734 research outputs found
Invariant Characterisation of the Hough Transform for Pose Estimation of Arbitrary Shapes
No full textIn this paper we develop a new formulation and methodology for including invariance in a general form of the Hough transform. Essentially, the transformations that control a shape's appearance are extracted using invariance, for arbitrary shapes with a continuous description. We first develop a formal definition of the Hough transform mapping for arbitrary shapes and general transformations. We then include an invariant characterisation of shapes and develop and apply our new technique to extract shapes under similarity and affine transformations. Our formulation and implementation is based directly on parametric curves and so avoids the use of indexed look-up tables. This confers the attributes of a continuous shape description avoiding discretisation problems inherent in earlier formulations. To obtain an invariant characterisation, each point in the model is related to a collection of other points defining a geometric arrangement. This characterisation does not require the computation of properties for lines or other primitives that compose the model, but is based solely on the local geometry of the points on shapes. The transformation is obtained by solving for the parameters of the curve according to an arrangement of points defined for a point in the image and a corresponding arrangement of points for a point in the model with the same invariant properties. The location parameters can be gathered in a 2D accumulator space independent of the transformation and of a shape's complexity. Experimental results show that the new technique is capable of extracting arbitrary shapes under occlusion and when the image contains noise. As such this new formulation retains the known performance advantages of the Hough transform, whilst combining a continuous shape description with invariant mappings
On using Directional Information for Parameter Space Decomposition in Ellipse Detection
No full textIn this paper we use the parametric polar representation to extend the application of edge directional information from circle to ellipse extraction. As a result we obtain a mapping which decomposes the parameter space required for ellipse extraction into two independent sub-spaces and one final histogram accumulator. The mapping includes the tangent of the angle of the first and second directional derivatives. These tangents are computed by considering edge direction at two border points. We show that the use of gradient information for parameter space decomposition avoids the intensive point labelling imposed by geometric constraints used by other approaches
Semi-Supervised Lane Detection With Deep Hough Transform
No full textCurrent work on lane detection relies on large manually annotated datasets. We reduce the dependency on annotations by leveraging massive cheaply available unlabelled data. We propose a novel loss function exploiting geometric knowledge of lanes in Hough space, where a lane can be identified as a local maximum. By splitting lanes into separate channels, we can localize each lane via simple global max-pooling. The location of the maximum encodes the layout of a lane, while the intensity indicates the the probability of a lane being present. Maximizing the log-probability of the maximal bins helps neural networks find lanes without labels. On the CULane and TuSimple datasets, we show that the proposed Hough Transform loss improves performance significantly by learning from large amounts of unlabelled images.Accepted author manuscriptPattern Recognition and Bioinformatic
Detection of image structures using the Fisher information and the Rao metric
No full textIn many detection problems, the structures to be detected are parameterized by the points of a parameter space. If the conditional probability density function for the measurements is known, then detection can be achieved by sampling the parameter space at a finite number of points and checking each point to see if the corresponding structure is supported by the data. The number of samples and the distances between neighboring samples are calculated using the Rao metric on the parameter space. The Rao metric is obtained from the Fisher information which is, in turn, obtained from the conditional probability density function. An upper bound is obtained for the probability of a false detection. The calculations are simplified in the low noise case by making an asymptotic approximation to the Fisher information. An application to line detection is described. Expressions are obtained for the asymptotic approximation to the Fisher information, the volume of the parameter space, and the number of samples. The time complexity for line detection is estimated. An experimental comparison is made with a Hough transform-based method for detecting lines
Introduction
No full textBook synopsis: "Tackling prison overcrowding" is a response to controversial proposals for prisons and sentencing set out in by Lord Patrick Carter's "Review of Prisons", published in 2007. The Carter review proposed the construction of vast 'Titan' prisons to deal with the immediate problem of prison overcrowding, the establishment of a Sentencing Commission as a mechanism for keeping judicial demand for prison places in line with supply, along with further use of the private sector, including private sector management methods. "Tackling prison overcrowding" comprises nine chapters by leading academic experts, who expose these proposals to critical scrutiny. They take the Carter Report to task for construing the problems too narrowly, in terms of efficiency and economy, and for failing to understand the wider issues of justice that need addressing. They argue that the crisis of prison overcrowding is first and foremost a political problem - arising from penal populism - for which political solutions need to be found. This accessible report will be of interest to policy makers, probation practitioners, academics and other commentators on criminal policy
Coleridge’s laws: a study of Coleridge in Malta
No full textSamuel Taylor Coleridge is best known as a great poet and literary theorist, but for one, quite short, period of his life he held real political power — acting as Public Secretary to the British Civil Commissioner in Malta in 1805. This was a formative experience for Coleridge which he later identified as being one of the most instructive in his entire life. In this book, Barry Hough and Howard Davis show how Coleridge's actions whilst in a position of power differ markedly from the idealism he had advocated before taking office — shedding new light on Coleridge's sense of political and legal morality. Meticulously researched and including newly discovered archival materials, Coleridge's Laws provides detailed analysis of the laws and public notices drafted by Coleridge, together with the first published translations of them. Drawing from a wealth of primary sources, Hough and Davis identify the political challenges facing Coleridge and reveal that, in attempting to win over the Maltese public to support Britain's strategic interests, Coleridge was complicit in acts of government which were both inconsistent with the rule of law and contrary to his professed beliefs. Coleridge's willingness to overlook accepted legal processes and personal misgivings for political expediency is disturbing and, as explained by Michael John Kooy in his extensive introduction, necessarily alters our understanding of the author and his writing. Coleridge's Laws contributes in new ways to the current debates about Coleridge's achievements, British colonialism and its engagement with the rule of law, nationhood and the effectiveness of the British administration of Malta. It provides essential reading for anybody interested in Coleridge specifically and the Romantics more generally, for political and legal historians and for students of colonial government
A sentencing commission for England and Wales?
No full textBook Synopsis: Tackling prison overcrowding" is a response to controversial proposals for prisons and sentencing set out in by Lord Patrick Carter's "Review of Prisons", published in 2007. The Carter review proposed the construction of vast 'Titan' prisons to deal with the immediate problem of prison overcrowding, the establishment of a Sentencing Commission as a mechanism for keeping judicial demand for prison places in line with supply, along with further use of the private sector, including private sector management methods. "Tackling prison overcrowding" comprises nine chapters by leading academic experts, who expose these proposals to critical scrutiny. They take the Carter Report to task for construing the problems too narrowly, in terms of efficiency and economy, and for failing to understand the wider issues of justice that need addressing. They argue that the crisis of prison overcrowding is first and foremost a political problem - arising from penal populism - for which political solutions need to be found.This accessible report will be of interest to policy makers, probation practitioners, academics and other commentators on criminal policy
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