Ptex system for advanced texture mapping

Ptex is a texture mapping method. It’s main advantage is the elimination of UV mapping process by storing separate texture for each face. Ptex deals with the filtering across face boundaries, which makes all the little separate textures look seamless, as if they were one big texture. Ptex file format can efficiently store hundreds of thousands of images into a single file. Ptex API is released as open source, written in C++, which enables implementation of Ptex in various programs. This paper analyses advantages and drawbacks of this system and examines if Ptex is today usable outside of big production studios. Analysis leads us to a conclusion that Ptex can already be used by individuals outside of big production studios

VARIABLE LEVEL OF DETAIL IN ARCHAEOLOGICAL 3D MODELS OBTAINED THROUGH A DIGITAL SURVEY

[EN] This paper focuses on the use of information technologies in the field of archaeological representation. It is part of a series of studies on the VillaAdriana in Tivoli which have led us to investigate the decoration of the Maritime Theatre (Emperor Hadrian¿s personal residence) and other famous archaeological structures located within this UNESCO World Heritage listed site. The richness of detail that characterise the curved entablature pieces of this landmark building stimulated our research team 1 to develop new methods of representation, allowing the interactive assembling of digital models of a high geometric detail obtained by means of laser scanning. This article explains a new methodology for optimising digital survey data in the archaeological field which has previously been developed in other research sectors but not yet implemented in digital survey programs.[ES] Esta contribución, centrada en el uso de tecnologías informáticas para la representación, forma parte de una serie de estudios sobre la Villa Adriana en Tívoli, que nos han llevado a investigar la decoración del Teatro Marítimo, residencia personal del Emperador Adriano, así como otras famosas arquitecturas de este conjunto arqueológico perteneciente a la Lista del Patrimonio Mundial. La riqueza de detalles que caracteriza a las piezas del entablamento curvo de este emblemático edificio ha estimulado a nuestro equipo de investigación 1 para desarrollar nuevos métodos de representación, que permitan el uso interactivo de modelos digitales de alto detalle geométrico obtenidos con escáner laser. En este artículo se explicará una nueva metodología de optimización de los datos de levantamiento digital en el campo arqueológico, desarrollado en otros sectores de investigación, y que todavía no se han incluido en los programas para el levantamiento con escáner.Fantini, F. (2012). MODELOS CON NIVEL DE DETALLE VARIABLE REALIZADOS MEDIANTE UN LEVANTAMIENTO DIGITAL APLICADOS A LA ARQUEOLOGÍA. EGA. Revista de Expresión Gráfica Arquitectónica. 17(19):306-317. doi:10.4995/ega.2012.1383SWORD3063171719Adembri, B., 2010. La decorazione architettonica del Teatro Marittimo. En: Marina Sapelli Ragni, ed. 2010.Villa Adriana. Una storia mai finita. Electa, Milano, 2010.Apollonio, I., Gaiani, M., Manfredini, A.M., 2010. Modellazione semantica metodi a multirisoluzione. En: Benedetti, B., Gaiani, M., Remondino, F., ed. 2010. Modelli digitali 3D in archeologia: il caso di Pompei. Pisa. Edizioni della Normale.Battini, C., Fantini, F., 2007. Clouds and clay. Superfici di suddivisione e ottimizzazione. En: L. De Carlo, ed. 2007. Informatica e fondamenti scientifici della rappresentazione. Roma. Gangemi.Di Tondo, S., 2010. Modelli digitali per la comprensione dell'aspetto originario del manufatto: architettura e apparato decorativo del Teatro Marittimo a Villa Adriana. En: Mandelli, E., Velo, U.,ed. 2010. Il modello in architettura, cultura scientifica e rappresentazione. Firenze. Alinea.Gaiani, M., ed. 2006, La rappresentazione riconfigurata. Milano, Edizioni POLI.design.Guidi, G., Russo, M., Beraldin, J.A., 2010. Acquisizione 3D e modellazione poligonale. Milano. McGraw-Hill.Juan Vidal, F., Merlo, A., 2008. Nuevas aplicaciones del levantamiento integrado (rilievo). Arché, 2008, 3, p. 307-318.Lee, A., Moreton, H., & Hoppe, H. (2000). Displaced subdivision surfaces. Proceedings of the 27th annual conference on Computer graphics and interactive techniques - SIGGRAPH ’00. doi:10.1145/344779.344829Lévy, B. (2001). Constrained texture mapping for polygonal meshes. Proceedings of the 28th annual conference on Computer graphics and interactive techniques - SIGGRAPH ’01. doi:10.1145/383259.383308Migliari, R., ed. 2008, Prospettiva dinamica interattiva, la tecnologia dei videogiochi per l'esplorazione di modelli 3D di architettura. Roma, Edizioni Kappa.Piponi, D., & Borshukov, G. (2000). Seamless texture mapping of subdivision surfaces by model pelting and texture blending. Proceedings of the 27th annual conference on Computer graphics and interactive techniques - SIGGRAPH ’00. doi:10.1145/344779.34499

Constrained Texture Mapping And Foldover-free Condition

Texture mapping has been widely used in image processing and graphics to enhance the realism of CG scenes. However to perfectly match the feature points of a 3D model with the corresponding pixels in texture images, the parameterisation which maps a 3D mesh to the texture space must satisfy the positional constraints. Despite numerous research efforts, the construction of a mathematically robust foldover-free parameterisation subject to internal constraints is still a remaining issue. In this paper, we address this challenge by developing a two-step parameterisation method. First, we produce an initial parameterisation with a method traditionally used to solve structural engineering problems, called the bar-network. We then derive a mathematical foldover-free condition, which is incorporated into a Radial Basis Function based scheme. This method is therefore able to guarantee that the resulting parameterization meets the hard constraints without foldovers

An RBF-based reparameterization method for constrained texture mapping

Texture mapping has long been used in computer graphics to enhance the realism of virtual scenes. However, to match the 3D model feature points with the corresponding pixels in a texture image, surface parameterization must satisfy specific positional constraints. However, despite numerous research efforts, the construction of a mathematically robust, foldover‐free parameterization that is subject to positional constraints continues to be a challenge. In the present paper, this foldover problem is addressed by developing radial basis function (RBF) based reparameterization. Given initial 2D embedding of a 3D surface, the proposed method can reparameterize 2D embedding into a foldover ‐free 2D mesh, satisfying a set of user‐specified constraint points. In addition, this approach is mesh‐free. Therefore, generating smooth texture mapping results is possible without extra smoothing optimization

Tiled texture synthesis

In this thesis a new image-based texturing method has been developed. This new method allows users to synthesize tiled textures that can be mapped to any quadrilateral mesh without discontinuity or singularity. An interface has been developed that allows user control over out put textures. Three methods have been included in the interface to create a periodic looking texture for 3D models and two methods have been developed to create wallpaper images (repeating textures on a 2D surface). Using these texturing methods, texturing problems are simplified, and more time can be spent solving artistic problems

What you seam is what you get

3D paint systems opened the door to new texturing tools, directly operating on 3D objects. However, although time and effort was devoted to mesh parameterization, UV unwrapping is still known to be a tedious and time-consuming process in Computer Graphics production. We think that this is mainly due to the lack of well-adapted segmentation method. To make UV unwrapping easier, we propose a new system, based on three components : * A novel spectral segmentation method that proposes reasonable initial seams to the user; * Several tools to edit and constrain the seams. During editing, a parameterization is interactively updated, allowing for direct feedback. Our interactive constrained parameterization method is based on simple (yet original) modifications of the ABF++ method, that make it behave as an interactive constraint solver; * A method to map the two halves of symmetric objects to the same texels in UV space, thus halving texture memory requirements for symmetric objects

3D photogrammetric data modeling and optimization for multipurpose analysis and representation of Cultural Heritage assets

This research deals with the issues concerning the processing, managing, representation for further dissemination of the big amount of 3D data today achievable and storable with the modern geomatic techniques of 3D metric survey. In particular, this thesis is focused on the optimization process applied to 3D photogrammetric data of Cultural Heritage assets. Modern Geomatic techniques enable the acquisition and storage of a big amount of data, with high metric and radiometric accuracy and precision, also in the very close range field, and to process very detailed 3D textured models. Nowadays, the photogrammetric pipeline has well-established potentialities and it is considered one of the principal technique to produce, at low cost, detailed 3D textured models. The potentialities offered by high resolution and textured 3D models is today well-known and such representations are a powerful tool for many multidisciplinary purposes, at different scales and resolutions, from documentation, conservation and restoration to visualization and education. For example, their sub-millimetric precision makes them suitable for scientific studies applied to the geometry and materials (i.e. for structural and static tests, for planning restoration activities or for historical sources); their high fidelity to the real object and their navigability makes them optimal for web-based visualization and dissemination applications. Thanks to the improvement made in new visualization standard, they can be easily used as visualization interface linking different kinds of information in a highly intuitive way. Furthermore, many museums look today for more interactive exhibitions that may increase the visitors’ emotions and many recent applications make use of 3D contents (i.e. in virtual or augmented reality applications and through virtual museums). What all of these applications have to deal with concerns the issue deriving from the difficult of managing the big amount of data that have to be represented and navigated. Indeed, reality based models have very heavy file sizes (also tens of GB) that makes them difficult to be handled by common and portable devices, published on the internet or managed in real time applications. Even though recent advances produce more and more sophisticated and capable hardware and internet standards, empowering the ability to easily handle, visualize and share such contents, other researches aim at define a common pipeline for the generation and optimization of 3D models with a reduced number of polygons, however able to satisfy detailed radiometric and geometric requests. iii This thesis is inserted in this scenario and focuses on the 3D modeling process of photogrammetric data aimed at their easy sharing and visualization. In particular, this research tested a 3D models optimization, a process which aims at the generation of Low Polygons models, with very low byte file size, processed starting from the data of High Poly ones, that nevertheless offer a level of detail comparable to the original models. To do this, several tools borrowed from the game industry and game engine have been used. For this test, three case studies have been chosen, a modern sculpture of a contemporary Italian artist, a roman marble statue, preserved in the Civic Archaeological Museum of Torino, and the frieze of the Augustus arch preserved in the city of Susa (Piedmont- Italy). All the test cases have been surveyed by means of a close range photogrammetric acquisition and three high detailed 3D models have been generated by means of a Structure from Motion and image matching pipeline. On the final High Poly models generated, different optimization and decimation tools have been tested with the final aim to evaluate the quality of the information that can be extracted by the final optimized models, in comparison to those of the original High Polygon one. This study showed how tools borrowed from the Computer Graphic offer great potentialities also in the Cultural Heritage field. This application, in fact, may meet the needs of multipurpose and multiscale studies, using different levels of optimization, and this procedure could be applied to different kind of objects, with a variety of different sizes and shapes, also on multiscale and multisensor data, such as buildings, architectural complexes, data from UAV surveys and so on