Local Uniqueness of the Circular Integral Invariant

This article is concerned with the representation of curves by means of integral invariants. In contrast to the classical differential invariants they have the advantage of being less sensitive with respect to noise. The integral invariant most common in use is the circular integral invariant. A major drawback of this curve descriptor, however, is the absence of any uniqueness result for this representation. This article serves as a contribution towards closing this gap by showing that the circular integral invariant is injective in a neighbourhood of the circle. In addition, we provide a stability estimate valid on this neighbourhood. The proof is an application of Riesz-Schauder theory and the implicit function theorem in a Banach space setting

Semiautomatic fragments matching and virtual reconstruction: a case study on ceramics

Artefacts' reconstruction is a fundamental part of conservation and one of the most common remedial conservation activities with great contribution to archaeological research. The manual procedure for fragments' matching is a painstaking, time- and space-consuming operation. As a result the development of working methodologies for digital refitting of fragments is of fundamental importance for archaeological research and conservation practice. This study presents a comparative analysis of manual and digital reconstruction, which has never been explored even if computer scientists have achieved many developments in the field of digital refitting. Results indicate the parallels between manual and digital processes in terms of durability, integrity and practicality. Also, in order to provide methodological directions to conservators, three different semi-automatic fragments matching approaches based on their effectiveness in managing the project and alignment of fragments were used A combined strategy, making use of different pieces of software, is recommended. In addition, the modelling techniques for digital restoration were described along with the uses of the virtually restored artefact. Faenza maiolica, black-glazed, Gnathian and coarse ware ceramics were used as case studies

Sampled 3D models for Cultural Heritage: which uses beyond visualization?

[EN] Digital technologies are now mature for producing high quality digital replicas of Cultural Heritage (CH) artefacts. The research results produced in the last decade have shown an impressive evolution and consolidation of the technologies for acquiring high-quality digital 3D models (3D scanning) and for rendering those models at interactive speed. Technology is now mature enough to push us to go beyond the plain visualization of those assets, devising new tools able to extend our insight and intervention capabilities and to revise the current consolidated procedures for CH research and management. The paper presents a few recent experiences where high-quality 3D models have been used in CH research, restoration and conservation. These examples constitutes a broad review of different uses of digital 3Dassets in the CH domain.[ES] Se puede afirmar que las tecnologías digitales han alcanzado un punto de madurez suficiente como para producir réplicas digitales de alta calidad del patrimonio cultural, especialmente de artefactos. Los resultados de la investigación producidos en la última década han mostrado una impresionante evolución y consolidación de las tecnologías utilizadas para la producción de modelos digitales 3D de alta calidad (escaneado 3D) y para el renderizado de esos modelos a una velocidad interactiva. En este sentido la tecnología es hoy perfectamente capaz de empujarnos a ir más allá de la simple visualización de los bienes culturales, hasta elaborar nuevas herramientas capaces de ampliar nuestra visión y capacidades de intervención así como de revisar los procedimientos actuales de investigación y gestión del patrimonio cultural. Este artículo presenta algunas experiencias recientes en las que modelos 3D de alta calidad han sido utilizados para mejorar la investigación, restauración y conservacióThe research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007- 2013) under grant agreements no. 231809 (IST IP "3DCOFORM") and no. 270404 (IST NoE "V-Must.Net").Scopigno, R. (2012). Sampled 3D models for Cultural Heritage: which uses beyond visualization?. Virtual Archaeology Review. 3(5):109-115. https://doi.org/10.4995/var.2012.4537OJS10911535CALLIERI M., CIGNONI P., GANOVELLI F., IMPOCO G., MONTANI C., PINGI P., PONCHIO F., SCOPIGNO R. (2004): "Visualization and 3D data processing in David's restoration". IEEE Computer Graphics & Applications 24, 2 (Mar.-Apr. 2004), pp. 16-21. http://dx.doi.org/10.1109/MCG.2004.1274056CORSINI M., DELLEPIANE M., DERCKS U., PONCHIO F., CALLIERI M., KEULTJES D., MARINELLO A., SIGISMONDI R., SCOPIGNO R., WOLF G. (2010): "Cenobium - putting together the romanesque cloister capitals of the mediterranean region". In Bar International Series BAR S2118 2010 (Proc. of III International Conference on Remote Sensing in Archaeology, 17th-21st August 2009) (2010), S. Campana M. F., Liuzza C., (Eds.), pp. 189-194.DELLEPIANE M., CALIERI M., DELL'UNTO N. (2011): "Monitoring archeological excavation using dense stereo matching techniques". Tech. rep., CNR-ISTI, Pisa, Italy, 2011.DELLEPIANE M., CALLIERI M., FONDERSMITH M., CIGNONI P., SCOPIGNO R. (2007): "Using 3D scanning to analyze a proposal for the attribution of a bronze horse to Leonardo da Vinci". In The 8th Int. Symp. on International Symposium on Virtual Reality, Archaeology and Cultural Heritage (VAST 07) (Nov 2007), Eurographics, pp. 117-124.DYLLA K., FRISCHER B., MUELLER P., ULMER A., HAEGLER S. (2009): "Rome Reborn 2.0: A case study of virtual city reconstruction using procedural modeling techniques". In 37th Proceedings of the CAA Conference, March 22-26, 2009 (2009), pp. 62-66.HUANG Q.-X., FLORY S., GELFAND N., HOFER M., POTTMANN H. (2006): "Reassembling fractured objects by geometric matching". ACM Trans. Graphics 25, 3 (2006), pp. 569-578. http://dx.doi.org/10.1145/1141911.1141925LEVOY M., PULLI K., CURLESS B., RUSINKIEWICZ S., KOLLER D., PEREIRA L., GINZTON M., ANDERSON S., DAVIS J., GINSBERG J., SHADE J., FULK D. (2000): "The Digital Michelangelo Project: 3D scanning of large statues". In SIGGRAPH 2000, Computer Graphics Proceedings (July 24-28, 2000), Annual Conference Series, AddisonWesley, pp. 131-144. http://dx.doi.org/10.1145/344779.344849SCOPIGNO, Roberto et al. (2011): "Sampled 3D models for CH: beyond plain visualization", IEEE Computer, IEEE Press, July-Aug. 2011, (in press).STANCO F., BATTIATO S., GALLO G., (ed.) (2011): "Digital Imaging for Cultural Heritage Preservation". Taylor & Francis Group, 2011.TOLER-FRANKLIN C., BROWN B., WEYRICH T., FUNKHOUSER T., RUSINKIEWICZ S. (2010): "Multi-feature matching of fresco fragments". ACM Trans. Graphics (Proc. SIGGRAPH Asia) 29, 6 (2010), pp. 185-197. http://dx.doi.org/10.1145/1882262.1866207http://dx.doi.org/10.1145/1882261.186620

GEMA2:Geometrical matching analytical algorithm for fast mobile robots global self-localization

[EN] This paper presents a new algorithm for fast mobile robot self-localization in structured indoor environments based on geometrical and analytical matching, GEMA(2). The proposed method takes advantage of the available structural information to perform a geometrical matching with the environment information provided by measurements collected by a laser range finder. In contrast to other global self-localization algorithms like Monte Carlo or SLAM, GEMA(2) provides a linear cost with respect the number of measures collected, making it suitable for resource-constrained embedded systems. The proposed approach has been implemented and tested in a mobile robot with limited computational resources showing a fast converge from global self-localization. (C) 2014 Elsevier B.V. All rights reserved.This work has been partially funded by FEDER-CICYT projects with references DPI2011-28507-C02-01 and HAR2012-38391-C02-02 financed by Ministerio de Ciencia e Innovacion and Ministerio de Economia y Competitividad (Spain).Sánchez Belenguer, C.; Soriano Vigueras, Á.; Vallés Miquel, M.; Vendrell Vidal, E.; Valera Fernández, Á. (2014). GEMA2:Geometrical matching analytical algorithm for fast mobile robots global self-localization. Robotics and Autonomous Systems. 62(6):855-863. https://doi.org/10.1016/j.robot.2014.01.009S85586362

Computer-Assisted Assembling of Fragmented Objects

Si propone un medoto semi automatico ed interattivo per la ricostruzione virtuale di oggetti frammentati. Tramite un'interfaccia, l'utente specica un insieme di constraints tra coppie di frammenti ( digitalizzati come mesh di triangoli) o tra gruppi di frammenti. Il metodo ~A stato testato con successo su un inseme di casi reali

Robust surface segmentation and edge feature lines extraction from fractured fragments of relics

AbstractSurface segmentation and edge feature lines extraction from fractured fragments of relics are essential steps for computer assisted restoration of fragmented relics. As these fragments were heavily eroded, it is a challenging work to segment surface and extract edge feature lines. This paper presents a novel method to segment surface and extract edge feature lines from triangular meshes of irregular fractured fragments. Firstly, a rough surface segmentation is accomplished by using a clustering algorithm based on the vertex normal vector. Secondly, in order to differentiate between original and fracture faces, a novel integral invariant is introduced to compute the surface roughness. Thirdly, an accurate surface segmentation is implemented by merging faces based on face normal vector and roughness. Finally, edge feature lines are extracted based on the surface segmentation. Some experiments are made and analyzed, and the results show that our method can achieve surface segmentation and edge extraction effectively