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Showing papers in "Computer-aided Design and Applications in 2006"


Journal ArticleDOI
TL;DR: In this article, the authors derived a general equation of aesthetic curves that describes the relationship between its radius of curvature and length inclusively expressing these two curves and showed the self-affinity possessed by the curves satisfying the general equation.
Abstract: The curve is the most basic design element to determine shapes and silhouettes of industrial products and works for shape designers and it is inevitable for them to make it aesthetic and attractive to improve the total quality of the shape design. If we can find an equation of aesthetic curves, it is expected that the quality of the curve design improves drastically because we can use it as a standard to generate, evaluate, and deform the curves. In this paper, we derive a general equation of aesthetic curves that describes the relationship between its radius of curvature and length inclusively expressing these two curves. Furthermore we show the self-affinity possessed by the curves satisfying the general equation of aesthetic curves.

83 citations


Journal ArticleDOI
TL;DR: The basic concepts of feature modelling in general, and the state of the art in commercial feature modelling systems, will be presented first, followed by an overview of four major developments that solve shortcomings in such systems.
Abstract: Feature modelling is nowadays the predominant way of product modelling, in which geometric and functional information is stored in a single product model. The basic concepts of feature modelling in general, and the state of the art in commercial feature modelling systems, will be presented first. This will be followed by an overview of four major developments that solve shortcomings in such systems. First, in semantic feature modelling, it is possible to more adequately specify and maintain the meaning of features. Second, in multiple-view feature modelling, there is a specific feature model for each product development phase. Third, in collaborative feature modelling, teams of users can collaborate on the development of a product with full feature modeling functionality. Fourth, in freeform feature modelling, features with freeform shapes are made available. Some other developments are mentioned as well.

47 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a new approach that utilizes the so-called EP (Edge Proportion) value, local material stiffness and implicit function to develop a novel dental training system which has useful characteristics such as efficient collision detection, stable haptic interaction and accurate sculpting simulation.
Abstract: The virtual dental training system using a haptic device is becoming a very important training tool for dental education. We propose a new approach that utilizes the so-called EP (Edge Proportion) value, local material stiffness and implicit function to develop a novel dental training system which has useful characteristics such as efficient collision detection, stable haptic interaction and accurate sculpting simulation. In the efficient collision detection approach, the oriented bounding box tree and EP value can be quickly updated for collision detection. The EP value is very important in our approach, because it can also be used to compute haptic force and update the tooth model. In the stable haptic interaction approach, we use the spring-damper force model and a simple force filter to obtain stable force feedback. Finally, in the precision sculpting simulation, an implicit function is employed to exactly represent various kinds of dental tools so that accurate calculation of cutter- surface ...

44 citations


Journal ArticleDOI
TL;DR: A novel CAD framework that can automatically form a customized shoe last based on a scanned foot data and an existing shoe last data using the modified distant map method and an interactive local deformation method is presented.
Abstract: This paper presents a novel CAD framework for designing customized shoe last. The new approach consists of two parts. The first part is a global deformation approach that can automatically form a customized shoe last based on a scanned foot data and an existing shoe last data. It uses the modified distant map method giving the design being similar to the last and fit with the foot shape. The second part is an interactive local deformation method. It allows the shoe last be modified in specific regions to meet various needs. Preliminary simulation results show that the new approach is effective.

35 citations


Journal ArticleDOI
TL;DR: The MEMPHIS system is introduced, a data exchange middleware that closes the manual gap of data processing between CAD and VR environments and will allow the efficient reuse of VR specific modifications and eventually reduce time and repeated efforts during the design process of a product.
Abstract: The data exchange between CAD and VR systems is recognized as an essential element for the integration of the digital design process in the manufacturing industry. This paper introduces the MEMPHIS system, a data exchange middleware, that closes the manual gap of data processing between CAD and VR environments. This system was designed to integrate PDM, CAD and VR systems through common interfaces which are based on international standards. Taking advantage of these interfaces and standardized data structures, MEMPHIS will allow the efficient reuse of VR specific modifications and eventually reduce time and repeated efforts during the design process of a product.

33 citations


Journal ArticleDOI
TL;DR: The experience in managing the transition from traditional design education to CAD based design as a case study for comparison is documented.
Abstract: In the proposed paper, our experience in managing the transition from traditional design education to CAD based design as a case study for comparison is documented. Use of CAD technologies on both undergraduate and Master level is also discussed.

33 citations


Journal ArticleDOI
TL;DR: In this paper, a 5DOF haptic device and the driving computational engine have been developed to provide force-torque feedback to the users for computer-aided molecular design (CAMD).
Abstract: This paper presents a computer-aided design system for molecular docking and nanoscale assembly. A lab-built 5-DOF (degree of freedom) haptic device and the driving computational engine have been developed to provide force-torque feedback to the users for computer-aided molecular design (CAMD). The developed haptic force-torque feedback will enable researchers to visualize, touch, manipulate and assemble molecules in a virtual environment. The presented techniques can be used in the computer-aided molecular design to provide the researchers a realtime tool to better understand molecular interactions and to evaluate possible pharmaceutical drugs and nanoscale devices. Computer implementation and illustrative examples are also presented in this paper.

27 citations


Journal ArticleDOI
TL;DR: The distance and the subdivision depth computation techniques provide the long-needed precision/error control tools in subdivision surface trimming, finite element mesh generation, Boolean operations, and surface tessellation for rendering processes.
Abstract: A subdivision depth computation technique for Catmull-Clark subdivision surfaces (CCSS’s) is presented. The subdivision depth computation technique also includes distance evaluation techniques for CCSS patches with their control meshes. The distance and the subdivision depth computation techniques provide the long-needed precision/error control tools in subdivision surface trimming, finite element mesh generation, Boolean operations, and surface tessellation for rendering processes.

27 citations


Journal ArticleDOI
TL;DR: In this article, an algorithm of 3D modeling of fibers assemblies has been developed, which extends a concept of virtual location for simulation of fiber distributions in yarns cross-section from 2D to 3D modelling of yarns structure.
Abstract: An algorithm of 3D modeling of fibers assemblies has been developed. The method extends a concept of ‘virtual location’ for simulation of fiber distributions in yarns cross-section from 2D to 3D modeling of yarns structure. The distributions function used in the model demonstrates all of the properties of the ideal and real yarns. A series of further cross-section at equal intervals along the yarn length is given. Each cross-section is rotated by a pre-determined amount relative to previous one, to allow for the yarn twist and parameters of fibers migration. The fiber curve in each interval between two successive cross-sections is approximated by NURBS. Also curve generation based on twist of each fiber is determined by centerline configurations of their constituent fibers and the generative model. Each fiber is created by sweeping a closed curve along a centerline path. The simulated yarns structure using the algorithm described can model wider variety and yield an improved visual representation ...

26 citations


Journal ArticleDOI
TL;DR: This paper tries to understand what design intent is in the domain of 2D CAD drawings by providing a definition for it along with a survey of research and literature in the area of design intent.
Abstract: Design intent has received much attention in numerous disciplines ranging from mechanical engineering design, software engineering to human-computer interaction research. While it is universally acknowledged that knowing design intent is extremely useful, there is still a lack of both support for frameworks for design intent and widespread use in engineering. Design groups looking to use the latest design intent systems and tools face the problem that the bulk of their product data resides in unintelligent 2D drawings. There exists a need to propagate the design intent present in these 2D drawings to a structured, intelligent, reusable format. This paper tries to understand what design intent is in the domain of 2D CAD drawings by providing a definition for it along with a survey of research and literature in the area of design intent. The paper also focuses on the importance, capture, representation and retrieval of design intent from 2D CAD drawing.

26 citations


Journal ArticleDOI
TL;DR: The issues that arise when dealing with the capture, representation and retrieval of design intent from the legacy CAD data are addressed and a prototype system is implemented to address these issues from a software system point of view.
Abstract: There exist numerous design intent systems that convert captured information into structured design intent while providing intent representation and retrieval. These systems woefully neglect the design intent that is present in legacy CAD such as 2D drawings and 3D models. We address the issues that arise when dealing with the capture, representation and retrieval of design intent from the legacy CAD data. A definition for design intent in the CAD domain is presented which forms the basis of the proposed approach. The approach uses a unique context-based inference system to capture design intent from legacy CAD data. A brief explanation of context is provided along with the advantages of using context for this task. The need and use of an inference system is detailed. Additionally a prototype system is implemented to address these issues from a software system point of view.

Journal ArticleDOI
TL;DR: In this paper, the authors present current trends and issues in automatic mesh generation, and outline recent development of the two technical issues in order to encourage further research and development of advanced mesh generation technology.
Abstract: This paper presents current trends and issues in automatic mesh generation. Although automated mesh generation methods in two and three dimensions have been studied intensively, many analysis engineers still craft meshes manually for a certain class of analysis problems. In order to realize fully automated high-quality mesh generation, two technical issues need to be addressed: (1) automated mesh generators should be able to control the anisotropy and directionality of a mesh, and (2) geometric operations required prior to mesh generation should be made more robust and automated. This paper outlines recent development of the two technical issues in order to encourage further research and development of advanced mesh generation technology.

Journal ArticleDOI
TL;DR: In this article, a hybrid evolutionary approach to create non-functional art forms for jewelry design is presented, which is hybrid between EP, ES, GA and GP, and a new aesthetic measure is formulated, based on IFS's characteristics, aesthetic theory, and human perception.
Abstract: This paper presents a new evolutionary approach to create non-functional art forms for jewelry design. The proposed EA is hybrid between EP, ES, GA and GP. Art forms are represented by using Iterated Function Systems (IFS) fractal for jewelry ring’s ornaments. IFS are encoded in form of chromosomes. Mutation and crossover operators are developed to increase variations of art forms. Two-step fitness function is developed. The first step is morphological fitness function to evaluate compactness and connectivity of art forms. This fitness function screens the incompact and disconnected art forms out of the evolutionary process before going to the next step. The second step is aesthetic fitness function to evaluate aesthetics of art forms. A new aesthetic measure is formulated, based on IFS’s characteristics, aesthetic theory, and human perception. The experimental results of the study are also included in this paper.

Journal ArticleDOI
TL;DR: In this article, a reverse engineering approach for product form design is presented. And the potential effectiveness of the 3D laser technology for education is also assessed with live projects, where 3D models of design concepts are created in clay, and data points on the surface of the model are then measured using a non-contact 3D scan device.
Abstract: Advanced 3D Laser Scanning processes have developed over the last decade and are now available and affordable for medium to large companies as well as education. This study examines the overall efficiency of the 3D scanning process and potential value for use in design education. The potential effectiveness of the 3D laser technology for education is also assessed with live projects. This article explores a reverse engineering approach for product form design. Three-dimensional models of design concepts are created in clay, and data points on the surface of the model are then measured using a non-contact 3D scan device. The resulting data is then imported into an appropriate CAD design package for further design development.

Journal ArticleDOI
TL;DR: The entire eigenstructure of the subdivision matrix and its inverse are computed exactly and explicitly with no need to precompute anything and the new representation can be used not only for evaluation purpose, but for analysis purpose as well.
Abstract: A new parametrization technique and its applications for general Catmull-Clark subdivision surfaces are presented. The new technique extends J. Stam’s work by redefining all the eigen basis functions in the parametric representation for general Catmull-Clark subdivision surfaces and giving each of them an explicit form. The entire eigenstructure of the subdivision matrix and its inverse are computed exactly and explicitly with no need to precompute anything. Therefore, the new representation can be used not only for evaluation purpose, but for analysis purpose as well. The new approach is based on an Ω-partition of the parameter space and a detoured subdivision path. This results in a block diagonal matrix with constant size diagonal blocks (7×7) for the corresponding subdivision process. Consequently, eigen decomposition of the matrix is always possible and is simpler and more efficient. Furthermore, since the number of eigen basis functions required in the new approach is only one half of the pr...

Journal ArticleDOI
TL;DR: In this article, an extension of Greiner-Hormann polygon clipping is presented that handles the degenerate cases in a deterministic way, which in the previous approach is done by perturbing vertices in an indeterministic way.
Abstract: We present an extension of Greiner-Hormann polygon clipping that has been regarded as both computationally efficient and simple to implement. This extended version of the Greiner-Hormann polygon clipping elegantly handles the degenerate cases in a deterministic way, which in the previous approach is done by perturbing vertices in an indeterministic way.

Journal ArticleDOI
TL;DR: In this article, a set of modified spiral curves based on the geometry of the 2D region is used to cover the entire region, have the least number of sharp turns, and use a controllable step-over value.
Abstract: High speed machining is playing a more and more important role in modern machines shops, in particularly, in aerospace machining, mold and die machining In high speed milling operations, a path that has the least number of sharp turns is preferred Spiral curve is a special curve which can have no sharp turn, and the step-over between adjacent segments can also be controlled to a predefined value However, traditional approaches to finding such a path either work for very simple convex regions, or, for irregular shapes, many overlap linkage paths have to be used Thus, although spiral curves are promising, there is still not a good algorithm in generating a path which 1) covers the entire region, 2) has least number of turns, 3) uses a controllable step-over value In this paper, we will introduce a novel approach which covers a 2D region in a very efficient manner In particular, 1) it covers the 2D region using a set of modified spiral curves based on the geometry of the 2D region, 2) these cur

Journal ArticleDOI
TL;DR: A haptic system of virtual suture is developed for surgical training, and a realistic tissue modeling method based on either MRI or CT images is proposed, which can be used for soft tissue modeling and haptic modeling.
Abstract: Virtual surgical planning and training require high fidelity not only in visual modeling, but also in haptic modeling. As a fundamental and typical application of surgical simulation, virtual suturing deals with technical problems such as soft tissue modeling, collision detection, and force modeling. In this paper, a haptic system of virtual suture is developed for surgical training. A realistic tissue modeling method based on either MRI or CT images is proposed. Given a CT or MRI file, an STL file is constructed. The STL file is voxelized to generate a regular spatial lattice that provides the basis for constructing the mass-spring system (MSS). Surface textures are mapped to this MSS for better visual effect of human tissues. Haptic interaction between the tissue model and a haptic device is rendered on a piecewise linear stress-strain model. A prototype system based on the proposed method is implemented. When using this system, a user can feel the force change at different stage of the suturing...

Journal ArticleDOI
TL;DR: A dental training system which uses surfel models and carries out realistic cutting simulation using a haptic device and gets better visual quality with less memory cost.
Abstract: Recently, a new point-based geometric modeling approach using surfels (surface elements) has been introduced into the field of computer graphics. This new type of 3D model can be used to render complex geometry with less geometric and topological constraints. This paper presents a dental training system which uses surfel models and carries out realistic cutting simulation using a haptic device. We use surfel models to render dental tools and virtual teeth models to get better visual quality with less memory cost. By using surfel models to render dental tools, we can model cutters of many different shapes. The Boolean operation of the surfel model is implemented with local update; the modeling and visual update frequency of the system is about 30Hz. Collision detection and force computation are implemented on an Octree box to simulate physical interactions between a virtual dental tool and a tooth model. Dental training systems based on surfel models can work on any cutter shape. We add the materia...

Journal ArticleDOI
TL;DR: An overview of different types of part search techniques is presented and the open challenges in these areas are identified and outlines future research directions.
Abstract: The popularity of 3D CAD systems is resulting in large assembly and part databases being created by product development organizations Over the last few years several content-based techniques have emerged to search these databases Ability to perform content-based searches on CAD databases is expected to help the designers and manufacturing engineers in many different ways Representative examples include part-family formation, redesign suggestion generation, supplier selection, cost estimation, tooling design, machine selection, stock selection, and design reuse This paper covers the following three topics First, it presents an overview of different types of part search techniques Second, it presents an overview of the different aspects of assembly search techniques Finally, it identifies the open challenges in these areas and outlines future research directions

Journal ArticleDOI
TL;DR: A flexible, generic mechanism to define freeform surface feature classes that can be consistently archived, retrieved and re-used in an application-independent manner is presented.
Abstract: This paper presents a flexible, generic mechanism to define freeform surface feature classes. The method is applicable to pre-defined and user-defined features. A feature class definition includes, firstly, declaring a feature class, and then specifying the class using attributes specific to the feature. A generic taxonomy of freeform surface features is used to facilitate class declaration. Then, the dynamic mechanism facilitates general specification of attributes. It is demonstrated that such a class definition can be consistently archived, retrieved and re-used in an application-independent manner.

Journal ArticleDOI
TL;DR: Two fundamental approaches are introduced intended to improve the comfort and user-friendliness of new products by designing a product to reflect the geometry of the human body and a product based on the simulation of both product behavior and human motion.
Abstract: Severe competition in today’s marketplace has imposed additional demands on the products being sold. In addition to basic requirements, such as function, quality, price, and appearance, modern products must be increasingly comfortable and easy to use. The current discussion will introduce two fundamental approaches intended to improve the comfort and user-friendliness of new products. The first approach involves designing a product to reflect the geometry of the human body. This approach can be exploited when designing custom-tailored products, such as shoes, clothes, and helmets. Specialized CAD systems for custom tailoring these products will be introduced together with human body scanners and human body modelers. The other approach is to design a product based on the simulation of both product behavior and human motion. This approach can be used to design products that are used in close association with the human body to maximize its comfort and ease of use. To realize the simulation environmen...

Journal ArticleDOI
TL;DR: In this paper, a unique algorithm is presented to evaluate the accessibility of a cylindrical fillet-ended cutter to a point on the part surface by considering machine axis limit, avoidance of local gouging, rear-gouging and global collision.
Abstract: In 5-axis milling (finish cut) of sculptured surfaces, the cutter’s accessibility to the part surface is an important issue for subsequent process planning tasks. In this paper, a unique algorithm is presented to evaluate the accessibility of a cylindrical fillet-ended cutter to a point on the part surface by considering machine axis limit, avoidance of local-gouging, rear-gouging, and globalcollision. By applying this algorithm to the sampled points of a given part surface, the accessibility map (A-map) of the cutter to any point on the part surface can be obtained. More significantly, the A-maps can be subsequently employed for optimal cutter selection, optimal cutting direction selection, and optimal tool-path generation. It is expected that by employing this concept, the process planning tasks for 5-axis milling of sculptured surfaces can be carried out in an integrated and efficient manner.

Journal ArticleDOI
TL;DR: A novel progressive approach to generate a Binary Space Partition (BSP) tree and a convex cell decomposition for any input triangles boundary representation (B-rep) by utilizing a fast calculation of the surface inertia.
Abstract: We introduce a novel progressive approach to generate a Binary Space Partition (BSP ) tree and a convex cell decomposition for any input triangles boundary representation (B-rep), by utilizing a fast calculation of the surface inertia. We also generate a solid model at progressive levels of detail. This approach relies on a variation of standard BSP tree generation, allowing for labeling cells as in, out and fuzzy, and which permits a comprehensive representation of a solid as the Hasse diagram of a cell complex. Our new algorithm is embedded in a streaming computational framework, using four types of dataflow processes that continuously produce, transform, combine or consume subsets of cells depending on their number or input/output stream. A varied collection of geometric modeling techniques are integrated in this streaming framework, including polygonal, spline, solid and heterogeneous modeling with boundary and decompositive representations, Boolean set operations, Cartesian products and adapt...

Journal ArticleDOI
TL;DR: An innovative automated design-methodology for custom-made cranioplasty plates is presented, and the time durations and shape deviations are assessed and compared with results of the current artisanal design procedure.
Abstract: Large vulnerable openings in human cranium require a rigid anatomical reconstruction. A possible solution is the use of personalised thin titanium plates, also denoted membranes. The indirect production process, which is mainly hydroforming or casting, requires a single die, which is shaped manually or milled directly from a CAD-file.Currently, the design of membranes is mainly manual work, even with the use of CAD facilities, and results in a tedious and user-dependent skull reconstruction. A direct link between CAD-file and production is missing, and no studies evaluate the overall geometrical outcome quantitatively.This paper therefore presents an innovative automated design-methodology for custom-made cranioplasty plates. For a clinical case, the time durations and shape deviations are assessed and compared with results of the current artisanal design procedure. The afore-mentioned required improvements are achieved.

Journal ArticleDOI
TL;DR: This work provides a framework for reverse engineering of small objects and in particular jewelry that combines cross section identification, feature and constraint information exploitation to attain robust, accurate and editable CAD models.
Abstract: Reverse engineering is the process of obtaining a geometric CAD model from 3D points acquired by scanning an existing physical model. It is widely used in numerous applications, such as manufacturing, industrial design and jewelry design and reproduction. We argue that for creating editable CAD models meant for manufacturing it is more appropriate to use feature-based constraint-based representations, since they capture design intent. We provide a framework for reverse engineering of small objects and in particular jewelry that combines cross section identification, feature and constraint information exploitation to attain robust, accurate and editable CAD models. First, we extract certain candidate features for describing our point cloud. These features are then reconstructed to describe the solid object. Constraints are automatically detected and maintained. Constraints capture design intent and provide robustness guaranties. Voxel inspired techniques are also employed to describe repeated patte...

Journal ArticleDOI
TL;DR: An Assembly Design (AsD) ontology that explicitly represents AsD constraints and infers any remaining implicit ones is presented and the significance of ontology for realizing lean and selective assembly design information sharing is discussed.
Abstract: This paper presents an Assembly Design (AsD) ontology that explicitly represents AsD constraints and infers any remaining implicit ones. By relating concepts through ontology technology rather than just defining data syntax, assembly and joining concepts can be captured in their entirety or extended as necessary. Ontologies allow assembly and joining constraints to be represented in a standard manner regardless of geometry file formats. Such representation will significantly improve service-oriented design collaboration. The developed AsD ontology is tested using a realistic mechanical assembly and it is shown how the ontology can be used to capture design rationale and analyze the design intents. In conclusion, the significance of ontology for realizing lean and selective assembly design information sharing is discussed.

Journal ArticleDOI
TL;DR: In this paper, a CAD-centric approach is proposed to automate the CAD to CFD process, including fluid domain creation, while addressing the discrete feature problem that can occur during preliminary design.
Abstract: CAD models from conceptual design often follow the “over-the-wall” approach for downstream analyses such as FEA, CFD, heat transfer, and vibrations. The CAD-centric approach consists of using the CAD model as a source of data for downstream applications such as mesh generation, and CFD setup. The CAD model used in the CAD-centric approach contains the geometry to be analyzed and all non-geometric data required to mesh and solve the CFD model in the form of attributes. A special class of topology change, the discrete feature problem, is encountered when an array of features instances change in number. A method is proposed, developed and reported on that automates the CAD to CFD process, including fluid domain creation, while addressing the discrete feature problem that can occur during preliminary design.

Journal ArticleDOI
TL;DR: The proposed CMMVP system blocks out environmental disturbances such that designers can fully immerse in performing stereoscopic visualisation and quality analysis of the resulting multi-material prototypes for subsequent improvements of a product design.
Abstract: This paper proposes a CAVE-based multi-material virtual prototyping (CMMVP) system for immersive stereoscopic visualisation and optimisation of multi-material layered manufacturing (MMLM) processes. The CMMVP system consists mainly of a suite of software packages for simulation of MMLM processes, integrated with a multi-screen CAVE-based virtual reality (VR) system, to create an immersive virtual environment for digital fabrication of multi-material product prototypes. In comparison with desktop-based or semi-immersive VR systems, the CMMVP system blocks out environmental disturbances such that designers can fully immerse in performing stereoscopic visualisation and quality analysis of the resulting multi-material prototypes for subsequent improvements of a product design. The CMMVP system facilitates advanced product design and helps reduce product development time and cost substantially.

Journal ArticleDOI
TL;DR: An algorithm that assesses similarity between two parts by explicitly aligning their faces and hence accounts for these face attributes is described, which involves extracting attributed applied vectors from the face information of parts and aligning the two sets of attributed applied vector sets using rigid body transformations.
Abstract: In certain shape similarity assessment applications, type, locations, and orientations of faces in boundary representations plays a key role in determining similarity between two parts. This paper describes an algorithm that assesses similarity between two parts by explicitly aligning their faces and hence accounts for these face attributes. The approach involves extracting attributed applied vectors from the face information of parts and aligning the two sets of attributed applied vectors using rigid body transformations. The algorithm uses a customizable distance function to align attributed applied vectors. The distance between two aligned attributed applied vector sets is used as a measure of similarity between two parts. This paper also presents computational results to illustrate discrimination capability of the algorithm.