Dissertations / Theses on the topic 'Geometric fitting'
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Martínez-Morales, José L. "Geometric data fitting /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/5819.
Full textGrönwall, Christina. "Ground object recognition using laser radar data : geometric fitting, performance analysis, and applications /." Linköping : Department of Electrical Engineering, Linköping University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7582.
Full textGrönwall, Christna. "Ground Object Recognition using Laser Radar Data : Geometric Fitting, Performance Analysis, and Applications." Doctoral thesis, Linköpings universitet, Institutionen för systemteknik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7685.
Full textLeung, Nim Keung. "Convexity-Preserving Scattered Data Interpolation." Thesis, University of North Texas, 1995. https://digital.library.unt.edu/ark:/67531/metadc277609/.
Full textMiyawaki, Shinjiro. "Automatic construction and meshing of multiscale image-based human airway models for simulations of aerosol delivery." Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/1990.
Full textMamic, G. J. "Representation and recognition of 3-D free-form objects incorporating statistical techniques." Thesis, Queensland University of Technology, 2002.
Find full textMyles, Ashish. "Linear programming approach to fitting splines through 3D channels." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0006260.
Full textKříž, Radim. "Uniform Marker Field na válci." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2013. http://www.nusl.cz/ntk/nusl-236201.
Full textPereira, César Augusto Souto. "Estudo da distribuição de tensões em "channel fittings" pelo método dos elementos finitos." Instituto Tecnológico de Aeronáutica, 2004. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=561.
Full textAllavarapu, Santosh. "A New Additive Manufacturing (AM) File Format Using Bezier Patches." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1385114646.
Full textNivoliers, Vincent. "Échantillonnage pour l'approximation de fonctions sur des maillages." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0161/document.
Full textDigitalisation is an operation which consists in storing an object in a computer for further manipulation using data processing tools. In this document, we are interested in the digitalisation of three-dimensional objects. It is first a matter of recording the shape of the object. Many methods have been developed to address this problem, and we will focus on objects described as meshes. On such objects the storage of attributes like colour, temperature or electrical charge is often useful, depending on the application. We will describe two complementary approaches to deal with this issue. The first one relies on texture mapping. This technique consists in unfolding ? parametrising ? the mesh on a flat image in which the attribute is stored. A value recovered from the image can therefore be associated with each point of the object. We will describe a method which hides the seam artifact, commonly encountered using this technique. Unfolding the mesh demands that its quality be good, which is not always the case. We thus secondly describe a surface sampling method based on a restricted Voronoï diagram. We especially detail how to efficiently compute such an object and how to optimise it with respect to some quality measure. These results are then applied to the surface fitting problem
Heng-ChuanTsao and 曹恒銓. "Airborne LiDAR Point Cloud Fitting With Geometric Constrains." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/15785703157493051592.
Full text國立成功大學
測量及空間資訊學系
103
SUMMARY Many building models have been created and shared in the website. These user- created models have high-quality appearances. However, the size of these building models would not be suitable for each case. Therefore, a model refinement approach had proposed in this paper to refine building models by using airborne LiDAR data. The proposed approach consists of three steps: data processing, geometric reconstruction, and model refinement. First step is point cloud segmentation to model surface. Second step is to establish the geometric relations and constraints of building models. And the last step is to refine building models with the constraints built in second step. By using the proposed method, the building models can be refined more efficiently and accurately, and the original geometric relations can be also maintained. Keywords: point cloud reconstruction, building modeling, model refinement. INTRODUCTION Point cloud reconstruction is a fundamental step for building and city modeling with a variety of applications, such as urban planning, virtual tourism, real-time emergency response, and navigation. An increasing number of 3D building models have been available in the Internet with the developments of Web 2.0 techniques and scanning equipment. For example, Trimble 3D Warehouse and MakerBot Thingiverse allow users to upload and share their models in their web-based data-sharing platforms. Generally, models from these web platforms are built up manually or processed by semi-automated and complicated procedures. By using model retrieval techniques with an airborne LiDAR point cloud, several models similar to an input point cloud can be extracted from these databases. However, the extracted building models may not well fit the point cloud. Thus, a model refinement method is proposed in this study to fit and refine a building model with its corresponding point cloud. In addition, geometric relationships and geometric constraints of the building models are maintained with the proposed iterative refinement approaches. A set of airborne LiDAR point cloud data is tested to evaluate the proposed method. The experimental results demonstrate that the proposed method can refine building models efficiently and accurately without nontrivial modeling processes in related model reconstruction methods. MATERIALS AND METHODS In this study, a model refinement scheme is proposed to reduce the differences between point clouds and building models. Most of the roofs in building models are constructed by planes. Therefore, our refinement scheme is based on plane fitting, which refine a plane by using its corresponding points. The goal of our refinement scheme is to minimize the sum of the squared Euclidean distances between a point cloud and a plane. Figure 1 illustrates the workflow of the proposed approach which consists of three main procedures: geometric analysis, point cloud segmentation, and model refinement. In previous studies, the process of plane fitting is to find a fitting plane that minimizes the sum of the squared Euclidean distances to given point cloud. However, the geometric relationships of planes do not fully considered in the fitting process. In this study, the geometric relationships are taken to construct building models, including plane normal and angle. These geometric relationships are regarded as geometric constraints in the model fitting and refinement. Besides, these relationships are also used to reconstruct the surfaces of building model after the model refinement. The proposed refinement approach is based on plane fitting that fits planes by their corresponding points. Region growing is a standard approach to segment the point cloud by using features, e.g., normal and curvature. However, these features are sensitive to noise. In this study, the point cloud is segmented by the surface of the input model. This approach assigns each point to the nearest surface. The nearest surface is determined by using Euclidean distance. Our refinement procedure combines the geometric relationships and the corresponding points to refine the building model. This procedure is inspired by plane fitting which minimizes the sum of the squared Euclidean distances to the given point cloud. In this part, we used least square fitting to minimize the distance from point to their own plane. When updating the parameters of these plane equations that we can use these updating plane equations to do another least square procedure. The second time least square procedure used to calculate the coordinate of every corner for the candidate model. Therefore, we can get the updating coordinate in this procedure. For more details, please refer to the references [3]. Finally, the solved coordinate are used to reconstruct the surfaces of building model by geometric relationships. Each point of point cloud data is assigned to the nearest surface. However, some points near the corners of a building model may be assigned to incorrect surface. In order to avoid fail assignment, an iterative optimization procedure is adopted to segment the point cloud and refine the model. After each refinement step, the surface is more close to the point cloud data, the point of point cloud would be re-assigned to the nearest and more correct surface. RESULTS AND DISCUSSION To demonstrate the robustness and feasibility of the proposed approach, we use LiDAR point cloud and building model from Trimble 3D Warehouse to verify the geometric constraints. Figure 2 show the refinement result of Technology Building in National Cheng Kung University. Figure 3 show the relation between iterations and root mean-square error (RMSE). CONCLUSION A model refinement method is presented to refine building models by using the newest point cloud data. The experimental results show that our approach can deal with multi-plane fitting by geometric constraints. In addition, the building models can be refined efficiently and accurately, and the original geometric relationships can also be maintained.
Tran, Quoc Huy. "Robust parameter estimation in computer vision: geometric fitting and deformable registration." Thesis, 2014. http://hdl.handle.net/2440/86270.
Full textThesis (Ph.D.) -- University of Adelaide, School of Computer Science, 2014
Wong, Hoi Sim. "A preference analysis approach to robust geometric model fitting in computer vision." Thesis, 2013. http://hdl.handle.net/2440/82075.
Full textThesis (Ph.D.) -- University of Adelaide, School of Computer Science, 2013
Chen, Tai-yo, and 陳泰有. "Studies on The Geometric Modeling and NC Machining of Scroll Profile Using Biarcs –Fitting Method." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/74985709120317062649.
Full text正修科技大學
機電工程研究所
94
Scroll type compressors have been becoming increasingly popular in refrigeration and air conditioning applications due to their high efficiency, low noise, fewer components, low vibration and small size compared with other types of compressors. To design and manufacture scroll compressors is not easy as their key parts have complex shapes with involute curves. In order to comprehensive the concepts of design and improve the flexibility of the machining, the aims of the thesis are the regeneration of scroll profile and the study of the curve fitting and the interpolators. The geometry of example’s profile is unrecognized, so it is compared with the scroll configuration based on the reverse engineering firstly. The design parameters are retrieved and confirmed by the analysis of the obtained surface data. Then, the geometry of the scroll is derived in accordance with the conjugate surface theory. The error analysis between the theoretical curve and the actual curve is implemented to modify the design parameters. In order to generate a continuous smooth toolpath, a circular biarcs-fitting method is adopted to approximate the profile of the scroll. The developed biarcs-fitting method eliminates the problem in conventional straight-line approximation toolpath where it leaves ridges on the finished surface of the workpiece. The geometric model and the assembly of the components are constructed using the CAD/CAM software. The interference check between the built components can be performed to provide the exactness in the design stage. The cutting simulations with solid model are performed to verify the proposed toolpath generation method. The method and technique established in this thesis will confirm the design concepts of the scroll configuration.
Chung, Meng-Kong, and 鍾孟剛. "Fitting Method and Geometric Analysis of Evolution of Yield Surfaces in Axial-Torsional-Hoop Stress Space." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/txg3pu.
Full text國立臺灣大學
土木工程學研究所
106
This thesis continues the experimental and theoretical researches on yield surface conducted in the MSV lab of the NTU. The present emphasis was on the observation of the whole evolution process of initial and several subsequent yield surfaces in three dimensional axial-torsional-hoop stress space for alloy Al 6061. Combined with the fitting method developed in the lab, we studied the evolution behavior of yield surfaces. In the experiments, the tubes at annealed state were tested along multiple pre-strain paths to produce successive plastic behavior, combined with automated experimental method, improved procedure and appropriate yield point determination method. By probing yield points on different planes of constant hoop stress, the yield surfaces in three-dimensional stress space were built up using cubic polynomial fitting method, while the fitting method for a single yield surface proposed by Liu & Hong and modified by Huang was researched and further modified. In so doing we have reduced the complexity of the fitting process yet ensured better results, improving the applicability of the fitting method and making each parameter acquiring a specific geometric/physical meaning, such as the internal time of plasticity, translation, rotation, linear transformation, and projective transformation. We endeavored to connect these parameters so as to reveal what underlie the evolution behavior of yield surface. It is expected these would provide helpful clues in establishing an evolution rule.
"Standardization of CMM Algorithms and Development of Inspection Maps for Geometric Tolerances." Master's thesis, 2011. http://hdl.handle.net/2286/R.I.8838.
Full textDissertation/Thesis
M.S. Mechanical Engineering 2011
Yang, Yonghong (Fred). "Two aspects of measurement error models generalization of the geometric mean functional relationship : the effects of under- and over-fitting in measurement error models /." 1996. http://catalog.hathitrust.org/api/volumes/oclc/36174583.html.
Full textOchoa, Mayorga Victor Manuel. "Geometric approach to multi-scale 3D gesture comparison." Phd thesis, 2010. http://hdl.handle.net/10048/1530.
Full textWang, Kai-Cheng, and 王凱政. "Lighting Design Fitting Geometrical Shape for Specific Sport Field." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/26383884291241116902.
Full text國立中央大學
光電科學與工程學系
105
In the thesis, according to the lighting condition of several international sport fields and the badminton lighting standard by SportAccord, we used LED as the light source and proposed a lighting design with a specific lens for beam shaping. The optical efficiency of the specific lens was 77.6%. Besides, we introduced the designed luminaire and general commercial lamps to international sport fields with three different geometry arrangements, such as at two sides, at four-corner, and along ring structure. The lighting performance in these sport fields were analyzed. Finally, with use of the designed luminaire, the average illuminance and the uniformity on the ground of sport field were higher than 1000 lx and 0.9, respectively. The optical utilization factor at the region of 36 m × 21 m was higher than 60%. Therefore, the proposed luminaire with beam shaping effect not only fits the lighting standard of international sport field but also achieves anti-glare property. Also, the illuminance and contrast across the sports field were enhanced, so that the design perform high-quality lighting and energy saving.
Shen, Jesse. "Une nouvelle méthode pour estimer la torsion géométrique en scoliose idiopathique de l’adolescent." Thèse, 2014. http://hdl.handle.net/1866/13877.
Full textAdolescent idiopathic scoliosis (AIS) is a three dimensional (3D) deformity of the spine. For most patients, no surgical intervention is required. However, for patients with severe deformities, surgery is often recommended. Postero-anterior (PA) and antero-posterior (AP) x-rays are the most common modality for viewing and evaluating this deformity. From this imaging modality, clinical indices such as the Cobb angle can quantify and evaluate the severity of AIS. Clinical decision making is often based on this descriptor. However, the descriptors based on spinal radiographies are two- dimensional (2D) by nature. Therefore, they do not fully describe the deformity in AIS due to its three-dimensional (3D) nature. Poncet et al. have studied and presented geometric torsion as a 3D descriptor of AIS. This index measures a curve’s tendency to twist out of a plane. However, the method presented in their study is susceptible to errors from an imperfect 3D spinal reconstruction due to the local approach taken and is presented in a qualitative fashion. Hence, the objective of this study is to evaluate a new method of estimating geometric torsion in AIS employing parametric curve fitting techniques based on local arc-length approximations. The first study attempts to evaluate the sensitivity of the presented method of estimating geometric torsion against noisy data or 3D reconstruction errors. Two clinical studies will then present this descriptor as a quantitative measurement of AIS and will attempt to identify potential new sub-groups and demonstrate the clinical relevance of these new sub-groups. vi The first study evaluated the robustness of the new method in estimating geometric torsion in the presence of reconstruction errors. This study demonstrated that the new method is robust to 3D spinal reconstruction errors and achieves quantitative measures in a global fashion. The second study evaluated this new method of estimating geometric torsion in patients with Lenke type 1 deformities. This study identified two sub-groups based on torsion values, a high torsion and a low torsion group. These two sub-groups showed differences in the orientation of the planes of maximum deformity (PMC) in the thoraco-lumbar segment of the spine with the high torsion group having greater values. The last study evaluated the surgical results of patients with Lenke type 1 deformities having been sub-classified in high and low torsion groups. This study showed differences in TLL PMC with the high torsion group of patients having higher values pre and post-operatively, These studies present a novel method of estimating geometric torsion in AIS and present this 3D descriptor quantitatively. They have demonstrated the existence of new sub-groups within current classification systems that were previously undetected and have shown the clinical relevance of this new method of estimating geometric torsion in AIS. This project contributes towards the development of new 3D indices for AIS and opens the door to potential new 3D classifications.
Guo, De Ning, and 郭德寧. "Mathematical models for geometric tolerances and fittings and their application in tolerance analysis." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/08950867784173882382.
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