Investigating the Segmentation of Freeform Triangulated Surfaces Using a Self-Organizing Map

2006 ◽  
Author(s):  
Alexander D. MacLennan ◽  
Geoff West ◽  
Michael Cardew-Hall
Keyword(s):  
Point Clouds ◽  
Free Form ◽  
Complex Object ◽  
Self Organizing Map ◽  
Discrete Curvature ◽  
Planar Surfaces ◽  
Object Based ◽  
Triangulated Surfaces ◽  
Free Form Surfaces ◽  
Self Organizing

Freeform surfaces can be used to describe manufactured objects. These surfaces can be represented as point clouds, triangulated surfaces and range images. Before these objects can be analysed in any way they need to be broken down into their constituent parts. Using this description stamped parts can be indexed and retrieved to assist in determining how to manufacture a part that has similar properties. One means of performing this task is to segment the object based upon its surface properties. Curvature can be used to describe the behaviour of a surface. In order to use these metrics a single Self-Organizing Map is used to automatically categorise surface into regions of similar curvature. The SOM is first trained using a small number of simple shapes and curvature metrics. It is then used to segment an object that is a mixture of free form surfaces and planes. The combination of these metrics, shapes and the use of a SOM allows for the representation of many types of surfaces. The shapes and curvature metrics used to train the model determine how sensitive it is to different surface descriptions. This technique is successfully applied to a complex object that combines free form surfaces and planar surfaces using robust discrete curvature metrics.

Parting Line Formation by Slicing a Trimmed Surface Model

1996 ◽  
Author(s):  
T. Wong ◽  
S. T. Tan ◽  
W. S. Sze
Keyword(s):  
Product Design ◽  
Free Form ◽  
Surface Model ◽  
Curved Surfaces ◽  
Line Formation ◽  
Planar Surfaces ◽  
Manufacturing Efficiency ◽  
Computer Aided ◽  
Trimmed Surface ◽  
Free Form Surfaces

Abstract The parting line on a product affects the final layout of the mould blocks and hence the manufacturing efficiency. The increased usage of free-form surfaces in product design increases the burden of computer aided parting line and parting surface determination. Previous proposed algorithms may not be sufficient to deal with such situation since most of them were originally designed to deal with products having planar surfaces or simple curved surfaces. A new algorithm is proposed to deal with such situation. The algorithm adopted a recursive uneven slicing on a trimmed surface model. The method provides a quick and efficient way of locating the parting line of a product.

scholarly journals Congruence analysis of point clouds from unstable stereo image sequences

2014 ◽  
Vol XL-5 ◽  
pp. 301-306 ◽  
Author(s):  
C. Jepping ◽  
F. Bethmann ◽  
T. Luhmann
Keyword(s):  
High Speed ◽  
Image Data ◽  
Point Clouds ◽  
Image Sequences ◽  
Stereo Image ◽  
Free Form ◽  
Crash Test ◽  
3D Point Clouds ◽  
Congruence Analysis ◽  
Free Form Surfaces

This paper deals with the correction of exterior orientation parameters of stereo image sequences over deformed free-form surfaces without control points. Such imaging situation can occur, for example, during photogrammetric car crash test recordings where onboard high-speed stereo cameras are used to measure 3D surfaces. As a result of such measurements 3D point clouds of deformed surfaces are generated for a complete stereo sequence. The first objective of this research focusses on the development and investigation of methods for the detection of corresponding spatial and temporal tie points within the stereo image sequences (by stereo image matching and 3D point tracking) that are robust enough for a reliable handling of occlusions and other disturbances that may occur. The second objective of this research is the analysis of object deformations in order to detect stable areas (congruence analysis). For this purpose a RANSAC-based method for congruence analysis has been developed. This process is based on the sequential transformation of randomly selected point groups from one epoch to another by using a 3D similarity transformation. The paper gives a detailed description of the congruence analysis. The approach has been tested successfully on synthetic and real image data.

Insertion of Planar Areas Into Free-Form Surfaces in Early Product Design

2005 ◽  
Author(s):  
V. Cheutet ◽  
J. P. Pernot ◽  
J. C. Le´on ◽  
B. Falcidieno ◽  
F. Giannini
Keyword(s):  
Product Design ◽  
Free Form ◽  
Functional Constraints ◽  
Aesthetic Design ◽  
Early Design ◽  
Planar Surfaces ◽  
Light Effects ◽  
Free Form Surface ◽  
Definition Of ◽  
Free Form Surfaces

Surfaces, like planes, cylinders or spheres, are basic primitive surfaces not only for mechanical engineering but also for aesthetic design, world of free-form surfaces, where they are essentially used to answer some functional constraints, like assembling and manufacturing ones, or to achieve specific light effects. The early design steps are characterised by the uncertainty in the definition of the precise geometry and most of the time, product constraints are only partially available. Unfortunately, until now, the insertion of primitive surfaces requires precise curve and surface specifications together with trimming operations, thus imposing that the free-form geometry is recreated each time a modification occurs. In this paper we present a method for the insertion of planar surfaces suitable to handle the uncertainty in the first draft of a product. The approach does not provide effective precise primitive surfaces, but it is able to introduce regions resembling such a behaviour in a free-form surface, without requiring trimming operations, so allowing more efficient shape alternative evaluations.

Digital Measurement and its Error Analysis for the Machining Free-Form Surface

2014 ◽  
Vol 664 ◽  
pp. 263-267
Author(s):  
Feng Lu ◽  
Ning Li ◽  
Xiao Fei Zhang
Keyword(s):  
Laser Scanning ◽  
Optical Measurement ◽  
Three Dimensional ◽  
Point Clouds ◽  
Free Form ◽  
Digital Measurement ◽  
Machining Errors ◽  
Three Dimensional Measurement ◽  
Free Form Surface ◽  
Free Form Surfaces

To deal with the lack of accurate and efficient inspection methods in complex free-form surfaces, three-dimensional measurement method based on the optical measurement and computer image processing technology was proposed. It adopted laser scanning technology to get point clouds of free-form surface. Used rapid measurement software to inspect precision of point cloud& CAD model. What could be the cause of machining errors was analyzed. 3D deviation inspection of complex surfaces was applied by an artifact. Detected the machining error of an important section, and outputted test report. This research provides a convenient and swift method for the inspection of free-form surface and processing quality control.

Contour Representation by Clustering Curvatures of the 3D Objects

2009 ◽  
Vol 147-149 ◽  
pp. 633-638
Author(s):  
Arūnas Lipnickas ◽  
Vidas Raudonis
Keyword(s):  
Free Form ◽  
Distance Measurements ◽  
3D Object ◽  
Human Foot ◽  
3D Objects ◽  
Large Size ◽  
Contour Representation ◽  
Triangulated Surfaces ◽  
Curvature Estimation ◽  
Free Form Surfaces

The purpose of this work is to segment large size triangulated surfaces and the contours extraction of the 3D object by the use of the object curvature value. The curvatures values allow categorizing the type of the local surface of the 3D object. In present work the curvature was estimated for the free-form surfaces obtained by the 3D range scanner. A free-form surface is the surface such that the surface normal is defined and continuous everywhere, except at sharp corners and edges [2, 5]. Two types of distance measurements functions based on Euclidian distance, bounded box and topology of surface were used for the curvature estimation. Clustering technique has been involved to cluster the values of the curvature for 3D object contour representation. The described technique was applied to the 3D objects with free-form surfaces such as the human foot and cube.

Reverse Engineering of Geometric Surfaces Using Tabu Search Optimization Technique

2007 ◽  
Author(s):  
Ayman M. A. Youssef ◽  
Ashraf O. Nassef ◽  
Sayed M. Metwalli
Keyword(s):  
Tabu Search ◽  
Reverse Engineering ◽  
Optimization Technique ◽  
Point Clouds ◽  
Local Minimizer ◽  
Free Form ◽  
Time Saving ◽  
Reactive Tabu Search ◽  
Search Optimization ◽  
Free Form Surfaces

Creating unavailable geometric models from existing parts plays an important role in the process of reverse engineering, for which the accuracy and fitting time of the created models are important factors. This paper proposes the use of Tabu Search (TS) technique in the optimal fitting of NURBS (Non Uniform Rational B-Spline) surfaces to laser-scanned point clouds of free-form surfaces for existing parts. The fitting process involves the initial estimation of the NURBS surface control points using least-squares approximation, followed by optimization of NURBS weights to minimize fitting error. Optimization is performed using a hybrid coding scheme, namely; Modified Continuous Reactive Tabu Search (M-C-RTS), in which a combinatorial optimization component, based on Reactive Tabu Search (RTS), co-operates with Sequential Quadratic Programming (SQP), as a local minimizer. The developed fitting algorithm was applied to a number of simulated free-form surfaces in addition to a laser-scanned PC mouse. Implementation was carried out using MATLAB software and the results were compared to those obtained using Genetic Algorithms (GAs) in an earlier publication. The results show the superiority of the proposed algorithm to the GA-based method with respect to the number of objective function evaluations (about 50% reduction). In addition to this time saving achievement, and surprisingly, M-C-RTS proved to be capable of finding better solutions than GAs.

CAD Model Generation Using 3D Scanning

2007 ◽  
Vol 23 ◽  
pp. 169-172
Author(s):  
Khalil Khalili ◽  
Seyed Yousef Ahmadi-Brooghani ◽  
M. Rakhshkhorshid
Keyword(s):  
Programming Languages ◽  
Point Clouds ◽  
3D Scanning ◽  
Industrial Applications ◽  
Free Form ◽  
Depth Information ◽  
Fuzzy Logic Algorithm ◽  
3D Scanners ◽  
Processing Techniques ◽  
Free Form Surfaces

3D Scanners are used in industrial applications such as reverse engineering and inspection. Customization of existing CAD systems is one of rapid ways to supplying a 3D Scanning software. In this paper, using AutoLisp and Visual Basic programming languages, AutoCAD has been customized. Also facilities of automatic scanning of physical parts, in the domain of free form surfaces, have been provided. Furthermore, possibilities such as, control of scanner automotive system, representation of registered point clouds, generation of polygon and /or NURBS model from primary or modified point clouds, have been prepared. Triangulation and image processing techniques along with a new fuzzy logic algorithm have been used to extract the depth information more accurate. These, accompanying with AutoCAD capabilities have provided acceptable facilities for 3D scanning.

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