Papers by Isabel P H D Martínez-Espejo Zaragoza
L'obiettivo della tesi è l'analisi delle nuove tecnologie per il rilievo architettonico integrato... more L'obiettivo della tesi è l'analisi delle nuove tecnologie per il rilievo architettonico integrato, che si svilupperà mediante lo studio di vantaggi e dei limiti di ognuna di queste nei diversi ambiti di impiego, dando una visione globale e cercando di unificare terminologia e metodologia nel campo dell'architettura e dell'ingegneria. In particolare, fra le nuove tecnologie sono state analizzate il laser a scansione, sia a tempo di volo che a triangolazione, la modellazione 3D da immagini, la fotogrammetria da drone e la loro integrazione con le tecniche classiche di rilievo.
In the last decades, the field of Geomatics applied to architectural and cultural heritage has be... more In the last decades, the field of Geomatics applied to architectural and cultural heritage has benefited from some major advances. Upon their introduction, laser scanners have revolutionized the surveying world, gradually establishing as a basic tool, at first for terrestrial and later for airborne surveys. At about the same time, photogrammetry also experienced its own evolution, culminating with Structure from Motion (SfM) and MVS (Multi-View Stereo) algorithms. These algorithms generate dense 3D colour point clouds that however may not always be considered reliable. In fact, matching algorithms can be very sensitive to data collection, lighting and texture, and accuracy control is difficult. The high automation levels attainable also require caution because, while allowing for quicker modelling, control and perception of the steps to follow become looser. In terrestrial surveys, accessibility can still present challenging issues, where both Terrestrial Laser Scanning (TLS) and te...
The recent technological advancements in the field of digital photogrammetry together with the im... more The recent technological advancements in the field of digital photogrammetry together with the improvement of computational methods for image analysis have been show to aid laser technologies in architectural measurements, yielding high-resolution surveys of unprecedented resolution. In theory (and in many real applications) an integrated survey coming from both laser scanning and photogrammetry is able to meet all the requirements to perform a correct architectural survey, both in terms of the centimeter resolution and for fine aesthetic representations. The presented study deals a survey of the attic and the top surface of the domes of the left and right naves of the San Francesco Basilica in Ferrara (Italy), in which not all the ideal conditions required for a good quality integrated survey are present. Different practical problems may pose due to a recent earthquake (2012). The present job will be focused on survey planning and performing, in such emergency condition, on the used techniques and the final products. The results of such survey will be used for a future restoration of the Basilica.
Current methodologies used in architectural surveys allow to obtain 3-D models featuring high pre... more Current methodologies used in architectural surveys allow to obtain 3-D models featuring high precision for geometry and shape and good quality for chromatic data. Several researches are available in bibliography, showing how easily high-precision models, with high-quality photorealistic textures, can be obtained by using and combining laser scanning and terrestrial photogrammetry. Anyway, there are some contexts in which achieving good quality surveys with these techniques is logistically complex, such in the case of areas with difficult or no access (roofing, high façades, etc.). In many of these cases, a solution can be found in an innovative survey methodology, which is becoming more and more popular: Unmanned Airborne Vehicle (UAV)- based photogrammetry, with processing of data via Structure from Motion (SfM) procedures. The present paper describes a study of the integration of different survey methodologies (laser scanning, ground- and UAV-based photogrammetry, total station) in order to obtain a full featured 3-D model, whose accuracy has been checked.
ISPRS International Journal of Geo-Information, 2018
This paper presents an original methodology for planar development of a frescoed dome with an ova... more This paper presents an original methodology for planar development of a frescoed dome with an oval plan. Input data include a rigorous geometric survey, performed with a laser scanner, and a photogrammetry campaign, which associates a high-quality photographic texture to the 3D model. Therefore, the main topics include the development of geometry and, contextually, of the associated textures. In order to overcome the inability to directly develop the surface, an orthographic azimuthal projection is used. Starting from a prerequisite study of building methodology, the dome is divided into sectors and bands, each linked with the maximum acceptable deformations and the actual geometric discontinuities detectable by the analysis of Gaussian curvature. Upon definition of the development model, a custom automation script has been devised for geometry projection. This effectively generates a (u,v) map, associated to the model, which is used for model texturing and provides the planar devel...
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2018
Management of disaster scenarios requires applying emergency procedures ensuring maximum safety a... more Management of disaster scenarios requires applying emergency procedures ensuring maximum safety and protection for field operators. Actual conditions of disaster sites are labelled as "Triple-D: Dull, Dusty, Dangerous" areas. It is well known that in this kind of areas and situations remote surveying systems are at their very best effective, and among these UAVs currently are an effective and performing field tool. Indoor spaces are a particularly complex scenario for this kind of surveys. In this case, technological advances currently offer micro-UAV systems, featuring 360° protective cages, which are able to collect video streams while flying in very tight spaces. Such cases require manual control of the vehicle, with the operator piloting the aircraft without prior knowledge of the status quo of the survey object and therefore without prior planning of flight paths. A possible benefit in terms of knowledge of the survey object could lay in the creation of a 3D model based on images extracted by video streams; to date, widely tested methods and techniques are available for processing UAV-borne video streams to obtain such models. Anyway, the protective cage and the need to use, in these operating conditions, wide-angle lenses presents some issues linked to ever-changing image framing, due to the presence of the cage wires on the field of view. The present work focused on this issue. Using this type of UAVs, video streams have been collected in different environments, both indoors and outdoors, testing several procedures for photogrammetric processing in order to assess the ability to create 3D models. These have been tested for reliability based on data collection conditions, also assessing the level of automation and speed attainable in post-processing. The present paper describes the different tests carried out and the related results.
Applied Geomatics, 2018
Over the last years, the area of conservation and enhancement of cultural heritage has benefited ... more Over the last years, the area of conservation and enhancement of cultural heritage has benefited from new surveying methodologies. In particular, laser scanners and the latest evolutions in digital photogrammetry and processing software based on structure from motion and multi-view stereo algorithms allowed to achieve 3D models of the status quo whose features include precision suitable for restoration scales and high-quality textures. Besides methodological and technical issues, another key requirement for any intervention on this kind of buildings is their full, in-depth knowledge, which includes building design, modifications’ timeline, current conditions, present-day and historical causes of degradation etc. In this view, surveys are a valuable asset for the investigation of historical sources. The present work investigates historical photographic sources, focusing on the possibility of orientation by means of photogrammetry techniques, which provides an additional texture layer as a support tool for historical analysis. The paper displays a case study featuring the availability of a reference survey, which allows validation of the results, and two other cases highlighting the importance of this kind of documents to restoring teams.
Geomatics, Natural Hazards and Risk, 2017
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2016
Sometimes it is difficult to represent “on paper" the existing reality of architectonic elem... more Sometimes it is difficult to represent “on paper" the existing reality of architectonic elements, depending on the complexity of his geometry, but not only in cases with complex geometries: non-relief surfaces, can need a “special planar format” for its graphical representation. <br><br> Nowadays, there are a lot of methods to obtain tridimensional recovery of our Cultural Heritage with different ranges of the relationship accuracy / costs, even getting high accuracy using “low-cost” recovery methods as digital photogrammetry, which allow us easily to obtain a graphical representation “on paper”: ortho-images of different points of view. This can be useful for many purposes but, for others, an orthographic projection is not really very interesting. <br><br> In non-site restoration tasks of frescoed vaults, a “planar format” representation in needed to see in true magnitude the paintings represented on the intrados vault, because of the general methodolog...
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2015
The evolution of Structure from Motion (SfM) techniques and their integration with the establishe... more The evolution of Structure from Motion (SfM) techniques and their integration with the established procedures of classic stereoscopic photogrammetric survey have provided a very effective tool for the production of three-dimensional textured models. Such models are not only aesthetically pleasing but can also contain metric information, the quality of which depends on both survey type and applied processing methodologies. An open research topic in this area refers to checking attainable accuracy levels. The knowledge of such accuracy is essential, especially in the integration of models obtained through SfM with other models derived from different sensors or methods (laser scanning, classic photogrammetry ...). Accuracy checks may be conducted by either comparing SfM models against a reference one or measuring the deviation of control points identified on models and measured with classic topographic instrumentation and methodologies. This paper presents an analysis of attainable acc...
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2015
In the restoration of the frescoed vaults it is not only important to know the geometric shape of... more In the restoration of the frescoed vaults it is not only important to know the geometric shape of the painted surface, but it is essential to document its chromatic characterization and conservation status. The new techniques of range-based and image-based modelling, each with its limitations and advantages, offer a wide range of methods to obtain the geometric shape. In fact, several studies widely document that laser scanning enable obtaining three-dimensional models with high morphological precision. However, the quality level of the colour obtained with built-in laser scanner cameras is not comparable to that obtained for the shape. It is possible to improve the texture quality by means of a dedicated photographic campaign. This procedure, however, requires to calculate the external orientation of each image identifying the control points on it and on the model through a costly step of post processing. With image-based modelling techniques it is possible to obtain models that ma...
The new survey tools used in studies aimed to preserving architectural heritage often show some d... more The new survey tools used in studies aimed to preserving architectural heritage often show some dilemmas. Several studies have been able to confirm that laser scanner surveys allow to obtain three-dimensional models of high accuracy in morphology and topological level. However, nowadays the quality level of colour obtained with laser scanners is not acceptable for high quality texturing. Moreover, high quality colour medels can be obtained through techniques of Structure from Modeling, but feature a lower precision of mesh, even though results obtainable by Computer Vision programs, make this approach increasingly viable. In this context, a case study is proposed on a vault located in the Palazzo Roncioni (Pisa, Italy) decorated with a important fresco painted by the painter Giovan Battista Tempesti in the second half of the eighth century. In this case, different tests will be carried out by Structure from Modeling techniques to have a high resolution texture applied to the model o...
"Keywords: Laser Scanner Survey, Data intregration, Virtual anastylosis, Spanish Medieval Ar... more "Keywords: Laser Scanner Survey, Data intregration, Virtual anastylosis, Spanish Medieval Architecture. Purpose: The Desamparados’Church of Les Coves de Viromá (Castellón, Spain) belonging to the Order Monchs of the Calatrava was built during the XII century. The Church was constantly changing, and in the XV and XVI centuries was when the ribbed vaults were built. Nowadays it appears as small church characterized by the typical gothic vaults despite its former Romanic shape. For many centuries it was the only church of Coves de Vinromá, but during XVIII century it was built a bigger church (Iglesia de la Asunción) that became the new religious center of the town; anyway the excellent stereotomic solution adopted for it construction still appears as one of the main heritage of the Comunidad Valenciana. During the Spanish Civil War the main chapel of the church was used as a pit for a machine gun and it was intentionally destroyed using dynamite: the consequence was that the nine...
This project is presented as a line of research that analyzes an anastylosis of some figurative f... more This project is presented as a line of research that analyzes an anastylosis of some figurative friezes of hunting themes held at La Piazza d'Oro Villa Adriana (Tivoli, Rome, Italy) in the 70's. However, this anastylosis was done with an arbitrary position in some cases. Shortly after it was decided that it is wrong and it is disassembled. With this background, it creates a line of research using new technologies. This line of research, as a result of a collaboration between the "Soprintendenza Archeologica per il Lazio" and "Instituto Universitario de Restauración del Patrimonio” de la Universidad Politécnica de Valencia, is intended to integrate with other research on the building. It is proposed to use new technologies to conduct a review of the anastylosis already done in the 70s by using the 3D surveys and some models with high level of detail, and by designing a more accurate anastylosis. It is intended to apply the same methodology to the friezes of hun...
Use of new technologies in the study of ancient architectural heritage is sometimes hampered by a... more Use of new technologies in the study of ancient architectural heritage is sometimes hampered by an alleged incompatibility of high-precision instruments dealing with old drawings and buildings. The present chapter aims to prove the premise wrong. A case study, involving the keystone and some wedges from a collapsed medieval vault, allowed to reformulate the previous hypotheses about its layout and geometry. It must be however emphasized that, each on its own, neither the use of new technologies nor the study of old drawings, can handle every aspect of the investigation. It must be clear that, in order to achieve optimal results both complement each other, because reconstruction works involve preliminary studies to understand the historical period, drawings, methods used at that time... In a second phase, these data will allow for the use of new technologies to make a hypothesis and a consistent virtual reconstruction.
Cultural heritage studies often require the analysis of buildings that have undergone several cha... more Cultural heritage studies often require the analysis of buildings that have undergone several changes and alterations during their lifetime. This often implies the loss of architectural elements or the construction of new elements, which both change the characteristics of the former buildings. The recovery of lost elements or structures through virtual reconstruction is of paramount importance in both scientific and cultural applications. Novel procedures in surveying and photogrammetric processing including historical photogrammetry and historical terrestrial laser scanning offer powerful tools that enable the extraction of geometric information from historical documentation such as archival images. This paper presents the integration of a metric 3D model with information present in archival surveys of lost architectural volumes. The methodology implies the availability of historical plans representing the survey object at scales consistent with UAV surveys and featuring shared ele...
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Papers by Isabel P H D Martínez-Espejo Zaragoza