2020-07-10T00:47:23Z
https://researchspace.auckland.ac.nz/dspace-oai/request
oai:researchspace.auckland.ac.nz:2292/271
2012-11-01T03:56:39Z
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Iyer, Kamendrie
author
2005
Previous research suggests that the speech perceptual abilities of children with normal hearing differ from those of children with cochlear implants when auditory and visual information are presented simultaneously. The current study aims to investigate the audiovisual integration abilities of nine children and young people with cochlear implants (aged 6-23 years) and 31 children with normal hearing (aged 7, 11 or 15 years). Participants took part in an audiovisual speech reading assessment and an audiovisual attention task. The audiovisual speech reading task involved listening to and repeating sentences under four different listening conditions; audiovisual, auditory alone, audiovisual+noise and auditory+noise. The audiovisual attention task involved attending to a computer presentation of a sequence of auditory and visual stimuli. For this assessment the participants were required to click the mouse whenever he/she 'heard' or 'saw' the target '1'. For the speech reading task, the addition of visual cues was beneficial for speech perception in ideal listening conditions for both groups. Interestingly the presence of visual cues was neither beneficial nor detrimental to speech perception in poor listening conditions for both groups. The presence of noise had a detrimental affect on the speech perceptual abilities of both groups.
http://hdl.handle.net/2292/271
Audiovisual Speech Perception Abilities of Children with Normal Hearing in Quiet and in Noise & Comparison to Participants with Cochlear Implants
oai:researchspace.auckland.ac.nz:2292/402
2012-11-01T03:50:39Z
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Ray, James
author
2006
Background Paragraph
In previous studies that have investigated quality of life (QOL) of stroke survivors, stroke survivors with aphasia have often been excluded. The Stroke and Aphasia Quality of Life scale (SAQOL-39) is a new reliable measure, which has recently been used with British stroke survivors with aphasia to investigate health-related quality of life (HRQL). This measure is beneficial for clinical decisions and rehabilitation outcomes for stroke survivors with aphasia.
http://hdl.handle.net/2292/402
Health-related quality of life and aphasia severity: a pilot study for the New Zealand population
oai:researchspace.auckland.ac.nz:2292/405
2012-11-01T11:31:33Z
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Carey, Anna
author
2006
This study investigated the effects of computer-based auditory training software (Otto’s World of Sound) on auditory discrimination, speech perception and auditory attention skills in New Zealand children who have a hearing impairment. Four school-age participants with moderate to profound hearing loss participated in the study. A pre versus post test case study series design was employed to obtain pilot information on effectiveness of the intervention. The results for speech perception and auditory attention skills were promising. Hence further research is warranted using Otto’s World of Sound computer-based auditory training to demonstrate efficacy of the training, using a larger group of participants in a randomised controlled trial.
http://hdl.handle.net/2292/405
hearing impairment
children
auditory training
computer
speech perception
auditory attention
The effectiveness of Otto’s World of Sound computer-based auditory training for improving auditory discrimination and auditory attention skills in children who have a hearing impairment
oai:researchspace.auckland.ac.nz:2292/406
2015-04-09T23:46:39Z
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Newlove, Sarah
author
2007-04-03
Dysphagia is very common following a stroke and in the US alone 500,000 individuals experience a stroke each year. As a result, advances in dysphagia management are growing and include the use of surface electromyography (sEMG) as a biofeedback tool. There is also a shift taking place in terms of how patients are viewed by professionals. In rehabilitation there is less of a focus on impairment-based rehabilitation and more on how the patient functions holistically in their environment, based on the International Classification of Functioning (ICF) framework. The current study aimed to investigate the effectiveness of sEMG as a therapy tool; the effect it has on a person’s quality of life (measured by the SWAL-QOL); and the impact it has on treatment outcomes when therapy is delivered intensively. The results indicated a trend to significance in the progress made by the participant (as measured by videofluoroscopy interpretation) and additionally in the dietary changes after treatment. There was also a significant change in the participant’s perception of their quality of life after treatment. These findings provide a useful basis for the generation of future hypotheses in larger research yet to be conducted.
http://hdl.handle.net/2292/406
sEMG
dysphagia
SWAL-QOL
quality of life
therapy
rehabilitation
A case study examining the effectiveness of surface electromyography (sEMG) biofeedback in dysphagia rehabilitation and the SWAL-QOL quality of life outcome measure
oai:researchspace.auckland.ac.nz:2292/2399
2014-05-26T00:13:58Z
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Fenaughty, John
author
Braun, Virginia
author
Gavey, Nicola
author
Aspin, Clive
author
Reynolds, Paul
author
Schmidt, Johanna
author
2006
Background
• The existence of sexual assault, sexual coercion and unwanted sex among gay, bisexual and other men who have sex with men is seldom acknowledged — within gay communities, society at large, or in policy.
• Although prevalence is difficult to determine, international research has established that sexual assault, sexual coercion and unwanted sex are experienced by a significant number of gay, bisexual, and other men who have sex with men.
Our project
• This project consisted of two separate, but related, studies: a broader project, and a Kaupapa Māori project.
• The broader project was designed to explore the phenomenon of sexual coercion among gay and bisexual men in Aotearoa/New Zealand.
• It did not set out to investigate the broader issue of sexual assault against gay and bisexual men by men who do not identify as gay or bisexual (i.e., sexual violence which could more easily be categorised as hate crime).
• Twenty-three key informants were interviewed about their observations and views on sexual coercion among gay, bisexual, and other men who have sex with men.
• Eighteen gay and bisexual men were interviewed about their experiences of sexual coercion.
• Six focus groups were held with gay and bisexual men in order to generate accounts about how sexuality is understood and negotiated in gay communities.
• Five takatāpui tāne were interviewed for the Kaupapa Māori project on Māori men’s experiences of sexual coercion.
Research Report. Department of Psychology, The University of Auckland. (2006)
ISBN-10: 0 908689 79 9
ISBN-13 978 0 908689 79 9
http://hdl.handle.net/2292/2399
sexual coercion
gay men
bisexual men
takatāpui tāne
unwanted sex
safer sex
Sexual Coercion among Gay Men, Bisexual Men and Takatāpui Tāne in Aotearoa/New Zealand.
oai:researchspace.auckland.ac.nz:2292/2624
2008-08-13T04:37:30Z
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Rosenfeld, Azriel
author
1997
Digital geometry deals with geometrical properties of "digital objects", which are usually taken to be sets of lattice points in the discrete space Zⁿ. Such objects are often the result of applying a "digitization" process to objects in the Euclidean space Rⁿ. A central theme in digital geometry is how to characterize digital objects that could be the digitizations of "real" objects that have given geometric properties. The literature on digital geometry dates back to the late 1960's. The report includes a bibliography of more then 900 papers on the subject, organized by topic. It outlines the main lines of development of the field, and indicates areas in which interesting problems remain open.
Communication and Information Technology Research Technical Report 1, (1997)
1178-3524
http://hdl.handle.net/2292/2624
Digital Geometry: Introduction and Bibliography
oai:researchspace.auckland.ac.nz:2292/2631
2008-08-26T03:40:42Z
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Schlüns, Karsten
author
Fellenz, Winfried
author
Koschan, Andreas
author
Teschner, Matthias
author
1997
We present a low-cost active vision system with ten degrees of freedom which has been built from off-the-shelf parts. To obtain high resolution depth information of fixated objects in the scene a general purpose calibration procedure is proposed which estimates intrinsic and extrinsic camera parameters including the vergence axes of both cameras. To produce enhanced dense depth maps a hierarchical block matching procedure is presented which employs color information. To simplify the development of controlling strategies for the head a modular hierarchy is proposed that distributes various tasks among different levels employing basic capabilities of the components of the head.
Communication and Information Technology Research Technical Report 2 (1997)
1178-3524
http://hdl.handle.net/2292/2631
A Modular 10-DOF Vision System for High-Resolution Active Stereo
oai:researchspace.auckland.ac.nz:2292/2670
2016-06-09T04:04:54Z
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Cumming, Alan
author
1980
Since the establishment of the University of Auckland's Marine Laboratory at Leigh in 1964, there has been a number of published papers and unpublished theses dealing with local physical and biological phenomena, though few, if any, have given a comprehensive picture of the area. The creation of a Marine Reserve in 1975 has brought about a serious attempt to co-ordinate the knowledge gained and provide an integrated baseline to which the understanding gained from future research can be added. To date, there have been many noteworthy attempts to centralize information within the bounds of the Reserve. The first, a booklet compiled by Norton and Chapman (1968) deals with the ecology of local species within the spectrum of available habitats along the rocky shoreline. The second is a succinct review of knowledge of the Reserve compiled shortly after its official inception in 1975 by Gordon and Ballantine (1976). The third, of which this exercise may be regarded as an addendum, is a sub-tidal survey of the main marine habitats of the Reserve (Ayling, 1978). This latter survey has attempted to define these habitats on a geographical-biological basis and to 'provide a quantitative estimate of the numbers, size and distribution of the important organisms in the Reserve.'
http://hdl.handle.net/2292/2670
Cape Rodney to Okakari Point Marine Reserve survey 2. Rocky shores
oai:researchspace.auckland.ac.nz:2292/2676
2012-02-02T23:13:51Z
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Guan, Shushi
author
Klette, Reinhard
author
2008
This paper studies different specifications of belief propagation for stereo analysis of seven rectified stereo night-vision sequences (provided by Daimler AG). As it was shown earlier by the authors, Sobel preprocessing of images had obvious impacts on improving disparity calculations. This paper also considers other options of preprocessing (Canny and Kovesi-Owens edge operators), and concludes with a recommended setting for belief propagation on those sequences.
Multimedia Imaging Report 17 (2008)
1178-5789
http://hdl.handle.net/2292/2676
Belief Propagation for Stereo Analysis of Night-Vision Sequences
oai:researchspace.auckland.ac.nz:2292/2678
2008-08-29T04:56:01Z
com_2292_122
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Huang, Fay
author
Kang, Shou
author
2001
This paper proposes a novel approach for the calibration of a panoramic camera using geometric information available in real scenes. A panoramic camera possesses some flexibility in acquiring different types of panoramas, such as single-center (e.g. as assumed for QTVR), symmetric stereo, concentric or polycentric panoramas. Panoramic camera are based on the use of line sensors rotating around an axis, and are of increasing value for various applications in computer vision, computer graphics or robotics. Previously developed camera calibration methods (for 'standard' camera architectures) are not applicable due to the non-linearity of the panoramic camera, defined by the existence of multiple (nonlinear) optical points and a cylindrical image surface. This article addresses the calibration subject of panoramic cameras for the first time. The paper focuses on the calibration of two dominant parameters that characterize the camera model and provide flexibility in selecting different types of panoramas. It elab rates selected geometric constraints (for increasing numerical stability), experiments with captured image data, an error-sensitivity analysis by simulation, and a discussion why other approaches (designed for 'standard' camera architectures) would fail.
Communication and Information Technology Research Technical Report 108, (2001)
1178-3637
http://hdl.handle.net/2292/2678
Calibration of Panoramic Cameras Using 3D Scene Information
oai:researchspace.auckland.ac.nz:2292/2679
2008-08-29T04:56:03Z
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Klette, Reinhard
author
2001
This paper presents a new method for defining grid-point adjacencies, called the switch approach. It is discussed how it relates to connectedness definition in multi-valued images. The paper illustrates how the method can be used, and provides a few experimental data illustrating the rele-vance and simplicity of the approach.
Communication and Information Technology Research Technical Report 107, (2001)
1178-3638
http://hdl.handle.net/2292/2679
Switches May Solve Adjacency Problems
oai:researchspace.auckland.ac.nz:2292/2680
2008-08-29T04:56:04Z
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Klette, Reinhard
author
2001
This paper discusses different topologies on the planar orthogonal grid and shows homeomorphy between cellular models. It also points out that graph-theoretical topologies exist defined by planar extensions of the 4-adjacency graph. All these topologies are potential models for image carriers.
Communication and Information Technology Research Technical Report 106, (2001)
1178-3639
http://hdl.handle.net/2292/2680
Topologies on the Planar Orthogonal Grid
oai:researchspace.auckland.ac.nz:2292/2681
2008-08-29T04:56:08Z
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Coeurjolly, David
author
Klette, Reinhard
author
2001
The paper compares previously published length estimators having digitized curves as input. The evaluation uses multigrid convergence (theoretical results and measured speed of convergence) and further measures as criteria. The paper also suggests a new gradient-based method for length estimation.
Communication and Information Technology Research Technical Report 105, (2001)
1178-3640
http://hdl.handle.net/2292/2681
A Comparative Evaluation of Length Estimators
oai:researchspace.auckland.ac.nz:2292/2682
2008-08-29T04:56:09Z
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Yu, Linjiang
author
Klette, Reinhard
author
2001
Relative convex hulls have been suggested for multigrid-convergent surface area estimation. Besides the existence of a convergence theorem there is no efficient algorithmic solution so far for calculating relative convex hulls. This article discusses an approximative solution based on minimum-length polygon calculations. It is illustrated that this approximative calculation also proves (experimentally) to provide a multigrid convergent measurement.
Communication and Information Technology Research Technical Report 104, (2001)
1178-3641
http://hdl.handle.net/2292/2682
An Approximative Calculation of Relative Convex Hulls for Surface Area Estimation
oai:researchspace.auckland.ac.nz:2292/2683
2008-08-29T04:56:10Z
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Wei, Tiangong
author
Klette, Reinhard
author
2001
This paper proposes two improvements for reflectance based shape recovery. First, it is shown that albedo-independent photometric stereo allows albedo computation. This computation is based on photometric equations that relate surface normals to triplets of the image irradiances. Second, the paper also presents as the main result a new algorithm for depth recovery from surface normals. In order to improve the accuracy and robustness and to strengthen the relation between the depth map and surface normals, two new constraints are added into the associated cost function. They constrain the behavior of high-order change rate between the variables. Therefore, the changes of depth maps will be more regular. The Frankot-Chellappa-algorithm is a special case of our algorithm in the sense that it uses a subset of constraints only.
Communication and Information Technology Research Technical Report 103, (2001)
1178-3642
http://hdl.handle.net/2292/2683
A New Algorithm for Gradient Field Integration
oai:researchspace.auckland.ac.nz:2292/2684
2008-08-29T04:56:11Z
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Barron, John
author
Klette, Reinhard
author
2001
The paper studies optical flow methods on colour frames captured by a digital video camera. The paper reviews related work,specifies some new colour optical flow constraints and reports on experimental evaluations for one image sequence.
Communication and Information Technology Research Technical Report 102, (2001)
1178-3643
http://hdl.handle.net/2292/2684
Experience with Optical Flow in Colour Video Image Sequences
oai:researchspace.auckland.ac.nz:2292/2685
2008-08-29T04:56:19Z
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Klette, Reinhard
author
2001
This report is about basic material on digital topology within the context of image analysis. This first part informs about basics in topology, and different options for two-dimensional homogeneous image carriers. It discusses adjacency graphs more in detail as a possible unifying approach for modelling and applying homogeneous or inhomogeneous planar image carriers. The second part of the report will focus on three-dimensional image carriers with a special treatment of complexes.
Communication and Information Technology Research Technical Report 101, (2001)
1178-3644
http://hdl.handle.net/2292/2685
Digital Topology for Image Analysis - Part 1
oai:researchspace.auckland.ac.nz:2292/2686
2008-08-29T04:56:22Z
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Chen, Chia-Yen
author
Klette, Reinhard
author
2001
This paper describes a method for the calculation of surface reflectance values via photometric stereo. Experimental results show that surfaces rendered with reflectance values calculated by the proposed method have more realistic appearances than those with constant albedo.
Communication and Information Technology Research Technical Report 100, (2001)
1178-3645
http://hdl.handle.net/2292/2686
Albedo Recovery Using a Photometric Stereo Method
oai:researchspace.auckland.ac.nz:2292/2687
2008-08-29T04:56:23Z
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Chen, Chia-Yen
author
Klette, Reinhard
author
2001
This paper reports about a method for merging shape data, obtained via photometric stereo and shape from contours, into a 3D model.
Communication and Information Technology Research Technical Report 95, (2001)
1178-3650
http://hdl.handle.net/2292/2687
Improved Fusion of Photometric Stereo and Shape from Contours
oai:researchspace.auckland.ac.nz:2292/2689
2008-08-29T04:56:06Z
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Wei, Shou-Kang
author
Huang, Fay
author
2001
This paper reports about basic algebraic relations between parameters and an error analysis for symmetric panorama acquisition. Symmetric panoramas are of importance in computer vision, computer graphics, and stereoscopic imaging and display. Advantages of symmetric panoramas include the possible reuse of stereo matching algorithms previously developed for 3D reconstruction, and possible applications in stereoscopic visualization. This paper formulates and studies problems which have not yet been approached previously: algebraic relations between application-specific parameters and imaging parameters, and how errors (incurred from measurements during imaging) are propagating and impacting the quality of resultant images. Without dealing with such problems, we are not able to answer the more difficult questions regarding the design and/or the capability assessment of symmetric panorama acquisition systems. The paper first summarizes the acquisition geometry followed by in-depth studies of algebraic parameter relations and error analyses.
Communication and Information Technology Research Technical Report 94, (2001)
1178-3651
http://hdl.handle.net/2292/2689
Analysis of Symmetric Panorama Acquisition
oai:researchspace.auckland.ac.nz:2292/2690
2008-08-29T04:56:26Z
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Rosenfeld, Azriel
author
Klette, Reinhard
author
2001
A digital arc is called `straight' if it is the digitization of a straight line segment. Since the concept of digital straightness was introduced in the mid-1970's, dozens of papers on the subject have appeared; many characterizations of digital straight lines have been formulated, and many algorithms for determining whether a digital arc is straight have been defined. This paper reviews the literature on digital straightness and discusses its relationship to other concepts of geometry, the theory of words, and number theory.
Communication and Information Technology Research Technical Report 93, (2001)
1178-3652
http://hdl.handle.net/2292/2690
Digital Straightness
oai:researchspace.auckland.ac.nz:2292/2691
2008-08-29T04:56:27Z
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Yip, Ben
author
Klette, Reinhard
author
2001
In the case of isothetic simple polyhedra there are only six different types of 3D angles. This article states and proofs a formula about counts of these angles. This complements formulas in combinatorial topology such as Euler's polyhedron formula, or the previously known formula on angle counts for isothetic polygons. The latter formula and the shown equality for angle counts of isothetic simple polyhedra are useful formulas for analyzing isothetic boundaries in 2D digital images (e.g. classification into inner (boundary of a hole) or outer boundaries, see [5]) and isothetic surfaces in 3D digital images (e.g. necessary condition for a complete surface scan).
Communication and Information Technology Research Technical Report 92, (2001)
1178-3653
http://hdl.handle.net/2292/2691
Angle Counts for Isothetic Polygons and Polyhedra
oai:researchspace.auckland.ac.nz:2292/2692
2008-08-29T04:56:28Z
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Bülow, Thomas
author
Klette, Reinhard
author
2001
One possible denition of the length of a digitized curve in 3D is the length of the shortest polygonal curve lying entirely in a cube curve. In earlier work the authors proposed an iterative algorithm for the calculation of this minimal length polygonal curve MLP. This paper reviews the algorithm and suggests methods to speed it up by reducing the set of possible locations of vertices of the MLP or by directly calculating MLP vertices in specific situations. Altogether the paper suggests an in depth analysis of cube curves.
Communication and Information Technology Research Technical Report 91, (2001)
1178-3654
http://hdl.handle.net/2292/2692
Approximation of 3D Shortest Polygons in Simple Cube Curves
oai:researchspace.auckland.ac.nz:2292/2693
2008-08-29T04:56:30Z
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Huang, Fay
author
Klette, Reinhard
author
Börner, Anko
author
Reulke, Ralf
author
Scheele, Martin
author
Scheibe, Karsten
author
2001
This report summarizes technical information regarding hyper-resolution and polycentric panoramic image acquisition and experimental data collection for a joint project between the Center for Image Technology and Robotics (CITR) in Auckland, New Zealand and the institute of space sensor technology and planetary exploration of German Aerospace Center (DLR) in Berlin, Germany.
Communication and Information Technology Research Technical Report 90, (2001)
1178-3655
http://hdl.handle.net/2292/2693
Hyper-resolution and Polycentric Panorama Acquisition and Experimental Data Collection
oai:researchspace.auckland.ac.nz:2292/2694
2008-08-29T04:56:30Z
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Zhang, Yongbao
author
2001
This note reports about a minor error in the original paper on Tsai's calibration method and in the corresponding implementation software available for free downloads on the Web. Tsai's camera calibration method allows a determination of eleven camera calibration parameters. There is an incorrectness in the formula for calculating the X-component of the translation vector T. This report corrects this minor problem.
Communication and Information Technology Research Technical Report 89, (2001)
1178-3656
http://hdl.handle.net/2292/2694
Correction of a Minor Error in the Implementation Software and the Original Paper of Tsai's Calibration Method
oai:researchspace.auckland.ac.nz:2292/2695
2008-08-29T04:56:30Z
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Kawamoto, Kazuhiko
author
Klette, Reinhard
author
2001
Video sequences capturing real scenes may be interpreted with respect to a dominant plane which is a planar surface covering more than 50% of a frame, or being that planar surface which is represented in the image with the largest number of pixels. This note shows a possible way for estimating the surface normal of this plane if just camera rotation is allowed.
Communication and Information Technology Research Technical Report 88, (2001)
1178-3657
http://hdl.handle.net/2292/2695
Dominant Plane Estimation
oai:researchspace.auckland.ac.nz:2292/2696
2008-08-29T04:56:32Z
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Klette, Reinhard
author
2001
Jordan, Peano and others introduced digitizations of sets in the plane and in the 3D space for the purpose of feature measurements. Features measured for digitized sets, such as perimeter, contents etc., should converge (for increasing grid resolution) towards the corresponding features of the given sets before digitization. This type of multigrid convergence is one option for performance evaluation of feature measurement in image analysis with respect to correctness. The paper reviews work in multigrid convergence in the context of digital image analysis. In 2D, problems of area estimations and lower-order moment estimations do have "classical" solutions (Gauss, Dirichlet, Landau et al.). Estimates of moments of arbitrary order are converging with speed $f(r)=r^{-15/11}$. The linearity of convergence is known for three techniques for curve length estimation based on regular grids and polygonal approximations. Piecewise Lagrange interpolants of sampled curves allow faster convergence speed. A first algorithmic solution for convergent length estimation for digital curves in 3D has been suggested quite recently. In 3D, for problems of volume estimations and lower-order moment estimations solutions are known for about one-hundred years (Minkowski, Scherrer et al.). But the problem of multigrid surface contents measurement is still a challenge, and there is recent progress in this field.
Communication and Information Technology Research Technical Report 87, (2001)
1178-3658
http://hdl.handle.net/2292/2696
Multigrid Convergence of Geometric Features
oai:researchspace.auckland.ac.nz:2292/2697
2008-08-29T04:56:44Z
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Klette, Reinhard
author
Gimel'farb, Georgy
author
2001
Recent camera technology provides new solutions for wide-angle image acquisition. Multi- or single-line cameras have been designed for spaceborne and airborne scanners to provide high resolution imagery. Line cameras may also work as panorama scanners, and models of these have already been studied in computer vision for a few years. These cameras or models require studies in calibration, registration and epipolar geometry to ensure accurate imaging and stereo analysis. The resulting images or depth maps also allow new approaches in 3D scene visualisation. The paper informs about line camera models and camera hardware, the historic background in photogrammetry and aerial mapping, calibration of line cameras, registration of captured images, epipolar geometry for along-track and panoramic stereo, stereo matching with a focus on dynamic programming, and visualisation. The paper illustrates sketched concepts using a few of the high-resolution aerial and panoramic image data.
Communication and Information Technology Research Technical Report 86, (2001)
1178-3659
http://hdl.handle.net/2292/2697
Wide-Angle Image Acquisition, Analysis and Visualisation
oai:researchspace.auckland.ac.nz:2292/2698
2008-08-29T05:16:56Z
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Noakes, Lyle
author
Kozera, Ryszard
author
Klette, Reinhard
author
2001
This paper looks at the problem of approximating the length of the unknown parametric curve
⋎ [0,1] → IRⁿ from points qᵢ = ⋎
(tᵢ), where the parameters
ti are not given. When the tᵢ are uniformly distributed Lagrange interpolation
by piecewise polynomials provides efficient length estimates, but in other cases this
method can behave very badly [15]. In the present paper we apply this simple
algorithm when the tᵢ are sampled in what we call an ε-uniform fashion, where
0 ≤ ε ≤ 1. Convergence of length estimates using Lagrange interpolants is not as
rapid as for uniform sampling, but better than for some of the examples of [15]. As
a side-issue we also consider the task of approximating ⋎ up to parameterization,
and numerical experiments are carried out to investigate sharpness of our theoretical
results. The results may be of interest in computer vision, computer graphics,
approximation and complexity theory, digital and computational geometry, and
digital image analysis.
Communication and Information Technology Research Technical Report 85, (2001)
1178-3660
http://hdl.handle.net/2292/2698
Length Estimation for Curves with Different Samplings
oai:researchspace.auckland.ac.nz:2292/2700
2008-08-29T04:56:48Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Asano, Tetsuo
author
Kawamura, Yasuyuki
author
Obokata, Koji
author
2001
The paper introduces a new approximation scheme for planar digital curves. This scheme defines an approximating sausage `around' the given digital curve, and calculates a minimum-length polygon in this approximating sausage. The length of the polygon is taken as an estimator for the length of the curve being the (unknown) preimage of the given digital curve. Assuming finer and finer grid resolution it is shown that this estimator converges to the true perimeter of an r-compact polygonal convex bounded set. This theorem provides theoretical evidence for practical convergence of the proposed method towards a `correct' estimation of the length of a curve. The validity of the scheme has been verified through experiments on various convex and non-convex curves. Experimental comparisons with two existing schemes have also been made.
Communication and Information Technology Research Technical Report 83, (2001)
1178-3662
http://hdl.handle.net/2292/2700
Minimum-Length Polygons In Approximation Sausages
oai:researchspace.auckland.ac.nz:2292/2701
2008-08-29T04:56:52Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Soma, Takashi
author
Ustimenko, Vasiliy
author
2001
We identify the eigenvalue problem for the graph Laplacian on a Hamming graph as an analog to the problem of modes of vibration on a continuum, and show that the eigenvectors of the graph Laplacian matrix are the basis functions for the Fourier transform on the Boolean domain.
Communication and Information Technology Research Technical Report 82, (2001)
1178-3663
http://hdl.handle.net/2292/2701
Graph Laplacians and Fourier Transforms on Boolean
oai:researchspace.auckland.ac.nz:2292/2702
2008-08-29T04:56:07Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Wei, Shou-Kang
author
Huang, Fay
author
2001
This paper proposes an approach for solving the parameter determination problem for a stereoscopic panorama camera. Image acquisition parameters have to be calculated under given constraints defined by application requirements, the image acquisition model, and specifications of the targeted 3D scenes. Previous studies on stereoscopic panorama imaging, such as [IYT92, MB95b, WHK99b, PPB00, SKS99, HWK01, Sei01, WP01], pay great attention on how a proposed imaging approach supports a chosen area of application. The image acquisition parameter determination problem has not yet been dealt with in these studies. The lack of guidance in selecting image acquisition parameters affects the validity of results obtained for subsequent processes [WHK00]. Our approach towards parameter determination allows to satisfying commonly demanded 3D scene visualization/reconstruction application requirements: proper scene composition in resultant images; adequate sampling at a particular scene distance; and desired stereo quality i.e. depth levels) over a diversity of scenes of interest. The paper details the models, constraints and criteria used for solving the parameter determination problem. Some practical examples are given for demonstrating the use of the formulas derived. The study contributes to the design of stereoscopic panorama cameras as well as to manuals for on-site image acquisition. The results of our studies are also useful for camera calibration, or pose estimation in stereoscopic panoramic imaging.
Communication and Information Technology Research Technical Report 81, (2001)
1178-3664
http://hdl.handle.net/2292/2702
Determination of Geometric Parameters for Stereoscopic Panorama Cameras
oai:researchspace.auckland.ac.nz:2292/2703
2008-08-29T04:56:54Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Wei, Shou-Kang
author
Huang, Fay
author
2001
Recently multiple panoramic images have emerged and received increasingly interest in applications of 3D scene visualization and reconstruction. Examples of such approaches and applications are discussed throughout the paper. Although many panoramic image acquisition models have been proposed in the literature, there is still a lack in studies about what principles are essential in the design/assessment of new/old panoramic image acquisition models in a formal way. Geometric studies such as epipolar geometry are well established for a pair of planar images. Compared to that, the computer vision literature still lacks work on pairs of panoramic images. There is a need to characterize and clarify their common natures and differences so that a more general form/framework or a better computational model can be further discovered or developed. This paper introduces some notions at an abstract level for characterizing the essential components of panoramic image acquisition models. Based on the result of this characterization, we develop a general computational model for describing the family of cylindrical panoramas. A classification within this family, and results of epipolar curve equations for different subclasses of this family are presented.
Communication and Information Technology Research Technical Report 80, (2001)
1178-3665
http://hdl.handle.net/2292/2703
Characterization of Image Acquisition and Epipolar Geometry of Multiple Panoramas
oai:researchspace.auckland.ac.nz:2292/2704
2008-08-29T04:56:56Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
2001
Digital geometry emerged with the rise of computer technologies in the second half of the 20th century as an application-oriented field influenced by the new possibilities in computer graphics and digital image analysis. Digital geometry is a subdiscipline of discrete geometry. Problems in image analysis are defined with respect to Euclidean geometry, and direct links to this geometric discipline are normally established for motivation or comparison. This directs digital geometry toward being a digitized Euclidean geometry. This report is written to become a chapter in a book to be published mid of 2001 as a Festschrift for Azriel Rosenfeld.
Communication and Information Technology Research Technical Report 79, (2001)
1178-3666
http://hdl.handle.net/2292/2704
Digital Geometry --- The Birth of a New Discipline
oai:researchspace.auckland.ac.nz:2292/2705
2008-08-29T04:56:57Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
McIvor, Alan
author
Zang, Qi
author
2000
This paper reviews papers on tracking people in a video surveillance system, and it presents a new system designed for being able to cope with shadows in a real-time application for counting people which is one of the remaining main problems in adaptive background subtraction in such video surveillance systems.
Communication and Information Technology Research Technical Report 78, (2000)
1178-3667
http://hdl.handle.net/2292/2705
The Background Subtraction Problem for Video Surveillance Systems
oai:researchspace.auckland.ac.nz:2292/2706
2008-08-29T04:56:59Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Baltes, Jacky
author
2000
This paper describes a practical method for the camera calibration given a single image of a regular texture. This paper uses the calibration of images of skyscrapers as an example. The paper introduces two algorithms for the assignment of realworld coordinates to feature points. The first algorithm selects five closely connected feature points and determines the orientation of the rectangular pattern. The second algorithm iteratively sorts the feature points and assigns real world coordinates to them. Lastly, the Tsai camera calibration algorithm is used to compute the camera parameters.
Communication and Information Technology Research Technical Report 77, (2000)
1178-3668
http://hdl.handle.net/2292/2706
Camera Calibration of Rectangular Textures
oai:researchspace.auckland.ac.nz:2292/2707
2008-08-29T04:56:59Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Yuen, David
author
MacDonald, Bruce
author
2000
A novel approach to computational binocular stereo based on the Neyman-Pearson criterion for discriminating between statistical hypotheses is proposed. An epipolar terrain profile is reconstructed by maximising its likelihood ratio with respect to a purely random profile. A simple generative Markov-chain model of an image-driven profile that extends the model of a random profile is introduced. The extended model relates transition probabilities for binocularly and monocularly visible points along the profile to grey level differences between corresponding pixels in mutually adapted stereo images. This allows for regularising the ill-posed stereo problem with respect to partial occlusions.
Communication and Information Technology Research Technical Report 75, (2000)
1178-3670
http://hdl.handle.net/2292/2707
Robot Localisation Using an Omnidirectional Colour Image
oai:researchspace.auckland.ac.nz:2292/2708
2008-08-29T04:57:00Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Baltes, Jacky
author
2000
This paper describes a novel approach to detecting orientation and identity of robots using a global vision system. Instead of additional markers, the original shape of the robot is used to determine an orientation using a general Hough transform. In addition the movement history as well as the command history are used to calculate the quadrant of the orientation as well as the identity of the robot. An empirical evaluation shows that the performance of the new video server is at least as good as that of a traditional approach using additional coloured markers.
Communication and Information Technology Research Technical Report 74, (2000)
1178-3671
http://hdl.handle.net/2292/2708
Horus: Object Orientation and Id without Additional Markers
oai:researchspace.auckland.ac.nz:2292/2709
2008-08-29T04:57:01Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Baltes, Jacky
author
2000
One of the reasons for organizing robotic games is that they allow researchers to evaluate their systems and approaches on a level playing field. This evaluation is important in a quickly developing field such as robotics with few real world applications. This paper investigates through a case-study how much participating at the RoboCup-99 competition has benefited a MSc. student at the University of Auckland. Although the participation was certainly stimulating, its influence on the research was indirect. The paper makes a number of suggestions that will make it easier to quantitatively evaluate research at these competitions and thus influence research more directly.
Communication and Information Technology Research Technical Report 73, (2000)
1178-3672
http://hdl.handle.net/2292/2709
RoboCup-99: A Student's Perspective
oai:researchspace.auckland.ac.nz:2292/2711
2008-08-29T04:57:03Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Wei, Tiangong
author
Klette, Reinhard
author
2000
This paper presents a wavelet-based algorithm for height from gradients. The tensor product of the third-order Daubechies' scaling functions is used to span the solution space. The surface height is described as a linear combination of a set of the scaling basis functions. This method efficiently discretize the cost function associated with the height from gradients problem. After discretization, the height from gradients problem becomes a discrete minimization problem rather than discretized PDE's. To solve the minimization problem, perturbation method is used. The surface height is finally decided after finding the weight coefficients.
Communication and Information Technology Research Technical Report 72, (2000)
1178-3673
http://hdl.handle.net/2292/2711
A Wavelet-based Algorithm for Height from Gradients
oai:researchspace.auckland.ac.nz:2292/2712
2008-08-29T04:57:04Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Austin, Nikki
author
Chen, Yen
author
Marshall, Robert
author
Tsai, Yuan-sheng
author
Zhang, Yongbao
author
2000
The paper reports about a performance comparison within a joint project of computer vision, and sport and exercise sciences. The project is directed on the understanding of human motion based on shape features and kinetic studies. Three shape recovery techniques, a traditional technique as used in sport and exercise sciences (manual measurement based on an elliptical zone assumption) and two computer vision techniques (based on a small number of occluding contours, and a new combination of photometric stereo and shape from boundaries), are compared using a mannequin as test object. The computer vision techniques have been designed to go towards dynamic shape recovery (humans in motion). The paper reports about these three techniques and their measurement accuracies.
Communication and Information Technology Research Technical Report 71, (2000)
1178-3674
http://hdl.handle.net/2292/2712
A Comparison of Feature Measurements for Kinetic Studies on Human Bodies
oai:researchspace.auckland.ac.nz:2292/2713
2008-08-29T04:57:06Z
com_2292_122
col_2292_3452
col_2292_2623
00925njm 22002777a 4500
dc
Wei, Tiangong
author
Klette, Reinhard
author
2000
This paper presents and analyzes four explicit, two implicit and four semi-implicit finite difference algorithms for the linear shape from shading problem. Comparisons of accuracy, solvability, stability and convergence of these schemes indicate that the weighted semi-implicit scheme and the box scheme are better than the other ones because they can be calculated more easily, they are more accurate, faster in convergence and unconditionally stable.
Communication and Information Technology Research Technical Report 70, (2000)
1178-3675
http://hdl.handle.net/2292/2713
Analysis of Finite Difference Algorithms for Linear Shape from Shading
oai:researchspace.auckland.ac.nz:2292/2714
2008-08-29T04:57:06Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
Sun, Hao
author
2000
The paper estimates the surface area of regular solids by a global segmentation of a digital representation of the given solid into digital plane segments, and the projection of these digital plane segments into Euclidean planes. Multigrid convergence experiments of the estimated surface area value are used to evaluate the performance of this new method for surface area measurement. multigrid convergence.
Communication and Information Technology Research Technical Report 69, (2000)
1178-3676
http://hdl.handle.net/2292/2714
A Global Surface Area Estimation Algorithm for Digital Regular Solids
oai:researchspace.auckland.ac.nz:2292/2715
2008-08-29T04:57:13Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Chen, Yen
author
Sara, Radim
author
2000
In this project, we have investigated the fusion of surface data obtained by two different surface recovery methods. In particular, we have fused the depth maps obtained by shape from contours and local surface orientation maps obtained by photometric stereo. It has been found that the surface obtained by fusing orientation and depth data is able to yield more precision when compared with the surfaces obtained by either type of data alone.
Communication and Information Technology Research Technical Report 68, (2000)
1178-3677
http://hdl.handle.net/2292/2715
Integration of Photometric Stereo and Shape from Occluding Contours by Fusing Orientation and Depth Data.
oai:researchspace.auckland.ac.nz:2292/2716
2008-08-29T04:57:15Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Wei, Tiangong
author
Klette, Reinhard
author
2000
The Schrödinger equation is solved by using the decomposition method. A rapidly convergent series solution is achieved. The accuracy of the results obtained indicates the superiority of the decomposition methods over the existing numerical methods that were applied to this equation.
Communication and Information Technology Research Technical Report 67, (2000)
1178-3678
http://hdl.handle.net/2292/2716
Decomposition Method for the Linear Schrödinger Equation
oai:researchspace.auckland.ac.nz:2292/2717
2008-08-29T04:57:04Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Asano, Tetsuo
author
Kawamura, Yasuyuki
author
Obokata, Koji
author
2000
The paper introduces a new approximation scheme for planar digital curves. This scheme defines an approximating sausage 'around' the given digital curve, and calculates a minimum-length polygon in this approximating sausage. The length of this polygon is taken as an estimator for the length of the curve being the (unknown) preimage of the given digital curve. Assuming finer and finer grid resolution it is shown that this estimator converges to the true perimeter of an r-compact polygonal convex bounded set. This theorem provides theoretical evidence for practical convergence of the proposed method towards a `correct' estimation of the length of a curve.
Communication and Information Technology Research Technical Report 65, (2000)
1178-3680
http://hdl.handle.net/2292/2717
A New Approximation Scheme for Digital Objects and Curve Length Estimations
oai:researchspace.auckland.ac.nz:2292/2718
2008-08-29T04:57:05Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Huang, Fay
author
Wei, Shou-Kang
author
2000
We introduce a new class of panoramic images, called polycentric panoramic images, which is a generalization from more specific classes such as single-center, multiple-center, or concentric panoramic images. This paper focuses on the derivation of an epipolar curve equation for poly- centric panoramic images. The epipolar curve equation derived provides a unified approach for the epipolar geometry in any of the more specific classes of panoramic images.
Communication and Information Technology Research Technical Report 64, (2000)
1178-3681
http://hdl.handle.net/2292/2718
Epipolar Geometry in Polycentric Panoramas
oai:researchspace.auckland.ac.nz:2292/2719
2008-08-29T04:57:16Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
Zunic, Jovisa
author
2000
The conceptual design of many procedures used in image analysis starts with models which assume as an input sets in Euclidean space which we regard as real objects. However, the application finally requires that the Euclidean (real) objects have to be modelled by digital sets, i.e. they are approximated by their corresponding digitizations. Also "continuous" operations (for example integrations or differentiations) are replaced by "discrete" counterparts (for example summations or differences) by assuming that such an replacement has only a minor impact on the accuracy or efficiency of the implemented procedure. This paper discusses applications of results in number theory with respect to error estimations, accuracy evalua- tions, correctness proofs etc. for image analysis procedures. Knowledge about digitization errors or approximation errors may help to suggest ways how they can be kept under required limits. Until now have been only minor impacts of image analysis on developments in number theory, by defining new problems, or by specifying ways how existing results may be discussed in the context of image analysis. There might be a more fruitful exchange between both disciplines in the future.
Communication and Information Technology Research Technical Report 63, (2000)
1178-3682
http://hdl.handle.net/2292/2719
Interactions between Number Theory and Image
oai:researchspace.auckland.ac.nz:2292/2720
2008-08-29T04:57:18Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Kenmochi, Yukiko
author
Klette, Reinhard
author
2000
Regularly gridded data in Euclidean 3-space are assumed to be digitizations of regular solids with respect to a chosen grid resolution. Gauss and Jordan introduced different digitization schemes, and the Gauss center point scheme is used in this paper. The surface area of regular solids can be expressed finitely in terms of standard functions for specific sets only, but it is well defined by triangulations for any regular solid. We consider surface approximations of regularly gridded data characterized to be polyhedrizations of boundaries of these data. The surface area of such a polyhedron is well defined, and it is parameterized by the chosen grid resolution. A surface area measurement technique is multigrid convergent for a class of regular solids iff it holds that for any set in this class the surface areas of approximating polyhedra of the digitized regular solid converge towards the surface area of the regular solid if the grid resolution goes to infinity. Multigrid convergent volume measurements have been studied in mathematics for more than one hundred years, and surface area measurements had been discussed for smooth surfaces. The problem of multigrid convergent surface area measurement came with the advent of computer-based image analysis. The paper proposes a classification scheme of local and global polyhedrization approaches which allows us to classify different surface area measurement techniques with respect to the underlying polyhedrization scheme. It is shown that a local polyhedrization technique such as marching cubes is not multigrid convergent towards the true value even for elementary convex regular solids such as cubes, spheres or cylinders. The paper summarizes work on global polyhedrization techniques with experimental results pointing towards correct multigrid convergence. The class of general ellipsoids is suggested to be a test set for such multigrid convergence studies.
Communication and Information Technology Research Technical Report 62, (2000)
1178-3683
http://hdl.handle.net/2292/2720
Surface Area Estimation for Digitized Regular Solids
oai:researchspace.auckland.ac.nz:2292/2722
2008-08-29T04:58:02Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
Zunic, Jovisa
author
2000
Digital moments approximate real moments where the accuracy depends upon grid resolution. There are theoretical results about the speed of convergence. However, there is a lack of more detailed studies with respect to selected shapes of regions, or with respect to experimental data about convergence. This paper discusses moments for specific shapes of regions, and provides some initial experimental data about measured convergence of digital moments.
Communication and Information Technology Research Technical Report 61, (2000)
1178-3684
http://hdl.handle.net/2292/2722
Towards Experimental Studies of Digital Moment Convergence
oai:researchspace.auckland.ac.nz:2292/2723
2008-08-29T04:58:04Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
2000
The history of cell complexes is closely related to the birth and development of topology in general. Johann Benedict Listing (1802-1882) introduced the term "topology" into mathematics in a paper published in 1847, and he also defined cell complexes for the first time in a paper published in 1862. Carl Friedrich Gauss (1777-1855) is often cited as the one who initiated these ideas, but he did not publish either on topology or on cell complexes. The pioneering work of Leonhard Euler (1707-1783) on graphs is also often cited as the birth of topology, and Euler's work was cited by Listing in 1862 as a stimulus for his research on cell complexes. There are different branches in topology which have little in common: point set topology, algebraic topology, differential topology etc. Confusion may arise if just "topology" is specied, without clarifying the used concept. Topological subjects in mathematics are often related to continuous models, and therefore quite irrelevant to computer based solutions in image analysis. Compared to this, only a minority of topology publications in mathematics addresses discrete spaces which are appropriate for computer-based image analysis. In these cases, often the notion of a cell complex plays a crucial role. This paper briefly reports on a few of these publications, which might be helpful or at least of interest for recent studies in topological issues in image analysis. It is not a balanced review, due to a certain randomness in the selection process of cited work. This paper is also not intended to cover the very lively progress in cell complex studies within the context of image analysis during the last two decades. Basically it stops its historic review at the time when this subject in image analysis research gained speed in 1980-1990. As a general point of view, the paper indicates that image analysis contributes to a fusion of two topological concepts, the geometric or abstract cell complex approach and point set topology, which leads to an in-depth study of topologies defined on geometric or abstract cell complexes.
Communication and Information Technology Research Technical Report 60, (2000)
1178-3685
http://hdl.handle.net/2292/2723
Cell Complexes through Time
oai:researchspace.auckland.ac.nz:2292/2724
2008-08-29T04:58:05Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Wei, Shou-Kang
author
Huang, Yu-Fei
author
2000
This paper discusses the techniques of image acquisition for 3D scene visualization and reconstruction applications (3DSVR). The existing image acquisition approaches in 3DSVR applications are briefly reviewed. There are still lacks of the studies about what principles are essential in the design and how we can characterize the limitations of an image acquisition model in a formal way. This paper addresses some of the main characteristics of existing image acquisition approaches, summarized through a classification scheme and illustrated with many examples. The results of the classification lead to general characterizations in establishing the notions (basic components) for design, analysis and assessment of image acquisition models. The notions introduced include: focal set, receptor set, reflector set etc. The definitions of the notions are given and supported with various examples (e.g. concentric panoramas, cataoptrical panoramas). The observations, important issues, and future directions from this study are also provided.
Communication and Information Technology Research Technical Report 59, (2000)
1178-3686
http://hdl.handle.net/2292/2724
Classification and Characerization of Image Acquisition for 3D Scene Visualization and Reconstruction Applications
oai:researchspace.auckland.ac.nz:2292/2725
2008-08-29T04:58:06Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Bräunl, Thomas
author
2000
Eyesim is a 2D simulator for the EyeBot mobile robot systems. The simulator is implemented as a library, which is linked to the robot application program. It allows the concurrent simulation of multiple robots in the same environment. The simulator integrates the robot console with buttons and LCD; it implements a "v-omega" (linear and angular velocity) driving interface and models a variety of sensors: shaft encoders, bumpers, infra-red proximity sensors, infra-red position sensors, and interfaces to a live color camera. The simulation can be executed in a "perfect" environment or with certain error ranges for individual sensors.
Communication and Information Technology Research Technical Report 58, (2000)
1178-3687
http://hdl.handle.net/2292/2725
The Eyesim Mobile Robot Simulator
oai:researchspace.auckland.ac.nz:2292/2726
2008-08-29T04:58:09Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Kenmochi, Yukiko
author
Imiya, Atsushi
author
2000
The simplest free boundary in a 3-dimensional space is a moving plane. For the numerical analyses of such simple free boundary problems, it is necessary to express moving planes in a grid space. A simple example of 3-dimensional grid spaces is a set of 3-dimensional lattice points whose coordinates are all integers. In this paper, therefore, we study geometric and topological properties of planes in such a 3-dimensional integer lattice space.
Communication and Information Technology Research Technical Report 57, (2000)
1178-3688
http://hdl.handle.net/2292/2726
On Combinatorial Properties Of Discrete Planar Surfaces
oai:researchspace.auckland.ac.nz:2292/2727
2008-08-29T04:58:12Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Bülow, Thomas
author
Klette, Reinhard
author
1999
We consider simple digital curves in a 3D orthogonal grid as special polyhedrally bounded sets. These digital curves model digitized curves or arcs in three-dimensional euclidian space. The length of such a simple digital curve is defined to be the length of the minimum-length polygonal curve fully contained and complete in the tube of this digital curve. So far no algorithm was known for the calculation of such a shortest polygonal curve. This paper provides an iterative algorithmic solution, including a presentation of its foundations and of experimental results.
Communication and Information Technology Research Technical Report 55, (1999)
1178-3690
http://hdl.handle.net/2292/2727
Digital Curves in 3D Sapce and a Linear-Time Length Estimation Algorithm
oai:researchspace.auckland.ac.nz:2292/2728
2008-08-29T04:58:14Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
Yip, Ben
author
1999
The paper discusses one of the elementary subjects in image analysis: how to measure the length of a digital curve? A digital curve in the plane is defined to be a cycle given either as an alternating sequence of vertices and edges, or an alternating sequence of edges and squares. The paper reports about two length estimators, ones based on the partition of a frontier of a simply-connected isothetic polygon into digital straight segments, and one based on calculating the minimum-length polygon within an open boundary of a simply-connected isothetic polygon. Both techniques are known to be implementations of convergent estimators of the perimeter of bounded, polygonal or smooth convex sets in the euclidean plane. For each technique a linear-time algorithm is specified, and both algorithms are compared with respect to convergence speed and number of generated segments. The experiments show convergent behavior also for perimeters of non-convex bounded subsets of the euclidean plane.
Communication and Information Technology Research Technical Report 54, (1999)
1178-3691
http://hdl.handle.net/2292/2728
The Length of Digital Curves
oai:researchspace.auckland.ac.nz:2292/2729
2008-08-29T04:58:35Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
Yip, Ben
author
1999
This paper compares two techniques for measuring the length of a digital curve. Both techniques (digital straight segment approximation, minimum length polygon) are known to be convergent estimators. Theoretical convergence result are cited. The main focus is on experimental evaluation: several measures are defined, applied and discussed. Test sets are digitized for consecutive resolutions.
Communication and Information Technology Research Technical Report 53, (1999)
1178-3692
http://hdl.handle.net/2292/2729
Evaluation of Curve Length Measurements
oai:researchspace.auckland.ac.nz:2292/2730
2008-08-29T04:58:39Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
Zunic, Jovisa
author
1999
This paper informs about estimates of worst-case bounds for quantization errors in calculating features such as moments, moment based features, or perimeters in image analysis, and about probability-theoretical estimates of error bounds (eg. standard derivations) for such digital approximations. New estimates (with proofs) and a review of previously known results are provided.
Communication and Information Technology Research Technical Report 52, (1999)
1178-3693
http://hdl.handle.net/2292/2730
Convergence of Calculated Features in Image Analysis
oai:researchspace.auckland.ac.nz:2292/2731
2008-08-29T04:58:47Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Baltes, Jacky
author
Lin, Yuming
author
1999
The problem investigated in this paper is that of driving a car-like robot along a race track and the use of reinforcement learning to find a good control function. The reinforcement learner uses a case-based function approximator to extend the reinfocement learning paradigm to handle continuous states. The learned controller performs similar to the best control functions in both simulation and also in practical driving.
Communication and Information Technology Research Technical Report 47, (1999)
1178-3698
http://hdl.handle.net/2292/2731
Path-Tracking Control of a Non-Holonomic Car-Like Robot with Reinforcement Learning
oai:researchspace.auckland.ac.nz:2292/2733
2008-08-29T04:58:53Z
com_2292_122
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Noakes, Lyle
author
Kozera, Ryszard
author
1999
In this paper we analyze a specic problem within the context of recovering the geometric shape of an unknown surface from multiple noisy shading patterns generated by consecutive parallel illuminations by different light-sources. Shading-based single-view shape recovery in computer vision often leads to vector fields (i.e. estimated surface normals) which have to be integrated for calculations of height or depth maps. We present an algorithm for enforcing the integrability condition of a given non-integrable vector field which ensures a global suboptimal solution by local optimizations. The scheme in question relies neither on a priori knowledge of boundary conditions nor on other global constraints imposed on the so-far derived noise contaminated gradient integration techniques. The discussion is supplemented by examples illustrating algorithm performance.
Communication and Information Technology Research Technical Report 46, (1999)
1178-3699
http://hdl.handle.net/2292/2733
The Lawn-Mowing Algorithm for Noisy Gradient Vector Fields
oai:researchspace.auckland.ac.nz:2292/2734
2008-08-29T04:58:56Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Klette, Reinhard
author
Kovalevsky, Vladimir
author
1999
The paper details two linear-time algorithms, one for the partition of the boundary line of a digital region into digital straight segments, and one for calculating the minimum length polygon within a simple open boundary of a digital region. Both techniques allow the estimation of the length of digital curves or the perimeter of digital regions due to known multigrid convergence theorems. The algorithms are compared with respect to convergence speed and number of generated segments.
Communication and Information Technology Research Technical Report 45, (1999)
1178-3700
http://hdl.handle.net/2292/2734
On the Length Estimation of Digital Curves
oai:researchspace.auckland.ac.nz:2292/2735
2008-08-29T04:58:58Z
com_2292_122
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00925njm 22002777a 4500
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Klette, Reinhard
author
Zunic, Jovisa
author
1999
Moments have been widely used in shape recognition and identification. In general, the (k,l)-moment, denoted by mk,l(S), of a planar measurable set S is defined by mk,l(S) = sxkyl dx dy We assume situations in image analysis and pattern recognition where real objects are acquired (by thresholding, segmentation etc.) as binary images D(S), i.e. as digital sets or digital regions. For a set S, in this paper its digitization is defined to be the set of all grid points with integer coordinates which belong to the region occupied by the given set S. Since in image processing applications, the exact values of the moments mk,l(S) remain unknown, they are usually approximated by discrete moments µk,l(S) where µk,l(S) = S(i,j)D(S)ik.jl = Si,jareintegers(i,j)S ik.jl. Moments of order up to two (i.e. k + l 2) are frequently used and our attention is focused on them, i.e. on the limitation in their estimation from the corresponding digital picture. In this paper it is proved that mk,l(S)-1/rk+l+2.µµ,l(r.S)=O(1/r15/11+e) O (1/r1.363636...) for k + l = 2, where S is a convex set in the plane with a boundary having continuous third derivative and positive curvature at every point, r is the number of pixels per unit (i.e. 1/r is the size of the pixel), while r S denotes the dilation of S by factor r.
Communication and Information Technology Research Technical Report 44, (1999)
1178-3701
http://hdl.handle.net/2292/2735
On Errors in Calculated Moments of Convex Sets Using Digital Images
oai:researchspace.auckland.ac.nz:2292/2736
2008-08-29T04:59:22Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Wei, Shou-Kang
author
1999
We develop a view synthesis system, which is capable to collect/reconstruct 3-D information of scenes from multiple calibrated/uncalibrated images; to store and access the 3-D information in an efficient way; and to synthesize, in real time, arbitrary views of the scene with a pre-specified viewing area.
Communication and Information Technology Research Technical Report 42, (1999)
1178-3703
http://hdl.handle.net/2292/2736
Three-dimensional View Synthesis From Multiple Images
oai:researchspace.auckland.ac.nz:2292/2737
2008-08-29T04:59:23Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
Zunic, Jovisa
author
1999
Representations of real regions by corresponding digital pictures cause an inherent loss of information. there are infinitely many different real regions with and identical corresponding digital picture. So, there are limitations in the reconstruction of the originals and their properties from digital pictures. The problem which will be studied here is what is the impact of a digitization process on the efficiency in the reconstruction of the basic geometric properties
Communication and Information Technology Research Technical Report 40, (1999)
1178-3705
http://hdl.handle.net/2292/2737
On Digitization Effects on Reconstruction of Geometric Properties of regions
oai:researchspace.auckland.ac.nz:2292/2738
2008-08-29T04:59:25Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Zhou, Shao-zheng
author
Klette, Reinhard
author
1998
Multiresolution surfaces are especially useful for fast rendering, real-time display and interactive manipulation of large and dense terrain surface models. This paper reviews major multiresolution terrain surface reconstruction techniques and analyses the corresponding data structures. We have proposed and implemented, based on Delaunay retriangulation, a greedy refinement algorithm with a straightforward data structure to reconstruct multiresolution terrain surfaces. Our greedy refinement algorithm is a multi-pass algorithm, having the complexity of O(n 2 ) if using global error metric and O(n log n) if using local error metric.
Communication and Information Technology Research Technical Report 39, (1998)
1178-3706
http://hdl.handle.net/2292/2738
Reconstruction of Multiresolution Terrain Surfaces
oai:researchspace.auckland.ac.nz:2292/2739
2008-08-29T04:59:26Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
Zunic, Jovisa
author
1998
Representations of real objects by corresponding digital pictures cause an inherent loss of information. There are infinitely many different real shapes with an identical corresponding digital picture. The problem we are interested in is how effciently the gravity center (or centroid) of a planar convex region whose boundary has a continuos third derivative and positive curvature (at every point) can be reconstructed from its digital picture. We derive an absolute upper error bound if such a smooth planar convex region is represented in a binary picture with resolution r, where r is the number of pixels per unit. This result can be extended to regions which may be obtained from smooth planar convex regions by finite applications of unions, intersections or set differences. The upper error bound remains the same which converges to zero with increase in grid resolution.
Communication and Information Technology Research Technical Report 38, (1998)
1178-3707
http://hdl.handle.net/2292/2739
Gravity Centers of Smooth Planar Convex Regions from Digital Pictures
oai:researchspace.auckland.ac.nz:2292/2740
2008-08-29T04:59:27Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Yang, Nan
author
Klette, Reinhard
author
1998
The length of curves may be measured by numeric integration if the curves are given by analytic formulas. Not all curves can or should be described parametrically. In this report we use the alternative grid topology approach. The shortest polygonal Jordan curve in a simple closed one-dimensional grid continuum is used to estimate a curve's length. An O(n) algorithm for finding the shortest polygonal Jordan curve is introduced, and its correctness and complexity is discussed.
Communication and Information Technology Research Technical Report 35, (1998)
1178-3710
http://hdl.handle.net/2292/2740
Linear Time Calculation of 2D Shortest Polygonal Jordan Curves
oai:researchspace.auckland.ac.nz:2292/2741
2008-08-29T04:59:28Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Ng, Angela
author
Schlüns, Karsten
author
1998
In this highly technological world, various methods have been developed for the purpose of recovering the shape of 3D objects from 2D images. In this paper, we introduce methods to combine a collection of range images, which is created by Photometric Stereo, into a single polygonal mesh completely describes an object. Experiments and analysis will be carried out to test the accuracy of our model reconstruction. Finally, results will be displayed.
Communication and Information Technology Research Technical Report 34, (1998)
1178-3711
http://hdl.handle.net/2292/2741
Towards 3D Model Reconstruction from Photometric Stereo
oai:researchspace.auckland.ac.nz:2292/2742
2008-08-29T04:59:30Z
com_2292_122
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00925njm 22002777a 4500
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Luo, Jin
author
Schlüns, Karsten
author
1998
This paper presents a new approach to integrate the gradient field to the relative depth or height map from multiple view directions in polar coordinates. Traditional integration techniques are based on cartesian coordinates. In this approach, the surface normals are calculated by photometric stereo method. The object is illuminated by three light sources and rotated on a controlled turntable. The experimantal results of the cross section of the synthetic and real objects are feasible and promising.
Communication and Information Technology Research Technical Report 33, (1998)
1178-3712
http://hdl.handle.net/2292/2742
Height from Gradients in Polar Coordinates
oai:researchspace.auckland.ac.nz:2292/2743
2008-08-29T04:59:31Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Shin, Bok-Suk
author
Cha, Eui-Young
author
Klette, Reinhard
author
2007
In a process of insect footprint recognition, footprint segments need to be extracted from scanned insect footprints in order to find out appropriate features for classification. In this paper, we use a clustering method in a preprocessing stage for extraction of insect footprint segments. In general, sizes and strides of footprints may be different according to type and size of an insect for recognition. Therefore we propose a method for insect footprint segment extraction using an improved ART2 algorithm regardless of size and stride of footprint pattern. In the improved ART2 algorithm, an initial threshold value for clustering is determined automatically using the contour shape of the graph created by accumulating distances between all the spots within a binarized footprint pattern image. In the experimental results, applying the proposed method to two kinds of insect footprint patterns, we illustrate that clustering is accomplished correctly.
Communication and Information Technology Research Technical Report 205, (2007)
1178-3540
http://hdl.handle.net/2292/2743
Segmentation of Scanned Insect Footprints Using ART2 for Threshold Selection
oai:researchspace.auckland.ac.nz:2292/2744
2008-08-29T04:59:32Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Fong, Fu
author
Klette, Reinhard
author
Hon, Man
author
1998
Chondrons form the fundamental biomechanical and metabolic unit of articular cartilage. But there is no accurate description of chondron volume which is known to change when articular cartilage is functionally loaded. This report discusses the 3D feature analysis of the confocal microscopy images of chondrons. The basic principle of confocal microscopy is described. The segmentation problem of confocal images is also discussed. Two different reconstruction algorithms, Marching Cubes and Dividing Cubes are also illustrated and their respectively ways of calculating volume and surface area are also discussed. The results of calculating 3D features of sperical polysterene beads using Marching Cubes algorithms are also given
Communication and Information Technology Research Technical Report 31, (1998)
1178-3714
http://hdl.handle.net/2292/2744
Surface Visualisation and 3D Feature Analysis in Confocal Microscopy Images
oai:researchspace.auckland.ac.nz:2292/2745
2008-08-29T04:59:44Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Chen, Chia-Yen
author
1998
In this work, we are mainly dealing with the stitching of panoramic images. However, the methods described and evaluated here can also be used for different applications in image mosaicing.
Communication and Information Technology Research Technical Report 30, (1998)
1178-3715
http://hdl.handle.net/2292/2745
Image Stitching - Comparisons and New Techniques
oai:researchspace.auckland.ac.nz:2292/2746
2008-08-29T04:59:46Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Haralick, Robert
author
1998
This paper describes how to propagate approximately additive random perturbations through any kind of vision algorithm step in which the appropriate random perturbation model for the estimated quantity produced by the vision step is also an additive random perturbation. We assume that the vision algorithm step can be modeled as a calculation (linear or non-linear) that produces an estimate that minimizes an implicit scaler function of the input quantity and the calculated estimate. The only assumption is that the scaler function be non-negative, have finite first and second partial derivatives, that its value is zero for ideal data, and that the random perturbations are small enough so that the relationship between the scaler function evaluated at the ideal but unknown input and output quantities and evaluated at the observed input quantity and perturbed output quantity can be approximated sufficiently well by a first order Taylor series expansion. The paper finally discusses the issues of verifying that the derived statistical behavior agrees with the experimentally observed statistical behavior.
Communication and Information Technology Research Technical Report 29, (1998)
1178-3716
http://hdl.handle.net/2292/2746
Propagating Covariance in Computer Vision
oai:researchspace.auckland.ac.nz:2292/2747
2008-08-29T04:59:51Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Huang, Yu-Fei
author
Wei, Shou-Kang
author
1998
Traditionally, to produce binocular stereo images, each single object view requires two shots with a proper camera displacement to generate a stereo pair. The total number of images required is twice as much as for monocular views. Special rigs, such as a slider, are also required for camera displacement if a normal single-eye camera is used. So, it is of advantage if the stereo views can be generated from multiple monocular images automatically. In this report, we present an image-based approach generating the stereo images automatically for multiple monocular object views. This approach does not include or require 3-D object reconstruction. The image reprojection technique is adopted and ensures the resulting images are physically valid. For fully calibrated images, the stereo pair can be generated directly using the image reprojection while for the uncalibrated case a preprocess is required to obtain the relative camera projection matrices. The concept of epipolar geometry and its role played in the perspective camera projection matrix recovery processes are then discussed in depth. If the viewing angle between two camera positions associated with two object reference images is sufficiently large, the closer in-between views are synthesized based on 3-D morphing.
Communication and Information Technology Research Technical Report 28, (1998)
1178-3717
http://hdl.handle.net/2292/2747
Automatic Generation of Stereo Images from Multiple Monocular Object Views
oai:researchspace.auckland.ac.nz:2292/2748
2008-08-29T05:00:04Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Kozera, Ryszard
author
Klette, Reinhard
author
1998
Differential equations (ODEs or PDEs) appear in many computer vision fields. Shape-from-shading, optical flow, optics, and 3D motion are examples of such fields. This report discusses theoretical criteria for the corresponding continuous problem, theoretical criteria for discrete numerical schemes, and experimental measurements for the implemented numerical schemes. These criteria are illustrated by discussing a shape-from-shading problem in which the reflectance map is linear.
Communication and Information Technology Research Technical Report 27, (1998)
1178-3718
http://hdl.handle.net/2292/2748
Criteria for Differential Equations in Computer Vision
oai:researchspace.auckland.ac.nz:2292/2749
2008-08-29T05:00:06Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
Yang, Nan
author
1998
Arc length's may be measured by numeric integration if the curves are given by analytic formulas. This report deals with an alternative way. A shortest polygonal Jordan curve may be used to estimate arc length's. This theoretically known result is illustrated in this report. Measured convergence of error values is discussed for a few examples of curves. A new error measure (approximation effectiveness) is proposed and discussed.
Communication and Information Technology Research Technical Report 26, (1998)
1178-3719
http://hdl.handle.net/2292/2749
Measurements of Arc Length's by Shortest Polygonal Jordan Curves
oai:researchspace.auckland.ac.nz:2292/2750
2008-08-29T05:00:07Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
Wu, Feng
author
1998
This report deals with multigrid approximations of surfaces. Surface area and volume approximations are discussed for regular grids (3D objects), and surface reconstruction for irregular grids (terrain surfaces). Convergence analysis and approximation error calculations are emphasized.
Communication and Information Technology Research Technical Report 25, (1998)
1178-3720
http://hdl.handle.net/2292/2750
Multigrid Convergence of Surface Approximations
oai:researchspace.auckland.ac.nz:2292/2751
2008-08-29T05:00:11Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Baltes, Jacky
author
Ewing, Bryce
author
1998
The problem of finding information on the Internet or on intranets is becoming increasingly more difficult, because of its explosive growth and lack of structure. This paper describes IWWWQ, a system that improves the ranking of a search engine's results by incorporating other features of a page, including the page type, content of a page, page formatting, and the relationship between pages. An empirical evaluation shows that incorporating these features improves the ranking of the results returned by a popular search engine. Furthermore, the evaluation showed that a combination of features is necessary to obtain this improvement. Finally, it shows that the algorithms used are relative insensitive to specic parameter settings.
Communication and Information Technology Research Technical Report 24, (1998)
1178-3721
http://hdl.handle.net/2292/2751
Intelligent Interpretation of World Wide Web Queries
oai:researchspace.auckland.ac.nz:2292/2752
2008-08-29T05:00:14Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Sloboda, Fridrich
author
Zat'ko, Bedrich
author
1998
One-dimensional and two-dimensional continua belong to the basic notions of set-theoretical topology and represent a subfield of the theory of dimensions developed by P. Urysohn and K. Menger. In this paper basic definitions and properties of grid continua in R2 and R3 are summarised. Particularly, simple one-dimensional grid continua in R2 and in R3, and simple closed two-dimensional grid continua in R3 are emphasised. Concepts for measuring the length of one-dimensional grid continua, or the surface area of two-dimensional grid continua are introduced and discussed.
Communication and Information Technology Research Technical Report 22, (1998)
1178-3723
http://hdl.handle.net/2292/2752
On the Topology of Grid Continua
oai:researchspace.auckland.ac.nz:2292/2753
2008-08-29T05:00:20Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
Kozera, Ryszard
author
1998
This TR is a review of shading based shape recovery (i.e. shape from shading, and photometric stereo methods). It reports about advances in applied work and about results in theoretical fundamentals.
Communication and Information Technology Research Technical Report 20, (1998)
1178-3725
http://hdl.handle.net/2292/2753
Shape from Shading and Photometric Stereo Methods
oai:researchspace.auckland.ac.nz:2292/2754
2008-08-29T05:00:21Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Li, Fajie
author
Klette, Reinhard
author
2007
Let p and q be two points on the surface of a polytope P . This report provides a rubberband algorithm for computing a Euclidean shortest path between p and q (surface ESP) that is contained on the surface of P . The algorithm has k1(e) · k2(e) · O(n^2) time complexity, where n is the number of vertices of P , ki(e) = (L0i - Li )/e, for the true length Li of some shortest path with initial (polygonal path) length L0i (used when approximating this shortest path), for i = 1, 2. Rubberband algorithms follow a straightforward design strategy, and the proposed algorithm is easy to implement and thus of importance for applications, e.g. when analyzing 3D ob jects in 3D image analysis (such as in biomedical or industrial image analysis, using 3D image scanners).
Communication and Information Technology Research Technical Report 204, (2007)
1178-3541
http://hdl.handle.net/2292/2754
Approximate ESPs on Surfaces of Polytopes Using a Rubberband Algorithm
oai:researchspace.auckland.ac.nz:2292/2755
2008-08-29T05:00:23Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Wei, Shou-Kang
author
Huang, Yu-Fei
author
1998
Traditional panorama visualization techniques give only the single eye's depth cues to the audience for the 3D world navigation. We introduce a new panorama visualization approach so that the depth cues for both eyes are provided in the panoramic image. The full color anaglyphs stereoscopic technique is adopted to produce and visualize the stereo panorama, which exploits human visual capability so the binocular depth and synthesized colors can be perceived and understood. Because both panoramic and anaglyphic image acquisition setups are incompatible intrinsically, we measure the errors of anaglyphic panorama image and deliver an error controlling formula that allows a better camera position to be determined at setup time. A real-time interactive player is developed for navigation in the stereo panoramic virtual world. In addition to the standard functions provided in the player, three new features are equipped to the player (i.e. a new driving method, manipulable objects embedded in the stereo panorama and a directional indicator).
Communication and Information Technology Research Technical Report 19, (1998)
1178-3726
http://hdl.handle.net/2292/2755
Color Anaglyphs for Panorama Visualizations
oai:researchspace.auckland.ac.nz:2292/2756
2008-08-29T05:00:24Z
com_2292_122
col_2292_3452
col_2292_2623
00925njm 22002777a 4500
dc
Stegner, Axel
author
Klette, Reinhard
author
1997
This paper describes on-going research about the development of an evaluation scheme which allows an objective comparison of different motion detection algorithms used while compressing image sequences: "real world" sequences as well as generated sequences containing special textures or objects. Its focus is on block motion detection algorithms used by MPEG video encoding and the goal is to develop an objective motion compensation quality.
Communication and Information Technology Research Technical Report 17, (1997)
1178-3728
http://hdl.handle.net/2292/2756
Evaluation of MPEG Motion Compensation Algorithms
oai:researchspace.auckland.ac.nz:2292/2757
2008-08-29T05:00:25Z
com_2292_122
col_2292_3452
col_2292_2623
00925njm 22002777a 4500
dc
Schlüns, Karsten
author
1997
Shadows usually cause various problems in three-dimensional shape recovery and measurement methods. In particular shading based approaches such as shape-from-shading or the photometric stereo method produce no or wrong results if the shadows are not treated appropriately. We show how information extracted from shadows can be employed to reduce the problems caused by them. This is done for multiple light-source photometric stereo. Unlike other published work, we formulate sufficient conditions to recover locally unique surface normals from two image irradiances (intensities) and a zero-irradiance caused by a shadow. We also distinguish between self-shadows and cast-shadows. Moreover we show how much information is obtainable by using the shadow analysis.
Communication and Information Technology Research Technical Report 14, (1997)
1178-3731
http://hdl.handle.net/2292/2757
Shading Based 3D Shape Recovery in the Presence of Shadows
oai:researchspace.auckland.ac.nz:2292/2758
2008-08-29T05:00:34Z
com_2292_122
col_2292_3452
col_2292_2623
00925njm 22002777a 4500
dc
Schlüns, Karsten
author
1997
This paper discusses some essential aspects on evaluating the three-source photometric stereo method (PSM). PSM is a shading based 3D shape recovery approach that calculates a dense set of surface orientations from three input images taken by changing the illumination direction without moving the optical sensor. A subsequent step can be used to convert the surface gradients into a dense height map by means of an integration method. In a previous paper [2] we carried out evaluations of integration approaches. Here we show how the resolution of surface orientations depends on perturbations in the image irradiances (intensities). Previous methods considered only single light source configurations or particular image irradiance triples, hence no general predictions could be made. We give a simple geometrical interpretation to estimate upper bounds of angular deviations with respect to expected errors in image irradiances. Such predictions are necessary for the practical application of the photometric stereo method.
Communication and Information Technology Research Technical Report 13, (1997)
1178-3732
http://hdl.handle.net/2292/2758
The Irradiance Error and its Effect in Photometric Stereo
oai:researchspace.auckland.ac.nz:2292/2759
2008-08-29T05:00:34Z
com_2292_122
col_2292_3452
col_2292_2623
00925njm 22002777a 4500
dc
Chen, Chia-Yen
author
Klette, Reinhard
author
1997
This paper describes the design and implementation of an image stitcher which can be used to join colour images. The images are joined in two steps. The first step involves registering two adjacent images using a minimum absolute difference method. The second step adjusts the contrast of the joined images using a linear interpolation of the intensity difference between the two images. The images joined by the stitcher can be used in many applications, such as panoramic viewing, architectural walk through and other teaching or researching purposes.
Communication and Information Technology Research Technical Report 12, (1997)
1178-3733
http://hdl.handle.net/2292/2759
An Image Stitcher and Its Application in Panoramic Movie Making
oai:researchspace.auckland.ac.nz:2292/2760
2008-08-29T05:00:35Z
com_2292_122
col_2292_3452
col_2292_2623
00925njm 22002777a 4500
dc
Yip, Ben
author
Klette, Reinhard
author
1997
This paper reports about two new approaches to visualise the three-dimensional object that is depicted by a MR (Magnetic Resonance) imaging series. The exterior of the object is visualised with a surface rotation approach, which is based on the concept of digital visibility. The interior of the object is visualised with a cut and view approach, which is based on a special solution for resampling. After image data pre-processing, the surface rotation approach allows the user to rotate and visualise the object in any angle of view; while the cut and view approach let the user see the interior of the object by creating a planar cut onto the three dimensional object and then visualise the cross-section. These two approaches complement each other. Together, they provide a simple, fast processing method for the medical experts to visualise the MR imaging series. The time complexity and the quality of the outcome are satisfactory even it is processed with Intel 486 processor.
Communication and Information Technology Research Technical Report 11, (1997)
1178-3734
http://hdl.handle.net/2292/2760
Digital Visibility and Visualisation of Magnetic Resonance Imaging Series
oai:researchspace.auckland.ac.nz:2292/2761
2008-08-29T05:00:36Z
com_2292_122
col_2292_3452
col_2292_2623
00925njm 22002777a 4500
dc
Zhou, Shao-zheng
author
Klette, Reinhard
author
1997
Multiresolution surfaces are especially useful for fast rendering, real-time display, and progressive transmission. This paper reviews major surface simplification techniques and multiresolution surface reconstruction approaches. Based on comparison among various approximation algorithms we propose an appropriate measure for surface approximation accuracy and essential concepts for multiresolution surface reconstruction. Having analyzed the surface simplification process, we propose our solution for multiresolution surface reconstruction - combination of the edge collapsing operation and simplification envelopes, which can generate continuous multiresolution surfaces with globally-guaranteed approximation errors.
Communication and Information Technology Research Technical Report 10, (1997)
1178-3735
http://hdl.handle.net/2292/2761
Multiresolution Surface Reconstruction: Edge Collapsing + Simplification Envelopes
oai:researchspace.auckland.ac.nz:2292/2762
2008-08-29T05:00:38Z
com_2292_122
col_2292_3452
col_2292_2623
00925njm 22002777a 4500
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Klette, Reinhard
author
1997
Advanced information technology deals with the computer technology appropriate to the capture, encoding, storage, communication, manipulation, and use of information in digital form. A special topic in this field is information capture; in particular, the capture of visual information. The acquisition of surface data for three-dimensional objects is a major problem in this field, approached by utilizing computer vision techniques. Surface data acquisition and related 3D object analysis is of importance in medicine and biology, in CAD modeling of industrial sites, for topographic models of the earth surface, for documenting museum objects, in architecture, in the movie industry, and in many other applications. This paper illustrates a few recently achieved practical results in computer vision (some obtained at CITR Tamaki) and briefly discusses directions in research.
Communication and Information Technology Research Technical Report 9 , (1997)
1178-3736
http://hdl.handle.net/2292/2762
Image Analysis and Object Surfaces
oai:researchspace.auckland.ac.nz:2292/2763
2008-08-29T05:00:42Z
com_2292_122
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00925njm 22002777a 4500
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Klette, Reinhard
author
1997
The report reviews selected results in the field of geometrical measurements and reconstructions of 3D objects (i.e. simply-connected compact sets of points) based on gridding techniques. Two soundness properties of approaches are discussed with respect to the selected grid resolution: convergence and convergence towards the "true" value. The existence of sound multigrid approaches is discussed for problems as (1) volume and surface area measurement for Jordan sets (i.e. 3D objects bounded by Jordan surfaces), (2) approximations of planes based on sampled data, (3) surface reconstructions based on gradient information, and (4) surface recovery by solving a (special) linear differential equation system. The paper concludes with a brief discussion of arising digital or computational geometry problems relevant to the discussed subjects.
Communication and Information Technology Research Technical Report 8 , (1997)
1178-3737
http://hdl.handle.net/2292/2763
Sound Analysis of 3D Objects Based on Digitized Data
oai:researchspace.auckland.ac.nz:2292/2764
2008-08-29T05:00:43Z
com_2292_122
col_2292_3452
col_2292_2623
00925njm 22002777a 4500
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Baltes, Jacky
author
1997
This paper describes multi-strategy planning and its implementation in the DOLITTLE system, which can combine many different planning strategies, including means-ends analysis, macro-based planning, abstraction-based planning (reduced and relaxed), and case-based planning on a single problem. Planning strategies are defined as methods to reduce the search space by exploiting some assumptions (so-called planning biases) about the problem domain. General operators are a generalization of standard STRIPS operators that conveniently represent many different planning strategies. The focus of this work is to develop a representation weak enough to represent a wide variety of different strategies, but still strong enough to emulate them. The search control method applies different general operators based on a strongest first principle; planning biases that are expected to lead to small search spaces are tried first. An empirical evaluation in three domains showed that multi-strategy planning performed significantly better than the best single strategy planners in some domains.
Communication and Information Technology Research Technical Report 7 , (1997)
1178-3738
http://hdl.handle.net/2292/2764
Planning strategy representation in DOLITTLE
oai:researchspace.auckland.ac.nz:2292/2765
2008-08-29T05:00:44Z
com_2292_122
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Wei, Tiangong
author
Klette, Reinhard
author
2007
Depth recovery from gradient vector fields is required when reconstructing a surface (in three-dimensional space) from its gradients. Such a reconstruction task results, for example, for techniques in computer vision aiming at calculating surface normals (such as shape from shading, photometric stereo, shape from texture, shape from contours and so on). Surprisingly, discrete integration has not been studied very intensively so far. This chapter presents three classes of methods for solving problems of depth recovery from gradient vector fields: a two-scan method, a Fourier-transform based method, and a wavelet-transform based method. These methods extend previously known techniques, and related proofs are given in a short but concise form. The two-scan method consists of two different scans through a given gradient vector field. The final surface height values can be determined by averaging these two scans. Fourier-transform based methods are noniterative so that boundary conditions are not needed, and their robustness to noisy gradient estimates can be improved by choosing associated weighting parameters. The wavelet-transform based method overcomes the disadvantage of the Fourier-transform based method, which implicitly require that a surface height function is periodic. Experimental results using synthetic and real images are also presented.
Communication and Information Technology Research Technical Report 203, (2007)
1178-3542
http://hdl.handle.net/2292/2765
On Depth Recovery from Gradient Vector Fields
oai:researchspace.auckland.ac.nz:2292/2766
2009-11-17T02:33:31Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Wiederhold, Petra
author
Wilson, Richard
author
1997
Alexandroff T0-spaces have been studied as topological models of the supports of digital images and as discrete models of continuous spaces in theoretical physics. In this paper we discuss three different dimension functions for this class of spaces, namely the Alexandroff dimension, the Order dimensionand the Krull dimension and we outline a proof of the equality of these dimension functions in this class. The first of these is essentially the small inductive dimension well-known in topology, the second has been studied in the theory of posets while the third has been studied extensively as a dimension function for lattices and rings and was first applied to topological spaces by Vinokurov in 1966. Since the category of Alexandroff T0-spaces is known to be isomorphic to the category of posets, these results could be formulated in this latter category as well.
Communication and Information Technology Research Technical Report 6 , (1997)
1178-3739
http://hdl.handle.net/2292/2766
Dimension functions for T0 digital spaces (CITR)
oai:researchspace.auckland.ac.nz:2292/2767
2008-08-29T05:00:58Z
com_2292_122
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00925njm 22002777a 4500
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Kozera, Ryszard
author
Klette, Reinhard
author
1997
We analyse different sequential algorithms for the recovery of object shape from a single shading pattern generated under the assumption of a linear reflectance map. The algorithms are based on the finite difference approximation of the derivatives. They operate on a rectangular discrete image (or part of it) and use the height of the sought-after surface along a curve in the image (image boundary) as initial data. The evaluation of different numerical schemes is achieved by comparing stability, convergence, and domains of influence of each scheme in question. The relative difficulty of handling a linear case indicates that the case of non-linear reflectance maps is far from being trivial.
Communication and Information Technology Research Technical Report 4 , (1997)
1178-3741
http://hdl.handle.net/2292/2767
Evaluation of Algorithms for Linear Shape from Shading
oai:researchspace.auckland.ac.nz:2292/2768
2008-08-29T05:00:59Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
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Li, Fajie
author
Klette, Reinhard
author
2007
Let p and q be two points in a simple polygon P. This chapter provides two rubberband algorithms for computing a shortest path between p and q that is contained in P. The two algorithms are based on previously known results on triangular or trapezoidal decompositions of simple polygons, and have either kappa(epsilon) times O(n) or kappa(epsilon) times O(n log n) time complexity, where kappa(epsilon) = (L0 - L)/epsilon, for the true length L of the shortest path and length L0 of a used initial polygonal path. Rubberband algorithms follow a straightforward design strategy, and the proposed algorithms ar easy to implement (after having the decompositions at hand).
Communication and Information Technology Research Technical Report 202, (2007)
1178-3543
http://hdl.handle.net/2292/2768
Euclidean Shortest Paths in Simple Polygons
oai:researchspace.auckland.ac.nz:2292/2769
2012-02-02T23:13:51Z
com_2292_122
col_2292_3205
00925njm 22002777a 4500
dc
Haeusler, Ralf
author
Klette, Reinhard
author
2008
This paper discusses ways of using a single panoramic image (captured by a rotating sensor-line camera having very-high spatial resolution) for the geometric shape recovery of a shown object. The objective is to create a sparse polyhedral model, only allowing a few interactive user inputs for a given single panoramic image. The study was motivated by the general question whether a single panoramic image projection allows some kind of 3D shape recovery, possibly bene tting from available monocular approaches for standard (say, pinhole-type) camera models.
Multimedia Imaging Report 15 (2008)
1178-5789
http://hdl.handle.net/2292/2769
Monocular 3D Reconstruction of Objects Based on Cylindrical Panoramas
oai:researchspace.auckland.ac.nz:2292/2770
2008-08-29T05:01:01Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Li, Fajie
author
Klette, Reinhard
author
2007
Given a sequence of k simple polygons in a plane, a start point p, and a target point q. We approximately compute a shortest path that starts at p, then visits each of the polygons in the specified order, and finally ends at q. So far no solution was known if the polygons are pairwise disjoint and non-convex. By applying a rubberband algorithm, we give an approximative algorithm with time complexity in kappa(epsilon) times O(n), where n is the total number of vertices of the given polygons, and function kappa(epsilon) is as follows: kappa(epsilon) = (L_0 - L)/epsilon, where L_0 is the length of the initial path, and L is the true (i.e., optimum) path length. The given rubberband algorithm can also be applied to solve approximately three NP-complete or NP-hard 3D Euclidean shortest path (ESP) problems in time kappa(epsilon) times O(k), where k is the number of layers in a stack which contains the defined obstacles.
Communication and Information Technology Research Technical Report 201, (2007)
1178-3544
http://hdl.handle.net/2292/2770
Touring Polygons, Parts Cutting, and q-Rectangles
oai:researchspace.auckland.ac.nz:2292/2771
2008-08-29T05:01:03Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Li, Fajie
author
Klette, Reinhard
author
2007
Chazelle's triangulation \cite{BC1991} forms today the common basis for linear-time Euclidean shortest path (ESP) calculations (where start and end point are given within a simple polygon). This paper provides an alternative method for subdividing a simple polygon into ``basic shapes'', using trapezoids instead of triangles. The authors consider the presented method as being substantially simpler than the linear-time triangulation method. However, it requires a sorting step (of a subset of vertices of the given simple polygon); all the other subprocesses are linear time.
Communication and Information Technology Research Technical Report 199, (2007)
1178-3546
http://hdl.handle.net/2292/2771
Decomposing a Simple Polygon into Trapezoids
oai:researchspace.auckland.ac.nz:2292/2772
2008-08-29T05:01:04Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Li, Fajie
author
Klette, Reinhard
author
2007
This paper reports about the development of two provably correct approximate algorithms which calculate the Euclidean shortest path (ESP) within a given cube-curve with arbitrary accuracy, defined by epsilon >0, and in time complexity kappa(epsilon) O(n), where kappa(epsilon) is the length difference between the path used for initialization and the minimum-length path, divided by epsilon. A run-time diagram also illustrates this linear-time behavior of the implemented ESP algorithm.
Communication and Information Technology Research Technical Report 198, (2007)
1178-3547
http://hdl.handle.net/2292/2772
Euclidean Shortest Paths in Simple Cube Curves at a Glance
oai:researchspace.auckland.ac.nz:2292/2773
2008-08-29T05:01:05Z
com_2292_122
col_2292_2623
00925njm 22002777a 4500
dc
Ohnishi, Naoya
author
Imiya, Atsushi
author
Klette, Reinhard
author
2007
This paper introduces a new algorithm for computing multi-resolution optical flow, and compares this new hierarchical method with the traditional combination of the Lucas-Kanade method with a pyramid transform. The paper shows that the new method promises convergent optical flow computation. Aiming at accurate and stable computation of optical flow, the new method propagates results of computations from low resolution images to those of higher resolution. The resolution of images increases this way for the sequence of images used in those calculations. The given input sequence of images defines the maximum of possible resolution.
Communication and Information Technology Research Technical Report 197, (2007)
1178-3548
http://hdl.handle.net/2292/2773
Zooming Optical Flow Computation
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