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Historic floors which consist of mosaic or decorative tiles are often of high cultural or academic value, but by their very nature are vulnerable to decay and damage. On the other hand floors and footings are often the only surviving parts of a ruined building, especially in an archaeological context. They present particular conservation challenges...
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... Unmanned aerial photogrammetric survey is a technique widely used in the study and documentation of Roman mosaics [12][13][14], but to date, there are few bibliographic examples that employ geophysical methods to inspect Roman mosaics. Most of these works use the ground penetrating radar method (GPR) as the better technique to obtain detailed information on these structures. ...
Over the past decade, high-resolution noninvasive sensors have been widely used in explorations of the first few meters underground at archaeological sites. However, remote sensing actions aimed at the study of structural elements that require a very high resolution are rare. In this study, layer characterization of the floor mosaic substrate of the Pisões Roman archaeological site was carried out. This work was performed with two noninvasive techniques: 3D ground penetrating radar (3D GPR) operating with a 1.6 GHz central frequency antenna, which is a very high-resolution geophysical method, and photogrammetry with imagery obtained by an unmanned aerial vehicle (UAV), which is a very high-resolution optical method. The first method allows penetration up to 30–40 cm depth and 3D models can be obtained, and with the second method, very high detail surface images and digital surface models can be obtained. In this study, we analyze a combination of data from both sensors to study a portion of the floor mosaic of the Pisões Roman Villa (Beja, Portugal) to obtain evidence of the inner structure. In this context, we have detected the main structural levels of the Roman mosaic and some internal characteristics, such as etched guides, internal cracking, and detection of higher humidity areas. The methodology that we introduce in this work can be referenced for the documentation of ancient pavements and may be used prior to carrying out preservation activities. Additionally, we intend to show that a Roman mosaic, understood as an archaeological structure, does not consist of only beautiful superficial drawings defined by the tesserae, but these mosaics are much more complex elements that must be considered in their entirety for preservation.
... Photogrammetric drawing presents a flexible and accessible survey tool. In particular, rectified photography, which is the most attractive photogrammetric product, is providing both geometric and surface texture for objects to be depicted [14]. The geometry is created by identifying sets of common points from two or more source photos also called stereoscopic or 3D imaging, and since standard digital cameras can be employed, the required images can be captured at low cost and relatively quickly [9]. ...
... 1). Se trataba de un sistema de circulación en correspondencia simétrica con la llamada Torre de la Antigua Audiencia, cuya organización interior difiere ligeramente respecto la del Pretorio debido a las condiciones orográficas y la distancia con la muralla tardorepublicana (Dupré, Carreté, 1993). Internamente, ambas torres disponían de diversas escaleras que permitían superar los desniveles existentes, permitiendo el acceso a los diversos ámbitos internos del porticado que rodeaba la plaza, así como a un podio sobreelevado de 14 m de anchura que permitía una correcta visualización de las ceremonias provinciales 1 . ...
This article details the use of photographic rectification as support for the documentation of the southern
facade of the Torre del Pretori (Praetorium Tower) in Tarragona. This Tower was one of the towers that
connected different parts of the Provincial Forum. The use of photographic rectification helped us to make a
direct analysis into two concepts: the construction processes and the architecture of the building. The
documentation permitted various analyses: the characterisation of the building modules, identification of the
tools used to work the building materials, etc.
... However, the analogue format has no in-built coordinates, can be time-consuming to work fi gure 1 Traditional method of hand measurement using two tapes, at the archaeological site of Vergina, Greece (1990). with, and produces data with some issues of accuracy (especially when images are enlarged (Agosto et al., 2005b;Andrews et al., 2005;Lerma et al., 2008). ...
... Analysing different documentation products, and considering the documented object, the Orthophoto 2 program is suffi cient to support a 2D drawing; a 2D representation can be obtained through the creation of an orthophoto, which is a useful and easy way of elaborating metrical data for untrained users (Bornaz and Dequal, 2004;Andrews et al., 2005;Haddad, 2007). Using Orthophoto it is possible to measure 2D elements, obtain 2D vector elements, and carry out various analyses (Agosto et al., 2005a), whilst also allowing for easier communication between the specialist and non-specialist users, compared to other survey products. ...
... Digital rectifi cation is the obvious progression from traditional rectifi ed photography and it is becoming increasingly accessible. Whilst requiring more photography, and a greater investment in hardware and software, digital orthophotography does offer several advantages (Andrews et al., 2005). Rapid advances being made in delivering 3D interactivity over the internet using Virtual Reality Modelling Language (VRML) will also make fast interaction with virtual historic monuments more feasible. ...
Digital technology has changed our approaches to cultural heritage documentation radically and promises to continue to bring rapid changes. Photographic and non-photographic (graphic) documentation tools are merging in one process, in which digital photographic technology is the main base. Due to digital technology, there is an increasing gap between specialist technicians and non-technical users involved in heritage documentation. 3D approaches are still not popular among users in cultural heritage. However, in order to build a bridge between the specialist and non-technical users, a dialogue between them needs to be developed, not only to discuss issues of data precision and 3D accuracy, but also visualization production systems, which can now easily be achieved by modern digital photographic technology. This paper presents a comparative evaluation and synthesis of cultural heritage documentation methods and survey techniques currently available, focusing on the needs and requirements of non-technical users of heritage documentation. It attempts to clarify some new aspects in cultural heritage documentation and to assess the impact of current technology. The paper undertakes a comparative evaluation of the potential application of digital methods in documentation — and examines issues such as quality, accuracy, time, costs and specific skills required — from pre-electronic techniques (hand measurement) to 3D laser scanning, which today represents the most advanced technology available for measuring and documenting objects, structures and landscapes.
... Actually, the type of the material hit by the pulse determines the intensity of the returning signal. These sometimes produce a degradation of the quality of the range data and it may even happen that no signal at all will return [2, 6, 7]. For example, red bricks were found to respond poorly to some scanners while the mortar provided a good response. ...
Several attempts and case studies had been conducted to document the cultural heritage using the 3D Laser scanner in the last few years. Now, it is possible to furnish a virtual model of an object from the pointcloud and to complete the direct measurements, just like if the user were physically present on the site. While the main users of this method are technical people (not archaeologist), the results of these studies could not be easily understood and clearly appreciated from a majority of the people involved in the process of documentation for the archaeological sites and monuments. By reviewing the latest articles and case studies of 3D laser scanner in heritage documentation, we can establish now, some general rules and recommendations, mainly for the non technical users involved in the process of this new documentation method and according to their actual needs. This paper attempts to present and evaluate the recently 3D laser scanner achievements and results in heritage documentation to create a dialogue between the specialized technician and non technician users, in order to decrease the gap and to build a bridge between them, taking into consideration the following factors: 1-Kind and type of the structure.2-Material and texture.3-Scale of the structure 4-Acquisition time in the field and the number of the required scan positions. 5-Data post processing time in the lab. 6-Accuracy and precision. 7-Benefit ratio and cost.
... Orthophoto generation methodologies mainly depend on the generation of accurate digital surface models (DSM) of the studied object. 19,20,21 The DSMs produced by image-based techniques or a CAD model have a low spatial resolution and cannot represent most cultural objects in detail. 22 The dense DSM generated by a laser scanner device is the optimal solution for a correct and complete 3D description of the shape of a complex object that could be used for a high-resolution true orthophoto of an irregular and complicated surface. ...
Traditional techniques for recording and modelling historical buildings using surveying instruments and CAD are tedious and time-consuming procedures, which do not provide detailed descriptions of complex façades. Recent developments in photogrammetry and laser-scanning techniques present non-contact, flexible and accessible surveying tools for 2D–3D recording. This paper discusses the potential for combining photogrammetry, laser scanning and computer vision for the documen-tation of heritage sites. By these means the efficiency of data collection can be optimized, and accurate true orthophotos of the studied structure can be generated using precise 3D surface representations derived from laser scanning and overlapping digital images. The final product allows the creation of detailed and complete façade plans, which are both graphically superior and accurate. The paper includes a study of the approach applied to historic buildings in Gharissa, one of the best preserved heritage villages in Jordan.
... favorable. [AND05]. L'ortho-image est également avide de points d'appuis : il faut, en théorie au moins trois points par portion plane, ce qui représente une quantité importante de points à mesurer 33 . ...
The external survey of an architectural work is a way to create a representation of the building in its conservation condition. Two techniques of remote acquisition differ by their effectiveness and the quality of the produced data: photogrammetry and laser scanning. These two techniques depend on optical principles: what cannot be seen cannot be measured. The combination of these techniques can improve the data quality, but unmeasured zones always remain, therefore cannot be represented. In order to solve this problem, we put forward the hypothesis that using architectural knowledge may allow to rebuild these zones during the modeling process. This study suggests a modeling process based on the combination of these two techniques and on the integration of the available architectural knowledge, from paper documentation or from the built works construction rules. An architectural work being complex and the data numerous, a division of the modeling process in several distinct stages appears necessary. We suggest dividing modeling process according to different figuration of level of details frequently used to represent architecture, and define a process using information in a progressive way. Thus our approach consists in integrating dimensional data into architectural documentation, in order to develop a modeling process providing a model as complete as possible.
... L'intégration numérique de la rectification d'image permet de prendre en compte les déformations de la chambre de prise de vue. plans constituant la partie visible de l'objet, et ce dans une orientation la plus favorable. [AND05]. L'ortho-image est également avide de points d'appuis : il faut, en théorie au moins trois points par portion plane, ce qui représente une quantité importante de points à mesurer 33 . ...
Le relevé extérieur d'ouvrage architectural est le moyen de créer une représentation du bâtiment dans son état de conservation. Deux techniques d'acquisition à distance se distinguent par leur efficacité et la qualité des données produites : la photogrammétrie et le balayage optique. Ces deux techniques sont soumises aux règles de l'optique et ne permettent pas de mesurer les parties invisibles de l'objet. La combinaison des techniques peut améliorer la qualité des données, mais il subsiste toujours des zones non mesurées et de ce fait non représentables. Pour palier ce problème, nous émettons l'hypothèse que l'usage de connaissances architecturales peut permettre de recomposer les parties manquantes lors de la modélisation. Cette thèse propose un processus basé sur la combinaison de ces deux techniques et sur l'intégration des connaissances architecturales accessibles depuis la documentation écrite ou encore par les règles de construction des édifices. La complexité d'un ouvrage architectural et la multitude des données imposent une division de la modélisation en plusieurs étapes identifiables. Nous proposons de découper le processus de modélisation selon le mode de figuration des niveaux de détail utilisé pour la représentation de l'architecture. Les niveaux différents de détail permettent d'obtenir des étapes de modélisation clairement indentifiables, mais aussi un processus progressif où les informations peuvent être utilisées au fur et à mesure. Notre approche intègre ainsi les données dimensionnelles à la documentation architecturale, pour permettre la mise en place d'un processus de modélisation afin d'obtenir un modèle le plus complet possible
This article details the use of photographic rectification as support for the graphic documentation of historical and archaeological heritage and specifically the southern facade of the Torre del Pretori (Praetorium Tower) in Tarragona. The Praetorium Tower is part of a larger monumental complex and one of the towers that connected different
parts of the Tarraco Provincial Forum, the politic-administrative centre of the ancient capital of Hispania Citerioris. It is therefore a valuable example of the evolution of Roman urban architecture. The aim of this project is to provide accurate graphic documentation of the structure to facilitate the restoration and conservation of the tower, as well as to provide a more profound architectural and archaeological understanding of the Roman forum. The use of photographic rectification enabled us to overcome the spatial and time difficulties involved in collecting data caused by the size and location of the building. Specific software made it easier to obtain accurate two-dimensional images. For this reason, in our case, photographic rectification helped us to make a direct analysis of the monument and facilitated interpretation of the architectural stratigraphy. We currently separate the line of research into two concepts: the construction processes and the architecture of the building. The documentation collected permitted various analyses: the characterisation of the building modules, identification of the tools used to work the building materials, etc. In conclusion, the use of orthoimages is a powerful tool that permits the systematic study of a Roman building that has evolved over the centuries and is now in a modern urban context.
