Within the scope of simulation of assembly/disassembly operations, flexible modelling for virtual reality environments is described. The study analyzes the adequacy of various mechanical models in the specific context of oil hoses. The model behaviour is checked against experiments for validation. As an issue of this comparison, a mechanical model is proposed through the concept of a dual mechanical approach. The adequacy of this last model is deduced from the experimental data. The mechanical model is coupled with a geometric model for free-form surfaces. The deformation criterion uses a functional based on the external forces applied to the mechanical model. This model is expressed as a prescribed displacement problem in order to obtain a more accurate model. The model proposed is also capable of handling interaction between the flexible area of the hose and rigid parts of its environment which model other components of an engine bay. To this end, the mechanical model is enriched with a contact boundary condition which preserves the coherence of the approach. The proposed approach is also a proposal for a methodology to model mechanical flexible parts for virtual reality applications. The model set up has been inserted into a virtual reality environment for efficiency evaluation.
{"title":"Modelling flexible parts for virtual reality assembly simulations which interact with their environment","authors":"J. Léon, U. Gandiaga, D. Dupont","doi":"10.1109/SMA.2001.923405","DOIUrl":"https://doi.org/10.1109/SMA.2001.923405","url":null,"abstract":"Within the scope of simulation of assembly/disassembly operations, flexible modelling for virtual reality environments is described. The study analyzes the adequacy of various mechanical models in the specific context of oil hoses. The model behaviour is checked against experiments for validation. As an issue of this comparison, a mechanical model is proposed through the concept of a dual mechanical approach. The adequacy of this last model is deduced from the experimental data. The mechanical model is coupled with a geometric model for free-form surfaces. The deformation criterion uses a functional based on the external forces applied to the mechanical model. This model is expressed as a prescribed displacement problem in order to obtain a more accurate model. The model proposed is also capable of handling interaction between the flexible area of the hose and rigid parts of its environment which model other components of an engine bay. To this end, the mechanical model is enriched with a contact boundary condition which preserves the coherence of the approach. The proposed approach is also a proposal for a methodology to model mechanical flexible parts for virtual reality applications. The model set up has been inserted into a virtual reality environment for efficiency evaluation.","PeriodicalId":247602,"journal":{"name":"Proceedings International Conference on Shape Modeling and Applications","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132257179","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}
Shape matching is an important ingredient in shape retrieval, recognition and classification, alignment and registration, and approximation and simplification. This paper treats various aspects that are needed to solve shape matching problems: choosing the precise problem, selecting the properties of the similarity measure that are needed for the problem, choosing the specific similarity measure, and constructing the algorithm to compute the similarity. The focus is on methods that lie close to the field of computational geometry.
{"title":"Shape matching: similarity measures and algorithms","authors":"R. Veltkamp","doi":"10.1109/SMA.2001.923389","DOIUrl":"https://doi.org/10.1109/SMA.2001.923389","url":null,"abstract":"Shape matching is an important ingredient in shape retrieval, recognition and classification, alignment and registration, and approximation and simplification. This paper treats various aspects that are needed to solve shape matching problems: choosing the precise problem, selecting the properties of the similarity measure that are needed for the problem, choosing the specific similarity measure, and constructing the algorithm to compute the similarity. The focus is on methods that lie close to the field of computational geometry.","PeriodicalId":247602,"journal":{"name":"Proceedings International Conference on Shape Modeling and Applications","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125218062","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}
Consider a 2D smooth closed curve evolving in time, the skeleton (medial axis) of the figure bounded by the curve, and the evolute of the curve. A new branch of the skeleton can appear/disappear when an evolute cusp intersects the skeleton. In this paper, we describe exact conditions of the skeleton bifurcations corresponding to such intersections. Similar results are also obtained for 3D surfaces evolving in time.
{"title":"On evolute cusps and skeleton bifurcations","authors":"A. Belyaev, S. Yoshizawa","doi":"10.1109/SMA.2001.923384","DOIUrl":"https://doi.org/10.1109/SMA.2001.923384","url":null,"abstract":"Consider a 2D smooth closed curve evolving in time, the skeleton (medial axis) of the figure bounded by the curve, and the evolute of the curve. A new branch of the skeleton can appear/disappear when an evolute cusp intersects the skeleton. In this paper, we describe exact conditions of the skeleton bifurcations corresponding to such intersections. Similar results are also obtained for 3D surfaces evolving in time.","PeriodicalId":247602,"journal":{"name":"Proceedings International Conference on Shape Modeling and Applications","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124377635","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 major applications of implicit surface modeling systems has been the generation of cartoon-like characters. Recently, additional modeling methods have been combined with implicit surfaces to create much more complex models. These methods include constructive solid geometry (CSG), warping, and two-dimensional texture mapping (among others). The BlobTree has been introduced to organize all of these elements into a single structure which allows both local and global applications of each of these techniques in a general and intuitive fashion. The BlobTree lends itself well to rapid and direct specification of complex models, however current implementations of the BlobTree have not been engineered for efficiency, and perform poorly when attempting to render large models. In this work we apply established techniques, such as spatial subdivision and tree optimization, to the BlobTree. The objective is to increase efficiency during rendering without restricting the functionality of the BlobTree as a modeling tool.
{"title":"Efficient use of the BlobTree for rendering purposes","authors":"M. Fox, C. Galbraith, B. Wyvill","doi":"10.1109/SMA.2001.923402","DOIUrl":"https://doi.org/10.1109/SMA.2001.923402","url":null,"abstract":"One of the major applications of implicit surface modeling systems has been the generation of cartoon-like characters. Recently, additional modeling methods have been combined with implicit surfaces to create much more complex models. These methods include constructive solid geometry (CSG), warping, and two-dimensional texture mapping (among others). The BlobTree has been introduced to organize all of these elements into a single structure which allows both local and global applications of each of these techniques in a general and intuitive fashion. The BlobTree lends itself well to rapid and direct specification of complex models, however current implementations of the BlobTree have not been engineered for efficiency, and perform poorly when attempting to render large models. In this work we apply established techniques, such as spatial subdivision and tree optimization, to the BlobTree. The objective is to increase efficiency during rendering without restricting the functionality of the BlobTree as a modeling tool.","PeriodicalId":247602,"journal":{"name":"Proceedings International Conference on Shape Modeling and Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122629851","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}
Shape modeling is still in its infancy. Fifty years of research has produced only a few isolated techniques that describe a tiny subset of shapes usefully. We need to find some more general principles that coordinate shape description just as scientific laws coordinate a description of nature. Underlying the laws of science are even more general principles of thermodynamics. Although we are not yet ready to describe the 'laws of shape', we can begin to establish some underlying principles that these laws must follow. In trying to do this we have uncovered some interesting inconsistencies in existing practice.
{"title":"The 'thermodynamics' of shape","authors":"G. Wyvill, C. Handley","doi":"10.1109/SMA.2001.923369","DOIUrl":"https://doi.org/10.1109/SMA.2001.923369","url":null,"abstract":"Shape modeling is still in its infancy. Fifty years of research has produced only a few isolated techniques that describe a tiny subset of shapes usefully. We need to find some more general principles that coordinate shape description just as scientific laws coordinate a description of nature. Underlying the laws of science are even more general principles of thermodynamics. Although we are not yet ready to describe the 'laws of shape', we can begin to establish some underlying principles that these laws must follow. In trying to do this we have uncovered some interesting inconsistencies in existing practice.","PeriodicalId":247602,"journal":{"name":"Proceedings International Conference on Shape Modeling and Applications","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115486225","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 a novel modeling technique and develops an interactive algorithm that facilitates the automatic determination of non-uniform knot vectors as well as other control variables for NURBS curves and surfaces through the unified methodology of energy minimization, variational principle, and numerical techniques. Many geometric algorithms have been developed for NURBS during the past three decades. Recently, the optimization principle has been widely studied, which affords designers to interactively manipulate NURBS via energy functionals, simulated forces, qualitative and quantitative constraints, etc. The existing techniques primarily concentrate on NURBS control points. In this paper we further augment our NURBS modeling capabilities by incorporating NURBS' non-uniform knot sequence into our shape parameter set. The automatic determination of NURBS knots will facilitate the realization of the full geometric potential of NURBS. We also have developed a modeling framework which supports a large variety of functionals ranging from simple quadratic energy forms to non-linear curvature-based (or area-based) objective functionals.
{"title":"Automatic knot determination of NURBS for interactive geometric design","authors":"Hui Xie, Hong Qin","doi":"10.1109/SMA.2001.923398","DOIUrl":"https://doi.org/10.1109/SMA.2001.923398","url":null,"abstract":"This paper presents a novel modeling technique and develops an interactive algorithm that facilitates the automatic determination of non-uniform knot vectors as well as other control variables for NURBS curves and surfaces through the unified methodology of energy minimization, variational principle, and numerical techniques. Many geometric algorithms have been developed for NURBS during the past three decades. Recently, the optimization principle has been widely studied, which affords designers to interactively manipulate NURBS via energy functionals, simulated forces, qualitative and quantitative constraints, etc. The existing techniques primarily concentrate on NURBS control points. In this paper we further augment our NURBS modeling capabilities by incorporating NURBS' non-uniform knot sequence into our shape parameter set. The automatic determination of NURBS knots will facilitate the realization of the full geometric potential of NURBS. We also have developed a modeling framework which supports a large variety of functionals ranging from simple quadratic energy forms to non-linear curvature-based (or area-based) objective functionals.","PeriodicalId":247602,"journal":{"name":"Proceedings International Conference on Shape Modeling and Applications","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114871085","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}
Voxelisation is the process of converting a source object of any data type into a three-dimensional grid of voxel values. This voxel grid should represent the original object as closely as possible, although some inaccuracies will occur due to the discrete nature of the voxel grid representation. In this paper we report our ongoing research into methods for representing objects as voxelised distance fields, in particular we report fast methods for accurate distance field production. A review of current alternative voxelisation methods is also given.
{"title":"Shape representation using space filled sub-voxel distance fields","authors":"Mark W. Jones, Richard Satherley","doi":"10.1109/SMA.2001.923403","DOIUrl":"https://doi.org/10.1109/SMA.2001.923403","url":null,"abstract":"Voxelisation is the process of converting a source object of any data type into a three-dimensional grid of voxel values. This voxel grid should represent the original object as closely as possible, although some inaccuracies will occur due to the discrete nature of the voxel grid representation. In this paper we report our ongoing research into methods for representing objects as voxelised distance fields, in particular we report fast methods for accurate distance field production. A review of current alternative voxelisation methods is also given.","PeriodicalId":247602,"journal":{"name":"Proceedings International Conference on Shape Modeling and Applications","volume":"369 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123414985","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 a method for adaptive refinement within an integrated mechanically based CAE system. The system uses a mechanical B-spline finite element model for both geometric design and mechanical analysis. A technique for locally refining a solution by B-spline finite elements is presented. The key component in the proposed method is the linear coordinate transformation introduced into the refined element. The transformation is constructed in such a way that the transformed nodal configuration of the refined element is identical to the nodal configuration of the neighbor elements. Therefore, the assembly proceeds in the regular fashion, while the C/sup 0/ continuity is forced along the inter-element boundary exactly. The proposed adaptive refinement method has been implemented both for surface and solid design without substantial differences in technical complexity. Its feasibility as applied to sculptured surface and solid objects is demonstrated by several examples.
{"title":"Mechanically based design: adaptive refinement for B-spline finite element","authors":"P. Kagan, A. Fischer, P. Bar-Yoseph","doi":"10.1109/SMA.2001.923406","DOIUrl":"https://doi.org/10.1109/SMA.2001.923406","url":null,"abstract":"This paper presents a method for adaptive refinement within an integrated mechanically based CAE system. The system uses a mechanical B-spline finite element model for both geometric design and mechanical analysis. A technique for locally refining a solution by B-spline finite elements is presented. The key component in the proposed method is the linear coordinate transformation introduced into the refined element. The transformation is constructed in such a way that the transformed nodal configuration of the refined element is identical to the nodal configuration of the neighbor elements. Therefore, the assembly proceeds in the regular fashion, while the C/sup 0/ continuity is forced along the inter-element boundary exactly. The proposed adaptive refinement method has been implemented both for surface and solid design without substantial differences in technical complexity. Its feasibility as applied to sculptured surface and solid objects is demonstrated by several examples.","PeriodicalId":247602,"journal":{"name":"Proceedings International Conference on Shape Modeling and Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129671393","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}
Mesh morphing techniques are capable of producing a sequence of meshes, gradually changing from a source to a target shape. However, current techniques do not allow to describe the local behavior of the morph. A solution to this problem is presented. The main idea is to describe mesh geometry in a differential way, thus, insertion of local features from one shape into another does not suffer from difference in absolute coordinates. Besides interesting possibilities for animation the technique proves to be a powerful modeling tool.
{"title":"Local control for mesh morphing","authors":"M. Alexa","doi":"10.1109/SMA.2001.923392","DOIUrl":"https://doi.org/10.1109/SMA.2001.923392","url":null,"abstract":"Mesh morphing techniques are capable of producing a sequence of meshes, gradually changing from a source to a target shape. However, current techniques do not allow to describe the local behavior of the morph. A solution to this problem is presented. The main idea is to describe mesh geometry in a differential way, thus, insertion of local features from one shape into another does not suffer from difference in absolute coordinates. Besides interesting possibilities for animation the technique proves to be a powerful modeling tool.","PeriodicalId":247602,"journal":{"name":"Proceedings International Conference on Shape Modeling and Applications","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129769901","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}
Solid models are the critical data elements in modern computer-aided design (CAD) environments, describing the shape and form of manufactured artifacts. Their growing ubiquity has created new problems in how to effectively manage the many models that are now stored in the digital libraries of large design and manufacturing enterprises. Existing techniques from the engineering literature and from industrial practice, such as group technology, rely on human-supervised encoding and classification, while techniques from the multimedia database and computer graphics/vision communities often ignore the manufacturing attributes most significant in the classification of models. This paper presents our approach to the manufacturing similarly assessment of solid models of mechanical parts based on machining features. Our technical approach is three-fold: (1) perform machining feature extraction to map the solid model to a set of STEP AP 224 machining features; (2) construct a model dependency graph from the set of machining features; and (3) find the nearest neighbors to the query graph using an iterative improvement search across a database of other models. We also present empirical experiments to validate our approach using our testbed, the National Design Repository (). The contribution of this research is the first fully automated technique for machining feature-based comparisons of mechanical artifacts. We believe that this work can lead to radical changes in the way in which design data is managed in modern engineering enterprises.
实体模型是现代计算机辅助设计(CAD)环境中的关键数据元素，描述了制造工件的形状和形式。它们的日益普及产生了新的问题，即如何有效地管理现在存储在大型设计和制造企业数字图书馆中的许多模型。来自工程文献和工业实践的现有技术，如成组技术，依赖于人类监督的编码和分类，而来自多媒体数据库和计算机图形学/视觉社区的技术往往忽略了模型分类中最重要的制造属性。本文介绍了基于加工特征的机械零件实体模型的制造类似评估方法。我们的技术方法有三个方面:(1)进行加工特征提取，将实体模型映射到STEP AP 224加工特征集;(2)从加工特征集构造模型依赖图;(3)在其他模型的数据库中使用迭代改进搜索找到查询图的最近邻居。我们还提出了经验实验来验证我们的方法，使用我们的测试平台，国家设计存储库()。这项研究的贡献是第一个完全自动化的技术加工特征为基础的机械工件的比较。我们相信，这项工作可以彻底改变现代工程企业管理设计数据的方式。
{"title":"Machining feature-based comparisons of mechanical parts","authors":"V. Cicirello, W. Regli","doi":"10.1109/SMA.2001.923388","DOIUrl":"https://doi.org/10.1109/SMA.2001.923388","url":null,"abstract":"Solid models are the critical data elements in modern computer-aided design (CAD) environments, describing the shape and form of manufactured artifacts. Their growing ubiquity has created new problems in how to effectively manage the many models that are now stored in the digital libraries of large design and manufacturing enterprises. Existing techniques from the engineering literature and from industrial practice, such as group technology, rely on human-supervised encoding and classification, while techniques from the multimedia database and computer graphics/vision communities often ignore the manufacturing attributes most significant in the classification of models. This paper presents our approach to the manufacturing similarly assessment of solid models of mechanical parts based on machining features. Our technical approach is three-fold: (1) perform machining feature extraction to map the solid model to a set of STEP AP 224 machining features; (2) construct a model dependency graph from the set of machining features; and (3) find the nearest neighbors to the query graph using an iterative improvement search across a database of other models. We also present empirical experiments to validate our approach using our testbed, the National Design Repository (). The contribution of this research is the first fully automated technique for machining feature-based comparisons of mechanical artifacts. We believe that this work can lead to radical changes in the way in which design data is managed in modern engineering enterprises.","PeriodicalId":247602,"journal":{"name":"Proceedings International Conference on Shape Modeling and Applications","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130099184","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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