scholarly journals CAD Model Segmentation Algorithm Using the Fusion of PERT and Spectral Technology

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Li Hao ◽  
Rong Mo ◽  
Binbin Wei
Keyword(s):  
Human Cognition ◽  
Cad Model ◽  
Two Dimensional ◽  
Segmentation Method ◽  
Topological Information ◽  
Model Segmentation ◽  
Model Retrieval ◽  
Cad Models ◽  
Point Set ◽  
Cluster Points

For complex CAD models, model segmentation technology is an important support for model retrieval and reuse. In this article, we first propose a novel CAD model segmentation method that uses the fusion of the program/project evaluation and review technique (PERT) and the Laplacian spectrum theory. By means of PERT, spectral theory, and the CAD models’ geometrical and topological information, we transform the b-rep model faces into two-dimensional coordinate points corresponding to the nodes of the attributed adjacent graph (AAG). The k-means approach with the Silhouette coefficient was employed to conduct unsupervised learning of the coordinate points. The experimental results demonstrate that (1) the proposed approach can effectively transform the b-rep model into a two-dimensional coordinate point set; (2) the k-means algorithm can efficiently cluster points to achieve segmentation; and (3) in view of human cognition, the segmentation results are more reasonable. It can effectively divide the point set into several groups to achieve the model segmentation.

Toward Effective Mechanical Design Reuse: CAD Model Retrieval Based on General and Partial Shapes

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Min Li ◽  
Y. F. Zhang ◽  
J. Y. H. Fuh ◽  
Z. M. Qiu
Keyword(s):  
Computer Aided Design ◽  
Mechanical Design ◽  
Three Dimensional ◽  
Cad Model ◽  
Model Retrieval ◽  
Cad Models ◽  
Feature Based ◽  
Novel Method ◽  
Aided Design ◽  
Model Similarity

In product design, a large proportion of three-dimensional (3D) computer-aided design (CAD) models can be reused to facilitate future product development due to their similarities in function and shape. This paper presents a novel method that incorporates modeling knowledge into CAD model similarity assessment to improve the effectiveness of reuse-oriented retrieval. First, knowledge extraction is performed on archived feature-based CAD models to construct feature dependency directed acyclic graph (FDAG). Second, based on the FDAG subgraph decomposition, two useful component partitioning approaches are developed to extract simplified essential shapes and meaningful subparts from CAD models. Third, the extracted shapes and their FDAG subgraphs are indexed. Finally, the indexed shapes that are similar to user-sketched queries are retrieved to reuse, and FDAG information of the retrieved shapes is provided as redesign suggestions. Experimental results suggest that the incorporation of modeling knowledge greatly facilitates CAD model retrieval and reuse. Algorithm evaluations also show the presented method outperforms other 3D retrieval methods.

3D CAD Model Retrieval Algorithm Based on Accessibility Cone Distributions

2013 ◽  
Vol 834-836 ◽  
pp. 1444-1447
Author(s):  
Wei Qiang
Keyword(s):  
Engineering Application ◽  
Similarity Coefficient ◽  
Retrieval Algorithm ◽  
Cad Model ◽  
3D Cad ◽  
Planar Grid ◽  
Model Retrieval ◽  
Cad Models ◽  
The Given ◽  
3D Cad Model Retrieval

To reuse 3D CAD models more efficiently, a new 3D CAD model retrieval algorithm based on accessibility cone distributions is proposed. Firstly, a sufficiently large number of random sample points on surface of 3D CAD model are taken and the normal direction of each sample point is recorded. Then, the accessibility cone of the given sampled point is computed. Secondly, a planar grid is constructed to express the accessibility cone distribution by obtaining a statistic data of the sampled points. Lastly, the L1 distance metric method is taken to compute the similarity between the two accessibility cone matrices, which can give the similarity coefficient for two compared 3D CAD models. Experiments results show that the algorithm can effectively support 3D CAD model retrieval, and the efficiency meets the requirement of engineering application.

Bag-of-Features Sampling Techniques for 3D CAD Model Retrieval

2011 ◽  
Author(s):  
Y. Wang ◽  
W. F. Lu ◽  
J. Y. H. Fuh ◽  
Y. S. Wong
Keyword(s):  
Feature Detection ◽  
Sampling Techniques ◽  
Cad Model ◽  
Sampling Strategies ◽  
3D Cad ◽  
Bag Of Features ◽  
Model Retrieval ◽  
Cad Models ◽  
Dense Sampling ◽  
3D Cad Model Retrieval

This paper investigates two sampling strategies, dense sampling and PHOW sampling, for bag-of-features 3D CAD model retrieval. Previous methods [1] use original salient SIFT feature detection for general 3D model retrieval which does not suit the need for CAD models representation. CAD models contain mostly piecewise-smooth surfaces and thus only sharp edges can be described. To overcome these limitations, two new sampling strategies are investigated to improve the feature extraction process. Dense sampling extracts SIFT features on regular spatial grids with even spacing. Pyramid Histogram Of visual Words (PHOW) [2] extracts features on repeatedly finer scales. Both the two sampling methods extract features that are covered the whole shape. In addition, the influences of codebook size and distance metric are also studied to optimize the retrieval performance. Experiments on Purdue Engineering Benchmark [3] show that the proposed sampling techniques achieve better retrieval accuracy than the original salient SIFT sampling method.

scholarly journals Direct 3D model extraction method for color volume images

2021 ◽  
Vol 29 ◽  
pp. 133-140
Author(s):  
Bin Liu ◽  
Shujun Liu ◽  
Guanning Shang ◽  
Yanjie Chen ◽  
Qifeng Wang ◽  
...  
Keyword(s):  
3D Model ◽  
Clinical Medicine ◽  
Three Dimensional ◽  
Laplacian Matrix ◽  
Segmentation Method ◽  
Human Organs ◽  
Model Segmentation ◽  
Treatment Objective ◽  
Organ Models ◽  
Different Parts

BACKGROUND: There is a great demand for the extraction of organ models from three-dimensional (3D) medical images in clinical medicine diagnosis and treatment. OBJECTIVE: We aimed to aid doctors in seeing the real shape of human organs more clearly and vividly. METHODS: The method uses the minimum eigenvectors of Laplacian matrix to automatically calculate a group of basic matting components that can properly define the volume image. These matting components can then be used to build foreground images with the help of a few user marks. RESULTS: We propose a direct 3D model segmentation method for volume images. This is a process of extracting foreground objects from volume images and estimating the opacity of the voxels covered by the objects. CONCLUSIONS: The results of segmentation experiments on different parts of human body prove the applicability of this method.

scholarly journals Automatized Evaluation of Students’ CAD Models

2021 ◽  
Vol 11 (4) ◽  
pp. 145
Author(s):  
Nenad Bojcetic ◽  
Filip Valjak ◽  
Dragan Zezelj ◽  
Tomislav Martinec
Keyword(s):  
Computer Aided Design ◽  
Three Dimensional ◽  
Computer Application ◽  
Test Cases ◽  
Cad Model ◽  
Computer Solution ◽  
3D Cad ◽  
Computer Aided ◽  
Cad Models ◽  
Aided Design

The article describes an attempt to address the automatized evaluation of student three-dimensional (3D) computer-aided design (CAD) models. The driving idea was conceptualized under the restraints of the COVID pandemic, driven by the problem of evaluating a large number of student 3D CAD models. The described computer solution can be implemented using any CAD computer application that supports customization. Test cases showed that the proposed solution was valid and could be used to evaluate many students’ 3D CAD models. The computer solution can also be used to help students to better understand how to create a 3D CAD model, thereby complying with the requirements of particular teachers.

A 3D CAD model input pipeline for REFMUL3 full-wave FDTD 3D simulator

2021 ◽  
Vol 16 (11) ◽  
pp. C11013
Author(s):  
J.M. Santos ◽  
E. Ricardo ◽  
F.J. da Silva ◽  
T. Ribeiro ◽  
S. Heuraux ◽  
...  
Keyword(s):  
Vessel Wall ◽  
Thermal Protection ◽  
Interface Problem ◽  
Cad Model ◽  
Fusion Plasma ◽  
3D Cad ◽  
Full Wave ◽  
Wall Structures ◽  
Design Cycle ◽  
Cad Models

Abstract The use of advanced simulation has become increasingly more important in the planning, design, and assessment phases of future fusion plasma diagnostics, and in the interpretation of experimental data from existing ones. The design cycle of complex reflectometry systems, such as the ones being planned for next generation machines (IDTT and DEMO), relies heavily on the results produced by synthetic diagnostics, used for system performance evaluation and prediction, both crucial in the design process decision making. These synthetic diagnostics need realistic representations of all system components to incorporate the main effects that shape their behavior. Some of the most important elements that are required to be well modelled and integrated in simulations are the wave launcher structures, such as the waveguides, tapers, and antennas, as well as the vessel wall structures and access to the plasma. The latter are of paramount importance and are often neglected in this type of studies. Faithfully modelling them is not an easy task, especially in 3D simulations. The procedure herein proposed consists in using CAD models of a given machine, together with parameterizable models of the launcher, to produce a description suited for Finite Difference Time Domain (FDTD) 3D simulation, combining the capabilities of real-world CAD design with the power of simulation. However, CAD model geometric descriptions are incompatible with the ones used by standard FDTD codes. CAD software usually outputs models in a tessellated mesh while FDTD simulators use Volumetric Pixel (VOXEL) descriptions. To solve this interface problem, we implemented a pipeline to automatically convert complex CAD models of tokamak vessel components and wave launcher structures to the VOXEL input required by REFMUL3, a full wave 3D Maxwell FDTD parallel code. To illustrate the full procedure, a complex reflectometry synthetic diagnostic for IDTT was setup, converted and simulated. This setup includes 3 antennas recessed into the vessel wall, for thermal protection, one for transmission and reception, and two just for reception.

Statistical measures of two dimensional point set uniformity

2012 ◽  
Vol 56 (6) ◽  
pp. 2159-2181 ◽  
Author(s):  
Meng Sang Ong ◽  
Ye Chow Kuang ◽  
Melanie Po-Leen Ooi
Keyword(s):  
Two Dimensional ◽  
Statistical Measures ◽  
Point Set

An Automated System for Design for Manufacturability Analysis for Die-Casting

2018 ◽  
Author(s):  
Sunil Kumar ◽  
Jatinder Madan
Keyword(s):  
Die Casting ◽  
Automated System ◽  
Design For Manufacturability ◽  
Design Stage ◽  
Present System ◽  
Cad Model ◽  
Cast Part ◽  
Early Design Stage ◽  
Die Cast ◽  
Cad Models

Design for manufacturing (DFM) is an important concept that helps to incorporate manufacturability considerations at early design stage. Development of automated DFM tools has become important especially when design and manufacturing are being done by different teams often distantly located. An automated system for design for manufacturability analysis for die-cast parts has been presented in this paper. The paper discusses: (i) knowledgebase of DFM guidelines (ii) die casting feature extraction from part CAD model, and (iii) automated system for DFM analysis and model updation of the die-cast part CAD model. The capabilities of the system are demonstrated by applying it on die cast part CAD models. The results have been validated with the industrial experts. The present system works with CAD models having features such as boss, rib, hole and draft, created using feature based modeling.

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