The tedious task of manually placing feathers on computer animated objects involves aligning feathers, ensuring that they do not insect each other or penetrate the surface, deforming every feather to match the local surface features, and ensuring that the feather coat is consistent when the underlying object is animated. We present a technique for generating a feather coat over an object. Feather orientation is specified quickly and easily, feathers are deformed while ensuring collision prevention, and the coat can be animated. We create a vector field in the space surrounding the body object and deform feathers to align with the field lines. The non-intersection property of the field lines ensures that feather intersections are avoided. We provide a formulation of a suitable vector field and demonstrate that it is capable of producing realistic feather coats. The process can easily be integrated into the work-flow of standard modelling and animation processes. We show examples of feather coat creation on a range of objects, proving that field line based placement of feather coats provides the desired functionality for feather modelling and animation.
{"title":"Animated feather coats using field lines","authors":"S. Bangay","doi":"10.1145/1294685.1294713","DOIUrl":"https://doi.org/10.1145/1294685.1294713","url":null,"abstract":"The tedious task of manually placing feathers on computer animated objects involves aligning feathers, ensuring that they do not insect each other or penetrate the surface, deforming every feather to match the local surface features, and ensuring that the feather coat is consistent when the underlying object is animated.\u0000 We present a technique for generating a feather coat over an object. Feather orientation is specified quickly and easily, feathers are deformed while ensuring collision prevention, and the coat can be animated. We create a vector field in the space surrounding the body object and deform feathers to align with the field lines. The non-intersection property of the field lines ensures that feather intersections are avoided. We provide a formulation of a suitable vector field and demonstrate that it is capable of producing realistic feather coats. The process can easily be integrated into the work-flow of standard modelling and animation processes.\u0000 We show examples of feather coat creation on a range of objects, proving that field line based placement of feather coats provides the desired functionality for feather modelling and animation.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114643192","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}
Real objects present an enormous amount of detail, including aging effects. Artists need an intuitive control when they iteratively review and redesign their work to achieve a specific aging effect pattern but physically based and empirical simulations rarely provide an appropriate control. Our motivation comes from simplifying the redesign step by providing appropriate tools. In our system the user interactively identifies aging effects in a source image or photograph. The user then designs a target aging mask presenting the wanted aging effects pattern. Our system then synthesizes the output texture within a few seconds using a texture synthesis approach adapted to aged object texture editing. Thus, the user can quickly redesign the aging mask to achieve better results or test new configurations.
{"title":"Efficient editing of aged object textures","authors":"Olivier Clément, Jocelyn Benoit, Eric Paquette","doi":"10.1145/1294685.1294711","DOIUrl":"https://doi.org/10.1145/1294685.1294711","url":null,"abstract":"Real objects present an enormous amount of detail, including aging effects. Artists need an intuitive control when they iteratively review and redesign their work to achieve a specific aging effect pattern but physically based and empirical simulations rarely provide an appropriate control. Our motivation comes from simplifying the redesign step by providing appropriate tools. In our system the user interactively identifies aging effects in a source image or photograph. The user then designs a target aging mask presenting the wanted aging effects pattern. Our system then synthesizes the output texture within a few seconds using a texture synthesis approach adapted to aged object texture editing. Thus, the user can quickly redesign the aging mask to achieve better results or test new configurations.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124099190","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}
One of the long-term goals in human-computer interaction is to utilize more intuitive and natural methods such as speech and hand gesture that a user would employ for communication. In this paper, we present a multi-modal 3D interaction mechanism, in which user can interact with a 3D model of a tourist location displayed on the kiosk screen from a one meter distance by means of gestures and voice commands without wearing any special device in a public place, with a complex and non-static background environment. The system can be used in many applications such entertainment, touring, education, museum displays, and advertising.
{"title":"A 3D interactive kiosk system","authors":"C. Manders, F. Farbiz, Jyh Herng Chong, K. Tang","doi":"10.1145/1294685.1294693","DOIUrl":"https://doi.org/10.1145/1294685.1294693","url":null,"abstract":"One of the long-term goals in human-computer interaction is to utilize more intuitive and natural methods such as speech and hand gesture that a user would employ for communication. In this paper, we present a multi-modal 3D interaction mechanism, in which user can interact with a 3D model of a tourist location displayed on the kiosk screen from a one meter distance by means of gestures and voice commands without wearing any special device in a public place, with a complex and non-static background environment. The system can be used in many applications such entertainment, touring, education, museum displays, and advertising.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115759834","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}
This paper presents two novel techniques for visualization of tunnels in complex molecules of proteins. Long-term research in the field of protein analysis proved that the reactivity of the protein molecule depends on the presence of tunnels. These structures are very important mainly in the process of finding new pharmaceuticals. Visualization of a tunnel is the next very important step after the analysis because it enables the biochemists to determine the crucial regions of the tunnel, which can have a substantial effect in the process of designing new medication. Previous methods for the visualization of tunnels define a tunnel as a set of intersecting spheres. Our approach exploits tetrahedra obtained from the process of tunnel analysis based on the Voronoi diagrams and Delaunay tetrahedrization. We proposed two novel algorithms that visualize a tunnel as a surface derived from the tetrahedra, which form the boundary constraint of the tunnel in the space of the molecule.
{"title":"Visualization of tunnels in protein molecules","authors":"B. Kozlíková, F. Andres, Jirí Sochor","doi":"10.1145/1294685.1294704","DOIUrl":"https://doi.org/10.1145/1294685.1294704","url":null,"abstract":"This paper presents two novel techniques for visualization of tunnels in complex molecules of proteins. Long-term research in the field of protein analysis proved that the reactivity of the protein molecule depends on the presence of tunnels. These structures are very important mainly in the process of finding new pharmaceuticals. Visualization of a tunnel is the next very important step after the analysis because it enables the biochemists to determine the crucial regions of the tunnel, which can have a substantial effect in the process of designing new medication.\u0000 Previous methods for the visualization of tunnels define a tunnel as a set of intersecting spheres. Our approach exploits tetrahedra obtained from the process of tunnel analysis based on the Voronoi diagrams and Delaunay tetrahedrization. We proposed two novel algorithms that visualize a tunnel as a surface derived from the tetrahedra, which form the boundary constraint of the tunnel in the space of the molecule.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"163 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115999463","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}
The simulated evolution of botanical trees and other plants is explored in this paper. We present a model to simplify the creation of plants by following the genotype/phenotype approach of Gene Expression Programming to generate L-Systems. Our model describes a specific organism (a plant) with a genotype that can be expressed as an L-System. This L-System, and subsequently it's interpreted graphical image, forms the phenotype, and is used to assess the fitness of the organism. The human eye is used as a fitness function, and a user assigns fitness ratings to the organisms in a population based on the aesthetic value of the images. The user is able to create a plant without knowledge of the underlying algorithms or specific botanical knowledge.
{"title":"Generating plants with gene expression programming","authors":"Johannes Venter, A. Hardy","doi":"10.1145/1294685.1294712","DOIUrl":"https://doi.org/10.1145/1294685.1294712","url":null,"abstract":"The simulated evolution of botanical trees and other plants is explored in this paper. We present a model to simplify the creation of plants by following the genotype/phenotype approach of Gene Expression Programming to generate L-Systems. Our model describes a specific organism (a plant) with a genotype that can be expressed as an L-System. This L-System, and subsequently it's interpreted graphical image, forms the phenotype, and is used to assess the fitness of the organism. The human eye is used as a fitness function, and a user assigns fitness ratings to the organisms in a population based on the aesthetic value of the images. The user is able to create a plant without knowledge of the underlying algorithms or specific botanical knowledge.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"239 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121575181","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}
Subdivision surfaces possess many appealing properties applicable to interactive computer graphics. However, the necessity to access a variable-sized neighborhood in a control mesh makes it difficult to efficiently accelerate tessellation calculations in graphics hardware. The paper addresses this problem in two ways. First, it proposes a simple and inexpensive calculation scheme for the tessellation of Catmull-Clark subdivision surfaces which can be implemented in a geometry shader. It operates on the shader's vertex input only and does not require external texture memory access or multi-pass processing for tessellation. Second, the paper presents an extension to the post-transform and lighting (T'n'L) vertex cache operation that efficiently accelerates the processing of variable-size primitives serving as input for the geometry shader. We demonstrate on-chip tessellation of Catmull-Clark subdivision surfaces on an embedded hardware implementation. The described calculation scheme will be implementable on desktop hardware if limitations on the maximal input primitive size for the geometry shader are relaxed.
{"title":"Catmull-Clark subdivision for geometry shaders","authors":"M. Kazakov","doi":"10.1145/1294685.1294699","DOIUrl":"https://doi.org/10.1145/1294685.1294699","url":null,"abstract":"Subdivision surfaces possess many appealing properties applicable to interactive computer graphics. However, the necessity to access a variable-sized neighborhood in a control mesh makes it difficult to efficiently accelerate tessellation calculations in graphics hardware. The paper addresses this problem in two ways. First, it proposes a simple and inexpensive calculation scheme for the tessellation of Catmull-Clark subdivision surfaces which can be implemented in a geometry shader. It operates on the shader's vertex input only and does not require external texture memory access or multi-pass processing for tessellation. Second, the paper presents an extension to the post-transform and lighting (T'n'L) vertex cache operation that efficiently accelerates the processing of variable-size primitives serving as input for the geometry shader. We demonstrate on-chip tessellation of Catmull-Clark subdivision surfaces on an embedded hardware implementation. The described calculation scheme will be implementable on desktop hardware if limitations on the maximal input primitive size for the geometry shader are relaxed.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132453818","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}
We consider the rendering of geometry images obtained by parameterization of terrain geometry. This technique reduces texture warping in areas of steep gradient. The selected terrain representation allows terrain that cannot be represented by a heightfield to be rendered. Finally, we demonstrate that the slightly irregular sampling can be rendered efficiently using modern graphics hardware. We introduce an efficient level of detail algorithm that can be applied to terrain geometry images or regular terrain.
{"title":"Level of detail for terrain geometry images","authors":"D. K. Roberts, A. Hardy","doi":"10.1145/1294685.1294689","DOIUrl":"https://doi.org/10.1145/1294685.1294689","url":null,"abstract":"We consider the rendering of geometry images obtained by parameterization of terrain geometry. This technique reduces texture warping in areas of steep gradient. The selected terrain representation allows terrain that cannot be represented by a heightfield to be rendered. Finally, we demonstrate that the slightly irregular sampling can be rendered efficiently using modern graphics hardware. We introduce an efficient level of detail algorithm that can be applied to terrain geometry images or regular terrain.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128288414","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}
We present an algorithm mainly designed to reconstruct Digital Elevation Maps (DEM). Our approach relays on a fast and highly controllable fractal-based algorithm, we are able to create DEMs according to given constraints. Thus, these constraints can be given as scattered dataset of elevations obtained by satellite, our method supersamples this data and creates the according smooth terrain surface. Moreover, as a painter can make a sketch of his model, the final user can give or edit the main characteristics, local details and morphology, of his wanted DEM instantaneously obtaining the resulting terrain surface. Note that there is no limitation on the number of local constraints (that could vary from 0 to the number of points of the final DEM). Thus, the method we propose gives the ability to modify the global aspect (the surface behavior) as well as to constrain any local detail of the final terrain model. This paper presents the algorithm and reconstruction examples. Using a Root Mean Square Error computation between an original model and its downsampled-then-reconstructed version, the results confirm the method good behavior and show its efficiency. Other various terrain models and alternative applications are presented.
{"title":"Terrain modeling: a constrained fractal model","authors":"Farès Belhadj","doi":"10.1145/1294685.1294717","DOIUrl":"https://doi.org/10.1145/1294685.1294717","url":null,"abstract":"We present an algorithm mainly designed to reconstruct Digital Elevation Maps (DEM). Our approach relays on a fast and highly controllable fractal-based algorithm, we are able to create DEMs according to given constraints. Thus, these constraints can be given as scattered dataset of elevations obtained by satellite, our method supersamples this data and creates the according smooth terrain surface. Moreover, as a painter can make a sketch of his model, the final user can give or edit the main characteristics, local details and morphology, of his wanted DEM instantaneously obtaining the resulting terrain surface. Note that there is no limitation on the number of local constraints (that could vary from 0 to the number of points of the final DEM). Thus, the method we propose gives the ability to modify the global aspect (the surface behavior) as well as to constrain any local detail of the final terrain model. This paper presents the algorithm and reconstruction examples. Using a Root Mean Square Error computation between an original model and its downsampled-then-reconstructed version, the results confirm the method good behavior and show its efficiency. Other various terrain models and alternative applications are presented.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128815012","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}
Meva Dodo, F. Andriamanampisoa, P. Torguet, J. Jessel
This paper describes a novel force-directed placement approach for 3D drawing of large graphs. The main idea behind our approach consists in optimizing the layout by equitably distributing vertices in the space. We consider the largest sphere inscribed in the 3D space and the vertices are then assigned random initial positions that are improved by force-directed placement. In order to ensure the effectiveness of the algorithm, we propose a new energy function minimization which uses the conjugated gradient of Fletcher-Reeves [1, 2]. Our algorithm is not only addressed to general undirected graphs but also it produces good layout of large trees. This work is motivated by our need to offer 3D visualization tools for large computing networks but this first phase will be focused on the graph representation.
{"title":"A new method to optimize the force-directed placement for 3D large graph drawing","authors":"Meva Dodo, F. Andriamanampisoa, P. Torguet, J. Jessel","doi":"10.1145/1294685.1294709","DOIUrl":"https://doi.org/10.1145/1294685.1294709","url":null,"abstract":"This paper describes a novel force-directed placement approach for 3D drawing of large graphs. The main idea behind our approach consists in optimizing the layout by equitably distributing vertices in the space. We consider the largest sphere inscribed in the 3D space and the vertices are then assigned random initial positions that are improved by force-directed placement. In order to ensure the effectiveness of the algorithm, we propose a new energy function minimization which uses the conjugated gradient of Fletcher-Reeves [1, 2]. Our algorithm is not only addressed to general undirected graphs but also it produces good layout of large trees. This work is motivated by our need to offer 3D visualization tools for large computing networks but this first phase will be focused on the graph representation.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132868566","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}
Various ways of categorizing software visualization tools have been developed in the past. This paper presents a hybrid tools requirements classification for tool developers that builds onto the previous taxonomies and research results. Ten software visualization tools that differ in their functionalities are then measured on the categorization in order to show the extent to which they fulfill the requirements that are desired by tool users. It is not an extensive in-depth coverage of the tools but a comparison of the tools with the perceived requirements in an effort to address the tool adoption issue.
{"title":"Tool users requirements classification: how software visualization tools measure up","authors":"Mariam Sensalire, P. Ogao","doi":"10.1145/1294685.1294705","DOIUrl":"https://doi.org/10.1145/1294685.1294705","url":null,"abstract":"Various ways of categorizing software visualization tools have been developed in the past. This paper presents a hybrid tools requirements classification for tool developers that builds onto the previous taxonomies and research results. Ten software visualization tools that differ in their functionalities are then measured on the categorization in order to show the extent to which they fulfill the requirements that are desired by tool users. It is not an extensive in-depth coverage of the tools but a comparison of the tools with the perceived requirements in an effort to address the tool adoption issue.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131233387","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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