HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific ... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et a ̀ la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Copyright Interactive hydraulic erosion using CUDA
Les paysages naturels résultent d'une succession d'événements géomorphologiques qu'il convient de... more Les paysages naturels résultent d'une succession d'événements géomorphologiques qu'il convient de simuler pour produires des résultats plausibles. En particulier, les changements topologiques doivent être pris en compte durant la formation de géométries complexes comme les arches, les ponts ou les tunnels naturels. Nous présentons une nouvelle approche pour simuler les évolutions géomorphologiques d'un terrain en 3D conçu comme un ensemble de volumes dé•nis dans un modèle topologique, et décrivons un ensemble d'opérations atomiques a•n de gérer les événements topologiques de manière robuste. Ces opérations somt combinées pour produire des scénarios d'évolutions plus complexes dans un modeleur basé sur les cartes généralisées, permettant de réduire le coût mémoire par rapport aux méthodes utilisant des voxels par exemple.
Purpose – The purpose of this paper is to introduce a novel framework for visual-aided ontology-b... more Purpose – The purpose of this paper is to introduce a novel framework for visual-aided ontology-based multidimensional ranking and to demonstrate a case study in the academic domain. Design/methodology/approach – The paper presents a method for adapting semantic web technologies on multiple criteria decision-making algorithms to endow to them dynamic characteristics. It also showcases the enhancement of the decision-making process by visual analytics. Findings – The semantic enhanced ranking method enables the reproducibility and transparency of ranking results, while the visual representation of this information further benefits decision makers into making well-informed and insightful deductions about the problem. Research limitations/implications – This approach is suitable for application domains that are ranked on the basis of multiple criteria. Originality/value – The discussed approach provides a dynamic ranking methodology, instead of focusing only on one application field, or one multiple criteria decision-making method. It proposes a framework that allows integration of multidimensional, domain-specific information and produces complex ranking results in both textual and visual form.
The water animation by moving soft bodies, changing their shapes, is the subject of the present w... more The water animation by moving soft bodies, changing their shapes, is the subject of the present work. The mechanism of movement transformation from a body to a liquid is elaborated on the basis of Lattice-Boltzmann method of fluid modeling. The use of boundary conditions, destined to perform this transformation visually realistic and computationally quite inexpensive, is one of the main innovations of our approach. The model is applied to the jellyfish propulsion water.
Creating realistic plants and trees require the ability to generate thousands of leaves with diff... more Creating realistic plants and trees require the ability to generate thousands of leaves with different shapes and textures for different given species. This paper presents an original method to generate large atlases of leaves with many details from a single formal grammar. Leaves are described by a parameterized 2Gmap L-system that describes their evolution in shape and texture through out their entire life cycle. Our approach automatically synthesizes the deformations as well as the color and texture changes as the leaves age, as well as defects such as holes or cracks produced by insect attacks or accidents.
A tool permitting to improve various steps of the visualisation process is presented in this pape... more A tool permitting to improve various steps of the visualisation process is presented in this paper. More precisely, this tool should concern the phase of preparing visualisation and also the visualisation phase itself. The tool presented in the paper, named visibility map, is based on the use of planar maps containing information on visibility and lighting, together with adjacency information inherent to planar maps. The proposed structure should permit to simplify the user's work, to accelerate some phases of visualisation and to improve the quality of produced images. In particular, this method permits to display a scene with ray tracing-like quality images, with very efficient antialiasing.
The educational institutions need to have a clear mission, comprehensive vision and attainable ob... more The educational institutions need to have a clear mission, comprehensive vision and attainable objectives that can be interpreted and analyzed by using terms of strategic planning. Our work is part of prototype system that supports academic evaluation and decision-making strategies concerning the research policy of an institute, using visual analytics. It focuses on the analysis and visualization of the relationships that exist between authors, scientific publications and research fields, within an academic unit. Using, initially, the research field as a filter we create a co-authoring network of authors connected to each other through weighted associations. Weight values are produced by applying more than one algorithm to key attributes of the publications (citation, publisher, etc.) and characterize the connections (edges) of the network. The graph nodes represent authors (researchers) with their attributes. Our data is enriched by analysis and metrics of the graph. The online use of successive vectors of thresholds in the characteristics of the graph enables users to get a "visual multi-criteria analysis" for the validation of the main hypotheses of institutional research policies and the support of further decision making.
Mass-spring systems simulations rely on the numerical integration method used for solving the res... more Mass-spring systems simulations rely on the numerical integration method used for solving the resulting ordinary differential equations. Implicit schemes, which solve such equations, are unconditionally stable and are thus widely used. Part of this stability is due to force filtering which is inherent to the implicit formulation and is referred to artificial damping. We extract this artificial damping and we analyse frequencies. This analysis enables us to define a non arbitrary damping value and a stability criterion in accordance to filtering. This directly comes from a decrease of velocity vectors' eigenvalues resulting in an increase of the time step in the same proportion. Moreover we applied a simple filtering model reproducing artificial damping to explicit schemes and results reveal an increase of the time step. Implementation of this method is straightforward for existing physically based simulators. Applications to cloth and fish animations are presented.
Water is one of the most important natural phenomena to be rendered in computer graphics. Althoug... more Water is one of the most important natural phenomena to be rendered in computer graphics. Although ocean waves animation has been well studied in Computer graphics, only few studies have been done for underwater animation. In this paper, we present a new real-time method for animation of suspended particles and seaweeds in underwater scenes. One of the main advantages of this method, compared to other approaches, is the real-time animation of submerged objects by taking into account some natural underwater forces that govern their movements, such as forces generated by water surface in deep and shallow waters as well as underwater currents. Taking into account forces generated by ocean surface is an original approach in Computer Graphics. In addition, real-time animation of complex underwater scenes composed of a great number of particles and seaweeds can be performed by the use of appropriate levels of details.
ABSTRACT Flowering plants have an enormous variety of shapes both within and between individuals,... more ABSTRACT Flowering plants have an enormous variety of shapes both within and between individuals, providing a vast area of objectives which the image synthesis must challenge. The structure of a flower has such properties as self-similarity, symmetry, branching arrangement, which make a modeling process quite tedious. We propose to apply mathematical methods to determine botanical natural laws, using 3Gmap L-systems. Describing the structure of a flowering plant with a grammar we are able to obtain an unlimited number of its geometrical interpretations. Our approach combines L-systems grammar writing with interactive control of parameter settings. The L-systems grammars are used for describing the entire model, with stems,stamens, petals, leaves, etc., by simply operating with 3Gmap volumes. The presented contributions will make the task of a user more obvious and intuitive enabling her/him to create more accurate models. 3Gmap L-systems grammars have a nested structure, enabling to use a huge amount of grammars in a more obvious way. Moreover the way the model is built allows us to take into account its internal structure. As the flower tissue is non-homogeneous, the possibility of obtaining its internal composition could be quite useful for rendering, allowing for instance to render more accurate subsurface scattering.
Higher Education Institutes worldwide are facing an increased demand to strengthen their capaciti... more Higher Education Institutes worldwide are facing an increased demand to strengthen their capacities for research and innovation. This study introduces an ontology-based software system architecture that supports research policy evaluation processes and decision-making strategies, using visual analytics. A knowledge modeling technique drawing on multi criteria analysis and data visualisation is proposed. In addition, the paper presents a prototype built on Protegé, Pellet reasoner and Java Technologies, which is friendly to the user and capable of interactive synthesis of institutional decision support criteria. In this work we make a transition from knowledge to visual web-based decision support systems with different kinds of visualisations. The developed system enables research managers to evaluate key aspects of academic research activity in the context of specific policies and criteria, correlate strategic goals with research performance and make informed decisions on the establishment of research strategies.
2012 16th Panhellenic Conference on Informatics, 2012
Educational institutions increasingly need to assess and enhance their activities, in order to im... more Educational institutions increasingly need to assess and enhance their activities, in order to improve research effectiveness and measure future capability as well as past performance. Research effectiveness is, among others, an important indicator of the quality assurance process in Higher Education. This study examines the research collaboration structures within a Higher Education academic unit, over a four-year period, with the aim of supporting institutional evaluation and reaching a deeper understanding of the process by which academics share research activities. Our approach focuses on the analysis and visualization of the relationships that exist among authors as well as of the researchers' activity and participativeness in intra and inter-institutional research groups.
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific ... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et a ̀ la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Copyright Interactive hydraulic erosion using CUDA
Les paysages naturels résultent d'une succession d'événements géomorphologiques qu'il convient de... more Les paysages naturels résultent d'une succession d'événements géomorphologiques qu'il convient de simuler pour produires des résultats plausibles. En particulier, les changements topologiques doivent être pris en compte durant la formation de géométries complexes comme les arches, les ponts ou les tunnels naturels. Nous présentons une nouvelle approche pour simuler les évolutions géomorphologiques d'un terrain en 3D conçu comme un ensemble de volumes dé•nis dans un modèle topologique, et décrivons un ensemble d'opérations atomiques a•n de gérer les événements topologiques de manière robuste. Ces opérations somt combinées pour produire des scénarios d'évolutions plus complexes dans un modeleur basé sur les cartes généralisées, permettant de réduire le coût mémoire par rapport aux méthodes utilisant des voxels par exemple.
Purpose – The purpose of this paper is to introduce a novel framework for visual-aided ontology-b... more Purpose – The purpose of this paper is to introduce a novel framework for visual-aided ontology-based multidimensional ranking and to demonstrate a case study in the academic domain. Design/methodology/approach – The paper presents a method for adapting semantic web technologies on multiple criteria decision-making algorithms to endow to them dynamic characteristics. It also showcases the enhancement of the decision-making process by visual analytics. Findings – The semantic enhanced ranking method enables the reproducibility and transparency of ranking results, while the visual representation of this information further benefits decision makers into making well-informed and insightful deductions about the problem. Research limitations/implications – This approach is suitable for application domains that are ranked on the basis of multiple criteria. Originality/value – The discussed approach provides a dynamic ranking methodology, instead of focusing only on one application field, or one multiple criteria decision-making method. It proposes a framework that allows integration of multidimensional, domain-specific information and produces complex ranking results in both textual and visual form.
The water animation by moving soft bodies, changing their shapes, is the subject of the present w... more The water animation by moving soft bodies, changing their shapes, is the subject of the present work. The mechanism of movement transformation from a body to a liquid is elaborated on the basis of Lattice-Boltzmann method of fluid modeling. The use of boundary conditions, destined to perform this transformation visually realistic and computationally quite inexpensive, is one of the main innovations of our approach. The model is applied to the jellyfish propulsion water.
Creating realistic plants and trees require the ability to generate thousands of leaves with diff... more Creating realistic plants and trees require the ability to generate thousands of leaves with different shapes and textures for different given species. This paper presents an original method to generate large atlases of leaves with many details from a single formal grammar. Leaves are described by a parameterized 2Gmap L-system that describes their evolution in shape and texture through out their entire life cycle. Our approach automatically synthesizes the deformations as well as the color and texture changes as the leaves age, as well as defects such as holes or cracks produced by insect attacks or accidents.
A tool permitting to improve various steps of the visualisation process is presented in this pape... more A tool permitting to improve various steps of the visualisation process is presented in this paper. More precisely, this tool should concern the phase of preparing visualisation and also the visualisation phase itself. The tool presented in the paper, named visibility map, is based on the use of planar maps containing information on visibility and lighting, together with adjacency information inherent to planar maps. The proposed structure should permit to simplify the user's work, to accelerate some phases of visualisation and to improve the quality of produced images. In particular, this method permits to display a scene with ray tracing-like quality images, with very efficient antialiasing.
The educational institutions need to have a clear mission, comprehensive vision and attainable ob... more The educational institutions need to have a clear mission, comprehensive vision and attainable objectives that can be interpreted and analyzed by using terms of strategic planning. Our work is part of prototype system that supports academic evaluation and decision-making strategies concerning the research policy of an institute, using visual analytics. It focuses on the analysis and visualization of the relationships that exist between authors, scientific publications and research fields, within an academic unit. Using, initially, the research field as a filter we create a co-authoring network of authors connected to each other through weighted associations. Weight values are produced by applying more than one algorithm to key attributes of the publications (citation, publisher, etc.) and characterize the connections (edges) of the network. The graph nodes represent authors (researchers) with their attributes. Our data is enriched by analysis and metrics of the graph. The online use of successive vectors of thresholds in the characteristics of the graph enables users to get a "visual multi-criteria analysis" for the validation of the main hypotheses of institutional research policies and the support of further decision making.
Mass-spring systems simulations rely on the numerical integration method used for solving the res... more Mass-spring systems simulations rely on the numerical integration method used for solving the resulting ordinary differential equations. Implicit schemes, which solve such equations, are unconditionally stable and are thus widely used. Part of this stability is due to force filtering which is inherent to the implicit formulation and is referred to artificial damping. We extract this artificial damping and we analyse frequencies. This analysis enables us to define a non arbitrary damping value and a stability criterion in accordance to filtering. This directly comes from a decrease of velocity vectors' eigenvalues resulting in an increase of the time step in the same proportion. Moreover we applied a simple filtering model reproducing artificial damping to explicit schemes and results reveal an increase of the time step. Implementation of this method is straightforward for existing physically based simulators. Applications to cloth and fish animations are presented.
Water is one of the most important natural phenomena to be rendered in computer graphics. Althoug... more Water is one of the most important natural phenomena to be rendered in computer graphics. Although ocean waves animation has been well studied in Computer graphics, only few studies have been done for underwater animation. In this paper, we present a new real-time method for animation of suspended particles and seaweeds in underwater scenes. One of the main advantages of this method, compared to other approaches, is the real-time animation of submerged objects by taking into account some natural underwater forces that govern their movements, such as forces generated by water surface in deep and shallow waters as well as underwater currents. Taking into account forces generated by ocean surface is an original approach in Computer Graphics. In addition, real-time animation of complex underwater scenes composed of a great number of particles and seaweeds can be performed by the use of appropriate levels of details.
ABSTRACT Flowering plants have an enormous variety of shapes both within and between individuals,... more ABSTRACT Flowering plants have an enormous variety of shapes both within and between individuals, providing a vast area of objectives which the image synthesis must challenge. The structure of a flower has such properties as self-similarity, symmetry, branching arrangement, which make a modeling process quite tedious. We propose to apply mathematical methods to determine botanical natural laws, using 3Gmap L-systems. Describing the structure of a flowering plant with a grammar we are able to obtain an unlimited number of its geometrical interpretations. Our approach combines L-systems grammar writing with interactive control of parameter settings. The L-systems grammars are used for describing the entire model, with stems,stamens, petals, leaves, etc., by simply operating with 3Gmap volumes. The presented contributions will make the task of a user more obvious and intuitive enabling her/him to create more accurate models. 3Gmap L-systems grammars have a nested structure, enabling to use a huge amount of grammars in a more obvious way. Moreover the way the model is built allows us to take into account its internal structure. As the flower tissue is non-homogeneous, the possibility of obtaining its internal composition could be quite useful for rendering, allowing for instance to render more accurate subsurface scattering.
Higher Education Institutes worldwide are facing an increased demand to strengthen their capaciti... more Higher Education Institutes worldwide are facing an increased demand to strengthen their capacities for research and innovation. This study introduces an ontology-based software system architecture that supports research policy evaluation processes and decision-making strategies, using visual analytics. A knowledge modeling technique drawing on multi criteria analysis and data visualisation is proposed. In addition, the paper presents a prototype built on Protegé, Pellet reasoner and Java Technologies, which is friendly to the user and capable of interactive synthesis of institutional decision support criteria. In this work we make a transition from knowledge to visual web-based decision support systems with different kinds of visualisations. The developed system enables research managers to evaluate key aspects of academic research activity in the context of specific policies and criteria, correlate strategic goals with research performance and make informed decisions on the establishment of research strategies.
2012 16th Panhellenic Conference on Informatics, 2012
Educational institutions increasingly need to assess and enhance their activities, in order to im... more Educational institutions increasingly need to assess and enhance their activities, in order to improve research effectiveness and measure future capability as well as past performance. Research effectiveness is, among others, an important indicator of the quality assurance process in Higher Education. This study examines the research collaboration structures within a Higher Education academic unit, over a four-year period, with the aim of supporting institutional evaluation and reaching a deeper understanding of the process by which academics share research activities. Our approach focuses on the analysis and visualization of the relationships that exist among authors as well as of the researchers' activity and participativeness in intra and inter-institutional research groups.
Uploads
Papers by Olivier Terraz