Aplicaciones de la digitalización 3D del patrimonio

[ES] La digitalización 3D se ha convertido en un herramienta habitual en arqueología. No obstante, el procesamiento de los datos generados por los escáneres láser sigue siendo complejo, y la utilidad dada a los modelos obtenidos es aún muy limitada.En este trabajo analizamos algunos de los puntos más conflictivos en el procesamiento de las nubes de puntos, revisamos algunas de las aplicaciones usuales de los modelos digitales y proponemos un marco conceptual para la utilización de los modelos 3D en la documentación arqueológica.[EN] 3D digitalization has become a common tool in archaeology. However, the post processing of the data produced by the scanners is still quite complex, and the computer models generated are given very few practical applications.In this paper, we analyse the key steps involved in the processing of the point clouds. We also review some of the more usual applications for the digital models and propose a conceptual framework for the use of this models in the documentation of cultural heritage.Ministerio de Ciencia y Tecnología y los fondos FEDER (TIN2007-67474-C03-02), Consejería de Innovación Ciencia y Empresa, Junta de Andalucía ( TIC-401.)Torres, JC.; Cano, P.; Melero, J.; España, M.; Moreno, J. (2010). Aplicaciones de la digitalización 3D del patrimonio. Virtual Archaeology Review. 1(1):51-54. https://doi.org/10.4995/var.2010.4768OJS515411AGNELLO, F. et al. (2003): Cultural heritage and information systems, an investigation into a dedicated hypertext. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol. 34, Part 5.BESORA, I. et al.(2008): "Real-Time Exploration of the Virtual Reconstruction of the Entrance of the Ripoll Monastery", en Actas del XIX Congreso Español de Informática Gráfica CEIG'08.CALLIERI, M. et al.(2008):Virtual Inspector: "A Flexible Visualizer for Dense 3D Scanned Models". IEEE Computer Graphics and Applications, vol. 28, no.1, pp. 44-54 http://dx.doi.org/10.1109/MCG.2008.20GRANDE LEON, A. (2002): "Italica virtual. Un proyecto educativo que hace Historia", en PH Boletín del Instituto Andaluz del Patrimonio Histórico, no 40/41, pp. 241-247.HODAČ J. (2005): 3D Information System of Historical Site - Proposal and Realisation of a Functional Prototype. Acta Polytechnica. Vol. 45 No. 1IOANNIDIS, C. et al. (2003): An integrated spatial information system for the development of the archaeological site of mycenae. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol. 34, Part 5.LAMOLDA F. et al. (2008): "Registro mediante la utilizacion de escaner 3D del estado previo a la intervencion de la Fuente de los Leones". Taller en el IX Congreso Internacional de Rehabilitación del Patrimonio Arquitectónico y Edificación, Sevilla.MELERO J. et al. (2005): "Combining SP-octrees and impostors for the visualisation of multiresolution models". Computer & Graphics, vol. 29, pp: 225-233 http://dx.doi.org/10.1016/j.cag.2004.12.008MEYER, E. et al. (2006): "Intra-site Level Cultural Heritage Documentation: Combination of Survey, Modeling and Imagery Data in a Web Information System". 7th International Symposium on Virtual Reality, Archaeology and Cultural Heritage. VAST.NAGLIČ K.K. (2003): "Cultural Heritage Information System in The Republic of Slovenia". ARIADNE 5 Workshop on Documentation, Interpretation, Presentation and Publication of Cultural Heritage. Prague.PAPAGIANNAKIS, G. et al. (2005): "Mixing Virtual and Real scenes in the site of ancient Pompeii". Computer Animation and Virtual Worlds, 16(1), 11-24. http://dx.doi.org/10.1002/cav.53OKAMOTO, Y.,(2008): "Editing, Retrieval, and Display System of Archeological Information on Large 3D Geometric Models". Digitally Archiving Cultural Objects, chapter 21 http://dx.doi.org/10.1007/978-0-387-75807_21SCOPIGNO R. et al. (2003): "Using optically scanned 3D data in the restoration of Michelangelo's David. Optical Metrology for Arts and Multimedia". Proceedings of the SPIE, Vol. 5146, pp. 44-53 http://dx.doi.org/10.1117/12.49992

Towards Predictive Rendering in Virtual Reality

The strive for generating predictive images, i.e., images representing radiometrically correct renditions of reality, has been a longstanding problem in computer graphics. The exactness of such images is extremely important for Virtual Reality applications like Virtual Prototyping, where users need to make decisions impacting large investments based on the simulated images. Unfortunately, generation of predictive imagery is still an unsolved problem due to manifold reasons, especially if real-time restrictions apply. First, existing scenes used for rendering are not modeled accurately enough to create predictive images. Second, even with huge computational efforts existing rendering algorithms are not able to produce radiometrically correct images. Third, current display devices need to convert rendered images into some low-dimensional color space, which prohibits display of radiometrically correct images. Overcoming these limitations is the focus of current state-of-the-art research. This thesis also contributes to this task. First, it briefly introduces the necessary background and identifies the steps required for real-time predictive image generation. Then, existing techniques targeting these steps are presented and their limitations are pointed out. To solve some of the remaining problems, novel techniques are proposed. They cover various steps in the predictive image generation process, ranging from accurate scene modeling over efficient data representation to high-quality, real-time rendering. A special focus of this thesis lays on real-time generation of predictive images using bidirectional texture functions (BTFs), i.e., very accurate representations for spatially varying surface materials. The techniques proposed by this thesis enable efficient handling of BTFs by compressing the huge amount of data contained in this material representation, applying them to geometric surfaces using texture and BTF synthesis techniques, and rendering BTF covered objects in real-time. Further approaches proposed in this thesis target inclusion of real-time global illumination effects or more efficient rendering using novel level-of-detail representations for geometric objects. Finally, this thesis assesses the rendering quality achievable with BTF materials, indicating a significant increase in realism but also confirming the remainder of problems to be solved to achieve truly predictive image generation

Appearance Preserving Rendering of Out-of-Core Polygon and NURBS Models

In Computer Aided Design (CAD) trimmed NURBS surfaces are widely used due to their flexibility. For rendering and simulation however, piecewise linear representations of these objects are required. A relatively new field in CAD is the analysis of long-term strain tests. After such a test the object is scanned with a 3d laser scanner for further processing on a PC. In all these areas of CAD the number of primitives as well as their complexity has grown constantly in the recent years. This growth is exceeding the increase of processor speed and memory size by far and posing the need for fast out-of-core algorithms. This thesis describes a processing pipeline from the input data in the form of triangular or trimmed NURBS models until the interactive rendering of these models at high visual quality. After discussing the motivation for this work and introducing basic concepts on complex polygon and NURBS models, the second part of this thesis starts with a review of existing simplification and tessellation algorithms. Additionally, an improved stitching algorithm to generate a consistent model after tessellation of a trimmed NURBS model is presented. Since surfaces need to be modified interactively during the design phase, a novel trimmed NURBS rendering algorithm is presented. This algorithm removes the bottleneck of generating and transmitting a new tessellation to the graphics card after each modification of a surface by evaluating and trimming the surface on the GPU. To achieve high visual quality, the appearance of a surface can be preserved using texture mapping. Therefore, a texture mapping algorithm for trimmed NURBS surfaces is presented. To reduce the memory requirements for the textures, the algorithm is modified to generate compressed normal maps to preserve the shading of the original surface. Since texturing is only possible, when a parametric mapping of the surface - requiring additional memory - is available, a new simplification and tessellation error measure is introduced that preserves the appearance of the original surface by controlling the deviation of normal vectors. The preservation of normals and possibly other surface attributes allows interactive visualization for quality control applications (e.g. isophotes and reflection lines). In the last part out-of-core techniques for processing and rendering of gigabyte-sized polygonal and trimmed NURBS models are presented. Then the modifications necessary to support streaming of simplified geometry from a central server are discussed and finally and LOD selection algorithm to support interactive rendering of hard and soft shadows is described

Actas do 10º Encontro Português de Computação Gráfica

Actas do 10º Encontro Portugês de Computação Gráfica, Lisboa, 1-3 de Outubro de 2001A investigação, o desenvolvimento e o ensino na área da Computação Gráfica constituem, em Portugal, uma realidade positiva e de largas tradições. O Encontro Português de Computação Gráfica (EPCG), realizado no âmbito das actividades do Grupo Português de Computação Gráfica (GPCG), tem permitido reunir regularmente, desde o 1º EPCG realizado também em Lisboa, mas no já longínquo mês de Julho de 1988, todos os que trabalham nesta área abrangente e com inúmeras aplicações. Pela primeira vez no historial destes Encontros, o 10º EPCG foi organizado em ligação estreita com as comunidades do Processamento de Imagem e da Visão por Computador, através da Associação Portuguesa de Reconhecimento de Padrões (APRP), salientando-se, assim, a acrescida colaboração, e a convergência, entre essas duas áreas e a Computação Gráfica. Este é o livro de actas deste 10º EPCG.INSATUniWebIcep PortugalMicrografAutodes