Mesh2Brep: B-Rep Reconstruction via Robust Primitive Fitting and Intersection-Aware Constraints.

Ordinary triangular mesh model can be constructed from discrete point cloud. However, this kind of model contains large amount of data. It is not only difficult to split, but also lacks topological relation information. We proposed a CSG---BRep (Constructive Solid Geometry--Boundary Representation) topological model to overcome these problems. CSG---BRep model can record topological relationship of 3D model in great detail. We first introduced aspects of the topological model: location, orientation and sub-shape. Then we proposed two algorithms to access topological structure. We also proposed algorithms for performing Boolean operation on CSG---BRep models. Finally, we demonstrated CSG---BRep construction using LIDAR point cloud as a data source. We would show that, compared to ordinary triangular mesh model, CSG---BRep model is composable and can effectively reduce data volume. In addition, CSG---BRep model has detailed topological relation information, allowing further querying and analysis of 3D spatial topological information.

Future prospects of computer-aided design (CAD) – A review from the perspective of artificial intelligence (AI), extended reality, and 3D printing

Recently, concurrent engineering (CE) has become one of the major conceptual approaches in reducing product developing time. Design for manufacturing (DFM) and design for assembly (DFA) are two of the major areas in CE. Several researchers have integrated a CAD/CAM system and a knowledge-based system to implement DFA and DFM concepts. However, the incompatibility of the data representation methods between CAD/CAM and knowledge-based systems is the major issue in this integration method. In this paper, an approach is proposed to find the minimum wall thickness of a part from its boundary representation (B-Rep) model. These data can then be directly utilized by a knowledge-based system to analyse the manufacturability of thin wall parts such as injection moulded or diecast parts.

[EN] Students of the Degree in Industrial Design and Product Development Engineering of the University\nJaume I of Castellón (Spain) received an integrated training in the subject of Technical Drawing and\nGraphics (TDG) and Computer Aided Design (CAD) through 4 one-semester courses: Technical\nDrawing and Graphics I & II of 1st year and Computer Aided Design I and II (CADI and CADII),\ncompleted in 2nd and 3rd year respectively.\nWhile the first subject (TDGI) focuses on the fundamentals of representation systems and on the\nknowledge of volumetric forms and elementary surfaces, the following three subjects (TDGII, CADI\nand CADII) are focused on developing the abilities needed to sketch (TDGII) and create engineering\ntechnical drawings with CAD applications. TDGII deepens the sketch, focusing on proportionality,\nlanguage and graphic representation techniques for engineering technical drawings, being these skills\nextended in CADI and CADII through the use of 2D and 3D CAD systems.\nConsidering this framework, TDGII, CADI and CADII courses have been coordinating for several\nyears, sharing a general structure of the common teaching-learning process. The original structure of\nthese classes included a standard lecture format and practical sessions where students worked\ndifferent types of exercises, including the development of a graphic project.\nTeachers¿ experience over the years and students¿ opinion have allowed authors to recognize main\ndrawbacks of the standard class structure. Firstly, standard lecture format is not attractive for students.\nSecondly, due to the differences in the previous training of students (some have already used some\nCAD software) the levels with which they start the classes may not be homogeneous, which means\nthat some of them may arrive to get bored in class while others take more effort to understand\ncontents.\nFlipped learning is a methodology used in teaching that helps teachers to prioritize active learning\nduring class by using that time for group activities and individual attention. This model allows\nmodifying the standard class structure of sessions where the content of the subject is presented by the\nteacher in the classroom. In this new model the content of the subject is viewed at home or outside the\nclassroom through the use of tools and resources classified within the Information and Communication\nTechnologies (ICT).\nAs a first step in the analysis of experiences in learning Technical Drawing and Graphics and CAD,\nthis study shows the results of an academic experience that compares the classic methodology of\nstandard lecture format versus flipped classroom in teaching Technical Drawing and Graphics (TDGII).\nStudents from standard lecture format received the lesson in the traditional way, while students from\nthe flipped classroom had to prepare themselves before attending the class, by using this time to\ncomplete questionnaires and team activities. Both groups filled a knowledge assessment test before\nand after class. Student involved in flipped classroom had to complete as well a survey on their\nperception of the method.\nThe results obtained show that the level of knowledge after the class is slightly higher for those\nstudents involved in the flipped classroom. In addition, the students' opinion on the methodology is\nquite positive. They consider that it is a more effective method than the standard lecture format, since\nit has allowed them to better understand the content and to significantly increased their knowledge.

Knowledge-based Expert Systems are rapidly finding widespread application in computer-aided design and manufacturing processes. The paper concerns the application of Artificial Intelligence methods in Power Switchgear arrangements design. The design process in this domain requires knowledge, human experience and skill which are represented in a convenient way in a knowledge base. The description of the problem and the two resources of knowledge that uses today an expert designer are first presented. Then, the expert system is constructed and its architecture is described.

In this chapter we shall study numerical methods to approximate arbitrary functions by easy ones. Our interest in these studies is motivated by the more far-reaching goal of solving numerically more general problems such as integration of functions which cannot be integrated exactly in closed form or for which such an integration would be computationally too expensive. Further problems comprise applications in computer-aided design, the numerical solution of differential equations, or even more generally, of operator equations. Further applications comprise machine learning, engineering, the reconstruction of complicated graphs of functions from measurements, and so on.

A new agent-based paradigm for recognition of free-hand sketches

Information and communication technologies have found their application in the healthcare sector, including the frameworks of modern dentistry. CAD / CAM application in dentistry is the process by which is attained finished dental restoration through fine milling process of ready ceramic blocks. CAD / CAM is an acronym of english words Computer-Aided-Design (CAD) / Computer-Aided-Manufacture (CAM), respectively dental computer aided design and computer aided manufacture of inlays, onlays, crowns and bridges. CAD / CAM technology essentially allows you to create a two-dimensional and three-dimensional models and their materialization by numerical controlled machines. In order to operate more efficiently, reduce costs, increase user/patient satisfaction and ultimately achieve profits, many dental offices in the world have their attention focused on implementation of modern IT solutions in everyday practice. In addition to the specialized clinic management software, inventory control, etc., or hardware such as the use of lasers in cosmetic dentistry or intraoral scanning, recently the importance is given to the application of CAD / CAM technology in the field of prosthetic. After the removal of pathologically altered tooth structure, it is necessary to achieve restoration that will be most similar to the anatomy of a natural tooth. Applying CAD / CAM technology on applicable ceramic blocks it can be obtained very quick, but also very accurate restoration, in the forms of inlays, onlays, bridges and crowns.The paper presents the advantages of using this technology as well as satisfaction of the patients and dentists by using systems as: Cercon, Celay, Cerec, Lava, Everest, which represent imperative of modern dentistry in creating fixed dental restorations.

Structural optimization with CADO method for a three-dimensional sheet-metal vehicle body

Analysis in computer aided design: Nonlinear isogeometric B-Rep analysis of shell structures

Most of the treatment head components of medical linear accelerators used in radiation therapy have complex geometrical shapes. They are typically designed using computer-aided design (CAD) applications. In Monte Carlo simulations of radiotherapy beam transport through the treatment head components, the relevant beam-generating and beam-modifying devices are inserted in the simulation toolkit using geometrical approximations of these components. Depending on their complexity, such approximations may introduce errors that can be propagated throughout the simulation. This drawback can be minimized by exporting a more precise geometry of the linac components from CAD and importing it into the Monte Carlo simulation environment. We present a technique that links three-dimensional CAD drawings of the treatment head components to Geant4 Monte Carlo simulations of dose deposition.

All kinds of mining enterprises prefer to use computer-aided design (CAD) in drawing figures of mining reserves. CAD is convenient to operate and ensures the creation of intuitive and beautiful figures. However, CAD causes data error easily due to human intervention. Moreover, CAD wastes time and is prone to omit records. To reduce the incidence of such errors, the current paper examines the transformation of CAD-drawn reserves’ figures and databases into “block” form. This paper also aims to realize the conversion of figure blocks and databases using Visual Basic (VB) in CAD and database applications. To achieve this result, the circle and text are first extracted from CAD form. Then, a series of changes is implemented. Lastly, figure blocks are endowed with new properties. Using this approach can quickly transform figure elements into block properties, achieving good application effects.

Loops are critical elements in boundary representation (B-rep) models because they link all edges corresponding to a face. Loops can be used in feature recognition for identifying depressions or protrusions. In real 3D CAD models, however, features typically lie across multiple faces, which is beyond the data structure of current B-rep models. This study presents a virtual loop concept to account for all loop types used in CAD models, and develops algorithms for recognizing them. In accordance with the complexity of the recognition algorithm, this study defines three types of loop: single, virtual, and multivirtual. A single loop is the current loop recorded in the B-rep model. A virtual loop lies across faces that are at least G1 continuous. Finally, a multivirtual loop lies across faces that are either G0 or G1 continuous. The proposed loop structure provides a more complete data structure for recognizing various types of features in feature-recognition modules. Several realistic CAD models are presented to confirm the feasibility of the proposed loop-recognition and feature-recognition methods.

Adaptive reconstruction of free-form surfaces using Bernstein basis function networks

This article analyses the need and benefit of the working of industrial designers and product engineers together. According to engineers and others at the forefront of product development, to do the job right requires a collaboration involving design engineers, industrial designers, manufacturing engineers, and several other players, like marketing people, all of whom have important knowledge that needs to influence a design. Companies such as Trek Bicycle Corp. and Empire Level Manufacturing Corp. have developed practices that foster innovative, human-centered product development. Experts agree that computer-aided design (CAD) and rapid prototyping applications are the two most helpful systems, even though the two types of designers may use the tools in somewhat several ways. According to Rainer Gawlick, vice president of marketing at SolidWorks in Concord, Massachusetts, current CAD systems can help bridge the design-to-engineering-to-manufacturing gap.