Solid reconstruction using recognition of quadric surfaces from orthographic views

International audienceThe reconstruction of 3D objects from 2D orthographic views is crucial for maintaining and further developing existing product designs. A B-rep oriented method for reconstructing curved objects from three orthographic views is presented by employing a hybrid wire-frame in place of an intermediate wire-frame. The Link-Relation Graph (LRG) is introduced as a multi-graph representation of orthographic views, and quadric surface features (QSFs) are defined by special basic patterns of LRG as well as aggregation rules. By hint-based pattern matching in the LRGs of three orthographic views in an order of priority, the corresponding QSFs are recognized, and the geometry and topology of quadric surfaces are recovered simultaneously. This method can handle objects with interacting quadric surfaces and avoids the combinatorial search for tracing all the quadric surfaces in an intermediate wire-frame by the existing methods. Several examples are provided

Converting Hybrid Wire-frames to B-rep Models

International audienceSolid reconstruction from engineering drawings is one of the efficient technologies to product solid models. The B-rep oriented approach provides a practical way for reconstructing a wide range of objects. However, its major limitation is the computational complexity involved in the search for all valid faces from the intermediate wire-frame, especially for objects with complicated face topologies. In previous work, we presented a hint-based algorithm to recognize quadric surfaces from orthographic views and generate a hybrid wire-frame as the intermediate model of our B-rep oriented method. As a key stage in the process of solid reconstructing, we propose an algorithm to convert the hybrid wire-frame to the final B-rep model by extracting all the rest faces of planes based on graph theory. The entities lying on the same planar surface are first collected in a plane graph. After all the cycles are traced in a simplified edge-adjacency matrix of the graph, the face loops of the plane are formed by testing loop containment and assigning loop directions. Finally, the B-rep model is constructed by sewing all the plane faces based on the M¨obius rule. The method can efficiently construct 2- manifold objects with a variety of face topologies, which is illustrated by results of implementatio

The role of computer-aided design in the learning of practical 3D-descriptive geometry: a case study

There are a number of problems surrounding the teaching of practical 3-D descriptive geometry to children in secondary education, notably the difficulty pupils have with visualising an object's form from orthographic views, and the interpretation of an object's geometric attributes into the descriptive geometry representation. The purpose of the current research is to evaluate the use of computer-aided design in this area of the curriculum and is based upon work undertaken in a North London comprehensive school. The school and its context is described and evaluated. Theories of child development and educational psychology of relevance to the study are reviewed, notably the work of Piaget, Bryant, Gagne, and Freeman. The history and nature of 3-D descriptive geometry is reviewed in practice and in education, with special reference to various methods employed in instruction. Dr. J. Vince's PICASO SYSTEM of computer subroutines and functions written in FORTRAN for graphic applications is explained as a means of teaching the subject, with special reference to the researcher's own instructional material and computer programs. The use and effectiveness of these teaching materials are related and evaluated in the light of students' performance and results. The research concludes that the special benefits of computer graphics in this field are: the economic production of appropriate didactic material under the direct control of the teacher, increased pupil motivation due to the use of better illustration and the interest generated by computer-aided design project work. and an opportunity to employ analytic geometry to support learning. Its limitations include: the high cost of the computer and peripheral devices, and the lack of a facility for modelling objects by the removal of solid volumes in the existing software. Further research is recommended in the areas of computer graphics, descriptive geometry, and psychology

Perceived importance of national occupational CADD skill standards among faculty of NAIT accredited institutions

This study presents a descriptive survey that examined the importance and relevance of National Occupational CARD Skills based on the perceptions of faculty teaching at National Association of Industrial Technology (NAIT) accredited institutions. The major goal of the study was to determine what National Occupational CADD Skill Standards are relevant and important to faculty teaching CARD courses. The study was also designed to determine ratings of the perceived importance and relevance of National Occupational CADD Skill Standards by faculty teaching CADD courses at NAIT accredited institutions based on their area of specialization, professional ranking, and teaching experience. This study provided NAIT accredited programs, professionals, and affiliated organizations a reflection of CADD standards developed, adopted, and practiced by faculty teaching CADD courses at NAIT accredited institutions in relation to National Occupational CADD Skill Standards. The population used for this study includes faculty teaching CADD courses in various Industrial Technology programs. For testing hypothesis I, a single sample was used for survey responses. Independent samples were used for survey responses in hypotheses II, III, and V. A single survey instrument was developed for this study. The survey instrument has five sections representing: demographics, fundamental drafting skills, fundamental computer skills, basic CADD skills, and advanced CADD skills. A research hypothesis (H1 : μ ≠ 3) was established for hypothesis I for each item. Research hypotheses (H1 At least one pair of the category means would be different) were established for hypotheses II, III, and IV. Hypothesis I was tested using a single sample t -test at the .O5 level of significance for each of the CADD skill standard item. The ANOVA was used to test hypotheses II, III, and IV. The results of the statistical analyses were used to arrive at inferences on the importance and relevance of National Occupational CADD Skill Standards developed by National Coalition for Advanced Manufacturing (NACFAM) by faculty teaching at NAIT accredited institutions. Statistical analyses also checked on the balance of opinions on importance and relevance of National Occupational CADD Skill Standards between industry and educators. Statistical analyses failed to establish significant mean differences on how faculty teaching CADD at NAIT accredited institutions perceive the importance and relevance of National Occupational CADD Skill Standards in the four hypotheses tested. The four hypotheses are stated in Chapter 1 of the study. Recommendations for further studies are provided in Chapter 5

Course of study and a teacher's manual for a thirty-lesson course in engineering drawing.

Thesis (M.A.)--Boston Universit

3D reconstruction of curved objects from single 2D line drawings.

Wang, Yingze.Thesis (M.Phil.)--Chinese University of Hong Kong, 2009.Includes bibliographical references (leaves 42-47).Abstract also in Chinese.Chapter 1 --- Introduction --- p.1Chapter 2 --- Related Work --- p.5Chapter 2.1 --- Line labeling and realization problem --- p.5Chapter 2.2 --- 3D reconstruction from multiple views --- p.6Chapter 2.3 --- 3D reconstruction from single line drawings --- p.7Chapter 2.3.1 --- Face identification from the line drawings --- p.7Chapter 2.3.2 --- 3D geometry reconstruction --- p.9Chapter 2.4 --- Our research topic and contributions --- p.13Chapter 3 --- Reconstruction of Curved Manifold Objects --- p.14Chapter 3.1 --- Assumptions and terminology --- p.14Chapter 3.2 --- Reconstruction of curved manifold objects --- p.17Chapter 3.2.1 --- Distinguishing between curved and planar faces --- p.17Chapter 3.2.2 --- Transformation of Line Drawings --- p.20Chapter 3.2.3 --- Regularities --- p.23Chapter 3.2.4 --- 3D Wireframe Reconstruction --- p.26Chapter 3.2.5 --- Generating Curved Faces --- p.28Chapter 3.2.6 --- The Complete 3D Reconstruction Algorithm --- p.33Chapter 4 --- Experiments --- p.35Chapter 5 --- Conclusions and Future Work --- p.40Chapter 5.1 --- Conclusions --- p.40Chapter 5.2 --- Future work --- p.40Bibliography --- p.4

BIM for architectural design exploration and representation

Magistrsko delo proučuje vpliv BIM (Building Information Modeling – informacijsko modeliranje stavb) metodologije kot orodja in tehnologije za izvajnje kreativnega procesa snovanja stavbe v arhitekturnih birojih. Za razumevanje vpliva BIM metodologije je potrebno razumeti zgodoviski razvoj digitalnih in analognih orodji za načrtovanje in njihovo interakcijo ter vpliv na načrtovalski process. Ključnega pomena je kako vpeljava nove tehnologije vpliva na pristop k načertovanju znotraj arhitekturnega biroja. BIM kot nova tehnologija istopa predvsem z možnostjo večje in lažje optimizacije načrtovanih rešitev ter vzpodbuja vlogo arhitekta pri oblikovanju boljših rešitev s hitrejšim načrtovanjem in večjo kakovostjo oblikovanja. Uporaba vgrajenega virtualnega okolja omogoča v procesu arhitekturnega načrtovanja lažjo predstavitev in primerjavo načrtovalskih rešitev kot tudi preveritev izvedljivosti zasnovane rešitve iz tehnološkega stališča. Glavni cilj naloge je osvetliti in bolje razumeti kako konceptualno razumvanje BIM metodologije vpliva na kreativni process načrtovanja ter identificirti formalne in operativne izzive, ki se pojavljajo z vpeljavo nove tehnologije. V sklopu naloge je raziskano tudi kako lahko uporaba BIM spodbudi načrtovalca k raziskovanju novih načrtovalskih možnosti ter k večji integraciji in interoperabilnosti z drugimi načrtovalskimi strokami, ki sodelujejo v načrtovalskem procesu stavb.This master thesis studies the impact of BIM (Building Information Modelling) methodology as a technology and a representation tool in the creative process approach in architecture offices. Through this approach, and for a better understanding of it, it is necessary to return some steps and understand how the design and the creative process were affected by digital innovations throughout architecture history and how new technologies are currently impacting the architecture routine. As a new possible technology, BIM stands out as an excellent solution to optimize and to stimulate the architect’s work, with some visible advantages in application, like greater speed and higher quality in the design development. Among the solutions offered, the virtual building method in the architectural process noticeably brings the professional closer to constructive techniques, since it enables the construction of a virtual model with a set of information that allows a more integrated and consistent product. The challenge of the work presented in this thesis resides in conceptually understand the BIM methodology as directly related to the creative process through the formal and operational challenges of technology, and how it can collaborate to make the design process more efficient in the representation field. This work aims to understand how the BIM concept will stimulate the architects to explore new thinking processes and new abilities for their creative approach, such as better interoperability with other disciplines and better and more consistent control of the whole project

STEM KIT: Teachers’ Notebook

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