Particle Swarm Optimisation Based 3D Reconstruction of Sketched Line Drawings

The purpose of this paper is to demonstrate the application of particle swarm optimisation to line drawings reconstruction. The paper’s new contribution is the application of swarm intelligence in dealing with machine perception of sketch-based modelling interfaces. Traditional descent or gradient- based optimisation algorithms are not always practical in this context because of the severe numerical noise and ill-defined objective function of the optimisation-based reconstruction problem Our results point to particle swarm optimisation as a promising alternative.This work was partially supported by Universitat Jaume I (Plan 2002 de promoció de la investigació a l’UJI, Project P1-1B2002-08, entitled “From sketch to model: new user interfaces for CAD systems”)

Automatic creation of boundary-representation models from single line drawings

This thesis presents methods for the automatic creation of boundary-representation models of polyhedral objects from single line drawings depicting the objects. This topic is important in that automated interpretation of freehand sketches would remove a bottleneck in current engineering design methods. The thesis does not consider conversion of freehand sketches to line drawings or methods which require manual intervention or multiple drawings. The thesis contains a number of novel contributions to the art of machine interpretation of line drawings. Line labelling has been extended by cataloguing the possible tetrahedral junctions and by development of heuristics aimed at selecting a preferred labelling from many possible. The ”bundling” method of grouping probably-parallel lines, and the use of feature detection to detect and classify hole loops, are both believed to be original. The junction-line-pair formalisation which translates the problem of depth estimation into a system of linear equations is new. Treating topological reconstruction as a tree-search is not only a new approach but tackles a problem which has not been fully investigated in previous work

Understanding drawing: a cognitive account of observational process

This thesis contributes to theorising observational drawing from a cognitive perspective. Our current understanding of drawing is developing rapidly through artistic and scientific enquiry. However, it remains fragmented because the frames of reference of those modes of enquiry do not coincide. Therefore, the foundations for a truly interdisciplinary understanding of observational drawing are still inceptive. This thesis seeks to add to those foundations by bridging artistic and scientific perspectives on observational process and the cognitive aptitudes underpinning it. The project is based on four case studies of experienced artists drawing processes, with quantitative and qualitative data gathered: timing of eye and hand movements, and artists verbal reports. The data sets are analysed with a generative approach, using behavioural and protocol analysis methods to yield comparative models that describe cognitive strategies for drawing. This forms a grounded framework that elucidates the cognitive activities and competences observational process entails. Cognitive psychological theory is consulted to explain the observed behaviours, and the combined evidence is applied to understanding apparent discrepancies in existing accounts of drawing. In addition, the use of verbal reporting methods in drawing studies is evaluated. The study observes how drawing process involves a segregation of activities that enables efficient use of limited and parametrically constrained cognitive resources. Differing drawing strategies are shown to share common key characteristics; including a staged use of selective visual attention, and the capacity to temporarily postpone critical judgement in order to engage fully in periods of direct perception and action. The autonomy and regularity of those activities, demonstrated by the artists studied, indicate that drawing ability entails tacit self‐knowledge concerning the cognitive and perceptual capacities described in this thesis. This thesis presents drawing as a skill that involves strategic use of visual deconstruction, comparison, analogical transfer and repetitive cycles of construction, evaluation and revision. I argue that drawing skill acquisition and transfer can be facilitated by the elucidation of these processes. As such, this framework for describing and understanding drawing is offered to those who seek to understand, learn or teach observational practice, and to those who are taking a renewed interest in drawing as a tool for thought

Detection and Analysis of Low Energy Electrons in a Scanning Electron Microscope using a novel detector design based on the Bessel Box Energy Analyser

Advancements in the field of scanning electron microscopy have been one of the major nano technology enablers. A scanning electron microscope (SEM) generates a magnified image of the sample by bombarding it with an electron beam and detecting the electrons that scatter off the surface along with the electrons that are generated in the sample. In conventional SEMs, the generated or secondary electrons are detected by the famous Everhart Thornley detector via positively biased input-grid. However, in doing so, it loses energy and angular information of the electrons. This information is crucial to interpret the SEM image of the sample under study. What is needed is a small and compact detector that can detect electrons and furnish energy information inside an SEM chamber. The detector designed to achieve these aims is able to detect low energy electrons at the same time able to take the geometrical constraints of the SEM into account. This study presents a design and implementation of a novel secondary electron detector based on the Bessel Box (BB) energy analyser for SEM Simulations were carried out for the design in SIMION 8.1 ray tracing software. An energy resolution of 0.4% has been numerically calculated and experimentally tested in an ultra-high-vacuum chamber. This was followed by the integration of the BB detector to a conventional scanning electron microscope. The device described would be appealing to the electron microscopy and spectroscopy at large. The detector has been successfully demonstrated for electron spectroscopy applications: Auger and secondary electron. It has also been demonstrated for secondary electron microscopy, all obtained by as-designed BB detector

Copula models for epidemiological research and practice

Investigating associations between random variables (rvs) is one of many topics in the heart of statistical science. Graphical displays show emerging patterns between rvs, and the strength of their association is conventionally quantified via correlation coefficients. When two or more of these rvs are thought of as outcomes, their association is governed by a joint probability distribution function (pdf). When the joint pdf is bivariate normal, scalar correlation coefficients will produce a satisfactory summary of the association, otherwise alternative measures are needed. Local dependence functions, together with their corresponding graphical displays, quantify and show how the strength of the association varies across the span of the data. Additionally, the multivariate distribution function can be explicitly formulated and explored. Copulas model joint distributions of varying shapes by combining the separate (univariate) marginal cumulative distribution functions of each rv under a specified correlation structure. Copula models can be used to analyse complex relationships and incorporate covariates into their parameters. Therefore, they offer increased flexibility in modelling dependence between rvs. Copula models may also be used to construct bivariate analogues of centiles, an application for which few references are available in the literature though it is of particular interest for many paediatric applications. Population centiles are widely used to highlight children or adults who have unusual univariate outcomes. Whilst the methodology for the construction of univariate centiles is well established there has been very little work in the area of bivariate analogues of centiles where two outcomes are jointly considered. Conditional models can increase the efficiency of centile analogues in detection of individuals who require some form of intervention. Such adjustments can be readily incorporated into the modelling of the marginal distributions and of the dependence parameter within the copula model

Methods and Systems for Characterization of an Anomaly Using Infrared Flash Thermography

A method for characterizing an anomaly in a material comprises (a) extracting contrast data; (b) measuring a contrast evolution; (c) filtering the contrast evolution; (d) measuring a peak amplitude of the contrast evolution; (d) determining a diameter and a depth of the anomaly, and (e) repeating the step of determining the diameter and the depth of the anomaly until a change in the estimate of the depth is less than a set value. The step of determining the diameter and the depth of the anomaly comprises estimating the depth using a diameter constant C.sub.D equal to one for the first iteration of determining the diameter and the depth; estimating the diameter; and comparing the estimate of the depth of the anomaly after each iteration of estimating to the prior estimate of the depth to calculate the change in the estimate of the depth of the anomaly

The measurement of rough surface topography using coherence scanning interferometry

This guide describes good practice for the measurement and characterisation of rough surface topography using coherence scanning interferometry (commonly referred to as vertical scanning white light interferometry). It is aimed at users of coherence scanning interferometry for the optical measurement of surface texture within production and research environments. The general guidelines described herein can be applied to the measurement of rough surfaces exhibiting different types of surface topography. For the purpose of this guide, the definition of a rough surface is one that has features with heights ranging from approximately 10 nm to less than 100 µ