Pub Date : 1900-01-01DOI: 10.2312/LocalChapterEvents/CEIG/CEIG12/031-040
P. Hermosilla, R. Brecheisen, Pere-Pau Vázquez, A. Vilanova
Diffuse Tensor Imaging (DTI) is an acquisition method based on Magnetic Resonance (MR) that provides information on the white matter fiber pathways in the living human brain. Such knowledge is crucial for understanding the way different parts of the brain work and how they interact with each other. The reconstruction of fiber tracts, however, depends on a number of parameters that introduce a degree of uncertainty in the data. Together with the parameter setting, other elements such as noise, motion, partial volume effects, or image artifacts increase the uncertainty. Therefore, fiber tracking algorithms may produce misleading results. Visualizing such uncertainty is important to avoid taking wrong decisions in medical environments. In this paper we present a set of techniques that provide a better understanding on the visualization of brain fibers by means of textures, silhouettes, occlusion, and animation.
{"title":"Uncertainty Visualization of Brain Fibers","authors":"P. Hermosilla, R. Brecheisen, Pere-Pau Vázquez, A. Vilanova","doi":"10.2312/LocalChapterEvents/CEIG/CEIG12/031-040","DOIUrl":"https://doi.org/10.2312/LocalChapterEvents/CEIG/CEIG12/031-040","url":null,"abstract":"Diffuse Tensor Imaging (DTI) is an acquisition method based on Magnetic Resonance (MR) that provides information on the white matter fiber pathways in the living human brain. Such knowledge is crucial for understanding the way different parts of the brain work and how they interact with each other. The reconstruction of fiber tracts, however, depends on a number of parameters that introduce a degree of uncertainty in the data. Together with the parameter setting, other elements such as noise, motion, partial volume effects, or image artifacts increase the uncertainty. Therefore, fiber tracking algorithms may produce misleading results. Visualizing such uncertainty is important to avoid taking wrong decisions in medical environments. In this paper we present a set of techniques that provide a better understanding on the visualization of brain fibers by means of textures, silhouettes, occlusion, and animation.","PeriodicalId":385751,"journal":{"name":"Spanish Computer Graphics Conference","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127692341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In many applications, such as urban physics simulations or the study of the solar impact effects at different scales, complex 3D city models are required to evaluate physical values. In this paper we present a new technique which, through the use of an electrical analogy and the calculation of sky view factors and form factors, allows to simulate and study the thermal behaviour of an urban environment, taking into account the solar and sky radiation, the air and sky temperatures, and even the thermal interaction between nearby buildings. We also show that it is possible, from a 3D recreation of a large urban environment, to simulate the heat exchanges that take place between the buildings of a city and its immediate surroundings. In the same way, taking into account the terrestrial zone, the altitude and the type of climate with which the simulations are carried out, it is possible to compare the thermal behaviour of a large urban environment according to the chosen conditions.
{"title":"A Level-of-Detail Technique for Urban Physics Calculations in Large Urban Environments","authors":"D. Novoa, G. Besuievsky, G. Patow","doi":"10.2312/ceig.20191198","DOIUrl":"https://doi.org/10.2312/ceig.20191198","url":null,"abstract":"In many applications, such as urban physics simulations or the study of the solar impact effects at different scales, complex 3D city models are required to evaluate physical values. In this paper we present a new technique which, through the use of an electrical analogy and the calculation of sky view factors and form factors, allows to simulate and study the thermal behaviour of an urban environment, taking into account the solar and sky radiation, the air and sky temperatures, and even the thermal interaction between nearby buildings. We also show that it is possible, from a 3D recreation of a large urban environment, to simulate the heat exchanges that take place between the buildings of a city and its immediate surroundings. In the same way, taking into account the terrestrial zone, the altitude and the type of climate with which the simulations are carried out, it is possible to compare the thermal behaviour of a large urban environment according to the chosen conditions.","PeriodicalId":385751,"journal":{"name":"Spanish Computer Graphics Conference","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115953461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.2312/LocalChapterEvents/CEIG/CEIG08/133-139
Adrián Cuevas, J. Rodríguez-Navarro, A. Susín
In this paper we propose a fast algorithm for the automatic labeling of a set of predefined markers in an optical motion capture system. This algorithm is facing the problem as a minimization problem, using a virtual representation of the real model to predict possible occlusions that happen in the captured images. Moreover, we take advan-tage of the knowledge of the cameras parameters to solve potential labeling conflicts between markers. Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism - animation.
{"title":"Auto-labeling as a Minimization Problem with Virtual Occlusions","authors":"Adrián Cuevas, J. Rodríguez-Navarro, A. Susín","doi":"10.2312/LocalChapterEvents/CEIG/CEIG08/133-139","DOIUrl":"https://doi.org/10.2312/LocalChapterEvents/CEIG/CEIG08/133-139","url":null,"abstract":"In this paper we propose a fast algorithm for the automatic labeling of a set of predefined markers in an optical motion capture system. This algorithm is facing the problem as a minimization problem, using a virtual representation of the real model to predict possible occlusions that happen in the captured images. Moreover, we take advan-tage of the knowledge of the cameras parameters to solve potential labeling conflicts between markers. Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism - animation.","PeriodicalId":385751,"journal":{"name":"Spanish Computer Graphics Conference","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121125841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Damping is a critical phenomenon in determining the dynamic behavior of animated objects. For yarn-level cloth models, setting the correct damping behavior is particularly complicated, because common damping models in computer graphics do not account for the mixed Eulerian-Lagrangian discretization of efficient yarn-level models. In this paper, we show how to derive a damping model for yarn-level cloth from dissipation potentials. We develop specific formulations for the deformation modes present in yarn-level cloth, circumventing various numerical difficulties. We show that the proposed model enables independent control of the damping behavior of each deformation mode, unlike other previous models. CCS Concepts •Computing methodologies → Physical simulation;
{"title":"Dissipation Potentials for Yarn-Level Cloth","authors":"R. M. Sánchez-Banderas, M. Otaduy","doi":"10.2312/CEIG.20171202","DOIUrl":"https://doi.org/10.2312/CEIG.20171202","url":null,"abstract":"Damping is a critical phenomenon in determining the dynamic behavior of animated objects. For yarn-level cloth models, setting the correct damping behavior is particularly complicated, because common damping models in computer graphics do not account for the mixed Eulerian-Lagrangian discretization of efficient yarn-level models. In this paper, we show how to derive a damping model for yarn-level cloth from dissipation potentials. We develop specific formulations for the deformation modes present in yarn-level cloth, circumventing various numerical difficulties. We show that the proposed model enables independent control of the damping behavior of each deformation mode, unlike other previous models. CCS Concepts •Computing methodologies → Physical simulation;","PeriodicalId":385751,"journal":{"name":"Spanish Computer Graphics Conference","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125278112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.2312/LocalChapterEvents/CEIG/CEIG12/156-156
José Olmos Martínez, F. Ramos, Carlos González
{"title":"Management of 3D Geometry on Portable Devices","authors":"José Olmos Martínez, F. Ramos, Carlos González","doi":"10.2312/LocalChapterEvents/CEIG/CEIG12/156-156","DOIUrl":"https://doi.org/10.2312/LocalChapterEvents/CEIG/CEIG12/156-156","url":null,"abstract":"","PeriodicalId":385751,"journal":{"name":"Spanish Computer Graphics Conference","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124012504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.2312/LocalChapterEvents/CEIG/CEIG12/141-150
Gustavo Rovelo, F. Abad, E. Camahort
Augmented Reality (AR) applications have become more popular beyond the research laboratory due to recent technological breakthroughs in computer hardware and mobile devices. Users are starting to interact with virtual content mixed with real environments at their offices, homes, and schools using their mobile phones. For this growing market, developers have first to decide the platform in which they will develop the application (e.g. Apple iOS or Android). Then they must decide whether start writing the application from scratch using only platform native tools, or using one of the available Software Development Kits (SDKs), or using high-level authoring tools for the chosen platform. Besides, developers have to face different AR related issues according to the application’s requirements: markers, barcodes or general image tracking, geolocation, efficient rendering of 3D objects, and designing a robust GUI for the target devices. To help developers and researchers to start writing mobile AR applications, this survey identifies the main features of several freeware and commercial SDKs and authoring tools. Categories and Subject Descriptors (according to ACM CCS) :
{"title":"A Survey on Development Tools for Mobile Augmented Reality","authors":"Gustavo Rovelo, F. Abad, E. Camahort","doi":"10.2312/LocalChapterEvents/CEIG/CEIG12/141-150","DOIUrl":"https://doi.org/10.2312/LocalChapterEvents/CEIG/CEIG12/141-150","url":null,"abstract":"Augmented Reality (AR) applications have become more popular beyond the research laboratory due to recent technological breakthroughs in computer hardware and mobile devices. Users are starting to interact with virtual content mixed with real environments at their offices, homes, and schools using their mobile phones. For this growing market, developers have first to decide the platform in which they will develop the application (e.g. Apple iOS or Android). Then they must decide whether start writing the application from scratch using only platform native tools, or using one of the available Software Development Kits (SDKs), or using high-level authoring tools for the chosen platform. Besides, developers have to face different AR related issues according to the application’s requirements: markers, barcodes or general image tracking, geolocation, efficient rendering of 3D objects, and designing a robust GUI for the target devices. To help developers and researchers to start writing mobile AR applications, this survey identifies the main features of several freeware and commercial SDKs and authoring tools. Categories and Subject Descriptors (according to ACM CCS) :","PeriodicalId":385751,"journal":{"name":"Spanish Computer Graphics Conference","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127871217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
José Negrillo-Cárdenas, J. Jiménez, F. Feito-Higueruela
The number of virtual reality-based systems have considerably increased in recent years due to many technical improvements and lower prices. Nowadays, the applications of this kind of systems go further than videogames. Additionally, they enable new interaction paradigms adapted to this new technology. In this paper we propose a new interaction model to visualize objects in a virtual reality context. We describe our proposed mechanisms to achieve a set of graphical tasks and we conduct an experiment to assess the usability of the system, comparing it to other traditional methods.
{"title":"A Usability Study for a Novel Approach to Virtual Reality Interaction","authors":"José Negrillo-Cárdenas, J. Jiménez, F. Feito-Higueruela","doi":"10.2312/ceig.20181151","DOIUrl":"https://doi.org/10.2312/ceig.20181151","url":null,"abstract":"The number of virtual reality-based systems have considerably increased in recent years due to many technical improvements and lower prices. Nowadays, the applications of this kind of systems go further than videogames. Additionally, they enable new interaction paradigms adapted to this new technology. In this paper we propose a new interaction model to visualize objects in a virtual reality context. We describe our proposed mechanisms to achieve a set of graphical tasks and we conduct an experiment to assess the usability of the system, comparing it to other traditional methods.","PeriodicalId":385751,"journal":{"name":"Spanish Computer Graphics Conference","volume":"90 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127658602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In Computer Graphics is usual the modelling of dynamic systems through particles. The simulation of liquids, cloths, gas, smoke... are highlighted examples of that modelling. In this scope, is particularly relevant the procedure of neighbour particles searching, which represents a bottleneck in terms of computational cost. One of the most used searching techniques is the cell– based spatial division by cubes, where each cell is tagged by a hash value. Thus, all particles located into each cell have the same tag and are the candidate to be neighbours. The most useful feature of this technique is that it can be easily parallelized, what reduces the computational costs. Nevertheless, the parallelizing process has some drawbacks associated with data memory management. Also, during the process of neighbour search, it is necessary to trace into the adjacent cells to find neighbour particles, as a consequence, the computational cost is increased. To solve these shortcomings, we have developed a method that reduces the search space by considering the relative position of each particle in its own cell. This method, parallelized using CUDA, shows improvements in processing time and memory management over other “standard” spatial division techniques. (see http://www.acm.org/about/class/class/2012) CCS Concepts •Computing methodologies → Distributed computing methodologies; Physical simulation;
{"title":"An Improved Parallel Technique for Neighbour Search on CUDA","authors":"J. J. Perea, Juan M. Cordero","doi":"10.2312/ceig.20171201","DOIUrl":"https://doi.org/10.2312/ceig.20171201","url":null,"abstract":"In Computer Graphics is usual the modelling of dynamic systems through particles. The simulation of liquids, cloths, gas, smoke... are highlighted examples of that modelling. In this scope, is particularly relevant the procedure of neighbour particles searching, which represents a bottleneck in terms of computational cost. One of the most used searching techniques is the cell– based spatial division by cubes, where each cell is tagged by a hash value. Thus, all particles located into each cell have the same tag and are the candidate to be neighbours. The most useful feature of this technique is that it can be easily parallelized, what reduces the computational costs. Nevertheless, the parallelizing process has some drawbacks associated with data memory management. Also, during the process of neighbour search, it is necessary to trace into the adjacent cells to find neighbour particles, as a consequence, the computational cost is increased. To solve these shortcomings, we have developed a method that reduces the search space by considering the relative position of each particle in its own cell. This method, parallelized using CUDA, shows improvements in processing time and memory management over other “standard” spatial division techniques. (see http://www.acm.org/about/class/class/2012) CCS Concepts •Computing methodologies → Distributed computing methodologies; Physical simulation;","PeriodicalId":385751,"journal":{"name":"Spanish Computer Graphics Conference","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129180472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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. CCS Concepts •Computing methodologies → Collision detection; Physical simulation;
{"title":"Modelling the Fluid-Boundary Interaction in SPH","authors":"J. J. Perea, Juan M. Cordero","doi":"10.2312/ceig.20181147","DOIUrl":"https://doi.org/10.2312/ceig.20181147","url":null,"abstract":"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. CCS Concepts •Computing methodologies → Collision detection; Physical simulation;","PeriodicalId":385751,"journal":{"name":"Spanish Computer Graphics Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131279417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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