CEIG18

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https://diglib.eg.org/handle/10.2312/2632545

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3D Mapping Approach to Analyze the Evolution of Vegetation Using Multispectral Imagery
(The Eurographics Association, 2018) Jurado, Juan Manuel; Ortega, Lidia; Feito, Francisco Ramón; García-Fernández, Ignacio and Ureña, Carlos
The 3D simulation for the evolution process of crop types requires the management of large volume of data to make an accurate analysis of functional and structural vegetation characteristics. In fact, current geomatics technologies allow the capture of massive and heterogeneous data with a great spatial resolution. Regarding research advances for precision agriculture applications Unmanned Aerial Vehicles (UAV)-based remote sensing offers great possibilities to acquire field data in a fast and reliable way. The main aim of this paper is twofold: (1) the study of multispectral imaging from UAVs for reflectance maps calculation, (2) 3D mapping and modeling using RGB and multispectral imagery in order to create a 3D NDVI (Normalized Difference Vegetation Index) point cloud. We are focussed on 4D inspection of olive trees including spatio-temporal data for reflectance change detection in multispectral remote sensing images.
Blast Features and Requirements for Fracturing Osseous Models
(The Eurographics Association, 2018) Pérez, Francisco Daniel; Jiménez, Juan José; Jiménez, Juan Roberto; García-Fernández, Ignacio and Ureña, Carlos
Fracturing osseous models is a challenge in computer graphics. The generation of bone fractures is important in the field of traumatology mainly for training. This field of research can provide specialists with a rich and varied amount of fracture cases. Traditionally, the generation of bone fractures has been carried out by using a finite element method (FEM) approach. Nevertheless, this approach requires a precise physical information of the model and the incoming forces that are not usually available. Thus, we propose a geometric approach to avoid these initial requirements. This paper evaluates the adequacy of a given generic destruction library (Blast) within the bone fracture generation context. Our aim is to assess its suitability to provide varied, uncommon cases and morphologically rich fractures in the field of bone fractures. In order to achieve quality results, bone models are evaluated at different scales, spanning from the macroscale to the nanoscale. This study highlights the advantages and shortcomings of the revised library. Additionally, it provides a groundwork for the use of this library in the context of fracturing osseous models as well as a set of addons needed to get a tool specifically designed for this aim.
CEIG 2018: Frontmatter
(Eurographics Association, 2018) García-Fernández, Ignacio; Ureña, Carlos; García-Fernández, Ignacio; Ureña, Carlos
Depth Map Repairing for Building Reconstruction
(The Eurographics Association, 2018) Andújar, Carlos; Argudo, Oscar; Besora, Isaac; Brunet, Pere; Chica, Antoni; Comino Trinidad, Marc; García-Fernández, Ignacio and Ureña, Carlos
Structure-from-motion along with multi-view stereo techniques jointly allow for the inexpensive scanning of 3D objects (e.g. buildings) using just a collection of images taken from commodity cameras. Despite major advances in these fields, a major limitation of dense reconstruction algorithms is that correct depth/normal values are not recovered on specular surfaces (e.g. windows) and parts lacking image features (e.g. flat, textureless parts of the facade). Since these reflective properties are inherent to the surface being acquired, images from different viewpoints hardly contribute to solve this problem. In this paper we present a simple method for detecting, classifying and filling non-valid data regions in depth maps produced by dense stereo algorithms. Triangles meshes reconstructed from our repaired depth maps exhibit much higher quality than those produced by state-of-the-art reconstruction algorithms like Screened Poisson-based techniques.
Design and Implementation of a Volumetric Merging Tool
(The Eurographics Association, 2018) Vidaurre-Gallart, Isabel; Sújar, Aaron; García, Marcos; García-Fernández, Ignacio and Ureña, Carlos
The study of the human brain is one of the biggest research challenges nowadays. Thanks to the impressive improvement in technology, great advances are being achieved in the study of the microanatomical structures of the neurons, which are the main nervous system processing cells. The study of those structures requires to capture high-resolution images. In such cases, due to the resolution required, processing of complete neurons is unfeasible. The purpose of this project is to provide the neuroscientists with a tool that allows them to visualize and reconstruct complete neurons from multiple high-resolution sections. To this end, we developed a tool capable of loading different volumetric data sets and merging them into a new volume. A rendering engine was designed to support several volumetric rendering modes. The graphical user interface allows the user to interact with the volumes in intuitive way and facilitates volume stitching task. Furthermore, the implementation makes use of GPU to improve the application.
Experiences From the Development of a Prototype of an Spatial Augmented Reality System
(The Eurographics Association, 2018) Cárdenas-Donoso, José Luis; García-Fernández, Ángel-Luis; Conde-Rodríguez, Francisco-de-Asís; Ogáyar-Anguita, Carlos-Javier; García-Fernández, Ignacio and Ureña, Carlos
This paper describes the hardware and software of a prototype of a portable Spatial Augmented Reality system. This prototype is completely autonomous and projects the information on the real world, so that it is visible for a group of users. The system was built using mostly low-cost hardware (Raspberry Pi, plus a camera module and an inertial measurement unit), and the software was developed using C++ and OpenGL ES 2.0.
FORHHSS-TEA, Support to the Individual Work System for People With Autism Spectrum Disorder Using Virtual and Augmented Reality
(The Eurographics Association, 2018) Sevilla, Javier; Vera, Lucia; Herrera, Gerardo; Fernández, Marcos; García-Fernández, Ignacio and Ureña, Carlos
The Individual Work System (IWS) is an essential element from the TEACCH program, designed by The University of North Carolina (USA), one of the most used all over the world for work with persons with Autism Spectrum Disorder (ASD). The FORHHSS-TEA project uses spatial augmented reality and virtual reality technologies, following the IWS, to help persons with ASD to develop areas where they usually have problems. In the VR version, the end-users wear virtual reality glasses and 3D scanners to detect their hands in order to interact with a virtual setting. In the AR version, participants interact with a real scenario that is augmented with projection lights in order to improve independent completion of tasks. Thus, many technologies are involved to evaluate the process: eye tracking, biosignals, and emotion recognition through facial analysis and IP cameras. By using these technologies, the concentration level and the state of the person with ASD are evaluated. In the platform, there are also pressure sensors to process the user interaction with the platform elements. The platform has been evaluated with 4 persons with ASD during 5 weeks. In this paper, it is presented the design of the platform, the session description and the results of the evaluation.
LeoMCAD: A Lego-based Mechanical CAD system
(The Eurographics Association, 2018) García, Francisco González; Martín, Jesús Amador Pérez; Patow, Gustavo A.; García-Fernández, Ignacio and Ureña, Carlos
Mechanical Design (MCAD) tools are used for creating 3D digital prototypes used in the design, visualization, and simulation of products. In this paper we present LeoMCAD, a Lego-based mechanical system designed to be used as an education tool both for kids and Lego hobbyists; but which features a novel solver that naturally and seamlessly computes the interaction between the pieces that build-up a given model, solving an otherwise complex forward kinematic system of equations in a much simpler way. The results show how our system is able to cope with situations that would produce dead-lock situations in more advanced commercial systems.
Modelling the Fluid-Boundary Interaction in SPH
(The Eurographics Association, 2018) Perea, Juan J.; Cordero, Juan M.; García-Fernández, Ignacio and Ureña, Carlos
Smoothed Particle Hydrodynamics (SPH) is a numerical method based on mutually interacting meshfree particles, and has been widely applied to fluid simulation in Computer Graphics. Originally SPH does not define the behaviour of the particle system in the contour, so the different variants of SPH have been solving this deficiency with different techniques. Some of these techniques are based on fictitious forces, specular particles or semi-analytic fields. However, all these proposals present a drawback, that are may introduce additional inaccuracy as a divergent behaviour of the particle dynamics or an artificial separation between the fluid limits and the contour. To solve these limitations at this paper presents a new technique based on contour particles that are used during simulation to model the interaction with the fluid. The use of contour particles had already been used in other works to construct the contour like a particle layer. That solution presents problems especially when increasing the complexity of the contour shape. In addition, unlike other techniques, this paper presents an additional advantage, the possibility of obtaining all the dynamic magnitudes for improving efficiency and versatility.
Muscle Simulation with Extended Position Based Dynamics
(The Eurographics Association, 2018) Romeo, Marco; Monteagudo, Carlos; Sánchez-Quirós, Daniel; García-Fernández, Ignacio and Ureña, Carlos
Recent 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.
Noise Reduction Automation of LiDAR Point Clouds for Modeling and Representation of High Voltage Lines in a 3D Virtual Globe
(The Eurographics Association, 2018) Santana, Jaisiel; Ortega, Sebastián; Santana, José Miguel; Trujillo, Agustin; Suárez, Jose Pablo; García-Fernández, Ignacio and Ureña, Carlos
Due to the importance of electricity supply, electric companies must inspect their infrastructure in order to guarantee the reliability of the service. In this scenario, many companies use LiDAR technology for modeling the power line corridors and detect possible anomalies and risks. This process is quite expensive in terms of costs and human dependency so, maximizing the automation of the process is critical. In this paper, a method for reducing turbulence-noise in airborne LiDAR point clouds for a posterior visualization of a power line corridor in a virtual 3D-globe is presented. Based on an analysis performed against a set of point clouds that indicates that most noise is composed of a mass which follows the helicopter trajectory, the method attempts to integrate a noise reduction process using the distance between points and the helicopter as cleaning criterion. A comparison between a proposed variation of a classification method using a point cloud manually filtered and the same method variation but integrating the presented noise reduction method is carried out to validate the automation effectiveness. Finally, the resulting model is displayed using a virtual 3D-globe, easing analytical tasks.
On the Design of a Mixed-Reality Annotations Tool for the Inspection of Pre-fab Buildings
(The Eurographics Association, 2018) García-Pereira, Inma; Gimeno, Jesús; Portalés, Cristina; Vidal-González, María; Morillo, Pedro; García-Fernández, Ignacio and Ureña, Carlos
The introduction of Augmented Reality (AR) and Virtual Reality (VR) in the inspection works carried out during the construction of prefabricated buildings can allow the early detection and elimination of deviations in their quality and energy efficiency. These new tools let us change from the traditional note taking on paper to the use of an AR application that allows to make rich annotations. The later on-site or in-office revision of the information taken as well as the remote communication while the inspection is going on can speed up and optimize the detection of errors and the maintenance of quality through the use of AR and VR. In this paper, the work in progress that is being carried out within the SIRAE project is shown. With it, we intend to implement the use of AR annotations for their visualization and modification in real time or later either in situ (AR) or from any other location (VR). The obtained first lab results are quite promising, since the usability of the system, still in development, augurs an easy adaptation of the workers to the new work tool and a substantial streamlining of the inspection processes.
A Physically-Based Spatio-Temporal Sky Model
(The Eurographics Association, 2018) Guimera, David; Gutierrez, Diego; Jarabo, Adrián; García-Fernández, Ignacio and Ureña, Carlos
In this work we present a physically-based optical model of the atmosphere, that takes into account the seasonal and geographic variation of its composition. Based on data from the atmospheric science literature, we build a highly detailed the composition of the atmosphere, and how it varies depending on the position of the observer, or the time of the year. Then, based on precise measurements of the optical properties of the components of the atmosphere, we map our model into a radiative model, which can be rendered in any existing volumetric renderer. We demonstrate our model in multispectral renders of daylight sky-domes, showing the changes in the appearance occurring when varying the season or location of the observer.
A Procedural Approach for Thermal Visualization on Buildings
(The Eurographics Association, 2018) Muñoz, David; Besuievsky, Gonzalo; Patow, Gustavo A.; García-Fernández, Ignacio and Ureña, Carlos
Thermal behaviour analysis on buildings is an important goal for all tasks involving energy flow simulation in urban environments. One of the most widely used simplified thermal models is based on an electrical analogy, where nodes are set to simulate and solve a circuit network. In this paper we propose a procedural approach for automatically locate the nodes of the circuit, according to the building structure. We provide a conceptual technique to efficiently visualize thermal variations over time in buildings. We show that we can simulate and visually represent the variations of the interior temperatures of a building over a period of time. We believe that the technique could be helpful for rapid analysis for changing building parameters, such as materials, dimensions or number of floors.
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, Carlos
Parallel 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.
A Prototype of Virtual Reality System for the Visualization, Exploration and Modeling of Huge Point Clouds
(The Eurographics Association, 2018) Ortega-Donaire, José; Segura-Sánchez, Rafael Jesús; Ogáyar-Anguita, Carlos-Javier; Rueda-Ruiz, Antonio Jesús; García-Fernández, Ignacio and Ureña, Carlos
The use of specific techniques for the management and visualization of huge point clouds is necessary to solve the drawbacks of inefficiency derived from the size of the dataset and the techniques used to visualize it. This work presents a prototype of VR system for the visualization and management of extensive point clouds in 3D with the ability to edit specific points. For this, the tool incorporates multiresolution techniques, which improve the performance and efficiency of the system. The prototype also incorporates the management of the point cloud stored in an unstructured database; so the prototype can request parts of the dataset from the required fractions generated by an octree. This allows the progressive processing of 3D point clouds, which is very useful to control and visualize a large data set in real time.
PterosaVR MUVHN: una aplicación para la reconstrucción virtual de Tropeognathus mesembrinus
(The Eurographics Association, 2018) Ruiz-Gijón, Tonny; Cubells, Marcos Gutiérrez; Holgado, Borja; López, Hugo Salais; Vidal-González, María; Forner, Anna García; García-Fernández, Ignacio and Ureña, Carlos
Tanto el paleoarte como las nuevas tecnologías suponen herramientas muy útiles y visualmente atractivas para la representación de la vida extinta. En este proyecto, ambas disciplinas han sido combinadas en el desarrollo de una aplicación móvil que permite, mediante el uso de un casco de realidad virtual, asistir a la reconstrucción del pterosaurio Tropeognathus mesembrinus, paseando a través de tres niveles anatómicos: el esqueleto, la musculatura y el aspecto externo. La reconstrucción culmina con una escena de Tropeognathus sobrevolando un paisaje del Cretácico Inferior. Además, incluye un visor 3D por el que se puede navegar por la anatomía del pterosaurio, así como una opción de poder mostrarlo en realidad aumentada al encontrar el logo del museo. En conclusión, esta aplicación supone una forma novedosa y atractiva de exponer una pieza paleontológica al público general, que podrá familiarizarse no sólo con Tropeognathus y los pterosaurios, sino también con el proceso de reconstrucción de la vida extinta.
Rendering and Interacting With Volume Models in Immersive Environments
(The Eurographics Association, 2018) Fons, Joan; Monclús, Eva; Vázquez, Pere-Pau; Navazo, Isabel; García-Fernández, Ignacio and Ureña, Carlos
The recent advances in VR headsets, such as the Oculus Rift or HTC Vive, at affordable prices offering a high resolution display, has empowered the development of immersive VR applications. data. In this paper we propose an immersive VR system that uses some well-known acceleration algorithms to achieve real-time rendering of volumetric datasets in an immersive VR system. Moreover, we have incorporated different basic interaction techniques to facilitate the inspection of the volume dataset. The interaction has been designed to be as natural as possible in order to achieve the most comfortable, user-friendly virtual experience. We have conducted an informal user study to evaluate the user preferences. Our evaluation shows that our application is perceived usable, easy of learn and very effective in terms of the high level of immersion achieved.
Study of the Influence of User Characteristics on the Virtual Reality Presence
(The Eurographics Association, 2018) Mayor, Jesús; Sánchez, Alberto; Raya, Laura; García-Fernández, Ignacio and Ureña, Carlos
In recent years, virtual reality has grown a lot in different areas of application, including ludic, social and research, being used by a large and growing number of users with different profiles. Presence is one of the most distinctive and important features of a virtual reality experience. The aim of this article is to study the most suitable areas of application for users and to analyze the influence of different characteristics of the user's profile in the perceived presence. We have tested the interest applications indicated by 159 subjects and we have designed an immersive virtual reality experience, testing the behavior and performance of 48 users. The results obtained show that gender can influence the perceptual sensation of presence in these types of virtual environments.
Toward Estimation of Yarn-Level Cloth Simulation Models
(The Eurographics Association, 2018) Martín-Garrido, Alberto; Miguel, Eder; Otaduy, Miguel Ángel; García-Fernández, Ignacio and Ureña, Carlos
Efficient and realistic cloth simulation is an unsolved problem, with yarn-level models emerging as a new alternative thanks to new hardware capabilities. Modeling yarns as flexible rods with persistent contacts enables a very robust and efficient simulation. However, this assumption also complicates the definition of elastic deformation potentials. This work explores more accurate yarn-level cloth models together with experiments that compare model features in order to detect shortcomings in the persistent contact model. In particular, we have implemented a discrete elastic model of flexible yarns with contact which treats yarns as unidimensional splines, together with a model that discretizes yarns using three-dimensional finite elements.

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