Implicit Decals: Interactive Editing of Repetitive Patterns on Surfaces

11 pagesInternational audienceTexture mapping is an essential component for creating 3D models and is widely used in both the game and the movie industries. Creating texture maps has always been a complex task and existing methods carefully balance flexibility with ease of use. One difficulty in using texturing is the repeated placement of individual textures over larger areas. In this paper we propose a method which uses decals to place images onto a model. Our method allows the decals to compete for space and to deform as they are being pushed by other decals. A spherical field function is used to determine the position and the size of each decal and the deformation applied to fit the decals. The decals may span multiple objects with heterogeneous representations. Our method does not require an explicit parameterization of the model. As such, varieties of patterns including repeated patterns like rocks, tiles, and scales can be mapped. We have implemented the method using the GPU where placement, size, and orientation of thousands of decals are manipulated in real time

A new construction of smooth surfaces from triangle meshes using parametric pseudo-manifolds

We introduce a new manifold-based construction for fitting a smooth surface to a triangle mesh of arbitrary topology. Our construction combines in novel ways most of the best features of previous constructions and, thus, it fills the gap left by them. We also introduce a theoretical framework that provides a sound justification for the correctness of our construction. Finally, we demonstrate the effectiveness of our manifold-based construction with a few concrete examples

A new construction of smooth surfaces from triangle meshes using parametric pseudo-manifolds

We introduce a new manifold-based construction for fitting a smooth surface to a triangle mesh of arbitrary topology. Our construction combines in novel ways most of the best features of previous constructions and, thus, it fills the gap left by them. We also introduce a theoretical framework that provides a sound justification for the correctness of our construction. Finally, we demonstrate the effectiveness of our manifold-based construction with a few concrete examples

Modified half-edge data structure and its applications to 3D mesh generation for complex tube networks.

In computer graphics 3D mesh generation is an important topic, it is required for a vast number of applications. While there are currently solutions available for the generation of meshes, there is not one that suits our application well that is written in C#, for this reason a C# implementation of the half-edge data structure as well as a C# implementation of the mesh generation algorithms is needed. This document will discuss in detail the method by which the algorithms are implemented, the improvements that are made on the half-edge data structure, and the new features that have been added to the new application. Further this document will evaluate the performance improvement made by the improvements mentioned

3D Reconstruction Using High Resolution Implicit Surface Representations and Memory Management Strategies

La disponibilité de capteurs de numérisation 3D rapides et précis a permis de capturer de très grands ensembles de points à la surface de différents objets qui véhiculent la géométrie des objets. La métrologie appliquée consiste en l'application de mesures dans différents domaines tels que le contrôle qualité, l'inspection, la conception de produits et la rétroingénierie. Une fois que le nuage de points 3D non organisés couvrant toute la surface de l'objet a été capturé, un modèle de la surface doit être construit si des mesures métrologiques doivent être effectuées sur l'objet. Dans la reconstruction 3D en temps réel, à l'aide de scanners 3D portables, une représentation de surface implicite très efficace est le cadre de champ vectoriel, qui suppose que la surface est approchée par un plan dans chaque voxel. Le champ vectoriel contient la normale à la surface et la matrice de covariance des points tombant à l'intérieur d'un voxel. L'approche globale proposée dans ce projet est basée sur le cadre Vector Field. Le principal problème abordé dans ce projet est la résolution de l'incrément de consommation de mémoire et la précision du modèle reconstruit dans le champ vectoriel. Ce tte approche effectue une sélection objective de la taille optimale des voxels dans le cadre de champ vectoriel pour maintenir la consommation de mémoire aussi faible que possible et toujours obtenir un modèle précis de la surface. De plus, un ajustement d e surface d'ordre élevé est utilisé pour augmenter la précision du modèle. Étant donné que notre approche ne nécessite aucune paramétrisation ni calcul complexe, et qu'au lieu de travailler avec chaque point, nous travaillons avec des voxels dans le champ vectoriel, cela réduit la complexité du calcul.The availability of fast and accurate 3D scanning sensors has made it possible to capture very large sets of points at the surface of different objects that convey the geometry of the objects. A pplied metrology consists in the application of measurements in different fields such as quality control, inspection, product design and reverse engineering. Once the cloud of unorganized 3D points covering the entire surface of the object has been capture d, a model of the surface must be built if metrologic measurements are to be performed on the object. In realtime 3D reconstruction, using handheld 3D scanners a very efficient implicit surface representation is the Vector Field framework, which assumes that the surface is approximated by a plane in each voxel. The vector field contains the normal to the surface and the covariance matrix of the points falling inside a voxel. The proposed global approach in this project is based on the Vector Field framew ork. The main problem addressed in this project is solving the memory consumption increment and the accuracy of the reconstructed model in the vector field. This approach performs an objective selection of the optimal voxels size in the vector field frame work to keep the memory consumption as low as possible and still achieve an accurate model of the surface. Moreover, a highorder surface fitting is used to increase the accuracy of the model. Since our approach do not require any parametrization and compl ex calculation, and instead of working with each point we are working with voxels in the vector field, then it reduces the computational complexity

Augmented Reality Markerless Multi-Image Outdoor Tracking System for the Historical Buildings on Parliament Hill

[EN] Augmented Reality (AR) applications have experienced extraordinary growth recently, evolving into a well-established method for the dissemination and communication of content related to cultural heritage¿including education. AR applications have been used in museums and gallery exhibitions and virtual reconstructions of historic interiors. However, the circumstances of an outdoor environment can be problematic. This paper presents a methodology to develop immersive AR applications based on the recognition of outdoor buildings. To demonstrate this methodology, a case study focused on the Parliament Buildings National Historic Site in Ottawa, Canada has been conducted. The site is currently undergoing a multiyear rehabilitation program that will make access to parts of this national monument inaccessible to the public. AR experiences, including simulated photo merging of historic and present content, are proposed as one tool that can enrich the Parliament Hill visit during the rehabilitation. Outdoor AR experiences are limited by factors, such as variable lighting (and shadows) conditions, caused by changes in the environment (objects height and orientation, obstructions, occlusions), the weather, and the time of day. This paper proposes a workflow to solve some of these issues from a multi-image tracking approach.This work has been developed under the framework of the New Paradigms/New Tools for Heritage Conservation in Canada, a project funded through the Social Sciences and Humanities Research Council of Canada (SSHRC).Blanco-Pons, S.; Carrión-Ruiz, B.; Duong, M.; Chartrand, J.; Fai, S.; Lerma, JL. (2019). Augmented Reality Markerless Multi-Image Outdoor Tracking System for the Historical Buildings on Parliament Hill. Sustainability. 11(16):1-15. https://doi.org/10.3390/su11164268S1151116Bekele, M. K., Pierdicca, R., Frontoni, E., Malinverni, E. S., & Gain, J. (2018). A Survey of Augmented, Virtual, and Mixed Reality for Cultural Heritage. Journal on Computing and Cultural Heritage, 11(2), 1-36. doi:10.1145/3145534Gimeno, J., Portalés, C., Coma, I., Fernández, M., & Martínez, B. (2017). Combining traditional and indirect augmented reality for indoor crowded environments. A case study on the Casa Batlló museum. Computers & Graphics, 69, 92-103. doi:10.1016/j.cag.2017.09.001Kolivand, H., El Rhalibi, A., Shahrizal Sunar, M., & Saba, T. (2018). ReVitAge: Realistic virtual heritage taking shadows and sky illumination into account. Journal of Cultural Heritage, 32, 166-175. doi:10.1016/j.culher.2018.01.020Amakawa, J., & Westin, J. (2017). New Philadelphia: using augmented reality to interpret slavery and reconstruction era historical sites. International Journal of Heritage Studies, 24(3), 315-331. doi:10.1080/13527258.2017.1378909Kim, J.-B., & Park, C. (2011). Development of Mobile AR Tour Application for the National Palace Museum of Korea. Lecture Notes in Computer Science, 55-60. doi:10.1007/978-3-642-22021-0_7Barrile, V., Fotia, A., Bilotta, G., & De Carlo, D. (2019). Integration of geomatics methodologies and creation of a cultural heritage app using augmented reality. Virtual Archaeology Review, 10(20), 40. doi:10.4995/var.2019.10361Analysis of Tracking Accuracy for Single-Camera Square-Marker-Based Tracking. In Third Workshop on Virtual and Augmented Reality of the GI-Fachgruppe VR/AR, Koblenz, Germany, 2006http://campar.in.tum.de/Chair/PublicationDetail?pub=pentenrieder2006giCirulis, A., & Brigmanis, K. B. (2013). 3D Outdoor Augmented Reality for Architecture and Urban Planning. Procedia Computer Science, 25, 71-79. doi:10.1016/j.procs.2013.11.009You, S., Neumann, U., & Azuma, R. (1999). Orientation tracking for outdoor augmented reality registration. IEEE Computer Graphics and Applications, 19(6), 36-42. doi:10.1109/38.799738Wither, J., Tsai, Y.-T., & Azuma, R. (2011). Indirect augmented reality. Computers & Graphics, 35(4), 810-822. doi:10.1016/j.cag.2011.04.010Radkowski, R., & Oliver, J. (2013). Natural Feature Tracking Augmented Reality for On-Site Assembly Assistance Systems. Lecture Notes in Computer Science, 281-290. doi:10.1007/978-3-642-39420-1_30Rao, J., Qiao, Y., Ren, F., Wang, J., & Du, Q. (2017). A Mobile Outdoor Augmented Reality Method Combining Deep Learning Object Detection and Spatial Relationships for Geovisualization. Sensors, 17(9), 1951. doi:10.3390/s17091951Hoppe, H., DeRose, T., Duchamp, T., McDonald, J., & Stuetzle, W. (1993). Mesh optimization. Proceedings of the 20th annual conference on Computer graphics and interactive techniques - SIGGRAPH ’93. doi:10.1145/166117.166119Rossignac, J., & Borrel, P. (1993). Multi-resolution 3D approximations for rendering complex scenes. Modeling in Computer Graphics, 455-465. doi:10.1007/978-3-642-78114-8_29Gross, M. H., Staadt, O. G., & Gatti, R. (1996). Efficient triangular surface approximations using wavelets and quadtree data structures. IEEE Transactions on Visualization and Computer Graphics, 2(2), 130-143. doi:10.1109/2945.506225Botsch, M., Pauly, M., Rossl, C., Bischoff, S., & Kobbelt, L. (2006). Geometric modeling based on triangle meshes. ACM SIGGRAPH 2006 Courses on - SIGGRAPH ’06. doi:10.1145/1185657.1185839Pietroni, N., Tarini, M., & Cignoni, P. (2010). Almost Isometric Mesh Parameterization through Abstract Domains. IEEE Transactions on Visualization and Computer Graphics, 16(4), 621-635. doi:10.1109/tvcg.2009.96Khan, D., Yan, D.-M., Ding, F., Zhuang, Y., & Zhang, X. (2018). Surface remeshing with robust user-guided segmentation. Computational Visual Media, 4(2), 113-122. doi:10.1007/s41095-018-0107-yGuidi, G., Russo, M., Ercoli, S., Remondino, F., Rizzi, A., & Menna, F. (2009). A Multi-Resolution Methodology for the 3D Modeling of Large and Complex Archeological Areas. International Journal of Architectural Computing, 7(1), 39-55. doi:10.1260/147807709788549439Remondino, F., & El-Hakim, S. (2006). Image-based 3D Modelling: A Review. The Photogrammetric Record, 21(115), 269-291. doi:10.1111/j.1477-9730.2006.00383.xBruno, F., Bruno, S., De Sensi, G., Luchi, M.-L., Mancuso, S., & Muzzupappa, M. (2010). From 3D reconstruction to virtual reality: A complete methodology for digital archaeological exhibition. Journal of Cultural Heritage, 11(1), 42-49. doi:10.1016/j.culher.2009.02.006Unity, The Photogrammetry Workflowhttps://unity.com/solutions/photogrammetry.Blanco, S., Carrión, B., & Lerma, J. L. (2016). REVIEW OF AUGMENTED REALITY AND VIRTUAL REALITY TECHNIQUES IN ROCK ART. Proceedings of the ARQUEOLÓGICA 2.0 8th International Congress on Archaeology, Computer Graphics, Cultural Heritage and Innovation. doi:10.4995/arqueologica8.2016.3561Behzadan, A. H., & Kamat, V. R. (2010). Scalable Algorithm for Resolving Incorrect Occlusion in Dynamic Augmented Reality Engineering Environments. Computer-Aided Civil and Infrastructure Engineering, 25(1), 3-19. doi:10.1111/j.1467-8667.2009.00601.xTian, Y., Long, Y., Xia, D., Yao, H., & Zhang, J. (2015). Handling occlusions in augmented reality based on 3D reconstruction method. Neurocomputing, 156, 96-104. doi:10.1016/j.neucom.2014.12.081Tian, Y., Guan, T., & Wang, C. (2010). Real-Time Occlusion Handling in Augmented Reality Based on an Object Tracking Approach. Sensors, 10(4), 2885-2900. doi:10.3390/s10040288

Analysis and Development of Augmented Reality Applications for the Dissemination of Cultural Heritage

Tesis por compendio[ES] La RA consiste en la superposición de elementos virtuales sobre el entorno real, de manera que el usuario percibe estos elementos como si formaran parte de la realidad que está visualizando. Las aplicaciones de RA en dispositivos móviles permiten visualizar el contenido virtual a través de la cámara del dispositivo. La RA es una herramienta de divulgación muy potente ya que permite añadir a la realidad cualquier tipo de información, desde un simple texto informativo a un modelo 3D interactivo. Tiene infinitas utilidades, puede servir de guía en un museo, puede mostrar la recreación de un monumento destruido, o como en el caso de estudio aquí presentado, ayudar a la interpretación de pinturas rupestres. Esta tesis parte de la idea de que la RA puede mejorar mucho la interpretación del arte rupestre sin alterar ni dañar las pinturas. Puede servir para atraer a un público mayor, dar a conocer la historia de las pinturas rupestres y que al mismo tiempo el visitante tenga una experiencia mucho más enriquecedora. A lo largo de la tesis se ha estudiado en profundidad la técnica de visualización de RA mediante dispositivos móviles. Se han analizado las diferentes librerías de programación mediante casos de estudio en entornos reales y examinado los factores que pueden afectar al reconocimiento de las pinturas. Se ha desarrollado una aplicación de RA aplicada a un caso real de pinturas rupestres y posteriormente ha sido evaluada por un grupo de personas. Finalmente, se ha estudiado el efecto de la luz solar y sus cambios a lo largo del día sobre el reconocimiento de imágenes en entornos al aire libre. Este trabajo proporciona un punto de partida para el desarrollo de aplicaciones de RA aplicadas a la difusión del patrimonio cultural, especialmente centrado en el arte rupestre, un entorno que sufre de unas dificultades añadidas debido a su localización, dificultad de reconocimiento de puntos característicos en las pinturas y los cambios en la luz solar, problemas que se han tratado de resolver a lo largo del estudio. Las principales conclusiones han sido muy favorables, partiendo de librerías de programación disponibles y gratuitas. Se han podido desarrollar un conjunto de aplicaciones de RA en diferentes lugares. Las valoraciones han sido muy positivas, los usuarios que han probado las aplicaciones afirman que la interpretación de las pinturas les resulta más fácil y consiguen entender mejor el propósito de las mismas. El principal inconveniente encontrado es la falta de conocimiento sobre esta técnica y la pérdida de realismo en algunos casos debido a la oclusión, es decir, que los objetos virtuales no se posicionen por detrás de los objetos reales. La buena noticia es que esta tecnología evoluciona muy rápido y durante el desarrollo de la tesis ha habido avances muy grandes, entre ellos, el desarrollo de nuevas librerías de programación desarrolladas por Google y Apple, que proporcionan las herramientas necesarias para crear aplicaciones muy potentes e immersivas, donde el usuario se sentirá parte de los entornos creados.[CA] La RA consisteix en la superposició d'elements virtuals sobre l'entorn real, de manera que l'usuari percep aquests elements com si formaren part de la realitat que està visualitzant. Les aplicacions de RA en dispositius mòbils permeten visualitzar el contingut virtual a través de la cambra del dispositiu. La RA és una eina de divulgació molt potent ja que permet afegir a la realitat qualsevol tipus d'informació, des d'un simple text informatiu a un model 3D interactiu. Té infinites utilitats, pot servir de guia en un museu, pot mostrar la recreació d'un monument destruït, o com en el cas d'estudi ací presentat, ajudar a la interpretació de pintures rupestres. Aquesta tesi parteix de la idea que la RA pot millorar molt la interpretació de l'art rupestre sense alterar ni danyar les pintures. Pot servir per a atraure a un públic major, donar a conéixer la història de les pintures rupestres i que al mateix temps el visitant tinga una experiència molt més enriquidora. Al llarg de la tesi s'ha estudiat en profunditat la tècnica de visualització de RA mitjançant dispositius mòbils. S'han analitzat les diferents llibreries de programació mitjançant casos d'estudi en entorns reals i analitzat els factors que poden afectar el reconeixement de les pintures. S'ha desenvolupat una aplicació de RA aplicada a un cas real de pintures rupestres i posteriorment ha sigut avaluada per un grup de persones. Finalment, s'ha estudiat l'efecte de la llum solar i els seus canvis al llarg del dia sobre el reconeixement d'imatges en entorns a l'aire lliure. Aquest treball proporciona un punt de partida per al desenvolupament d'aplicacions de RA aplicades a la difusió del patrimoni cultural, especialment centrat en l'art rupestre, un entorn que pateix d'unes dificultats afegides a causa de la seua localització, dificultat de reconeixement de punts característics en les pintures i els canvis en la llum solar, problemes que s'han tractat de resoldre al llarg de l'estudi. Les principals conclusions han sigut molt favorables, partint de llibreries de programació disponibles i gratuïtes. S'han pogut desenvolupar un conjunt d'aplicacions de RA en diferents llocs. Les valoracions han sigut molt positives, els usuaris que han provat les aplicacions afirmen que la interpretació de les pintures els resulta més fàcil i aconsegueixen entendre millor el propòsit d'aquestes. El principal inconvenient trobat és la falta de coneixement sobre aquesta tècnica i la perduda de realisme en alguns casos a causa de l'oclusió, és a dir, que els objectes virtuals no es posicionen per darrere dels objectes reals. La bona notícia és que aquesta tecnologia evoluciona molt ràpid i durant el desenvolupament de la tesi hi ha hagut avanços molt grans, entre ells, el desenvolupament de noves llibreries de programació per Google i Apple, que proporcionen les eines necessàries per a crear aplicacions molt potents i immersives, on l'usuari se sentirà part dels entorns creats.[EN] AR consists of superimposing virtual elements on the real environment, so that the user perceives these elements as if they were part of the reality they are looking at. AR applications on smartphones allow virtual content to be visualised through the device's camera. AR is a very powerful tool for dissemination as it allows any type of information to be added to reality, from a simple informative text to an interactive 3D model. It can be used as a guide in a museum, it can show the recreation of a destroyed monument, or, as in the case study presented here, it can help in the interpretation of cave paintings. This thesis is based on the idea that AR can greatly enhance the interpretation of rock art without affecting or damaging the paintings. It can be used to attract a wider audience, to introduce the history of the rock art paintings and at the same time provide the visitor with a much more enriching experience. Throughout the thesis, the technique of AR visualisation using mobile devices has been studied in-depth. The different programming libraries have been analysed by means of case studies in real environments as well as the factors that can affect the paintings recognition. An AR application applied to a real case of rock art paintings has been developed and subsequently evaluated by a group of people. Finally, the effect of sunlight and its changes throughout the day on image recognition in outdoor environments has been studied. This work provides a starting point for the AR applications development applied to the dissemination of cultural heritage, especially focused on rock art, an environment that suffers from additional difficulties due to its location, the difficulty of characteristic points recognition and changes in sunlight, problems that have been tried to solve throughout the study. The main outcomes have been very favourable, using freely available programming libraries, and it has been possible to develop a set of AR applications in different places. The evaluations have been very positive, with users who have tested the applications confirming that the interpretation of the paintings is easier for them and they can better understand the purpose of the paintings. The major drawback is the lack of knowledge about this technique and the loss of realism in some cases due to occlusion, i.e. the virtual objects are not positioned behind the real objects. The good news is that this technology is evolving very fast and during the development of the thesis there have been great advances, among them, the development of new programming libraries developed by Google and Apple, which provide the necessary tools to create very powerful and immersive applications, where the user will feel part of the virtual environments created.Blanco Pons, S. (2021). Analysis and Development of Augmented Reality Applications for the Dissemination of Cultural Heritage [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/178895TESISCompendi

High-Quality Simplification and Repair of Polygonal Models

Because of the rapid evolution of 3D acquisition and modelling methods, highly complex and detailed polygonal models with constantly increasing polygon count are used as three-dimensional geometric representations of objects in computer graphics and engineering applications. The fact that this particular representation is arguably the most widespread one is due to its simplicity, flexibility and rendering support by 3D graphics hardware. Polygonal models are used for rendering of objects in a broad range of disciplines like medical imaging, scientific visualization, computer aided design, film industry, etc. The handling of huge scenes composed of these high-resolution models rapidly approaches the computational capabilities of any graphics accelerator. In order to be able to cope with the complexity and to build level-of-detail representations, concentrated efforts were dedicated in the recent years to the development of new mesh simplification methods that produce high-quality approximations of complex models by reducing the number of polygons used in the surface while keeping the overall shape, volume and boundaries preserved as much as possible. Many well-established methods and applications require "well-behaved" models as input. Degenerate or incorectly oriented faces, T-joints, cracks and holes are just a few of the possible degenaracies that are often disallowed by various algorithms. Unfortunately, it is all too common to find polygonal models that contain, due to incorrect modelling or acquisition, such artefacts. Applications that may require "clean" models include finite element analysis, surface smoothing, model simplification, stereo lithography. Mesh repair is the task of removing artefacts from a polygonal model in order to produce an output model that is suitable for further processing by methods and applications that have certain quality requirements on their input. This thesis introduces a set of new algorithms that address several particular aspects of mesh repair and mesh simplification. One of the two mesh repair methods is dealing with the inconsistency of normal orientation, while another one, removes the inconsistency of vertex connectivity. Of the three mesh simplification approaches presented here, the first one attempts to simplify polygonal models with the highest possible quality, the second, applies the developed technique to out-of-core simplification, and the third, prevents self-intersections of the model surface that can occur during mesh simplification

Estudos de métodos de esqueletização de formas 3D

Trabalho de Conclusão de Curso (Graduação)Este projeto apresenta um estudo sobre métodos de esqueletização de objetos tridimensionais. O processo de esqueletização busca extrair de um objeto 3D o seu esqueleto, que pode ser definido como uma estrutura curva semelhante a um grafo e capaz de descrever a topologia deste objeto de maneira simples e compacta. Esta estrutura possui diversas aplicações como animação na área de computação gráfica, comparação entre objetos com o objetivo de medir similaridade, segmentação de objetos e até mesmo reconstituição da superfície do objeto 3D