief, a vision system tracking the blind user's hands during “exploration” and an audio system providing verbal descriptions. The study, supported by preliminary tests, demonstrates the effectiveness of such an approach capable to transform a frustrating, bewildering and negative experience (i.e. the mere tactile exploration) into one that is liberating, fulfilling, stimulating and fun.

Keywords: Blind people , Cultural heritage , Hand tracking , Human-computer interaction

Although 3D models are useful to preserve the information about historical artefacts, the potential of these digital contents are not fully accomplished until they are not used to interactively communicate their significance to non-specialists. Starting from this consideration, a new way to provide museum visitors with more information was investigated. The research is aimed at valorising and making more accessible the Egyptian funeral objects exhibited in the Sforza Castle in Milan. The results of the research will be used for the renewal of the current exhibition, at the Archaeological Museum in Milan, by making it more attractive. A 3D virtual interactive scenario regarding the "path of the dead", an important ritual in ancient Egypt, was realized to augment the experience and the comprehension of the public through interactivity. Four important artefacts were considered for this scope: Two ushabty, a wooden sarcophagus and a heart scarab. The scenario was realized by integrating low-cost Virtual Reality technologies, as the Oculus Rift DK2 and the Leap Motion controller, and implementing a specific software by using Unity. The 3D models were implemented by adding responsive points of interest in relation to important symbols or features of the artefact. This allows highlighting single parts of the artefact in order to better identify the hieroglyphs and provide their translation. The paper describes the process for optimizing the 3D models, the implementation of the interactive scenario and the results of some test that have been carried out in the lab.

Keywords: 3D modelling , Cultural Heritage , Leap Motion , Oculus Rift , Unity , Virtual Reality , Visualisation

In the last decades several computer-based procedures have been devised with the aim of speeding up the 3D reconstruction from a single image in the form of bas-relief. At the same time, the use of rapid prototyping (RP) technology considerably spread enabling quick manufacture of 3D products directly from 3D modelling systems. The present paper presents a few consideration about different possible strategies for bas-reliefs manufacturing by using the main RP techniques (stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM) and Polyjet/Multi-jet technology). A practical example is used for discussing pros and cons of the different alternatives. © (2014) Trans Tech Publications, Switzerland.

Keywords: Artistic surfaces , Bas-relief , Rapid prototyping techniques

Cultural heritage is often not accessible to visually impaired and blind people, hardly ever when dealing with two-dimensional artworks like, for instance, paintings. In fact, despite tactile reproductions of 3D works of art such as sculptures or architectural models are quite common, a real barrier between blind people and pictorial artworks still exists, obviously due to their intrinsic 2D format. The translation of paintings into bas-relieves is recognized to be one of the most effective ways for breaking down such a barrier, thus allowing a sensible improvement in blind people's accessibility to this kind of works of art. Moving from these considerations, in this work the authors want to provide a bird's eye view on a new methodology for the semi-automatic generation of tactile 3D models starting from paintings, in particular those characterized by single-point perspective. The proposed method relies on an interactive Computer-based modelling procedure, which is conceived to be simple and effective to use. The procedure, which has been implemented into a prototypal software package, has been effectively used to 'translate' a set of paintings from the Italian Renaissance.

Visually impaired and blind people are more excluded from equal access to the world's visual culture, thus being often unable to achieve concrete benefits of art education or to experience the life enhancing power of art. Despite the fact that all over the world several initiatives based on the interaction with sculptures and tactile three-dimensional reproductions or architectural aids on scale have been devised, a "sensory barrier" between blind people and pictorial artworks still exists, obviously due to their intrinsic 2D format. Translation of paintings into tactile models in the form of bas-reliefs is recognized to be one of the most effective ways for breaking down such a barrier, thus allowing a tangible improvement of the blind people's accessibility to artworks. In the recent years, computer aided technologies for automatic or semi-automatic translation of paintings into tactile models dramatically have been devised all over the world, thus improving blind people's accessibility to artworks. Inspired by some of these impressive works, this paper describes a user-driven methodology for the semi-automatic generation of tactile 3D models starting from paintings. Particularly devoted to the reconstruction of pictorial artworks characterized by single-point perspective, the proposed method relies on an interactive Computer-based modelling procedure. The method has been tested on two masterpieces of the Italian Renaissance period.

Keywords: 3d computer based modelling , Blind people , Haptic exploration , Single-point perspective , Tactile bas-relief

Over the last few years, technologies like 3D scanning and rapid prototyping provided an extraordinary boost in improving reproductions of 3D artworks, like sculptures and historical buildings, all over the world. Physical 3D reproduction of subjects represented in paintings, is recognised to be one of the best ways to allow visually impaired people to enjoy such kind of artworks. However, the use of advanced technologies with the aim of realising 3D models starting from paintings has not been satisfactorily investigated yet. Though a number of algorithms coming from computer vision science exist to cope with similar issues, the specific problem of producing a 3D representation which is targeted at blind people tactile exploration has been only marginally investigated. Starting from these considerations, this work presents 1) a quite extensive review of the criteria proposed in literature for producing tactile models suitable for blind people and 2) four alternative computer-based methods for semi-automatic generation of tactile 3D models starting from RGB digital images of paintings. The outcomes of this study contribute new information to the field of visually impaired user-oriented 3D reconstruction and clearly indicate the strategy to be adopted in order to produce a meaningful reproduction of a bi-dimensional piece of artwork. © 2014 Inderscience Enterprises Ltd.

Keywords: 3D computer-based modelling , Blind , Haptic exploration , Visually impaired

3D reconstructions of small objects are more and more frequently employed in several disciplines such as medicine, archaeology, restoration of cultural heritage, forensics, etc. The capability of performing accurate analyses directly on a three-dimensional surface allows for a significant improvement in the accuracy of the measurements, which are otherwise performed on 2D images acquired through a microscope. In this work we present a new methodology for the 3D reconstruction of small sized objects based on a multi-view passive stereo technique applied on a sequence of macro images. The resolving power of macro lenses makes them ideal for photogrammetric applications, but the very small depth of field is their biggest limit. Our approach solves this issue by using an image fusion algorithm to extend the depth of field of the images used in the photogrammetric process. The paper aims to overcome the problems related to the use of macro lenses in photogrammetry, showing how it is possible to retrieve the camera calibration parameters of the sharp images by using an open source Structure from Motion software. Our approach has been tested on two case studies, on objects with a bounding box diagonal ranging from 13.5. mm to 41. mm. The accuracy analysis, performed on certified gauge blocks, demonstrates that the experimental setup returns a 3D model with an accuracy that can reach the 0.05% of the bounding box diagonal. © 2013 Elsevier Masson SAS.

Keywords: 3D reconstruction , Cultural heritage , Digital documentation , Image fusion , Macro lens , Small objects

The contribution regards the surveying of two statues of famous contemporary sculptors that have been placed in the central zone of Cosenza, which has been transformed in an open air museum. To realize a 3-D representation of the museum, different methodologies have been used, based on classical surveying (total stations and GNSS), image data and range data. The increasing performances of the new models of Time Of Flight (T.O.F.) laser scanners allow to build accurate models also for medium-size objects; on the other hand, the recent techniques of 3D modeling enable the processing of large amount of data and the effective removal of noises. Thus, if an extreme accuracy is not required, one can think to use the T.O.F. laser scanner, also for the surveying of statues. For the acquisition of the surfaces of the statues, two different types of laser scanning have been used: the Leica Scan StationC10, based on Time Of Flight, and the Minolta VIVID 300 triangulation scanner. In the paper, the comparison between the results obtained by using the different techniques is described.

Keywords: 3D modelling , Augmented reality , City model , Cultural heritage , Laser scanning , Multiresolution , Representation

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. © 2013 IEEE.

Keywords: Cultural Heritage , Multi-view stereo , texture mapping

The creation of three-dimensional virtual models by optical technologies typically involve uncontrolled metric errors, in particular, when small high-resolution 3-D imaging systems are used to reconstruct a large object. Within Cultural Heritage, the problem of metric accuracy is a major issue and no methods are currently available for controlling and enhancing it. This paper presents a methodology based on the integration of a 3D range camera system with an optical tracking technique. The basic idea is the generation of a global coordinate system determined by the optical tracker, which controls the rigid motions of the 3D range camera system during multi-scan processes. The tracking process is based on measuring the spatial coordinates of reference markers located onto the range camera. The metric reliability of the 3D model reconstruction is guaranteed to a known acceptable level. Experimental results on a Statue of Hope located at the English Cemetery in Florence, are also reported. © 2012 IEEE.

Keywords: 3D reconstruction , Cultural Heritage , optical tecquiques

Nowadays, optical sensors are used to digitize sculptural artworks by exploiting various contactless technologies. Cultural Heritage applications may concern 3D reconstructions of sculptural shapes distinguished by small details distributed over large surfaces. These applications require robust multi-view procedures based on aligning several high resolution 3D measurements. In this paper, the integration of a 3D structured light scanner and a stereo photogrammetric sensor is proposed with the aim of reliably reconstructing large free form artworks. The structured light scanner provides high resolution range maps captured from different views. The stereo photogrammetric sensor measures the spatial location of each view by tracking a marker frame integral to the optical scanner. This procedure allows the computation of the rotation-translation matrix to transpose the range maps from local view coordinate systems to a unique global reference system defined by the stereo photogrammetric sensor. The artwork reconstructions can be further augmented by referring metadata related to restoration processes. In this paper, a methodology has been developed to map metadata to 3D models by capturing spatial references using a passive stereo-photogrammetric sensor. The multi-sensor framework has been experienced through the 3D reconstruction of a Statue of Hope located at the English Cemetery in Florence. This sculptural artwork has been a severe test due to the non-cooperative environment and the complex shape features distributed over a large surface. © 2012 by the authors; licensee MDPI, Basel, Switzerland.

Keywords: 3D imaging sensors , 3D reference information system , Cultural heritage , Stereo-photogrammetry , Structured light scanning

In recent years, a number of works meant to define the criteria for translating two-dimensional art into tactile representation, to be benefit of blind and visually impaired people. Due to technology-related limitations, however, these studies mainly investigated only some kinds of possible representations (e.g. tactile diagrams). This work deals with the analysis of 4 alternative translation strategies, implemented using computer-based tools, to determine the most effective one in delivering blind people a correct perception of pictorial artworks. The outcomes of the study contribute new information to the field of tactile paintings for blind and visually impaired individuals by testing the response of a panel of potential users. © 2012 Springer-Verlag Berlin Heidelberg.

Keywords: blind , Computer-based 3D modeling , haptic exploration , tactile artwork , visually impaired

The diagnostic analysis of decay processes on small specimens is gaining importance in the restoration and maintenance of archeological finds. In this context, the 3D reconstruction is very useful for the study and identification of the different types of decay. In this paper we present the analysis conducted on two small specimens taken from an ancient underwater pavement, using a new technique for the 3D reconstruction of small sized objects based on a multi-view passive stereo technique applied on a sequence of macro images. In order to overcome the problems related to the use of macro lenses, such as the very small depth of field and the loss of sharpness due to diffraction, each image of the sequence is obtained by merging a stack of images acquired at different focus planes by the means of an image fusion algorithm. The experimentation involves a series of preliminary laboratory tests in which we validate the system accuracy and the 3D reconstruction of specimens taken from a marble pavement located in the underwater archeological site park of Baiae (Naples, Italy). The results show that with our approach it is possible to obtain high quality textured 3D models of objects with dimensions ranging from few millimeters to few centimeters, which can be usable both for interactive measurements and virtual presentations. © 2012 IEEE.

Keywords: 3D reconstruction , Cultural Heritage , Image Fusion , Macro Lens , Small Objects

Accurately measuring an artefact of historical significance generally results in being able to extract information which is useful for evaluating what remains of the materials from a distant time. This allows scholars arrive at an exhaustive historical reading of the same artefact. Compared to the traditional measuring techniques, which can often be imprecise and complicated, 3D laser scanners measure the morphological characteristics of an artefact with extreme accuracy. Despite this, it is not always possible to choose the most appropriate sensors due to the geometric peculiarities, or indeed, the size of the object. The present work deals with two non-destructive analyses of an ancient stone sculpture, which for its morphology and size was scarcely compatible with the technical characteristics of either of the scanners used. Both scanners operate on the same technical principal, but are quite different from each other in terms of scale and precision. For these reasons, a complex 3D model (extremely appropriate given the original artefact) was draw out through a synergy of the two techniques. The virtual particularities of the model allowed it to be manipulated with the appropriate software. In fact, on the basis of qualitative parameters devised by researchers, it proved possible to reproduce the artefact's geometric form, both virtually and in the form of physical models, obtained through non-conventional restoration methods (R.P. techniques).It has also been possible to verify the state of degradation of the surface of the stone caused by the traditional methods of applying cataloguing or storage information to it.Finally, the results achieved provide opportunities for further research on certain geometrical characteristics of the stone which, as highlighted by the elaboration on the virtual model, seem to be traceable to non-manual, perhaps mechanical, processes. Therefore, the historical considerations which derive from this fact call certain scholars into play. © 2011 Elsevier Ltd.

Keywords: Arteafct , Rapid prototyping , Reconstructing , Scanner , Sculpture

Historical documents often undergo various changes over time, that alter their original state and reduce their legibility. Digital techniques are widely applied for document preservation, archiving, analysis and dissemination over the Internet. The goal of restoration is to improve the document legibility for both human and automatic operators, to extract patterns and enhance colour reproduction. Our paper presents a framework for virtual restoration of ancient documents based on a combination of multispectral acquisition, 3D imaging and digital image analysis. The proposed framework consists of several steps. First, digital representations of the documents are acquired as multispectral images and 3D surface maps, the latter reconstructed by a structured light technique. A mul-tispectral camera and a digital projector are used in triangular configuration for 2D and 3D data acquisition. Then the multispectral images are registered against possible misalignments, and the 3D surface representation is used to correct geometrical distortions. Document flattening is then performed by 3D surface parameterization and texture mapping. Statistical techniques of decorrelation are applied to extract individual context parts of the document patterns (stamp, text, etc.) and to attenuate interferences. The processed data are then binarized by the proper segmentation technique. The entire digital object history - all the acquisition and processing steps, with the corresponding parameters - is stored in metadata files. These data can be exploited in a future evaluation of the restoration process and can be used for either the creation of an expert knowledge database or the extraction of cross-document observations and conclusions. © The Eurographics Association 2010.

Abstract: This paper presents some experiments on different image processing techniques combined and adapted to define a procedure aimed at improving the readability of ancient degraded documents. The focus is on documents affected by the bleed-through effect, which significantly reduces readability. The availability of the recto and verso scans of any single page is assumed. The proposed procedure is composed of three steps: recto-verso registration, image enhancement through statistical decorrelation and, finally, image segmentation. As the registration step can strongly influence the results obtained during the subsequent phases, we carried out a comparison of different registration algorithms, in order to evaluate their overall effectiveness on recto-verso processing. © 2009 IEEE.

Keywords: Ancient documents. , Binarization , Image enhancement , Registration

In this contribution we describe the modern 2D and 3D technologies for the documentation, analysis and restoration of paintings. RGB color imaging, IR and UV fluorescence sensors, together with highly precise active sensors are among the most widely technologies in this field. The devices provide information on the painting's materials, on the employed technique and on the conservation's state of the art work. However, all information must be correctly registered to be able to draw safe conclusions and perform the most adequate conservation interventions. We also present a complete example where multispectral visible images, IR refiectography, UV fluorescence and 3D data are acquired and then combined, showing how the integration gives a new and significant improvement in the analysis of painting. © 2007 SPIE-IS&T.

Keywords: 3D sensing , Cultural heritage , Image registration , Multispectral imaging , Reflectography

Italy has plenty of cultural heritages. The masterpieces are often placed in locations which are difficult to reach, moreover many artifacts, coming from man's creativity, have very complex functioning. The authors of this paper describe their experience in using the computer graphics capabilities in order to reproduce four ancient clocks functioning coming from different Italian regions. The study is based not only on the 3D-shapes reconstruction but also on the simulation of their complex mechanisms in order to mimic their functioning. The realism of the reconstruction allows to use the graphical products in exhibits, museums and also for maintenance programs. The rendering techniques together with an accurate camera path, allow to get into the clock mechanisms and to appreciate all the features (and even secrets) that a simple glance cannot reveal. Copyright © 2006 John Wiley & Sons, Ltd.

Keywords: Ancient clock , Computer-aided simulation , Cultural heritage , Virtual museum

In this paper, the activity aimed at the contact less acquisition, the generation of polygonal descriptive models, the generation of NURBS-based models and the reproduction by means of rapid prototyping tools of pieces of interest in both the heritage and the automotive domains are presented. The work gives an insight of how three-dimensional range cameras and suitable data modeling can be helpful in the reverse engineering and in the virtual representation of complex shapes. In addition, the research represents a valuable example of Computer Support Collaboration Work (CSCW) for the restoration and the rapid prototyping of the objects. © 2005 Taylor & Francis Group.