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Item User-reconfigurable CAD Feature Recognition in 1- and 2-topologies with Reduction of Search Space via Geometry Filters(The Eurographics Association, 2019) Corcho, Juan Camilo Pareja; Acosta, Oscar Mauricio Betancur; Ruiz, Oscar E.; Cadavid, Carlos; Casas, Dan and Jarabo, AdriánIn the context of Computer-Aided Design and Manufacturing, the problem of feature recognition plays a key role in the integration of systems. Until now, compromises have been reached by only using FACE-based geometric information of prismatic CAD models to prune the search domain. This manuscripts presents a feature recognition method which more aggressively prunes the search space with reconfigurable geometric tests. This reconfigurable approach allows to enforce arbitrary confluent tests which are topologic and geometric, with enlarged domain. The test sequence is itself a graph (i.e. not a linear or total-order sequence). Unlike the existing methods which are FACE-based, the present one permits combinations of topologies whose dimensions are 2, 1 or 0. This system has been implemented in an industrial environment. The industrial incarnation allows industry-based customization and is faster when compared to topology-based feature recognition. Future work is required in improving robustness of search conditions and improving the graphic input interface.Item Perfect Spatial Hashing for Point-cloud-to-mesh Registration(The Eurographics Association, 2019) Mejia-Parra, Daniel; Lalinde-Pulido, Juan; Sánchez, Jairo R.; Ruiz-Salguero, Oscar; Posada, Jorge; Casas, Dan and Jarabo, AdriánPoint-cloud-to-mesh registration estimates a rigid transformation that minimizes the distance between a point sample of a surface and a reference mesh of such a surface, both lying in different coordinate systems. Point-cloud-to-mesh-registration is an ubiquitous problem in medical imaging, CAD CAM CAE, reverse engineering, virtual reality and many other disciplines. Common registration methods include Iterative Closest Point (ICP), RANdom SAmple Consensus (RANSAC) and Normal Distribution Transform (NDT). These methods require to repeatedly estimate the distance between a point cloud and a mesh, which becomes computationally expensive as the point set sizes increase. To overcome this problem, this article presents the implementation of a Perfect Spatial Hashing for point-cloud-to-mesh registration. The complexity of the registration algorithm using Perfect Spatial Hashing is O(NYxn) (NY : point cloud size, n: number of max. ICP iterations), compared to standard octrees and kd-trees (time complexity O(NY log(NT)xn), NT : reference mesh size). The cost of pre-processing is O(NT +(N3H )2) (N3H : Hash table size). The test results show convergence of the algorithm (error below 7e-05) for massive point clouds / reference meshes (NY = 50k and NT = 28055k, respectively). Future work includes GPU implementation of the algorithm for fast registration of massive point clouds.Item Visiting Ancient Rome with a Serious Game(The Eurographics Association, 2019) Galí, Carlos; Remolar, Inmaculada; Rebollo, Cristina; Casas, Dan and Jarabo, AdriánThe current rise of video games has made that different fields of research feel attracted to these new technologies in order to enhance their works and make their results more attractive. It is for this reason that so-called serious games have arisen, with different purposes than leisure. Related to this topic, this article presents a serious game that allows the user to build historical cities dated in the ancient Roman era. The game reproduces as accurately as possible the different buildings and constructions of the time, making it possible for the player to create Roman cities in a simple way. Once they are already built, the user can visit them, access to the buildings and be able to interact with the objects and characters that appear. This video game has been addressed to the education field and, to evaluate its quality and usability, several experiments have been carried out taking as sample high school students. Initially, the playability of this serious game has been evaluated and, subsequently, the motivation of the game in learning history. The results obtained support on the one hand the gameplay and attractiveness of the video game, and on the second hand, the increase of the interest of the students in the learning of the history, as well as the greater fixation of different concepts treated in this video game.Item Extending Industrial Digital Twins with Optical Object Tracking(The Eurographics Association, 2017) Tammaro, Antonio; Segura, Álvaro; Moreno, Aitor; Sánchez, Jairo R.; Fco. Javier Melero and Nuria PelechanoIn the last year, the concept of Industry 4.0 and smart factories has increasingly gained more importance. One of the central aspects of this innovation is the coupling of physical systems with a corresponding virtual representation, known as the Digital Twin. This technology enables new powerful applications, such as real-time production optimization or advanced cloud services. To ensure the real-virtual equivalence it is necessary to implement multimodal data acquisition frameworks for each production system using their sensing capabilities, as well as appropriate communication and control architectures. In this paper we extend the concept of the digital twin of a production system adding a virtual representation of its operational environment. In this way the paper describes a proof of concept using an industrial robot, where the objects inside its working volume are captured by an optical tracking system. Detected objects are added to the digital twin model of the cell along with the robot, having in this way a synchronized virtual representation of the complete system that is updated in real time. The paper describes this tracking system as well as the integration of the digital twin in a Web3D based virtual environment that can be accessed from any compatible devices such as PCs, tablets and smartphones.Item Aplicación del motor de videojuegos Unity para la reconstrucción virtual de yacimientos arqueológicos(The Eurographics Association, 2021) Calzado-Martínez, Alberto; García-Fernández, Ángel Luis; Ortega-Alvarado, Lidia M.; Ortega, Lidia M. and Chica, AntonioEn este trabajo se presenta una aplicación desarrollada para enriquecer y ampliar las técnicas actuales de registro arqueológico. Basada en una arquitectura cliente-servidor, se ha utilizado el motor de videojuegos Unity para implementar una aplicación cliente sencilla e intuitiva que permite realizar la reconstrucción virtual de un yacimiento a partir del escaneado 3D in situ del terreno excavado, así como del escaneado 3D en laboratorio de los hallazgos más importantes. Así se consigue preservar la información espacial del yacimiento, y se facilita la visita virtual del mismo desde cualquier equipo conectado a Internet.Item Muscle Simulation with Extended Position Based Dynamics(The Eurographics Association, 2018) Romeo, Marco; Monteagudo, Carlos; Sánchez-Quirós, Daniel; García-Fernández, Ignacio and Ureña, CarlosRecent research on muscle simulation for Visual Effects relies on numerical methods such as the Finite Element Method or Finite Volume Method. These approaches produce realistic results, but require high computational time and are complex to set up. On the other hand Position Based Dynamics offers a fast and controllable solution to simulate surfaces and volumes, but there is no literature on how to implement constraints that could be used to realistically simulate muscles for digital creatures with this method. In this paper we extend the current state-of-the-art in Position Based Dynamics to efficiently compute realistic skeletal-muscle simulation. In particular we embed muscle fibers in the solver by adding an anisotropic component to the distance constraints between mesh points and apply overpressure to realistically model muscle volume changes under contraction. We also present a technique that consistently provides an internal structure for our muscle volumes. We use this structure to preserve the shape and extract relevant information for the activation of the muscle fibers. Finally, we propose a modification of the Extended Position Based Dynamics algorithm and describe other details for proper simulation of character’'s muscle dynamics.Item Sensitivity Analysis in Shape Optimization using Voxel Density Penalization(The Eurographics Association, 2019) Montoya-Zapata, Diego; Acosta, Diego A.; Moreno, Aitor; Posada, Jorge; Ruiz-Salguero, Oscar; Casas, Dan and Jarabo, AdriánShape optimization in the context of technical design is the process by which mechanical demands (e.g. loads, stresses) govern a sequence of piece instances, which satisfy the demands, while at the same time evolving towards more attractive geometric features (e.g. lighter, cheaper, etc.). The SIMP (Solid Isotropic Material with Penalization) strategy seeks a redistribution of local densities of a part in order to stand stress / strain demands. Neighborhoods (e.g. voxels) whose density drifts to lower values are considered superfluous and removed, leading to an optimization of the part shape. This manuscript presents a study on how the parameters governing the voxel pruning affect the convergence speed and performance of the attained shape. A stronger penalization factor establishes the criteria by which thin voxels are considered void. In addition, the filter discourages punctured, chessboard pattern regions. The SIMP algorithm produces a forecasted density map on the whole piece voxels. A post-processing is applied to effectively eliminate voxels with low density, to obtain the effective shape. In the literature, mechanical performance finite element analyses are conducted on the full voxel set with diluted densities by linearly weakening each voxel resistance according to its diluted density. Numerical tests show that this approach predicts a more favorable mechanical performance as compared with the one obtained with the shape which actually lacks the voxels with low density. This voxel density - based optimization is particularly convenient for additive manufacturing, as shown with the piece actually produced in this work. Future endeavors include different evolution processes, albeit based on variable density voxel sets, and mechanical tests conducted on the actual sample produced by additive manufacture.Item A Virtual Reality Front-End for Earthquake Simulation(The Eurographics Association, 2019) Fita, Josep Lluis; Besuievsky, Gonzalo; Patow, Gustavo A.; Casas, Dan and Jarabo, AdriánVirtual Reality has traditionally been used in Cultural Heritage for giving to the final user an immersive experience over recreated scenarios, which usually have been designed and focused on static environment recreation. In spite of its importance for cultural heritage, we have found a lack of virtual reality applications to recreate structural and seismic simulations on historical buildings. In this paper we describe a low-cost virtual reality solution, affordable for all kinds of users that own a smart-phone. Through our application, the users can have an immersive experience that combines the ancient building recreation, its structural simulation and the natural phenomena simulation like earthquakes.Item ISSIGraph: An Open Source Multi-platform C++ Tool for Rapid 2D/3D Wireframe Sketching(The Eurographics Association, 2021) Jiménez de Parga, Carlos; ; Ortega, Lidia M. and Chica, AntonioRapid sketch modelling and Computer-Aided Design (CAD) initiation are increasingly demanded activities in the creative and educational areas. For this reason, this paper presents a cross-platform C++ toolkit with the aim to facilitate the illustration of technical concepts in a fast way using basic quadric objects, Bézier and NURBS surfaces with a wireframe representation. This tool was designed using Software Engineering principles guided by a basic Rational Unified Process (RUP) methodology with the application of the Unified Modelling Language (UML). This tool perfectly works in all computers with very elemental 3D graphics hardware and with OpenGL support. The resulting benchmarks demonstrate that ISSIGraph has a very small CPU footprint that make it suitable for any platform. As a consequence, this application is well suited for rapid 2D/3D project sketching in the creative and engineering fields, as well as an initiation to CAD techniques for students and computer fans.Item A Prototype of a Scalable Multi-GPU Molecular Dynamics Simulator for Large Molecular Systems(The Eurographics Association, 2018) Nicolas-Barreales, Gonzalo; Novalbos, Marcos; Otaduy, Miguel Ángel; Sánchez, Alberto; García-Fernández, Ignacio and Ureña, CarlosParallel architectures, in the form of multi-core or multiple computers, have produced a major impact in the field of information technology. GPU devices, as an extreme example of parallel architectures, have been adapted to enable generic computation in massively parallel architectures. Molecular dynamics is a problem that fits perfectly such architectures, as it relies on the computation of many similar interactions between atoms. Moreover, large molecular systems require resources that exceed those available in a single computer, even multi-GPU computers. Therefore, the ideal architecture to simulate molecular dynamics is a distributed multi-GPU cluster, which consists of multiple interconnected computers with one or more GPUs each. A molecular dynamics simulation usually needs days, and even weeks of computation time to produce results that represent only a few microseconds of atom interactions. In contrast, distributed multi-GPU clusters allows us to develop an efficient and scalable simulator. This paper aims to develop a prototype of a molecular dynamics simulator for large molecular systems. It uses the GPU as the main computing device, using only the CPU to control the workflow. We have implemented parallel processing techniques to develop a fully scalable system.