Memetic electromagnetism algorithm for surface reconstruction with rational bivariate Bernstein basis functions

Surface reconstruction is a very important issue with outstanding applications in fields such as medical imaging (computer tomography, magnetic resonance), biomedical engineering (customized prosthesis and medical implants), computer-aided design and manufacturing (reverse engineering for the automotive, aerospace and shipbuilding industries), rapid prototyping (scale models of physical parts from CAD data), computer animation and film industry (motion capture, character modeling), archaeology (digital representation and storage of archaeological sites and assets), virtual/augmented reality, and many others. In this paper we address the surface reconstruction problem by using rational Bézier surfaces. This problem is by far more complex than the case for curves we solved in a previous paper. In addition, we deal with data points subjected to measurement noise and irregular sampling, replicating the usual conditions of real-world applications. Our method is based on a memetic approach combining a powerful metaheuristic method for global optimization (the electromagnetism algorithm) with a local search method. This method is applied to a benchmark of five illustrative examples exhibiting challenging features. Our experimental results show that the method performs very well, and it can recover the underlying shape of surfaces with very good accuracy.This research is kindly supported by the Computer Science National Program of the Spanish Ministry of Economy and Competitiveness, Project #TIN2012-30768, Toho University, and the University of Cantabria. The authors are particularly grateful to the Department of Information Science of Toho University for all the facilities given to carry out this work. We also thank the Editor and the two anonymous reviewers who helped us to improve our paper with several constructive comments and suggestions

Adaptive isogeometric analysis for phase‐field modeling of anisotropic brittle fracture

The surface energy a phase‐field approach to brittle fracture in anisotropic materials is also anisotropic and gives rise to second‐order gradients in the phase field entering the energy functional. This necessitates C 1 continuity of the basis functions which are used to interpolate the phase field. The basis functions which are employed in isogeometric analysis (IGA), such as nonuniform rational B‐splines and T‐splines naturally possess a higher order continuity and are therefore ideally suited for phase‐field models which are equipped with an anisotropic surface energy. Moreover, the high accuracy of spline discretizations, also relative to their computational demand, significantly reduces the fineness of the required discretization. This holds a fortiori if adaptivity is included. Herein, we present two adaptive refinement schemes in IGA, namely, adaptive local refinement and adaptive hierarchical refinement, for phase‐field simulations of anisotropic brittle fracture. The refinement is carried out using a subdivision operator and exploits the Bézier extraction operator. Illustrative examples are included, which show that the method can simulate highly complex crack patterns such as zigzag crack propagation. An excellent agreement is obtained between the solutions from global refinement and adaptive refinement, with a reasonable reduction of the computational effort when using adaptivity

We flipped but did it work?

In the fall of 2014 Organic Chemistry was redesigned from a blended format course, where assignments and activities were completed online out of class, to a fully flipped course where lectures and reading materials were available online and activities and problems solved in class. TopHat (https://tophat.com) was used to link the in class and out of class components as it was used for both out of class for content and question delivery, as well as a classroom response system for problem solving in class. At the beginning of the winter semester students were surveyed to determine their level of satisfaction with the format as well as their engagement and participation in the course. Overall, students indicated a preference for the flipped classroom over the standard lecture format and felt a high degree of engagement relative to their other courses. In this presentation we will describe the course design and discuss the positive outcomes, caveats and next steps. We will engage the audience in a conversation around the challenges and benefits of this style of teaching in science disciplines

Dataflow and Remapping for Wavelet Compression and View-dependent Optimization of Billion-triangle Isosurfaces

Currently, large physics simulations produce 3D discretized field data whose individual isosurfaces, after conventional extraction processes, contain upwards of hundreds of millions of triangles. Detailed interactive viewing of these surfaces requires (a) powerful compression to minimize storage, and (b) fast view-dependent optimization of display triangulations to most effectively utilize high-performance graphics hardware. In this work, we introduce the first end-to-end multiresolution data flow strategy that can eectively combine the top performing subdivision-surface wavelet compression and view-dependent optimization methods, thus increasing efficiency by several orders of magnitude over conventional processing pipelines. In addition to the general development and analysis of the data ow, we present new algorithms at two steps in the pipeline that provide the "glue" that makes an integrated large-scale data visualization approach possible. A shrink-wrapping step converts highly detailed unstructured surfaces of arbitrary topology to the semi-structured meshes needed for wavelet compression. Remapping to triangle bintrees minimizes disturbing "pops" during realtime display-triangulation optimization and provides eective selective-transmission compres-ion for out-of-core and remote access to extremely large surfaces. Overall, this is the first effort to exploit semi-structured surface representations for a complete large-data visualization pipeline

Deconfliction and Surface Generation from Bathymetry Data Using LR B-splines

A set of bathymetry point clouds acquired by different measurement techniques at different times, having different accuracy and varying patterns of points, are approximated by an LR B-spline surface. The aim is to represent the sea bottom with good accuracy and at the same time reduce the data size considerably. In this process the point clouds must be cleaned by selecting the “best” points for surface generation. This cleaning process is called deconfliction, and we use a rough approximation of the combined point clouds as a reference surface to select a consistent set of points. The reference surface is updated using only the selected points to create an accurate approximation. LR B-splines is the selected surface format due to its suitability for adaptive refinement and approximation, and its ability to represent local detail without a global increase in the data size of the surface.acceptedVersio

The Seven Ages of Man

Works produced from 525 B.C. to the present are introduced as representing the human condition. Includes brief texts on the artists' life and works

Interactive Axial Deformations

This paper presents an interactive deformation technique. The entity employed for defining the deformation of an object is a 3D axis as well as some associated parameters. The technique allows an easy specification and control of deformations that can be defined with that entity such as bending, twisting and scaling. Contrary to existing techniques, the method developed is independent of both the geometric model of the object to be deformed and the creation technique used to define the object. Moreover, it can easily be integrated into traditional interactive modeling systems

The Elastic Surface Layer Model for Animated Character Construction

A model is described for creating three-dimensional animated characters. In this new type of layered construction technique, called the elastic surface layer model, a simulated elastically deformable skin surface is wrapped around a traditional kinematic articulated figure. Unlike previous layered models, the skin is free to slide along the underlying surface layers constrained by reaction forces which push the surface out and spring forces which pull the surface in to the underlying layers. By tuning the parameters of the physically-based model, a variety of surface shapes and behaviors can be obtained such as more realistic-looking skin deformation at the joints, skin sliding over muscles, and dynamic effects such as squash-and-stretch and followthrough. Since the elastic model derives all of its input forces from the underlying articulated figure, the animator may specify all of the physical properties of the character once, during the initial character design process, after which a complete animation sequence can be created using a traditional skeleton animation technique. A reasonably complex character at low surface resolution can be simulated at interactive speeds so than an animator can both design the character and animate it in a completely interactive, direct-manipulation environment. Once a motion sequence has been specified, the entire simulation can be recalculated at a higher surface resolution for better visual results. An implementation on a Silicon Graphics Iris workstation is described