231 research outputs found

    Revisión de los métodos computerizados para la reconstrucción de fragmentos arqueológicos de cerámica

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    [ES] Las cerámicas son los hallazgos más numerosos encontrados en las excavaciones arqueológicas; a menudo se usan para obtener información sobre la historia, la economía y el arte de un sitio. Los arqueólogos rara vez encuentran jarrones completos; en general, están dañados y en fragmentos, a menudo mezclados con otros grupos de cerámica.El análisis y la reconstrucción de fragmentos se realiza por un operador experto mediante el uso del método manual tradicional. Los artículos revisados proporcionaron evidencias de que el método tradicional no es reproducible, no es repetible, consume mucho tiempo y sus resultados generan grandes incertidumbres. Con el objetivo de superar los límites anteriores, en los últimos años, los investigadores han realizado esfuerzos para desarrollar métodos informáticos que permitan el análisis de fragmentos arqueológicos de cerámica, todo ello destinado a su reconstrucción. Para contribuir a este campo de estudio, en este artículo, se presenta un análisis exhaustivo de las publicaciones disponibles más importantes hasta finales de 2019. Este estudio, centrado únicamente en fragmentos de cerámica, se realiza mediante la recopilación de artículos en inglés de la base de datos Scopus, utilizando las siguientes palabras clave: "métodos informáticos en arqueología", "arqueología 3D", "reconstrucción 3D", "reconocimiento y reconstrucción automática de características", "restauración de reliquias en forma de cerámica ". La lista se completa con referencias adicionales que se encuentran a través de la lectura de documentos seleccionados. Los 53 trabajos seleccionados se dividen en tres períodos de tiempo. Según una revisión detallada de los estudios realizados, los elementos clave de cada método analizado se enumeran en función de las herramientas de adquisición de datos, las características extraídas, los procesos de clasificación y las técnicas de correspondencia. Finalmente, para superar las brechas reales, se proponen algunas recomendaciones para futuras investigaciones.[EN] Potteries are the most numerous finds found in archaeological excavations; they are often used to get information about the history, economy, and art of a site. Archaeologists rarely find complete vases but, generally, damaged and in fragments, often mixed with other pottery groups. By using the traditional manual method, the analysis and reconstruction of sherds are performed by a skilled operator. Reviewed papers provided evidence that the traditional method is not reproducible, not repeatable, time-consuming and its results have great uncertainties. To overcome the aforementioned limits, in the last years, researchers have made efforts to develop computer-based methods for archaeological ceramic sherds analysis, aimed at their reconstruction. To contribute to this field of study, in this paper, a comprehensive analysis of the most important available publications until the end of 2019 is presented. This study, focused on pottery fragments only, is performed by collecting papers in English by the Scopus database using the following keywords: “computer methods in archaeology", "3D archaeology", "3D reconstruction", "automatic feature recognition and reconstruction", "restoration of pottery shape relics”. The list is completed by additional references found through the reading of selected papers. The 53 selected papers are divided into three periods of time. According to a detailed review of the performed studies, the key elements of each analyzed method are listed based on data acquisition tools, features extracted, classification processes, and matching techniques. Finally, to overcome the actual gaps some recommendations for future researches are proposed.Highlights:The traditional manual method for reassembling sherds is very time-consuming and costly; it also requires a great deal effort from skilled archaeologists in repetitive and routine activities.Computer-based methods for archaeological ceramic sherds reconstruction can help archaeologists in the above-mentioned repetitive and routine activities.In this paper, the state-of-the-art computer-based methods for archaeological ceramic sherds reconstruction are reviewed, and some recommendations for future researches are proposed.Eslami, D.; Di Angelo, L.; Di Stefano, P.; Pane, C. (2020). Review of computer-based methods for archaeological ceramic sherds reconstruction. 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    Effective 3D Geometric Matching for Data Restoration and Its Forensic Application

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    3D geometric matching is the technique to detect the similar patterns among multiple objects. It is an important and fundamental problem and can facilitate many tasks in computer graphics and vision, including shape comparison and retrieval, data fusion, scene understanding and object recognition, and data restoration. For example, 3D scans of an object from different angles are matched and stitched together to form the complete geometry. In medical image analysis, the motion of deforming organs is modeled and predicted by matching a series of CT images. This problem is challenging and remains unsolved, especially when the similar patterns are 1) small and lack geometric saliency; 2) incomplete due to the occlusion of the scanning and damage of the data. We study the reliable matching algorithm that can tackle the above difficulties and its application in data restoration. Data restoration is the problem to restore the fragmented or damaged model to its original complete state. It is a new area and has direct applications in many scientific fields such as Forensics and Archeology. In this dissertation, we study novel effective geometric matching algorithms, including curve matching, surface matching, pairwise matching, multi-piece matching and template matching. We demonstrate its applications in an integrated digital pipeline of skull reassembly, skull completion, and facial reconstruction, which is developed to facilitate the state-of-the-art forensic skull/facial reconstruction processing pipeline in law enforcement

    A Survey of Geometric Analysis in Cultural Heritage

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    We present a review of recent techniques for performing geometric analysis in cultural heritage (CH) applications. The survey is aimed at researchers in the areas of computer graphics, computer vision and CH computing, as well as to scholars and practitioners in the CH field. The problems considered include shape perception enhancement, restoration and preservation support, monitoring over time, object interpretation and collection analysis. All of these problems typically rely on an understanding of the structure of the shapes in question at both a local and global level. In this survey, we discuss the different problem forms and review the main solution methods, aided by classification criteria based on the geometric scale at which the analysis is performed and the cardinality of the relationships among object parts exploited during the analysis. We finalize the report by discussing open problems and future perspectives

    Zn(II)-porphyrin metallacyles: versatile building units for the self-assembling of discrete 3D multi-component systems with tunable geometries and properties

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    il progetto di ricerca descritto nel presente lavoro di tesi si \ue8 focalizzato sulla progettazione, sintesi e caratterizzazione di strutture 3D supramolecolari ottenute mediante appropriata combinazione di leganti piridinici con pannelli metallaciclici di zinco porfirine. La versatilit\ue0 dell'approccio sintetico perseguito, ha permesso, a seguto di un astuto e pensato design delle unit\ue0 di base molecolari, di ottenere efficientemente una libreria di elaborate strutture supramolecolari tridimensionali, di modulabile forma e dimensione del sistema desiderato, regolandone le proprieta fotoindotti inter-componente e/o introducendo nuove funzionalit\ue0 derivanti dall'organizzazione geometrica di un preciso numero di centri metallici attivi. Parte del lavoro \ue8 stato dedicato ad una approfondita investigazione sulla possibilit\ue0 di ottenere strutture eterometalliche di ordine discreto, mediante autoassemblaggio di un metallaciclo di zinco porfirine in combinazione con appropriati leganti clatrochelati piridinici, tramite una collaborazionecon il gruppo di Prof. K. Severin (EPFL di Losanna). Lo scopo finale \ue8 di ottenere facilmente, mediante un approccio sintetico modulare, sistemi funzionali di ordine superiore contenenti un definito numero di ben organizzati centri metallici attivi (cio\ue8 magneticamente, cataliticamente o redox attivi). Ci si \ue8 inoltre concentrati sulla sintesi di architetture supramolecolari discrete aventi dimensioni e geometria modulabile e recanti un numero variabile di unit\ue0 porfiriniche, ottenute per semplice mescolamento di due o tre diversi moduli porfirinici. Scegliendo in modo appropriato i connettori piridinici, cio\ue8 variandone il numero di centri basici donatori e/o giocando sulla loro posizione relativa, strutture molecolari di dimensioni implememntate diventano facilmente ottenibili. Progettando in modo studiato le unit\ue0 molecolari di base, in termini di lablit\ue0/inerzia e discriminazione di tipo hard/soft, queste si autoassembleranno a formare in modo quantitativo tramite la formazione di legami di coordinazione complementari. Le strutture multi-porfiriniche cos\uec ottenute costituiscono un telaio ben ordinato di unit\ue0 cromoforiche coinvolti in processi fotoindotti di trasferimento di energia e di trasferimento di carica. Infine parte del lavoro di ricerca \ue8 stato svolto durante un periodo di 6 mesi trascorsi presso il laboratorio del Dr. Romain Ruppert dell\u2019Universit\ue0 di Strasburgo. Il progetto aveva lo scopo di sintetizzare dei dimeri di zinco porfirine connesse mediante coordinazione a un catione di Pd(II), e di studiare la loro possibile applicazione ed utilizzo come piattaforme fotoattive alternative per l\u2019autoassemblaggio di sistemi discreti suprmaolecolari a forma di sandwich. Da un punto di vista fotofisico il nuovo dimero presenta interessanti propriet\ue0 in quanto \ue8 presente una forte comunicazione elettroinica fra le due porfirne attraverso il ponte metallico di Pd(II). D\u2019altro canto, da un punto di vista di sintesi supramolecolare, il dimero presenta le caratteristiche richieste: due punti di ancoraggio costituiti dai due centri di Zn(II), un buon grado di inerzia del legame esociclico e una sufficiente coplanarit\ue0 a disposizione rigida delle componenti.The research carried out during this PhD project and reported in this Thesis is focused on the design, preparation and characterization of multi-component supramolecular 3D architectures obtained by appropriate paneling multitopic pyridyl ligands with flat Zn-porphyrin metallacycles. The versatility of the synthetic approach pursued, allowed to efficiently construct libraries of elaborated 3D structures, tuning the shape and dimension of the target systems, modulating the inter-component photo-induced properties and/or introducing new functions deriving from the geometrical organization of a precise number of active metal centers, by cleverly tailoring the molecular building blocks. In Chapter 1, a general introduction on key role of porphyrins as functional and structural building unit for the assembly of artificial discrete supramolecular structures is presented, together with the main designing concepts of the metal mediated self-assembling synthetic strategy. Few examples of elegant multiporphyrin architectures and their application are reported. Finally, the modular synthetic approach pursued during this research project is described. In Chapter 2, a thourough investigation on the possibility to produce new hetero-multimetallic ordered discrete structures, by self-assembling of a zinc-porphyrin metallacycle (1Zn) with dipyridyl clathrochelate metalloligands (provided by the group of Prof. K. Severin, EPFL, Lausanne, CH), is discussed. In particular, linear FeII metal containing ligands with terminal 4-pyridyl groups, lengthes between 1.5 and 3.2 nm, and containing either one or two clatrochelate cores were chosen. The final aim is the easy access, by a modular approach, to higher order functional systems comprising defined numbers and spacial organizations of metal-active centers (e.g. magnetically, redox or catalytically active). Chapter 3 reports on the metal mediated assembling of a linear dipyridyl diazadioxa[8]circulene (Circ, provided by the group of Prof. M. Pittelkow, University of Copenhagen, DK) with either 1Zn and of a cis-protected diphosphines PtII complex. Circ is a flat and conjugated compound presenting a central antiaromatic cyclooctatetraene core. The designing idea was to endow the ligand in structures, enforcing conformations which could enable, to find experimental evidences of the antiaromaticity, by observation of deshielding effect due to the diatropic ring current of the COT core. Discussion of their structural analysis in solution and in the solid state is described. The work described in Chapter 4 focused on the synthesis of giant 3D discrete supramolecular architectures, with tuned dimensions, geometry and varied number of porphyrin units, obtained by simple mixing different (metallo)porphyrin modules. By appropriate tailoring of the meso-4\u2019pyridylporphyrin connectors, i.e. increasing the number of basic donor sites and/or playing on their relative disposition, larger molecular architectures become easily available. Cleverly designed molecular building units, in terms of lability/inertness and hard/soft metal-to-ligand discriminations, quantitatively self-connect by formation of mutual coordination bonds. The obtained discrete multi-porphyrin structures constitute a spatially-ordered lattice of chromophores featuring photoinduced antenna-effect and charge transfer processes. Pursuing a modular synthetic approach, a library of fascinating In Chapter 5, Is reported the work performed during a six-month internship in the laboratories of Dr. Romain Ruppert, University of Strasbourg (FR), is devoted at investigating and tackling the possibility to employ a PdII-linked Zn(II)-porphyrin dimer (ZnPdZn), as alternative photo-active platforms for the assembling of discrete supramolecular sandwich structures

    Computer aided puzzle assembly based on shape and texture information /

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    Puzzle assembly’s importance lies into application in many areas such as restoration and reconstruction of archeological findings, the repairing of broken objects, solving of the jigsaw type puzzles, molecular docking problem, etc. Puzzle pieces usually include not only geometrical shape information but also visual information of texture, color, continuity of lines, and so on. Moreover, textural information is mainly used to assembly pieces in some cases, such as classic jigsaw puzzles. This research presents a new approach in that pictorial assembly, in contrast to previous curve matching methods, uses texture information as well as geometric shape. The assembly in this study is performed using textural features and geometrical constraints. First, the texture of a band outside the border of pieces is predicted by inpainting and texture synthesis methods. The feature values are derived by these original and predicted images of pieces. A combination of the feature and confidence values is used to generate an affinity measure of corresponding pieces. Two new algorithms using Fourier based image registration techniques are developed to optimize the affinity. The algorithms for inpainting, affinity and Fourier based assembly are explained with experimental results on real and artificial data. The main contributions of this research are: The development of a performance measure that indicates the level of success of assembly of pieces based on textural features and geometrical shape. Solution of the assembly problem by using of the Fourier based methods

    Image Processing Applications in Real Life: 2D Fragmented Image and Document Reassembly and Frequency Division Multiplexed Imaging

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    In this era of modern technology, image processing is one the most studied disciplines of signal processing and its applications can be found in every aspect of our daily life. In this work three main applications for image processing has been studied. In chapter 1, frequency division multiplexed imaging (FDMI), a novel idea in the field of computational photography, has been introduced. Using FDMI, multiple images are captured simultaneously in a single shot and can later be extracted from the multiplexed image. This is achieved by spatially modulating the images so that they are placed at different locations in the Fourier domain. Finally, a Texas Instruments digital micromirror device (DMD) based implementation of FDMI is presented and results are shown. Chapter 2 discusses the problem of image reassembly which is to restore an image back to its original form from its pieces after it has been fragmented due to different destructive reasons. We propose an efficient algorithm for 2D image fragment reassembly problem based on solving a variation of Longest Common Subsequence (LCS) problem. Our processing pipeline has three steps. First, the boundary of each fragment is extracted automatically; second, a novel boundary matching is performed by solving LCS to identify the best possible adjacency relationship among image fragment pairs; finally, a multi-piece global alignment is used to filter out incorrect pairwise matches and compose the final image. We perform experiments on complicated image fragment datasets and compare our results with existing methods to show the improved efficiency and robustness of our method. The problem of reassembling a hand-torn or machine-shredded document back to its original form is another useful version of the image reassembly problem. Reassembling a shredded document is different from reassembling an ordinary image because the geometric shape of fragments do not carry a lot of valuable information if the document has been machine-shredded rather than hand-torn. On the other hand, matching words and context can be used as an additional tool to help improve the task of reassembly. In the final chapter, document reassembly problem has been addressed through solving a graph optimization problem

    JigsawNet: Shredded Image Reassembly using Convolutional Neural Network and Loop-based Composition

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    This paper proposes a novel algorithm to reassemble an arbitrarily shredded image to its original status. Existing reassembly pipelines commonly consist of a local matching stage and a global compositions stage. In the local stage, a key challenge in fragment reassembly is to reliably compute and identify correct pairwise matching, for which most existing algorithms use handcrafted features, and hence, cannot reliably handle complicated puzzles. We build a deep convolutional neural network to detect the compatibility of a pairwise stitching, and use it to prune computed pairwise matches. To improve the network efficiency and accuracy, we transfer the calculation of CNN to the stitching region and apply a boost training strategy. In the global composition stage, we modify the commonly adopted greedy edge selection strategies to two new loop closure based searching algorithms. Extensive experiments show that our algorithm significantly outperforms existing methods on solving various puzzles, especially those challenging ones with many fragment pieces
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