82,937 results

  • Improving Image Reconstruction Accuracy Using Discrete Orthonormal Moments

    Mukundan, R. (2003)

    Conference Contributions - Published
    University of Canterbury Library

    Several pattern recognition applications use orthogonal moments to capture independent shape characteristics of an image, with minimum amount of information redundancy in a feature set. Legendre, Zernike, and Pseudo-Zernike moments are examples of such orthogonal feature descriptors. An image can also be reconstructed from a sufficiently large number of orthogonal moments. Discrete orthogonal moments provide a more accurate description of image features by evaluating the moment components directly in the image coordinate space. This paper examines some of the problems associated with the computation of large order Tchebichef moments, and proposes an orthonormal version to improve the quality of reconstructed images.

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  • Binary Vision Algorithms in Java

    Mukundan, R. (1999)

    Conference Contributions - Published
    University of Canterbury Library

    The capabilities of Java as a highly portable, multi-threaded general purpose programming language can be effectively utilized to provide an efficient framework for learning, coding, visualizing and demonstrating the fundamental concepts behind binary vision algorithms. Methods whose implementations are described in this paper include connected component labeling, boundary following algorithm, image feature extraction, and image thinning algorithm. The concept of a pseudo-screen in introduced to generate the display of a scaled pixel grid for a highly magnified view of the pixel level operations and the intermediate stages in recursive computing. The graphics and the user interface classes of Java together with the thread class are used to create methods necessary for interactive input and update of images and also for rendering the output on any Java enabled browser.

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  • Stereo Disparity Estimation in Moment Space

    Pang, A.; Mukundan, R.; Shing, N.L. (2003)

    Conference Contributions - Published
    University of Canterbury Library

    This paper explores various ways by which pixel disparities along epipolar rows of a stereo image pair could be obtained using Chebyshev moments of the corresponding 1D images. Chebyshev moments allow us to represent the image features based on orthogonal basis functions, and hence to reconstruct the intensity distribution from a set of moments fairly accurately. Disparity estimates can be obtained either analytically from the inverse moment transform, or by comparing the reconstructed intensity values. The paper also presents some preliminary results obtained using both synthetic and real images.

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  • Discrete Orthognal Moment Features Using Chebyshev Polynomials

    Mukundan, R.; Ong, S.H.; Lee, P.A. (2000)

    Conference Contributions - Published
    University of Canterbury Library

    This paper introduces a new set of moment functions based on Chebyshev polynomials which are orthogonal in the discrete domain of the image coordinate space. Chebyshev moments eliminate the problems associated with conventional orthogonal image moments such as the Legendre moments and the Zernike moments. The theoretical framework of discrete orthogonal moments is given, and their superior feature representation capability is demonstrated.

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  • A Comparison of Discrete Orthogonal Basis Functions for Image Compression

    Hunt, O.; Mukundan, R. (2004)

    Conference Contributions - Published
    University of Canterbury Library

    In this paper, we analyse the image reconstruction accuracy when using different orthogonal basis functions as the kernel for a reversible image transform. In particular, we examine the Discrete Cosine Transform (DCT), Discrete Tchebichef Transform (DTT), Haar Transform and Walsh-Hadamard Transform (WHT).

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  • Discrete vs. Continuous Orthogonal Moments for Image Analysis

    Mukundan, R.; Ong, S.H.; Lee, P.A. (2001)

    Conference Contributions - Other
    University of Canterbury Library

    Image feature representation techniques using orthogonal moment functions have been used in many applications such as invariant pattern recognition, object identification and image reconstruction. Legendre and Zernike moments are very popular in this class, owing to their feature representation capability with a minimal information redundancy measure. This paper presents a comparative analysis between these moments and a new set of discrete orthogonal moments based on Tchebichef polynomials. The implementation aspects of orthogonal moments are discussed, and experimental results using both binary and gray-level images are included to show the advantages of discrete orthogonal moments over continuous moments.

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  • Hierarchical matching techniques for automatic image mosaicing

    Begg, C.L.; Mukundan, R. (2004)

    Conference Contributions - Published
    University of Canterbury Library

    This paper looks at image mosaicing using hierarchical matching techniques as a way to create a novel view of a scene quickly. Several parameters including error function, region match and constraints are evaluated to find the fastest and most accurate mosaics. Constraints are shown to be very important to intensity matching.

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  • An efficient algorithm for fast computation of pseudo-Zernike moments

    Mukundan, R.; Chong, C.W.; Raveendran, P. (2001)

    Conference Contributions - Published
    University of Canterbury Library

    Pseudo-Zernike moments have better feature representation capabilities and are more robust to image noise than the conventional Zernike moments. However, pseudo-Zernike moments have not been extensively used as feature descriptors due to the computational complexity of the pseudo-Zernike radial polynomials. This paper discusses the drawbacks of the existing methods, and proposes an efficient recursive algorithm to compute the pseudo-Zernike moments. The algorithm consists of a two-stage recurrence relation for radial polynomials and coefficients of the polynomials, which are specifically derived for fast computation of pseudo-Zernike moments. The performance of the algorithm is experimentally examined using both binary and grayscale images, and it shows that the computational speed of pseudo-Zernike moments has been substantially improved over the present methods.

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  • A New Class of Rotational Invariants Using Discrete Orthogonal Moments

    Mukundan, R. (2004)

    Conference Contributions - Published
    University of Canterbury Library

    This paper presents a new class of Tchebichef moments in polar coordinate form, using which rotational invariants can be easily constructed. The structure of the invariants is very similar to that of Zernike and Pseudo-Zernike moments, and their computation does not involve discrete approximation of continuous integral terms. The invariants are thus very robust in the presence of image noise, and have far better recognition capabilities when compared with Zernike/Legendre moments. The new class of moment invariants presented in this paper can be used in pattern and character recognition tasks.

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  • Ray casting for incremental voxel colouring

    Batchelor, O.; Mukundan, R.; Green, R. (2005)

    Conference Contributions - Published
    University of Canterbury Library

    Image based volumetric reconstruction from multiple views is an interesting challenge. Recently several methods of optimisation–based voxel colouring have appeared, which make use of incremental visibility. Culbertson et al. presented a way of determining visibility incrementally by using layered depth images as a data structure (GVC-LDI). We present an alternative algorithm which provides the same outputs. We use ray casting which is simpler and more efficient than using layered depth images. We make some simple comparisons using rasterized images and look at how it can be applied to optimisation based carving as well as level of detail.

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  • Optimising Ventilation Using a Simple Model of The Ventilated ARDS Lung

    Shaw, G.M.; Chase, J.G.; Yuta, T.; Horn, B.; Hann, C.E. (2006)

    Conference Contributions - Other
    University of Canterbury Library

    Mechanical ventilation is a “bread and butter” therapy in critical care. It is well known that a properly or well ventilated patient has an increased likelihood of improved outcome. However, selecting optimal settings, such as PEEP and tidal volume are difficult. Especially, as these settings can change regularly as patient condition evolves, particularly in ARDS. Hence, a method of monitoring and capturing these changes and then optimising ventilation would offer significant clinical benefit. Models offer the opportunity to both monitor and optimise ventilated patient status for better outcomes.

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  • Tight Glycaemic Control in Critical Care Using Insulin and Nutrition - the SPRINT Protocol

    Chase, J.G.; Shaw, G.; LeCompte, A.; Lee, D.; Lonergan, T.; Willacy, M.; Wong, X-W.; Lin, J.; Lotz, T.; Hann, C. (2006)

    Conference Contributions - Other
    University of Canterbury Library

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  • The SPRINT Protocol for Tight Glycaemic Control

    Shaw, G.M.; Chase, J.G.; Wong, X-W.; Lin, J.; Lotz, T.; LeCompte, A.; Lonergan, T.; Willacy, M.; Hann, C.E. (2006)

    Conference Contributions - Other
    University of Canterbury Library

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  • Stochastic insulin sensitivity models for tight glycaemic control

    Chase, J.G.; Lin, J.; Lee, D.S.; Wong, J.; Hann, C.E.; Shaw, G.M. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    Hyperglycaemia is prevalent in critical care, and tight control reduces mortality. Targeted glycaemic control can be achieved by frequent fitting and prediction of a modelled insulin sensitivity index, SI. However, this parameter varies significantly in the critically ill as their condition evolves. A 3-D stochastic model of hourly SI variability is constructed using retrospective data from 18 critical care patients. The model provides a blood glucose level probability distribution one hour following an intervention, enabling accurate prediction and more optimal glycaemic control.

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  • Hierarchical Real-Time Filtering for Continuous Glucose Sensor Data

    Chase, J.G.; Chen, X.; Sirisena, H.; Shaw, G.; Wong, X-W.; Hann, C.; Le Compte, A.J.; Lin, J.; Lotz, T. (2006)

    Conference Contributions - Other
    University of Canterbury Library

    Point of care (POC) continuous glucose sensors offer significant promise for real-time control and artificial pancreas systems in general diabetes.

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  • The Flow of a Thin Liquid Film Past a Cylinder

    Sellier, M. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    This paper presents a numerical study of the flow of a thin liquid film past a circular cylinder. It is investigated in the framework of the lubrication approximation and the corresponding governing equations, formulated in a weak form, are solved in the FEMLAB environment. The effect of the diameter of the circular cylinder on the shape of the free surface is explored and potentially useful correlations derived.

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  • Optimal Mould Design for the Manufacture of High-Precision Lenses

    Sellier, M.; Breitbach, C.; Loch, H.; Siedow, N. (2006)

    Conference Contributions - Other
    University of Canterbury Library

    The increasing need for low-cost, high-precision optical devices requires innovative manufacturing techniques or the optimization of existing ones. The present study focuses on the latter alternative and proposes a computer-aided, mould optimization algorithm for the manufacturing of high-precision glass lenses by compression moulding. The intuitive, yet very efficient, algorithm computes at each optimization loop the mismatch between the desired and deformed glass shapes and uses this information to update the mould design. To solve this optimal shape design problem, a finite element model representative of the real industrial process is developed and solved in the commercial package ABAQUS. This model solves the several stages involved in the process and includes the thermo-mechanical coupling, the varying mechanical contact between the glass and the mould, and the stress and structure relaxation in the glass. The algorithm is successfully tested for the mould design for a plano-concave and a bi-concave lens as the residual error between the deformed and desired glass profiles is decreased to a value of the order of one micron.

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  • Using action research to investigate responses to diversity in a secondary school

    Conner, L. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    This paper reports on how teachers used small action research projects to investigate how they were responding to the diversity of their students in terms of planning and teaching. It was funded by the NZ Ministry of Education Teaching and learning Research Initiative. This project involved teachers investigating self-chosen issues related to the diversity within their own sphere of practice. They were mentored through the research process by researchers at the Christchurch College of Education and by their peers through regular research meetings and conversations. As a result of participating in this project, the teachers developed an awareness of themselves as practitioner researchers and have acquired a sound, though still emergent, understanding of research paradigms, processes and ethical considerations. This project can be seen as an example of how teachers can use a common focus to reflect on their own teaching, gather evidence to investigate their notions and develop their ideas as a community of learners.

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  • Assessing Bioethical Issues: A Case Study (Invited)

    Conner, L. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    A case study of a final year high school biology class in New Zealand is used to illustrate how the New Zealand assessment system allows students to demonstrate the knowledge, attributes and skills considered to be important in learning about bioethical issues. The New Zealand achievement standard system is briefly described. In this case, students were assessed by an essay (500 words) in an external exam. Self and peer assessment activities as well as a range of self-monitoring strategies were used to help students to improve their practice essays. Some of the problems highlighted in this study indicate that teachers need to emphasise what is required of students in more detail and they need to provide multiple opportunities for students to develop the skills of self-questioning, independent inquiry, critical thinking and essay writing.

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  • Investigation of Flexible Pavements' Edge Failure Distress

    Saleh, M.F. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    From practical observation, it was noted that failure near pavement edges is quite common in New Zealand. This failure mode is associated with the mountainous topography that makes constructing wide pavements expensive. The main objective of this research work is to investigate the different factors affecting this type of distress. A three-dimensional finite elements model was designed to study different loading and shoulder conditions. A half fractional factorial experimental design was developed to study five factors: shoulder width, shoulder stiffness, axle load, tire pressure and pavement thickness. The finite elements model solution was compared with multilayer analysis and actual field measurements carried out at the Transit New Zealand accelerated test track to ensure accurate predictions. None of the solutions provided a perfect match between the measured and predicted vertical strains. The multilayer linear elastic solution and the three-dimensional finite elements solutions were reasonably close. The order of importance of the different factors affecting pavement response in the outer wheel path relies on the type of response. Shoulder thickness was the most important factor affecting the maximum surface deflection under the outer wheel followed by axle load, tire pressure, and shoulder width. For the compressive strain on the top of the subgrade and the maximum shear strain in the base course, the order of importance of factors was different. The shoulder stiffness, width and thickness played a significant role in distributing the stresses and strains on the top of the subgrade, thus controlling the edge failure.

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