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Faculty of Informatics - Papers (Archive)

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Articles 1501 - 1530 of 2013

Full-Text Articles in Physical Sciences and Mathematics

An Activity Theory Framework For Computer Interface Design, E. Gould, I. Verenikina Jun 2003

An Activity Theory Framework For Computer Interface Design, E. Gould, I. Verenikina

Faculty of Informatics - Papers (Archive)

Computer interface design has the primary purpose of assisting information technology users in their professional activities. In order to accomplish this, users need to be able to work 'through the interface' to complete the tasks which achieve the goals associated with an activity. Although this is the conceptual province of psychology, very little use has been made of psychology in practical interface design. The attempts that have been made appear to have suffered from a lack of connection to real life problems which has been attributed to their foundations in the information processing structure of cognitive psychology. We elaborate an …

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Weighing Matrices And Self-Orthogonal Quaternary Codes, C. Charnes, Jennifer Seberry Jun 2003

Weighing Matrices And Self-Orthogonal Quaternary Codes, C. Charnes, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We consider families of linear self-orthogonal and self-dual codes over the ring Z4 which are generated by weighing matrices W (n, k) k ≡ 0 (mod 4), whose entries are interpreted as elements of the ring Z4. We obtain binary formally self-dual codes of minimal Hamming distance 4 by applying the Gray map to the quaternary codes generated by W (n, 4).

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On Full Orthogonal Designs In Order 72, S. Georgiou, C. Koukouvinos, Jennifer Seberry Jun 2003

On Full Orthogonal Designs In Order 72, S. Georgiou, C. Koukouvinos, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We find new full orthogonal designs in order 72 and show that of 2700 possible OD(72; s1, s2, s3, 72—s1—s2—s3) 335 are known, of 432 possible OD(72; s1, s2, 72—si—s2) 308 are known. All possible OD(72; s1, 72 — s1) are known.

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Further Observations On The Structure Of The Aes Algorithm, B. Song, Jennifer Seberry Jun 2003

Further Observations On The Structure Of The Aes Algorithm, B. Song, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

Abstract. We present our further observations on the structure of the AES algorithm relating to the cyclic properties of the functions used in this cipher. We note that the maximal period of the linear layer of the AES algorithm is short, as previously observed by S. Murphy and M.J.B. Robshaw. However, we also note that when the non-linear and the linear layer are combined, the maximal period is dramatically increased not to allow algebraic clues for its cryptanalysis. At the end of this paper we describe the impact of our observations on the security of the AES algorithm. We conclude …

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Regular Hadamard Matrices, Maximum Excess And Sbibd, Tianbing Xia, M. Xia, Jennifer Seberry Jun 2003

Regular Hadamard Matrices, Maximum Excess And Sbibd, Tianbing Xia, M. Xia, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

When k = q1, q2, q1q2, q1q4, q2q3N, q3q4N, q1, q2 and q3 are prime power, where q1 ≡ 1 (mod 4), q2 ≡ 3 (mod 8), q3 ≡ 5 (mod 8), q4 = 7 or 23, N = 2a3bt2, a, b = 0 or 1, t ≠ 0 is an arbitrary integer, we prove that there exist regular Hadamard matrices of order 4k2, and also there exist SBIBD(4k2, 2k2 + k, k2 + k). We find new SBIBD(4k2, 2k2 + k, k2 + k) for 233 values of k.

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Orthogonal Designs Of Kharaghani Type: I, C. Koukouvinos, Jennifer Seberry Jun 2003

Orthogonal Designs Of Kharaghani Type: I, C. Koukouvinos, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We use an array given in H. Kharaghani, Arrays for orthogonal designs, J. Combin. Designs, 8 (2000), 166-173, to obtain infinite families of 8-variable Kharaghani type orthogonal designs, OD(8t; hi, kl, kl, kl, k2, k2, k2, k2), where k1 and k2 must be the sum of two squares. In particular we obtain infinite families of 8-variable Kharaghani type orthogonal designs, OD(8t; k, k, k, k, k, k, k, k). For odd t orthogonal designs of order ≡ 8( mod 16) can have at most eight variables.

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Some Results On Kharaghani Type Orthogonal Designs, S. Georgiou, C. Koukouvinos, Jennifer Seberry Jun 2003

Some Results On Kharaghani Type Orthogonal Designs, S. Georgiou, C. Koukouvinos, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

In this paper we give a general theorem which can be used to multiply the length of amicable sequences keeping the amicability property and the type of the sequences. As a consequence we have that if there exist two, four or eight amicable sequences of length m and type (al, a2), (al, a2, a3, a4) or (al, a2, …, as) then there exist amicable sequences of length ℓ ≡ 0 (mod m) and of the same type. We also present a theorem that produces a set of 2v amicable sequences from a set of v (not necessary amicable) sequences and …

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An Algorithm To Find Formulae And Values Of Minors For Hadamard Matrices: Ii, C. Koukouvinos, E. Lappas, M. Mitrouli, Jennifer Seberry Jun 2003

An Algorithm To Find Formulae And Values Of Minors For Hadamard Matrices: Ii, C. Koukouvinos, E. Lappas, M. Mitrouli, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

An algorithm computing the (n — j) x (n — j ) , j = 1, 2, ... minors of Hadamard matrices of order n is presented. Its implementation is analytically described step by step for several values of n and j. For j = 7 the values of minors are computed for the first time. A formulae estimating all the values of (n — j) x (n — j) minors is predicted.

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Compression Tolerant Dct Based Image Hash, C. Kailasanathan, R. Safavi-Naini, P. Ogunbona May 2003

Compression Tolerant Dct Based Image Hash, C. Kailasanathan, R. Safavi-Naini, P. Ogunbona

Faculty of Informatics - Papers (Archive)

With the advent of Internet image authentication has become a central part of research in security. Since JPEG has recommended discrete cosine transform as one of the steps in image compression systems, a hash function which utilizes discrete cosine decomposition is desirable. In this paper, we propose a discrete cosine based hash function which distinguishes acceptable level of compression from image processing modifications such as Median filtering, Gaussian noise addition, and FMLR attack. To increase manipulation detection, we optimize the number of AC coefficients needed in smoothing.

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Sequential Traitor Tracing, R. Safavi-Naini, Yejing Wang May 2003

Sequential Traitor Tracing, R. Safavi-Naini, Yejing Wang

Faculty of Informatics - Papers (Archive)

We consider a new type of traitor tracing scheme, called sequential traitor tracing, that protects against rebroadcasting of decrypted content. Sequential traceability (TA) schemes trace all up to c traitors and remove the shortcomings of dynamic tracing schemes. We give two general constructions and show the relationship between c-TA codes and sequential tracing schemes.

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A Self-Organizing Map For Adaptive Processing Of Structured Data, Markus Hagenbuchner, A. Sperduti, Ah Chung Tsoi May 2003

A Self-Organizing Map For Adaptive Processing Of Structured Data, Markus Hagenbuchner, A. Sperduti, Ah Chung Tsoi

Faculty of Informatics - Papers (Archive)

Recent developments in the area of neural networks produced models capable of dealing with structured data. Here, we propose the first fully unsupervised model, namely an extension of traditional self-organizing maps (SOMs), for the processing of labeled directed acyclic graphs (DAGs). The extension is obtained by using the unfolding procedure adopted in recurrent and recursive neural networks, with the replicated neurons in the unfolded network comprising of a full SOM. This approach enables the discovery of similarities among objects including vectors consisting of numerical data. The capabilities of the model are analyzed in detail by utilizing a relatively large data …

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Fully Scalable Texture Coding Of Arbitrarily Shaped Video Objects, H. Danyali, Alfred Mertins Apr 2003

Fully Scalable Texture Coding Of Arbitrarily Shaped Video Objects, H. Danyali, Alfred Mertins

Faculty of Informatics - Papers (Archive)

This paper presents a fully scalable texture coding algorithm for arbitrarily shaped video object based on the 3D-SPIHT algorithm. The proposed algorithm, called Fully Scalable Object-based 3D-SPIHT (FSOB-3DSPIHT), modifies the 3D-SPIHT algorithm to code video objects with arbitrary shape and adds spatial and temporal scalability features to it. It keeps important features of the original 3D-SPIHT coder such as compression efficiency, full embeddedness, and rate scalability. The full scalability feature of the modified algorithm is achieved through the introduction of multiple resolution dependent lists for the sorting stage of the algorithm. The idea of bitstream transcoding without decoding to obtain …

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Low Bit Rate Wideband Wi Speech Coding, C. H. Ritz, I. Burnett, Jason Lukasiak Apr 2003

Low Bit Rate Wideband Wi Speech Coding, C. H. Ritz, I. Burnett, Jason Lukasiak

Faculty of Informatics - Papers (Archive)

This paper investigates waveform interpolation (WI) applied low bit rate wideband speech coding. An analysis of the evolutionary behaviour of wideband characteristic waveforms (CW) shows that direct application of the classical WI algorithm may not be appropriate for wideband speech. We propose a modification whereby CW quantisation is performed using classical WI decomposition for the low frequency region and noise modelling for the high frequency region. Wideband WI coders incorporating this modification and operating at 4 kbit/s and 6 kbit/s are described. Subjective testing of these coders shows that WI is a promising approach to low bit rate wideband speech …

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Robust Non-Interactive Oblivious Transfer, Y. Mu, J. Zhang, V. Varadharajan, Y. X. Lin Apr 2003

Robust Non-Interactive Oblivious Transfer, Y. Mu, J. Zhang, V. Varadharajan, Y. X. Lin

Faculty of Informatics - Papers (Archive)

We present a novel scheme of noninteractive m out of n oblivious transfer, which demonstrates significant improvement over the existing schemes in terms of completeness, robustness and flexibility. This scheme is useful for protection of user privacy in the Internet.

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Blind Deconvolution Of Dynamical Systems Using A Balanced Parameterized State Space Approach, Ah Chung Tsoi, L. S. Ma Apr 2003

Blind Deconvolution Of Dynamical Systems Using A Balanced Parameterized State Space Approach, Ah Chung Tsoi, L. S. Ma

Faculty of Informatics - Papers (Archive)

In this paper, the problem of blind deconvolution of dynamical systems is considered using a state space approach. A balanced parameterized canonical form is used as a model for the underlying dynamical system instead of the more common controller or observable canonical form. The results are compared with those obtained using a controller canonical form. It is shown experimentally that using the balanced parameterized canonical form is more robust than the ones using a controller canonical form.

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Universal Multimedia Experiences For Tomorrow, F. Pereira, I. Burnett Mar 2003

Universal Multimedia Experiences For Tomorrow, F. Pereira, I. Burnett

Faculty of Informatics - Papers (Archive)

The previous decade has seen a variety of trends and developments in the area of communications and thus multimedia access. While individual, isolated developments produced small advances on the status quo, their combination and cross-fertilization resulted in today's complex but exciting landscape. In particular, we are beginning to see delivery of all types of data for all types of users in all types of conditions. This article discusses the current status of universal multimedia access (UMA) technologies and investigates future directions in this area. Key developments and trends from the last few years have set the scene for ubiquitous multimedia …

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A Study On Sound Source Apparent Shape And Wideness, Guillaume Potard, Ian Burnett Jan 2003

A Study On Sound Source Apparent Shape And Wideness, Guillaume Potard, Ian Burnett

Faculty of Informatics - Papers (Archive)

This work is intended as an initial investigation into the perception of wideness and shape of sound sources. A method that employs mUltiple uncorrelated point sources is used in order to form "sound shapes". Several experiments were carried out in which, after some initial training, subjects were asked to indicate the shapes that were being played. Results indicate that vertical and horizontal source wideness are easily perceived and scenes that use broad sound sources are preferred 70% of the time over point source versions. However, shape perception was found to be ambiguous except for certain types of signals where results …

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Size And Power Considerations For Testing Loglinear Models Using Divergence Test Statistics, Noel A. Cressie, L Pardo, M Del Carmen Pardo Jan 2003

Size And Power Considerations For Testing Loglinear Models Using Divergence Test Statistics, Noel A. Cressie, L Pardo, M Del Carmen Pardo

Faculty of Informatics - Papers (Archive)

In this article, we assume that categorical data are distributed according to a multinomial distribution whose probabilities follow a loglinear model. The inference problem we consider is that of hypothesis testing in a loglinear-model setting. The null hypothesis is a composite hypothesis nested within the alternative. Test statistics are chosen from the general class of divergence statistics. This article collects together the operating characteristics of the hypothesis test based on both asymptotic (using large-sample theory) and finite-sample (using a designed simulation study) results. Members of the class of power divergence statistics are compared, and it is found that the Cressie-Read …

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Plenary: Nonparametric Hypothesis Testing For A Spatial Signal, Noel A. Cressie Jan 2003

Plenary: Nonparametric Hypothesis Testing For A Spatial Signal, Noel A. Cressie

Faculty of Informatics - Papers (Archive)

Summary form only given. Nonparametric hypothesis testing for a spatial signal can involve a large number of hypotheses. For instance, two satellite images of the same scene, taken before and after an event, could be used to test a hypothesis that the event has no environmental impact. This is equivalent to testing that the mean difference of "after-before" is zero at each of the (typically thousands of) pixels that make up the scene. In such a situation, conventional testing procedures that control the overall Type I error deteriorate as the number of hypotheses increase. Powerful testing procedures are needed for …

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In Process Surface Roughness Estimation In Grinding, Li Xue, Fazel Naghdy, Christopher David Cook Jan 2003

In Process Surface Roughness Estimation In Grinding, Li Xue, Fazel Naghdy, Christopher David Cook

Faculty of Informatics - Papers (Archive)

An intelligent sensor system for on-line estimation of surface roughness in the grinding process is developed. The system consists of a statistical signal processing algorithm and a neuro-fuzzy model of surface roughness. The model is established using a set of experimental data. The sensor signals of acoustic emission CAE), normal force and tangential force generated in grinding zone are acquired online in real time. The surface roughness of the ground workpiece is measured offline and used as the target output of the model. A first order Sugeno-type neuro-fuzzy inference system is employed to optimize the model by minimizing a sum …

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Six D.O.F Haptic Rendered Simulation Of The Peg-In-Hole Assembly, Shen Dong, Fazel Naghdy, Yan Chen Jan 2003

Six D.O.F Haptic Rendered Simulation Of The Peg-In-Hole Assembly, Shen Dong, Fazel Naghdy, Yan Chen

Faculty of Informatics - Papers (Archive)

A new paradigm for programming of robotics manipulator to perform complex constrained motion tasks is being studied. The teaching of the manipulation skills to the machine starts by demonstmting those skills in a haptic -rendered virtual environment. Position and contact force and torque data generated in the virtual environment combined with a priori knowledge about the task is used to identify and learn the skills in the newly demonstrated tasks and then to reproduce them in the robotics system. The peg-in-hole insertion problem is used as a case study. In the ftrst implementation of the virtual manipulahon envlfonment, a three …

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Application Of Nega-Cyclic Matrices To Generate Spreading Sequences, R. Ang, Jennifer Seberry, Beata J. Wysocki, Tadeusz A. Wysocki Jan 2003

Application Of Nega-Cyclic Matrices To Generate Spreading Sequences, R. Ang, Jennifer Seberry, Beata J. Wysocki, Tadeusz A. Wysocki

Faculty of Informatics - Papers (Archive)

In the paper, we present a new class of orthogonal bipolar spreading sequences designed based on Goethals-Seidel construction with nega-cyclic matrices. The sequences can be designed for any length equal to 4 (mod 8), and possess good correlation properties. In particular, their aperiodic autocorrelation characteristics are very good. That can be traded off for improvement in the cross-correlation performance using a diagonal modification method, as shown in the example.

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Williamson-Hadamard Spreading Sequences For Ds-Cdma Applications, Jennifer Seberry, Beata J. Wysocki, Tadeusz A. Wysocki Jan 2003

Williamson-Hadamard Spreading Sequences For Ds-Cdma Applications, Jennifer Seberry, Beata J. Wysocki, Tadeusz A. Wysocki

Faculty of Informatics - Papers (Archive)

Orthogonal bipolar spreading sequences are used in direct sequence code division multiple acces (DS-CDMA) systems for both spectrum spreading and channel separation. The most commonly used sequences are Walsh-Hadamard sequences of lenghts being an integer power of 2. A construction based on Williamson's arrays leading to sequences of lengths N ≡ 4(mod 8) is presented in the paper. Aperiodic correlation characteristics, for example sequence sets of lengths 12-252 are presented. The correlation properties of the sequence sets are later improved using a diagonal modification technique.

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Harmonics And Flicker Levels At A Sub-Transmission Substation: A Measurement Experience, D A. Robinson, Victor J. Gosbell, Sarath Perera, N Browne Jan 2003

Harmonics And Flicker Levels At A Sub-Transmission Substation: A Measurement Experience, D A. Robinson, Victor J. Gosbell, Sarath Perera, N Browne

Faculty of Informatics - Papers (Archive)

Proactive monitoring of power quality disturbance levels by electricity utilities is vital to allow cost-effective mitigation when disturbances are perceived to be approaching planning levels and also to protect the security of customer installations. Ensuring that disturbance levels are within limits at the HV and EHV points of supply of the network is essential if satisfactory levels downstream are to be maintained. This paper presents discussion on a power quality monitoring campaign performed at the sub-transmission point of supply of a distribution network with the objective of benchmarking background disturbance levels prior to modifications to the substation and to ensure …

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Harmonic Planning Levels For Australian Distribution Systems, Victor J. Gosbell, Victor W. Smith, D A. Robinson, W Miller Jan 2003

Harmonic Planning Levels For Australian Distribution Systems, Victor J. Gosbell, Victor W. Smith, D A. Robinson, W Miller

Faculty of Informatics - Papers (Archive)

A modelling technique is developed for determining the harmonic voltage distribution across a distribution system when there is an equitable distribution of harmonic emission. The harmonic voltages at the 132kV and 415V levels are fixed to values based on IEC Compatibility and Planning Levels and the intermediate voltages determined. Studies are made of six systems, typical of Australian distribution practice, to examine the effect of choice of voltage level and system parameters over the harmonic range of 2-40. Based on the study, harmonic Planning Levels are recommended for application to Australian distribution systems.

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A Transient Index For Reporting Power Quality Surveys, Victor J. Gosbell, Sarath Perera, D A. Robinson, Chandana Herath Jan 2003

A Transient Index For Reporting Power Quality Surveys, Victor J. Gosbell, Sarath Perera, D A. Robinson, Chandana Herath

Faculty of Informatics - Papers (Archive)

Impulsive transients are often blamed for the destruction of customer appliances. Advances in Power Quality (PQ) monitors will soon make it feasible to incorporate impulsive transients into routine power quality surveys. This paper considers how the transient events captured over a period at many sites may be reported in a simple but useful manner. The paper first summarizes a recent publication by some of the authors, which attempt to give a complete framework for the analysis of utility PQ data. This framework provides a basis for evaluating existing transient characterization practices as well as for the proposed new transient index …

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A Study Of Continuous Pq Disturbance Levels In Mv/Lv Distribution Systems, Victor J. Gosbell, D A. Robinson Jan 2003

A Study Of Continuous Pq Disturbance Levels In Mv/Lv Distribution Systems, Victor J. Gosbell, D A. Robinson

Faculty of Informatics - Papers (Archive)

Distribution Network Service Providers need to be aware of the general variation of PQ disturbances across their network, from the sites as diverse as the MV bus bar of a zone substation, the end of a MV feeder, and at the near and far ends of LV mains. This paper develops an understanding of PQ variations across such a system from survey results correlated with approximate analysis used to assign a PQ disturbance ranking to each site. The work will concentrate on continuous PQ disturbances, defined as those due to load current effects, for example voltage deviations, unbalance, fluctuations and …

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Affine Hecke Algebras, Cyclotomic Hecke Algebras And Clifford Theory, Arun Ram, Jacqueline Ramagge Jan 2003

Affine Hecke Algebras, Cyclotomic Hecke Algebras And Clifford Theory, Arun Ram, Jacqueline Ramagge

Faculty of Informatics - Papers (Archive)

We show that the Young tableaux theory and constructions of the irreducible representations of the Weyl groups of type A, B and D, Iwahori-Hecke algebras of types A, B, and D, the complex reflection groups G(r, p, n) and the corresponding cyclotomic Hecke algebras Hr,p,n, can be obtained, in all cases, from the affine Hecke algebra of type A. The Young tableaux theory was extended to affine Hecke algebras (of general Lie type) in recent work of A. Ram. We also show how (in general Lie type) the representations of general affine Hecke algebras can be constructed from the representations …

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A 96 X 64 Intelligent Digital Pixel Array With Extended Binary Stochastic Arithmetic, Tarik Hammadou, Magnus Nilson, Amine Bermak, Philip Ogunbona Jan 2003

A 96 X 64 Intelligent Digital Pixel Array With Extended Binary Stochastic Arithmetic, Tarik Hammadou, Magnus Nilson, Amine Bermak, Philip Ogunbona

Faculty of Informatics - Papers (Archive)

A chip architecture that integrates an optical sensor and a pixel level processing element based on binary stochastic arithmetic is proposed. The optical sensor is formed by an array of fully connected pixels, and each pixel contains a sensing element and a Pulse Frequency Modulator (PFM) converting the incident light to bit streams of identical pulses. The processing element is based on binary stochastic arithmetic to perform signal processing operations on the focal plane VLSI circuit. A 96 x 64 CMOS image sensor is fabricated using 0.5pm CMOS technology and achieves 29 x 29pm pixel size at 15% fill factor.

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Stereoscopic Panoramic Video Generation Using Centro-Circular Projection Technique, Chaminda Weerasinghe, Wanqing Li, Philip Ogunbona Jan 2003

Stereoscopic Panoramic Video Generation Using Centro-Circular Projection Technique, Chaminda Weerasinghe, Wanqing Li, Philip Ogunbona

Faculty of Informatics - Papers (Archive)

This paper presents a method of stereoscopic panoramic video generation including techniques for panorama projection, stitching and calibration for various depth planes. The methods described can be used on video sequences captured by an arrangement of multiple pairs of cameras or multiple stereoscopic cameras mounted on a regular polygonal shaped camera rig. Algorithms can also be used in combination or separately, for generating both stereoscopic and monoscopic video and still panoramas.

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