Nowadays digital replicas of artefacts belonging to the Cultural Heritage (CH) are one of the most promising innovations for museums exhibitions, since they foster new forms of interaction with ...collections, at different scales. However, practical digitization is still a complex task dedicated to specialized operators. Due to these premises, this paper introduces a novel approach to support non-experts working in museums with robust, easy-to-use workflows based on low-cost widespread devices, aimed at the study, classification, preservation, communication and restoration of CH artefacts. The proposed methodology introduces an automated combination of acquisition, based on mobile equipment and visualization, based on Real-Time Rendering. After the description of devices used along the workflow, the paper focuses on image pre-processing and geometry processing techniques adopted to generate accurate 3D models from photographs. Assessment criteria for the developed process evaluation are illustrated. Tests of the methodology on some effective museum case studies are presented and discussed.
Ensuring color fidelity in image-based 3D modeling of heritage scenarios is nowadays still an open research matter. Image colors are important during the data processing as they affect algorithm ...outcomes, therefore their correct treatment, reduction and enhancement is fundamental. In this contribution, we present an automated solution developed to improve the radiometric quality of an image datasets and the performances of two main steps of the photogrammetric pipeline (camera orientation and dense image matching). The suggested solution aims to achieve a robust automatic color balance and exposure equalization, stability of the RGB-to-gray image conversion and faithful color appearance of a digitized artifact. The innovative aspects of the article are: complete automation, better color target detection, a MATLAB implementation of the ACR scripts created by Fraser and the use of a specific weighted polynomial regression. A series of tests are presented to demonstrate the efficiency of the developed methodology and to evaluate color accuracy ('color characterization').
This open access book is a handbook for students, experts and interested parties who want to learn more about digital 3D reconstruction of historical architecture. The book provides answers to the ...core questions of the subject: What is a digital 3D model or a digital 3D reconstruction? How are they created and what are they used for? Practical instructions, condensed knowledge, explanations of technical terms and references to example projects, literature and further references provide information of varying density and thus enable an individual introduction to the subject. The book combines extensive knowledge on the topic of "digital 3D reconstruction of historical architecture" and provides practical instructions for independent implementation. Up to now, there has been no cross-disciplinary vocabulary for technical terms in this field, so this publication makes a start. The book is aimed at students, experts in the field and the interested public and offers various possibilities for the different target groups to delve deeply into the subject. The book was created within the research network "Digital 3D Reconstruction as Tools for Research in Architectural History," which was funded by the German Research Foundation (DFG) from 2018 to 2023. The authors combined their expertise in the fields of art and architectural history, architecture, university teaching and media informatics.
En el ámbito museístico es frecuente encontrarse con limitaciones logísticas que dificultan la documentación de las obras de arte. El patrimonio pictórico presenta además otras criticidades debidas a ...la imposibilidad de modificar la iluminación: basada en criterios de conservación y comunicación, haciendo resaltar las características materiales, cromáticas y de ejecución. Esto conduce a situaciones inadecuadas para el levantamientos por imágenes fotográficas, ya complicadas en sí por las complejas propiedades ópticas de los materiales. La técnica que aquí se presenta fue desarrollada para la documentación de la Anunciación (1430-32) de Fra Giovanni Angelico (Museo de la Basílica S. Maria delle Grazie, San Giovanni Valdarno, Arezzo) y permite eliminar y atenuar fenómenos indeseables debidos a las condiciones específicas del contexto museístico. Se mostrará una estrategia capaz de eliminar las sombras nitidas, así como los fenómenos de claroscuro, de las texturas asociadas al modelo digital de la pintura y su marco, garantizando su fidelidad visual.
For the hypothetical reconstruction of architectural heritage, there are still no scientific standards of reference concerning their sharing and documentation. Recent international initiatives ...established the basis to address this problem; however, still, much work needs to be done in order to systematise good practices for the process of reconstruction and its dissemination. This contribution aims to take a step forward in the analysis and visualisation of uncertainty. Some authors have suggested various approaches to visualise uncertainty for single buildings; however, case studies at the urban scale are rarely investigated. This research proposes an improved source-based multi-feature approach aimed at analysing and visualising (through false-colour shading) the uncertainty of hypothetical 3D digital models of urban areas. The assessment of uncertainty is also quantified qualitatively by using newly defined formulas which calculate the average uncertainty weighted on the volume of the 3D model. This methodology aims to improve the objectiveness, unambiguity, transparency, reusability, and readability of hypothetical reconstructive 3D models, and its use is exemplified in the case study of the hypothetical reconstruction of Piazza delle Erbe in Verona, a project presented in the form of a docufilm at EXPO 2015 in Milan.
This contribution to the literature presents an in-depth analysis of the scene drawn by Leonardo da Vinci in the preparatory drawing, Adoration of the Magi, dated 1481, that is now housed at the ...Département des Arts Graphiques du Musée du Louvre in Paris, France. This analysis focuses on the architectural elements and highlights how the drawing discloses three distinct vanishing points/centers of vision: one for the classical architecture to the left of the scene, one for the Nativity hut, and one for the structure with stairs. If we consider the structures as belonging to the same 2D projected space, at least two must be depicted out of square; conversely, if we consider them as straight, standard structures, they cannot belong to the same 2D projected space. Given this assumption, we propose, on the one hand, some variations of the scene where the structures are straightened and projected according to only one of the viewpoints at a time; on the other hand, a set of variants of the scene are presented, considering the out-of-square structures. The scenes are generated by applying inverse perspective projections. These results prompt a discussion on possible reasons why Leonardo made these conscious or unconscious “formal errors”.
Among many other themes, Leonardo da Vinci’s Manuscript B contains several drawings of centrally planned churches, some of which are represented using a plan view paired with a bird’s-eye view. The ...use of a bird’s-eye instead of an elevation represents an innovative depiction technique, which allows combining the immediacy of the perspective view with the measurability of the façades, and therefore to describe the three-dimensionality of the buildings. To understand the reasons behind the use of this original technique, the edifices’ shape and classify them, we decided to use 3D digital reconstruction techniques, for their ability to avoid misunderstandings in the reconstruction process and in the results. This article describes the method to create the digital models of sixteen churches. A Visual Programming Language (VPL) script was used as the 3D base for modelling the churches achieved from a classification code expressing the aggregative rules of the churches. Then, the geometric process for the construction of the plan and its relationship with the elevation measures were studied for each church. Finally, this information was used for the completion of the 3D models, distinguishing more output variants each time there was an inconsistency between plan and perspective view, a variability of one architectural element or an uncertainty.
El documento describe una metodología que cubre los procedimientos de levantamiento y las aplicaciones informáticas con el objetivo de convertir herramientas generalistas (teléfonos inteligentes) en ...dispositivos de adquisición rigurosa de BIC almacenados en los museos. Dos problemas diferentes se enfrentan: a) como las caracteristicas de dichos objetos a escala micro/meso afectan su documentación; b) desarrollo de una solución multipropósito para una adquisición de bajo costo y fácil de usar para digitalizar y visualizar artefactos BIC. Se presenta un procedimiento basado en un kit de adquisición digital destinado a lograr modelos y texturas confiables, así como representaciones de color precisas. Se han seleccionado varios objetos para probar la coherencia y flexibilidad de los métodos y técnicas propuestos, y los resultados se comparan con los de las técnicas de adquisición estándar.
Colours play a crucial role in the field of architectural heritage. Colour analysis and colour rendition are involved in several critical facets of heritage preservation, conservation and ...restoration. These aspects are related to accurate documentation and an accurate representation of heritage artefacts and architectural works. The aim of this paper is to describe critical issues and open problems of the processes involved in this field. Documentation is performed in multiple ways, acquiring heterogeneous data ranging from archival images, photographs, drawings using various consumer or professional instruments (eg, digital cameras and spectrophotometers). The reliability of colour acquisition might be influenced by instrumental reasons (the technology used to acquire colour information), by environmental changes (architectural heritage surveys are often performed outdoors), by morphology (complex architectural objects are characterised by concavities and convexities which complicate the reflection evaluation), or by materials (showing different reflection, porosity and transparency indexes). Identification of materials, such as colorants, pigments and dyes, is also a vital process in the heritage field. Colour information could be used as an approach to the identification of materials, but these methods are still under development, and many issues need to be solved to achieve reliable results. Visualisation techniques of a heritage artefact also present the problem of the correctness of the colour representation. Several problems need to be faced in this context: the reliability of the acquisition, colour management of the rendering software, model complexity, and fragmentation of the devices upon which the model is visualised.
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