Pub Date : 2018-04-15DOI: 10.2312/vriphys.20181064
G. Cattan, Anton Andreev, César Mendoza, M. Congedo
Thanks to the low price, the use of a head-mounted device (HMD) equipped with a smartphone is currently a common setup for virtual reality (VR). Brain-computer interface (BCI) based on electroencephalography (EEG) is a promising technology to enrich the VR experience. However, the effect of using HMDs on the acquisition of EEG signals remains still unknown. In fact, the smartphone is placed close to the head where EEG sensors are located, thus the smartphone's electronics may perturb the acquisition of the EEG signal. In the present study, we compare the spectral properties of the EEG signal acquired on 12 subjects wearing a SamsungGear HMD equipped with a Samsung S6 smartphone turned on and off. Our study shows that there is no significant difference in the spectral properties of the EEG in these two experimental conditions. We conclude that a smartphone-based HMD is compatible with EEG technology. Some technical problems related to the concurrent use of a HMD and an EEG-based BCI are also discussed.
{"title":"The Impact of Passive Head-Mounted Virtual Reality Devices on the Quality of EEG Signals","authors":"G. Cattan, Anton Andreev, César Mendoza, M. Congedo","doi":"10.2312/vriphys.20181064","DOIUrl":"https://doi.org/10.2312/vriphys.20181064","url":null,"abstract":"Thanks to the low price, the use of a head-mounted device (HMD) equipped with a smartphone is currently a common setup for virtual reality (VR). Brain-computer interface (BCI) based on electroencephalography (EEG) is a promising technology to enrich the VR experience. However, the effect of using HMDs on the acquisition of EEG signals remains still unknown. In fact, the smartphone is placed close to the head where EEG sensors are located, thus the smartphone's electronics may perturb the acquisition of the EEG signal. In the present study, we compare the spectral properties of the EEG signal acquired on 12 subjects wearing a SamsungGear HMD equipped with a Samsung S6 smartphone turned on and off. Our study shows that there is no significant difference in the spectral properties of the EEG in these two experimental conditions. We conclude that a smartphone-based HMD is compatible with EEG technology. Some technical problems related to the concurrent use of a HMD and an EEG-based BCI are also discussed.","PeriodicalId":446363,"journal":{"name":"Workshop on Virtual Reality Interactions and Physical Simulations","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128711532","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 : 2017-04-23DOI: 10.2312/vriphys.20171086
Benoit Le Gouis, M. Marchal, A. Lécuyer, B. Arnaldi
Physically-based simulation of heterogeneous objects remains computationally-demanding for many applications, especially when involving haptic interaction with virtual environments. In this paper, we introduce a novel multiresolution approach for haptic interaction with heterogeneous deformable objects. Our method called "Elasticity-based Clustering" is based on the clustering and aggregation of elasticity inside an object, in order to create large homogeneous volumes preserving important features of the initial distribution. The design of such large and homogeneous volumes improves the attribution of elasticity to the elements of the coarser geometry. We could successfully implement and test our approach within a complete and real-time haptic interaction pipeline compatible with consumer-grade haptic devices. We evaluated the performance of our approach on a large set of elasticity configurations using a perception-based quality criterion. Our results show that for 90% of studied cases our method can achieve a 6 times speedup in the simulation time with no theoretical perceptual difference.
{"title":"Elasticity-based Clustering for Haptic Interaction with Heterogeneous Deformable Objects","authors":"Benoit Le Gouis, M. Marchal, A. Lécuyer, B. Arnaldi","doi":"10.2312/vriphys.20171086","DOIUrl":"https://doi.org/10.2312/vriphys.20171086","url":null,"abstract":"Physically-based simulation of heterogeneous objects remains computationally-demanding for many applications, especially when involving haptic interaction with virtual environments. In this paper, we introduce a novel multiresolution approach for haptic interaction with heterogeneous deformable objects. Our method called \"Elasticity-based Clustering\" is based on the clustering and aggregation of elasticity inside an object, in order to create large homogeneous volumes preserving important features of the initial distribution. The design of such large and homogeneous volumes improves the attribution of elasticity to the elements of the coarser geometry. We could successfully implement and test our approach within a complete and real-time haptic interaction pipeline compatible with consumer-grade haptic devices. We evaluated the performance of our approach on a large set of elasticity configurations using a perception-based quality criterion. Our results show that for 90% of studied cases our method can achieve a 6 times speedup in the simulation time with no theoretical perceptual difference.","PeriodicalId":446363,"journal":{"name":"Workshop on Virtual Reality Interactions and Physical Simulations","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122029472","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 : 2017-04-23DOI: 10.2312/vriphys.20171079
C. Altenhofen, Felix Schuwirth, A. Stork, D. Fellner
In this paper, we present a novel approach for a tighter integration of 3D modeling and physically-based simulation. Instead of modeling 3D objects as surface models, we use a volumetric subdivision representation. Volumetric modeling operations allow designing 3D objects in similar ways as with surface-based modeling tools. Encoding the volumetric information already in the design mesh drastically simplifies and speeds up the mesh generation process for simulation. The transition between design, simulation and back to design is consistent and computationally cheap. Since the subdivision and mesh generation can be expressed as a precomputable matrix-vector multiplication, iteration times can be greatly reduced compared to common modeling and simulation setups. Therefore, this approach is especially well suited for early-stage modeling or optimization use cases, where many geometric changes are made in a short time and their physical effect on the model has to be evaluated frequently. To test our approach, we created, simulated and adapted several 3D models. Additionally, we measured and evaluated the timings for generating and applying the matrices for different subdivision levels. For comparison, we also measured the tetrahedral meshing functionality offered by CGAL for similar numbers of elements. For changing topology, our implicit meshing approach proves to be up to 70 times faster than creating the tetrahedral mesh only based on the outer surface. Without changing the topology and by precomputing the matrices, we achieve a speed-up of up to 2800.
{"title":"Implicit Mesh Generation using Volumetric Subdivision","authors":"C. Altenhofen, Felix Schuwirth, A. Stork, D. Fellner","doi":"10.2312/vriphys.20171079","DOIUrl":"https://doi.org/10.2312/vriphys.20171079","url":null,"abstract":"In this paper, we present a novel approach for a tighter integration of 3D modeling and physically-based simulation. Instead of modeling 3D objects as surface models, we use a volumetric subdivision representation. Volumetric modeling operations allow designing 3D objects in similar ways as with surface-based modeling tools. Encoding the volumetric information already in the design mesh drastically simplifies and speeds up the mesh generation process for simulation. The transition between design, simulation and back to design is consistent and computationally cheap. Since the subdivision and mesh generation can be expressed as a precomputable matrix-vector multiplication, iteration times can be greatly reduced compared to common modeling and simulation setups. Therefore, this approach is especially well suited for early-stage modeling or optimization use cases, where many geometric changes are made in a short time and their physical effect on the model has to be evaluated frequently. To test our approach, we created, simulated and adapted several 3D models. Additionally, we measured and evaluated the timings for generating and applying the matrices for different subdivision levels. For comparison, we also measured the tetrahedral meshing functionality offered by CGAL for similar numbers of elements. For changing topology, our implicit meshing approach proves to be up to 70 times faster than creating the tetrahedral mesh only based on the outer surface. Without changing the topology and by precomputing the matrices, we achieve a speed-up of up to 2800.","PeriodicalId":446363,"journal":{"name":"Workshop on Virtual Reality Interactions and Physical Simulations","volume":"222 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123112296","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 : 2015-11-04DOI: 10.2312/vriphys.20151337
Jérémie Dequidt, E. Coevoet, L. Thinès, C. Duriez
Virtual surgical simulators face many computational challenges: they need to provide biophysical accuracy, realistic feed-backs and high-rate responses. Better biophysical accuracy and more realistic feed-backs (be they visual, haptic.. .) induce more computational footprint. State-of-the-art approaches use high-performance hardware or find an acceptable trade-off between performance and accuracy to deliver interactive yet pedagogically relevant simulators. In this paper, we propose an interactive vascular neurosurgery simulator that provides bi-manual interaction with haptic feedback. The simulator is an original combination of states-of-the-art techniques that allows visual realism, bio-physical realism, complex interactions with the anatomical structures and the instruments and haptic feedback. Training exercises are also proposed to learn and to perform the different steps of intracranial aneurysm surgery (IAS). We assess the performance of our simulator with quantitative performance benchmarks and qualitative assessments of junior and senior clinicians.
{"title":"Vascular Neurosurgery Simulation with Bimanual Haptic Feedback","authors":"Jérémie Dequidt, E. Coevoet, L. Thinès, C. Duriez","doi":"10.2312/vriphys.20151337","DOIUrl":"https://doi.org/10.2312/vriphys.20151337","url":null,"abstract":"Virtual surgical simulators face many computational challenges: they need to provide biophysical accuracy, realistic feed-backs and high-rate responses. Better biophysical accuracy and more realistic feed-backs (be they visual, haptic.. .) induce more computational footprint. State-of-the-art approaches use high-performance hardware or find an acceptable trade-off between performance and accuracy to deliver interactive yet pedagogically relevant simulators. In this paper, we propose an interactive vascular neurosurgery simulator that provides bi-manual interaction with haptic feedback. The simulator is an original combination of states-of-the-art techniques that allows visual realism, bio-physical realism, complex interactions with the anatomical structures and the instruments and haptic feedback. Training exercises are also proposed to learn and to perform the different steps of intracranial aneurysm surgery (IAS). We assess the performance of our simulator with quantitative performance benchmarks and qualitative assessments of junior and senior clinicians.","PeriodicalId":446363,"journal":{"name":"Workshop on Virtual Reality Interactions and Physical Simulations","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131517275","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 : 2015-11-04DOI: 10.2312/vriphys.20151334
Mathias Brousset, Emmanuelle Darles, Daniel Méneveaux, Pierre Poulin, B. Crespin
(a) Multiple waves displayed from the side (b) from above (c) Waves interacting with static blocks Figure 1: Breaking waves obtained with our model. An ocean scene with multiple waves is displayed (a) from the side and (b) from above; (c) and breaking waves and backflow waves colliding with blocks. The waves combine naturally, while each of them is modeled with its specific parameters (height, width, speed, orientation, crest slope, breaking time). Abstract This paper presents a new method for controlling swells and breaking waves using fluid solvers. With conventional approaches that generate waves by pushing particles with oscillating planes, the resulting waves cannot be controlled easily, and breaking waves are even more difficult to obtain in practice. Instead, we propose to use a new wave model that physically describes the behavior of wave forces. We show that mapping those forces to particles produces various types of waves that can be controlled by the user with only a few parameters. Our method is based on a 2D representation that describes wave speed, width, and height. It handles many swell and wave configurations, with various breaking situations. Crespin / A New Force Model for Controllable Breaking Waves
{"title":"A New Force Model for Controllable Breaking Waves","authors":"Mathias Brousset, Emmanuelle Darles, Daniel Méneveaux, Pierre Poulin, B. Crespin","doi":"10.2312/vriphys.20151334","DOIUrl":"https://doi.org/10.2312/vriphys.20151334","url":null,"abstract":"(a) Multiple waves displayed from the side (b) from above (c) Waves interacting with static blocks Figure 1: Breaking waves obtained with our model. An ocean scene with multiple waves is displayed (a) from the side and (b) from above; (c) and breaking waves and backflow waves colliding with blocks. The waves combine naturally, while each of them is modeled with its specific parameters (height, width, speed, orientation, crest slope, breaking time). Abstract This paper presents a new method for controlling swells and breaking waves using fluid solvers. With conventional approaches that generate waves by pushing particles with oscillating planes, the resulting waves cannot be controlled easily, and breaking waves are even more difficult to obtain in practice. Instead, we propose to use a new wave model that physically describes the behavior of wave forces. We show that mapping those forces to particles produces various types of waves that can be controlled by the user with only a few parameters. Our method is based on a 2D representation that describes wave speed, width, and height. It handles many swell and wave configurations, with various breaking situations. Crespin / A New Force Model for Controllable Breaking Waves","PeriodicalId":446363,"journal":{"name":"Workshop on Virtual Reality Interactions and Physical Simulations","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131381803","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 : 2014-09-24DOI: 10.2312/vriphys.20141222
Elsa Fléchon, F. Zara, G. Damiand, F. Jaillet
In Computer Graphics, physically-based simulation of deformable objects is a current challenge, and many effi-cient models have been developed to reach real-time performance. However, these models are often limited when complex interactions involving topological modifications are required. To overcome this, the key issue is to manage concurrently, and at minimal cost, both the topology and physical properties. Thus, this paper presents a unified topological-physical model for soft body simulation. The complete embedding of physical and topological models will facilitate operations like piercing, fracture or cutting, as well as adap-tive refinement. Indeed, the difficulty is to treat topological changes during the simulation, requiring combined geometric and physics considerations. Rigorous topological operations guarantee the validity of the mesh, while direct access to the adjacent and incident relations will ease the update of physical properties of new elements created during these operations. These features are illustrated on an embedded mass-spring system undergoing topological modifications per-formed during simulation. Different levels of subdivision are also presented.
{"title":"A Unified Topological-Physical Model for Adaptive Refinement","authors":"Elsa Fléchon, F. Zara, G. Damiand, F. Jaillet","doi":"10.2312/vriphys.20141222","DOIUrl":"https://doi.org/10.2312/vriphys.20141222","url":null,"abstract":"In Computer Graphics, physically-based simulation of deformable objects is a current challenge, and many effi-cient models have been developed to reach real-time performance. However, these models are often limited when complex interactions involving topological modifications are required. To overcome this, the key issue is to manage concurrently, and at minimal cost, both the topology and physical properties. Thus, this paper presents a unified topological-physical model for soft body simulation. The complete embedding of physical and topological models will facilitate operations like piercing, fracture or cutting, as well as adap-tive refinement. Indeed, the difficulty is to treat topological changes during the simulation, requiring combined geometric and physics considerations. Rigorous topological operations guarantee the validity of the mesh, while direct access to the adjacent and incident relations will ease the update of physical properties of new elements created during these operations. These features are illustrated on an embedded mass-spring system undergoing topological modifications per-formed during simulation. Different levels of subdivision are also presented.","PeriodicalId":446363,"journal":{"name":"Workshop on Virtual Reality Interactions and Physical Simulations","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124677978","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 : 2013-11-27DOI: 10.2312/PE.vriphys.vriphys13.035-039
Christos Mousas, Paul F. Newbury, C. Anagnostopoulos
Considering that humans acting in constrained environments do not always plan according to shortest path criteria; rather, they conceptually measure the path which minimises the amount of expended energy. Hence, virtual characters should be able to execute their paths according to planning methods based not on path length but on the minimisation of actual expended energy. Thus, in this paper, we introduce a simple method that uses a formula for computing vanadium dioxide (VO2) levels, which is a proxy for the energy expended by humans during various activities.
{"title":"Rethinking Shortest Path: An Energy Expenditure Approach","authors":"Christos Mousas, Paul F. Newbury, C. Anagnostopoulos","doi":"10.2312/PE.vriphys.vriphys13.035-039","DOIUrl":"https://doi.org/10.2312/PE.vriphys.vriphys13.035-039","url":null,"abstract":"Considering that humans acting in constrained environments do not always plan according to shortest path criteria; rather, they conceptually measure the path which minimises the amount of expended energy. Hence, virtual characters should be able to execute their paths according to planning methods based not on path length but on the minimisation of actual expended energy. Thus, in this paper, we introduce a simple method that uses a formula for computing vanadium dioxide (VO2) levels, which is a proxy for the energy expended by humans during various activities.","PeriodicalId":446363,"journal":{"name":"Workshop on Virtual Reality Interactions and Physical Simulations","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121755760","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 : 2012-12-07DOI: 10.2312/PE/vriphys/vriphys12/147-156
P. Papadakis, F. Pirri
Motion planning for robots operating on 3D rough terrain requires the synergy of various robotic capabilities, from sensing and perception to simulation, planning and prediction. In this paper, we focus on the higher level of this pipeline where by means of physics-based simulation and geometric processing we extract the information that is semantically required for an articulated, tracked robot to optimally traverse 3D terrain. We propose a model that quantifies 3D traversability by accounting for intrinsic robot characteristics and articulating capabilities together with terrain characteristics. By building upon a set of generic cost criteria for a given robot state and 3D terrain patch, we augment the traversability cost estimation by: (i) unifying pose stabilization with traversability cost estimation, (ii) introducing new parameters into the problem that have been previously overlooked and (iii) adapting geometric computations to account for the complete 3D robot body and terrain surface. We apply the proposed model on a state-of-the-art Search and Rescue robot by performing a plurality of tests under varying conditions and demonstrate its efficiency and applicability in real-time.
{"title":"3D Mobility Learning and Regression of Articulated, Tracked Robotic Vehicles by Physics-based Optimization","authors":"P. Papadakis, F. Pirri","doi":"10.2312/PE/vriphys/vriphys12/147-156","DOIUrl":"https://doi.org/10.2312/PE/vriphys/vriphys12/147-156","url":null,"abstract":"Motion planning for robots operating on 3D rough terrain requires the synergy of various robotic capabilities, from sensing and perception to simulation, planning and prediction. In this paper, we focus on the higher level of this pipeline where by means of physics-based simulation and geometric processing we extract the information that is semantically required for an articulated, tracked robot to optimally traverse 3D terrain. We propose a model that quantifies 3D traversability by accounting for intrinsic robot characteristics and articulating capabilities together with terrain characteristics. By building upon a set of generic cost criteria for a given robot state and 3D terrain patch, we augment the traversability cost estimation by: (i) unifying pose stabilization with traversability cost estimation, (ii) introducing new parameters into the problem that have been previously overlooked and (iii) adapting geometric computations to account for the complete 3D robot body and terrain surface. We apply the proposed model on a state-of-the-art Search and Rescue robot by performing a plurality of tests under varying conditions and demonstrate its efficiency and applicability in real-time.","PeriodicalId":446363,"journal":{"name":"Workshop on Virtual Reality Interactions and Physical Simulations","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116701371","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 : 2012-12-06DOI: 10.2312/PE/vriphys/vriphys12/107-116
J. Bender, Arjan Kuijper, D. W. Fellner, É. Guérin, Tomas Golembiovsky, C. Duriez
There is a strong need, in surgical simulations, for physically based deformable model of thin or hollow structures. The use of shell theory allows to have a well-founded formulation resulting from continuum mechanics of thin objects. However, this formulation asks for second order spatial derivatives so requires the use of complex elements. In this paper, we present a new way of building the interpolation: First, we use the trianular cubic Bezier shell to allow for a good continuity inside and between the elements and second, we build a kinematic mapping to reduce the degrees of freedom of the element from 10 control points with 3 Degrees of Freedom ($=30$ DOFs) to only 3 nodes with 6 DOFs ($=18$ DOFs). This reduction allows for good computation performance. This new shell model description is also used to map a smooth surface (for the collision detection and response) on a coarse mechanical mesh to account for the complex contacts that take place during surgical procedures. We demonstrate the convergence and the computational efficiency of our approach as well as its use in two different simulation cases: the planning of surgery for congenital heart disease correction and a preliminary simulation of childbirth.
{"title":"Bézier Shell Finite Element for Interactive Surgical Simulation","authors":"J. Bender, Arjan Kuijper, D. W. Fellner, É. Guérin, Tomas Golembiovsky, C. Duriez","doi":"10.2312/PE/vriphys/vriphys12/107-116","DOIUrl":"https://doi.org/10.2312/PE/vriphys/vriphys12/107-116","url":null,"abstract":"There is a strong need, in surgical simulations, for physically based deformable model of thin or hollow structures. The use of shell theory allows to have a well-founded formulation resulting from continuum mechanics of thin objects. However, this formulation asks for second order spatial derivatives so requires the use of complex elements. In this paper, we present a new way of building the interpolation: First, we use the trianular cubic Bezier shell to allow for a good continuity inside and between the elements and second, we build a kinematic mapping to reduce the degrees of freedom of the element from 10 control points with 3 Degrees of Freedom ($=30$ DOFs) to only 3 nodes with 6 DOFs ($=18$ DOFs). This reduction allows for good computation performance. This new shell model description is also used to map a smooth surface (for the collision detection and response) on a coarse mechanical mesh to account for the complex contacts that take place during surgical procedures. We demonstrate the convergence and the computational efficiency of our approach as well as its use in two different simulation cases: the planning of surgery for congenital heart disease correction and a preliminary simulation of childbirth.","PeriodicalId":446363,"journal":{"name":"Workshop on Virtual Reality Interactions and Physical Simulations","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122427881","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 : 2012-12-06DOI: 10.2312/PE/vriphys/vriphys12/069-077
Marie Durand, B. Raffin, F. Faure
Neighbor identification is the most computationally intensive step in particle based simulations. To contain its cost, a common approach consists in using a regular grid to sort particles according to the cell they belong to. Then, neighbor search only needs to test the particles contained in a constant number of cells. During the simulation, a usually small amount of particles are moving between consecutive steps. Taking into account this temporal coherency to save on the maintenance cost of the acceleration data structure is difficult as it usually triggers costly dynamics memory allocations or data moves. In this paper we propose to rely on a Packed Memory Array (PMA) to efficiently keep particles sorted according to their cell index. The PMA maintains gaps in the particle array that enable to keep particle sorted with O(log2(n)) amortized data moves. We further improve the original PMA data structure to support efficient batch data moves. Experiments show that the PMA can outperform a compact sorted array for up to 50% element moves.
{"title":"A Packed Memory Array to Keep Moving Particles Sorted","authors":"Marie Durand, B. Raffin, F. Faure","doi":"10.2312/PE/vriphys/vriphys12/069-077","DOIUrl":"https://doi.org/10.2312/PE/vriphys/vriphys12/069-077","url":null,"abstract":"Neighbor identification is the most computationally intensive step in particle based simulations. To contain its cost, a common approach consists in using a regular grid to sort particles according to the cell they belong to. Then, neighbor search only needs to test the particles contained in a constant number of cells. During the simulation, a usually small amount of particles are moving between consecutive steps. Taking into account this temporal coherency to save on the maintenance cost of the acceleration data structure is difficult as it usually triggers costly dynamics memory allocations or data moves. In this paper we propose to rely on a Packed Memory Array (PMA) to efficiently keep particles sorted according to their cell index. The PMA maintains gaps in the particle array that enable to keep particle sorted with O(log2(n)) amortized data moves. We further improve the original PMA data structure to support efficient batch data moves. Experiments show that the PMA can outperform a compact sorted array for up to 50% element moves.","PeriodicalId":446363,"journal":{"name":"Workshop on Virtual Reality Interactions and Physical Simulations","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122285452","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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