Papers by Christodoulos Chamzas
ipet.gr
Virtual reconstruction of urban areas, which are lost due to natural or man-provoked disasters, i... more Virtual reconstruction of urban areas, which are lost due to natural or man-provoked disasters, is nowadays feasible through the usage of contemporary three-dimensional technologies and virtual reality. With the aid of topography, architecture, history and archaeology, the ...
information and made it more appealing to the public. Physical and chemical characteristics were,... more information and made it more appealing to the public. Physical and chemical characteristics were, however, still interesting only to a limited number of researchers. Images combined with historical excerpts in the form of digital catalogues became the standard in promoting private collections and museums. Catalogues with deeper descriptions and scientific facts were also used for educational purposes and typological research. Multimedia brought a new era with virtual worlds. Relatively simple catalogues, enriched with video and graphics, were transformed into virtual museums, while multimedia databases offer a multitude of information.Yet this wealth of information remains, to a great extent, bound to 2D media.
Two forms of a sampling theorem for concentric circles are established for a bandlimited two-dime... more Two forms of a sampling theorem for concentric circles are established for a bandlimited two-dimensional (2-D) function. The location of the samples is prescribed either on equidistant circles or on the roots of the Bessel functionJ0( ): Both methods give comparable results, however, the number of samples required for their numerical evaluation is significantly less for the root-sampling formulation.
2016 Digital Media Industry & Academic Forum (DMIAF), 2016
The aim of this research is to achieve spatial consistency of the UV map. We present an approach ... more The aim of this research is to achieve spatial consistency of the UV map. We present an approach to produce a fully spatially consistent UV mapping based on the planar parameterisation of the mesh. We apply our method on a 3D digital replica of an ancient Greek Lekythos vessel. We parameterise the mesh of a 3D model onto a unit square 2D plane using computational conformal geometry techniques. The proposed method is genus independent, due to an iterative 3D mesh cutting procedure. Having now the texture of a 3D model depicted on a spatially continuous two dimensional structure enables us to efficiently apply a vast range of image processing based techniques and algorithms.
Mobile Networks and Applications
Virtual reconstruction of urban areas, which are lost due to natural or man-provoked disasters, i... more Virtual reconstruction of urban areas, which are lost due to natural or man-provoked disasters, is nowadays feasible through the usage of contemporary threedimensional technologies and virtual reality. With the aid of topography, architecture, history and archaeology, the once existed urban areas, or even whole cities, can be reconstructed as close as possible to the original. The work presented in this paper is such an attempt. It focuses on the urban area of Argostoli in Kefalonia, Greece, which was completely destroyed by an earthquake during 1953. Using all kinds of information involving the town, a part of the urban area has been reconstructed in three dimensions and a virtual tour is now available.
Recent developments in three-dimensional technologies and measurement instrumentation combined wi... more Recent developments in three-dimensional technologies and measurement instrumentation combined with multimedia databases offer today new possibilities for the integrated and complete description of Cultural Heritage Objects (CHO). In this work, we present an attempt to develop a database for archaeological ceramic and glass artifacts, where in addition to digitized two-dimensional images and threedimensional reconstructions, description, typological characteristics and historical information for each artifact will also include point-wise surface data, forming a GIS-like environment for CHO. This information will contribute significantly to the comparative study of artifacts, provenance studies, determination of weathering, authentication and detection of forgery, inspection of past restorations, and ultimately, their preservation.
IEEE Global Telecommunications Conference and Exhibition. Communications for the Information Age
2002 14th International Conference on Digital Signal Processing Proceedings. DSP 2002 (Cat. No.02TH8628)
Recent developments in 2D and 3D digitization and visualization technologies, as well as in measu... more Recent developments in 2D and 3D digitization and visualization technologies, as well as in measurement instrumentation, combined with the emerging multimedia databases and network technologies offer today new possibilities for the integrated and complete description of cultural objects. Our Institute, with main interest in the preservation of Cultural Heritage, in an attempt to exploit these new technologies, is developing multimedia databases for cultural objects that include 3D geometric and physicochemical data and are able to be delivered through the Internet. The "Ark of Refugee Heirloom" [1][26] (recording and documentation of unknown heirlooms in the five prefectures of Eastern Macedonia and Thrace that belong to refugees whose origins lay in regions of the Ottoman Empire, south Russia, Bulgaria and others surrounding the Black Sea), is a first generation 3D-database, where, selectively, we have included 3D objects in parallel with their 2D images. "3D-ArCAD" [2][3] (database for archaeological ceramic and glass artifacts with 2D and 3D images, description, typological characteristics, historical information and point-wise surface data), is a second generation 3D-database, where in addition to 2D and 3D images, typological characteristics and historical information, we also include point-wise surface data.
Lecture Notes in Computer Science, 2006
The paper presents definition extensions to MPEG-7 metadata ones, mainly related to audio descrip... more The paper presents definition extensions to MPEG-7 metadata ones, mainly related to audio descriptors, introduced to efficiently describe traditional Greek music data features in order to further enable efficient music retrieval. A number of advanced content-based retrieval scenarios have been defined such as query by music rhythm, query by example and humming based on newly introduced music features, query by traditional Greek music genre, chroma-based query. MPEG-7 DDL extensions and appropriate traditional greek music genre dictionary entries are deemed necessary for accounting for the specificities of the music data under question and for attaining efficiency in music information retrieval. The reported work has been undertaken within the framework of an R&D project targeting an advanced music portal offering a number of content-based music retrieval services, namely POLYMNIA[12].
3rd International Symposium on Image and Signal Processing and Analysis, 2003. ISPA 2003. Proceedings of the
Abstract In complex color documents, text, drawings and graphics are appeared with millions of di... more Abstract In complex color documents, text, drawings and graphics are appeared with millions of different colors. In many cases, text regions are overlaid onto drawings or graphics. In this paper, a new method is proposed to automatically detect and extract text ...
In this paper a new protocol is proposed for reducing the power consumption of the battery-powere... more In this paper a new protocol is proposed for reducing the power consumption of the battery-powered terminals in a mobile computing environment. We exploit the fact that, in a mobile data network mobile terminals do not continuously receive data and therefore they need not continuously operate their receivers. Nevertheless, they need to periodically check their traffic condition, that is, whether there are pending data for them or not. The proposed energy-efficient protocol is based on a paging procedure wherein a dedicated channel is used to alert (page) the terminals with pending traffic. Each terminal may check its traffic condition whenever it decides to by monitoring the paging channel. The protocol is evaluated through an approximated theoretical model and through computer simulation. We focus on deriving approximate formulas for the mean message delay, the message delay variance and the power consumption. It is shown that the proposed protocol can achieve considerable power sa...
Journal of Cultural Heritage, 2014
ABSTRACT A number of software solutions based on the Structure-From-Motion (SFM) and Dense Multi-... more ABSTRACT A number of software solutions based on the Structure-From-Motion (SFM) and Dense Multi-View 3D Reconstruction (DMVR) algorithms have been made recently available. They allow the production of high quality 3D models by using unordered image collections that depict a scene or an object from different viewpoints. In this work, we question the quality of the data produced by a commercial SFM-DMVR software. An Ottoman monument located in the region of Xanthi, Greece has been selected as a case study. We attempted to quantify the quality of the SFM-DMVR data in relation to the data produced by a Time-of-Flight terrestrial 3D range scanner. We have implemented a number of comparisons between different parts of the monument in order to assess the mesh deviations and the reconstruction's accuracy. In order to further ensure the validity of our evaluation phase, we performed additional distance measurements between feature points on the monument's surface by using a total station and empirical measurements. The applicability of the SFM-DMVR method was questioned by creating a complete 3D digital replica of the monument.
In recent years, research and presentation of cultural heritage have an important ally: technolog... more In recent years, research and presentation of cultural heritage have an important ally: technology. The “Ark of Refugee Heirloom” is a project of high cultural importance, since it aims at the recording and documentation of unknown heirlooms, kept mainly in private collections. The objective is the classification and publication of primary data, in order to support further research on the field of Cultural Heritage. The project tracks down heirlooms in the five prefectures of Eastern Macedonia and Thrace that belong to refugees whose origins lay in regions of the Ottoman Empire, south Russia, Bulgaria and others surrounding the Black Sea.
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Papers by Christodoulos Chamzas