Surrogate Model for Ship Resistance : a Sensitivity Analysis of Shape Deformation

Shape optimization and sensitivity can now be considered a standard to design efficient ships and new unconventional hull forms. There might be very different strategies to achieve such a process, depending on many circumstances, both operational (e.g. available time windows for computations) and methodological (e.g. available numerical methods). As in most of the engineering cases, the best trade-off between accuracy of the solution and the time required to achieve it is searched. When using medium-fidelity methods e.g. Boundary Element Methods (BEMs) for wave resistance and seakeeping, population based optimization algorithm can still be a viable way to achieve a design solution (see e.g. Vernengo et al., 2015 or Vernengo and Brizzolara, 2017). However, when the solution of the quantity of interest becomes more demanding, alternative methods of searching through the design space are needed. In this perspective, a surrogate model based approach for hull form sensitivity analysis is presented. The method relies on the features of a Kriging response surface (see for instance Forrester et al., 2008) to interpolate few computed solutions and to predict the same solution over the whole explored domain. The sensitivity analysis focuses on the effect of hull form variations with respect to calm water resistance at a given forward speed. The total ship resistance is computed by means of a high-fidelity viscous solver based on the openFOAM libraries (Jasak et al., 2007). The shape variations are achieved by a combined approach specifically developed to preserve the fairness of the hull surface based on Subdivision Surface and Free Form Deformation (FFD) (Copped\ue9 et al., 2018). The hydrodynamic solver has been preliminary validated by comparison against available experimental measurements on the KRISO Container Ship (KCS) hull. The variation of the Kriging response surface performance with respect to different sizes of the initial sampling have been studied and possible optimum hull shape have been detected and compared in terms of calm water resistance, wave patterns and pressure on the surface

Subdivision surface fitting to a dense mesh using ridges and umbilics

Fitting a sparse surface to approximate vast dense data is of interest for many applications: reverse engineering, recognition and compression, etc. The present work provides an approach to fit a Loop subdivision surface to a dense triangular mesh of arbitrary topology, whilst preserving and aligning the original features. The natural ridge-joined connectivity of umbilics and ridge-crossings is used as the connectivity of the control mesh for subdivision, so that the edges follow salient features on the surface. Furthermore, the chosen features and connectivity characterise the overall shape of the original mesh, since ridges capture extreme principal curvatures and ridges start and end at umbilics. A metric of Hausdorff distance including curvature vectors is proposed and implemented in a distance transform algorithm to construct the connectivity. Ridge-colour matching is introduced as a criterion for edge flipping to improve feature alignment. Several examples are provided to demonstrate the feature-preserving capability of the proposed approach

Extracting surface representations from rim curves

LNCS v. 3852 is the conference proceedings of ACCV 2006In this paper, we design and implement a novel method for constructing a mixed triangle/quadrangle mesh from the 3D space curves (rims) estimated from the profiles of an object in an image sequence without knowing the original 3D topology of the object. To this aim, a contour data structure for representing visual hull, which is different from that for CT/MRI, is introduced. In this paper, we (1) solve the "branching structure" problem by introducing some additional "directed edge", and (2) extract a triangle/ quadrangle closed mesh from the contour structure with an algorithm based on dynamic programming. Both theoretical demonstration and real world results show that our proposed method has sufficient robustness with respect to the complex topology of the object, and the extracted mesh is of high quality. © Springer-Verlag Berlin Heidelberg 2006.postprintThe 7th Asian Conference on Computer Vision (ACCV 2006), Hyderabad, India, 13-16 January 2006. In Lecture Notes in Computer Science, 2006, v. 3852, p. 732-74

Etude et construction de schémas de subdivision quasi-linéaires sur des maillages bi-réguliers

Les schémas de subdivision et les schémas de subdivision inverse sont largement utilisés en informatiquegraphique; les uns pour lisser des objets 3D, et les autres pour minimiser le coût d encodagede l information. Ce sont les deux aspects abordés dans cette thèse.Les travaux présentés dans le cadre de la subdivision décrivent l études et la construction d un nouveautype de schémas de subdivision. Celui-ci unifie deux schémas de subdivision de type géométriquesdifférents. Cela permet de modéliser des objets 3D composés de zones issues de l applicationd un schéma approximant et de zones issues de l application d un schéma interpolant. Dans le cadrede la subdivision inverse, Nous présentons une méthode de construction des schémas de subdivisionbi-réguliers inverses (quadrilatères et triangles)Subdivision schemes are commonly used to generate a smooth shape from a much more coarseone. The reverse subdivision is designed to describe a high resolution mesh from a coarse one. Bothof these tools are used in numerous graphical modelisation domains. In this thesis, we focused ontwo distinct aspects: on one hand the construction of quasi-linear subdivision schemes and on theother hand the construction of reverse quad/triangle subdivision schemes. The work, presented inthe context of the subdivision, describes the construction of a new type of subdivision schemes, andtheirs applications to solve some problems coming from the application of linear subdivision schemes.The work presented in the context of the reverse subdivision describes a new method to reverse thequad/triangle subdivision schemesDIJON-BU Doc.électronique (212319901) / SudocSudocFranceF

An Interpolatory Subdivision Scheme for Triangular Meshes and Progressive Transmission

4 authors, including: chen ren Guangzhou cool-smart electronical inform

離散曲面細分列の収束

Tohoku University小谷元子課