2022-01-24T13:29:58Zhttps://researchspace.auckland.ac.nz/dspace-oai/requestoai:researchspace.auckland.ac.nz:2292/26812008-08-29T04:56:08Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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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:2292/27232008-08-29T04:58:04Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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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:2292/27922008-08-29T05:01:38Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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Klette, Gisela
author
2006
Branch indices of points on curves (introduced by Urysohn and Menger) are of basic importance in the mathematical theory of curves, defined in Euclidean space. This paper applies the concept of branch points in the 3D orthogonal grid, motivated by the need to analyze curve-like structures in digital images. These curve-like structures have been derived as 3D skeletons (by means of thinning). This paper discusses approaches of defining branch indices for voxels on 3D skeletons, where the notion of a junction will play a crucial role. We illustrate the potentials of using junctions in 3D image analysis based on a recent project of analyzing the distribution of astrocytes in human brain tissue.
Communication and Information Technology Research Technical Report 178, (2006)
1178-3567
http://hdl.handle.net/2292/2792
Branch Voxels and Junctions in 3D Skeletons
oai:researchspace.auckland.ac.nz:2292/28382008-08-29T05:03:22Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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Hermann, Simon
author
Klette, Reinhard
author
2003
This report explains a new method for the estimation of curvature of plane curves and compares it with a method which has been presented in [2]. Both methods are based on global approximations of tangents by digital straight line segments. Experimental studies show that a replacement of global by local approximation results in errors which, in contrast to the global approximation, converge to constants > 0. We also apply the new global method for curvature estimation of curves to surface curvature estimation, and discuss a method for estimating mean curvature of surfaces which is based on Meusnier's theorem.
Communication and Information Technology Research Technical Report 129, (2003)
1178-3616
http://hdl.handle.net/2292/2838
Multigrid Analysis of Curvature Estimators
oai:researchspace.auckland.ac.nz:2292/27422008-08-29T04:59:30Zcom_2292_122col_2292_2623
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:2292/26802008-08-29T04:56:04Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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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:2292/27272021-07-29T03:58:04Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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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 Space and a Linear-Time Length Estimation Algorithm
oai:researchspace.auckland.ac.nz:2292/27192008-08-29T04:57:16Zcom_2292_122col_2292_2623
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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:2292/27902008-08-29T05:01:33Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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Brimkov, Valentin
author
2006
Given a set M subset Z3, an enclosing polyhedron for M is any polyhedron P such that the set of integer points contained in P is precisely M . Representing a discrete volume by enclosing polyhedron is a fundamental problem in visualization. In this paper we propose the first proof of the long-standing conjecture that the problem of finding an enclosing polyhedron with a minimal number of 2-facets is strongly NP-hard and provide a lower bound for that number.
Communication and Information Technology Research Technical Report 179, (2006)
1178-3566
http://hdl.handle.net/2292/2790
Discrete Volume Polyhedrization is Strongly NP-Hard
oai:researchspace.auckland.ac.nz:2292/27052008-08-29T04:56:57Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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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:2292/28002008-08-29T05:01:53Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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Zhang, Xin
author
Morris, John
author
2005
This article discusses ways of measuring accuracy of a laser range finder (LRF) using a specially designed calibration cube (with 3D calibration marks) in the context of a particular application (i.e., measuring volumes). We also compare (by means of experiments) two alternative volume estimation methods.
Communication and Information Technology Research Technical Report 170, (2005)
1178-3575
http://hdl.handle.net/2292/2800
Volume Measurement Using a Laser Scanner
oai:researchspace.auckland.ac.nz:2292/27302008-08-29T04:58:39Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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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:2292/28432008-08-29T05:03:02Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Klette, Reinhard
author
Gimel'farb, Georgy
author
Huang, Fay
author
Scheibe, Karsten
author
Scheele, Martin
author
Börner, Anko
author
2003
This paper reviews research related to the design, production and application of cylindrical panoramic cameras. Such a camera is characterized by rotating linear sensors capturing one image column at a time. This allows for accurate mappings onto a cylindrical image surface and very high image resolutions paid by motion distortions in dynamic scenes. These panoramic images can be used, for example, for stereo visualization and stereo reconstruction in applications where extremely high image resolution is of benefit (for static scenes). The paper deals especially with aspects of stereo visualization and reconstruction.
Communication and Information Technology Research Technical Report 123, (2003)
1178-3622
http://hdl.handle.net/2292/2843
A Review on Research and Applications of Cylindrical Panoramas
oai:researchspace.auckland.ac.nz:2292/28542008-08-29T05:16:34Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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Kawamoto, Kazuhiko
author
Yamada, Daisuke
author
Klette, Reinhard
author
2002
Video sequences capturing real scenes may be interpreted with respect to a dominant plane which is a planar surface covering 'a majority' of pixels in an image of a video sequence, i.e. that planar surface which is represented in the image by a maximum number of pixels. In this paper, we propose an algorithm for the detection of dominant planes from optical flow fields caused by camera motion in a static scene. We, in particular, intend to adopt this algorithm as a module for obstacle detection in vision-based navigation of autonomous robots.
Communication and Information Technology Research Technical Report 111, (2002)
1178-3634
http://hdl.handle.net/2292/2854
Navigation Using Optical Flow Fields: An Application of Dominant Plane Detection
oai:researchspace.auckland.ac.nz:2292/28012008-08-29T05:01:55Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Liu, Gang
author
Klette, Reinhard
author
2005
Structure from Motion (SfM) is one of the most attractive approaches within computer vision which aims on estimating 3D structure from 2D image sequences. This paper focuses on a stability analysis and studies the error propagation of image noise. To stabilize SfM, we further present two optimization schemes by using a priori knowledge of the scene.
Communication and Information Technology Research Technical Report 169, (2005)
1178-3576
http://hdl.handle.net/2292/2801
Structure from Motion in the Presence of Noise
oai:researchspace.auckland.ac.nz:2292/27862008-08-29T05:01:22Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Brimkov, Valentin
author
Klette, Reinhard
author
2006
In this paper we define and study digital manifolds of arbitrary dimension, and provide (in particular) a general theoretical basis for curve or surface tracing in picture analysis. The studies involve properties such as one-dimensionality of digital curves and $(n-1)$-dimensionality of digital hypersurfaces that makes them discrete analogs of corresponding notions in topology. The presented approach is fully based on good pairs of adjacency relations and complements the concept of dimension as common in combinatorial topology. This work appears to be the first one on digital manifolds based on a graph-theoretical definition of dimension. In particular, a digital hypersurface in $n$D is an $(n-1)$-dimensional object, as it is in the case of continuous hypersurfaces. Relying on the obtained properties of digital hypersurfaces, we propose a uniform approach for studying good pairs defined by separations and obtain a classification of good pairs in arbitrary dimension.
Communication and Information Technology Research Technical Report 184, (2006)
1178-3561
http://hdl.handle.net/2292/2786
Curves, Hypersurfaces, and Good Pairs
oai:researchspace.auckland.ac.nz:2292/27402008-08-29T04:59:27Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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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:2292/26862008-08-29T04:56:22Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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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:2292/27482008-08-29T05:00:04Zcom_2292_122col_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:2292/27032008-08-29T04:56:54Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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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:2292/27892008-08-29T05:01:33Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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Nakamura, Akira
author
Morita, Kenichi
author
2006
Let us consider a 3D picture P = (Z^3, 26, 6, B), where B is well-composed and does not contain any cavity or any tunnel. This paper proves that B is SD-equivalent to a single voxel.
Communication and Information Technology Research Technical Report 180, (2006)
1178-3565
http://hdl.handle.net/2292/2789
B-problem
oai:researchspace.auckland.ac.nz:2292/27612008-08-29T05:00:36Zcom_2292_122col_2292_2623col_2292_3452
00925njm 22002777a 4500
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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:2292/28472008-08-29T05:16:19Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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Kozera, Ryszard
author
Noakes, Lyle
author
2002
This paper studies differences in estimating length (and also trajectory) of an unknown parametric curve from an ordered collection of data points qi = GAMA (ti), with either the ti's known or unknown. For the ti's uniform (known or unknown) piecewise Lagrange interpolation provides efficient length estimates, but in other cases it may fail. In this paper, we apply this classical algorithm when the ti's are sampled according to first ALPHA-order and then when sampling is EPSILON-uniform. The latter was introduced in [20] for the case where ti's are unknown. In the present paper we establish new results for the case when the ti's are known for both types of samplings. For curves sampled EPSILON-uniformly comparison is also made between the cases, where the tabular parameters ti's are known and unknown. Numerical experiments are carried out to investigate sharpness of our theoretical results. The work may be of interest in computer vision and graphics, approximation and complexity theory, digital and computational geometry, and digital image analysis.
Communication and Information Technology Research Technical Report 119, (2002)
1178-3626
http://hdl.handle.net/2292/2847
External versus Internal Parameterizations for Lengths of Curves with Nonuniform Samplings
oai:researchspace.auckland.ac.nz:2292/27572008-08-29T05:00:25Zcom_2292_122col_2292_2623col_2292_3452
00925njm 22002777a 4500
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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:2292/27452008-08-29T04:59:44Zcom_2292_122col_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:2292/28102008-08-29T05:02:00Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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Klette, Reinhard
author
Reulke, Ralf
author
2005
Modeling of 3D scenes has been the defining subject in photogrammetry or remote sensing for more than 100 years, and it is now for about 30 years one of the main subjects in computer vision. There are recently significant paradigm shifts in both areas. Digital imaging reshaped photogrammetry and remote sensing, and active vision (e.g., integrating laser range finder, SAR, or structured lighting) allows accurate and cost- and time-efficient 3D shape recovery in computer vision. Traditional approaches such as shading based shape analysis or binocular stereo are supported or even totally replaced by active vision technologies. New camera technologies (e.g., developments of different sensor geometries, increase in image resolution, and more accurate photometric properties) are a necessary prerequisite for these developments. This paper briefly reviews such processes and gives some conclusions.
Communication and Information Technology Research Technical Report 155, (2005)
1178-3590
http://hdl.handle.net/2292/2810
Modeling 3D Scenes: Paradigm Shifts in Photogrammetry, Remote Sensing and Computer Vision
oai:researchspace.auckland.ac.nz:2292/28532008-08-29T05:16:27Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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Klette, Gisela
author
2002
Skeletonization is a transformation of a component of a digital image into a subset of the original component. There are different categories of skeletonization methods: one category is based on distance transforms, and a specified subset of the transformed image is a distance skeleton. The original component can be reconstructed from the distance skeleton. Another category is defined by thinning approaches; and the result of skeletonization using thinning algorithms should be a connected set of digital curves or arcs. Motivations for interest in skeletonization algorithms are the need to compute a reduced amount of data or to simplify the shape of an object in order to find features for recognition algorithms and classifications. Additionally the transformation of a component into an image showing essential characteristics can eliminate local noise at the frontier. Thinning algorithms are a very active area of research, with a main focus on connectivity preserving methods allowing parallel implementation. There are hundreds of publications on different aspects of these transformations. This report reviews contributions in this area with respect to properties of algorithms and characterizations of simple points, and informs about a few new results.
Communication and Information Technology Research Technical Report 112, (2002)
1178-3633
http://hdl.handle.net/2292/2853
Skeletons in Digital Image Processing
oai:researchspace.auckland.ac.nz:2292/28282008-08-29T05:02:54Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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Brimkov, Valentin
author
Barneva, Reneta
author
2004
We consider the problem of estimating the Shannon capacity of a circulant graph C_nj of degree four with n vertices and chord length j, , by computing its Lovasz theta function theta(C_nj ). Our interest in this problem is driven by possible applications to error-free communication of data describing the structure of a digital line. The latter can be represented in terms of spyrographs [12], which, as a matter of fact, are circulants of degree four. We present an algorithm for theta(C_nj ) computation that takes O(j) operations if j is an odd number, and O(n/j) operations if j is even. On the considered class of graphs our algorithm strongly outperforms the known algorithms for theta function computation.
Communication and Information Technology Research Technical Report 138, (2004)
1178-3607
http://hdl.handle.net/2292/2828
Lovasz theta-function of a class of graphs representing digital lines
oai:researchspace.auckland.ac.nz:2292/28152008-08-29T05:02:36Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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Brimkov, Valentin
author
Barneva, Reneta
author
2004
In this paper we investigate the advantages of using hexagonal grids in raster and volume graphics. In 2D, we present a hexagonal graphical model based on a hexagonal grid. In 3D, we introduce two honeycomb graphical models in which the voxels are hexagonal prisms, and we show that these are the only possible models under certain reasonable conditions. In the framework of the proposed models, we design two- and three-dimensional analytical honeycomb geometry of linear objects, as well as of circles and spheres. We demonstrate certain advantages of the honeycomb models and address algorithmic and complexity issues.
Communication and Information Technology Research Technical Report 151, (2004)
1178-3594
http://hdl.handle.net/2292/2815
Analytical Honeycomb Geometry for Raster and Volume Graphics
oai:researchspace.auckland.ac.nz:2292/26312008-08-26T03:40:42Zcom_2292_122col_2292_2623col_2292_3452
00925njm 22002777a 4500
dc
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:2292/27722008-08-29T05:01:04Zcom_2292_122col_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:2292/27662009-11-17T02:33:31Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/28252008-08-29T05:02:50Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Brimkov, Valentin
author
Coeurjolly, David
author
2004
Digital planarity is defined by digitizing Euclidean planes in the three-dimensional digital space of voxels; voxels are given either in the grid point or the grid cube model. The paper summarizes results (also including most of the proofs) about different aspects of digital planarity, such as self-similarity, supporting or separating Euclidean planes, characterizations in arithmetic geometry, periodicity, connectivity, and algorithmic solutions. The paper provides a uniform presentation, which further extends and details a recent book chapter in (Klette and Rosenfeld 2004). [This report has been updated in April 2006, at the end of the reviewing process of its journal publication. Results stated are still as in the original 2004 report, but the report was improved at several places due to reviewers comments.]
Communication and Information Technology Research Technical Report 142, (2004)
1178-3603
http://hdl.handle.net/2292/2825
Digital Planarity - A Review
oai:researchspace.auckland.ac.nz:2292/28312008-08-29T05:03:11Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Lee, Byung-Doo
author
Guesgen, Hans
author
Jeong, Soo-Hyun
author
2003
This paper describes the result of applying a fuzzy reasoning method, which conducts Go term knowledge based on pattern knowledge, to the opening game in Go. We discuss the implementation of the fuzzy reasoning method for deciding the best next move to proceed through the opening game. We also let the fuzzy reasoning method play against the TD() learning method to compare the performance. The results reveal that the simple fuzzy reasoning system performs better than the TD learning method and it shows great potential to be applied to the real game of Go.
Communication and Information Technology Research Technical Report 135, (2003)
1178-3610
http://hdl.handle.net/2292/2831
The Application of Fuzzy Reasoning to the Opening Games of 19x19 Go
oai:researchspace.auckland.ac.nz:2292/27602008-08-29T05:00:35Zcom_2292_122col_2292_2623col_2292_3452
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:2292/28452008-08-29T05:16:17Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Brimkov, Valentin
author
2002
In the present notes we define and study the notion of digital flatness. We extend to two dimensions various definitions and results about digital straightness, in particular, we resolve a conjecture of M. Nivat for the case of digital planes and define and characterize 2D Sturmian rays.
Communication and Information Technology Research Technical Report 120, (2002)
1178-3625
http://hdl.handle.net/2292/2845
Digital flatness and related combinatorial problems
oai:researchspace.auckland.ac.nz:2292/28392008-08-29T05:03:23Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Zang, Qi
author
Klette, Reinhard
author
2003
The design of a video surveillance system is directed on automatic identification of events of interest, especially on tracking and classification of moving vehicles or pedestrians. In case of any abnormal activities, an alert should be issued. Normally a video surveillance system combines three phases of data processing: moving object extraction, moving object recognition and tracking, and decisions about actions. The extraction of moving objects, followed by object tracking and recognition, can often be defined in very general terms. The final component is largely depended upon the application context, such as pedestrian counting or traffic monitoring. In this paper, we review previous research on moving object tracking techniques, analyze some experimental results, and finally provide our conclusions for improved performances of traffic surveillance systems. One stationary camera has been used.
Communication and Information Technology Research Technical Report 128, (2003)
1178-3617
http://hdl.handle.net/2292/2839
Object Classification and Tracking in Video Surveillance
oai:researchspace.auckland.ac.nz:2292/27592008-08-29T05:00:34Zcom_2292_122col_2292_2623col_2292_3452
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:2292/27332008-08-29T04:58:53Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/27762009-11-19T01:04:25Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Tee, Garry
author
2007
The surface area and general surface integrals over a general segment of a 3-dimensional ellipsoid are computed.
Communication and Information Technology Research Technical Report 194, (2007)
1178-3551
http://hdl.handle.net/2292/2776
Surface Area and Surface Integrals on Ellipsoid Segments. (2007)
oai:researchspace.auckland.ac.nz:2292/28202008-08-29T05:02:41Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Huang, Yuman
author
Klette, Reinhard
author
2004
We consider selected geometric properties of 2D or 3D sets, given in form of binary digital pictures, and discuss their estimation. The properties examined are perimeter and area in 2D, and surface area and volume in 3D. We evaluate common estimators in stereology and digital geometry according to their multiprobe or multigrid convergence properties, and precision and efficiency of estimations.
Communication and Information Technology Research Technical Report 146, (2004)
1178-3599
http://hdl.handle.net/2292/2820
A Comparison of Property Estimators in Stereology and Digital Geometry
oai:researchspace.auckland.ac.nz:2292/27672008-08-29T05:00:58Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/28112008-08-29T05:02:27Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Brimkov, Valentin
author
Dantchev, Stefan
author
2004
We consider the following problem. Given a set of points M = {p1, p2, . . . , pm} ? Rn, decide whether M is a portion of a digital hyperplane and, if so, determine its analytical formulation. In our setting p1, p2, . . . , pm may be arbitrary points (possibly, with rational and/or irrational coefficients) and the dimension n may be any arbitrary fixed integer. We provide an algorithm that solves the problem with O(mlogD) arithmetic operations, where D is a bound on the value of the digital plane coefficients. The solution is based on reducing the digital hyperplane recognition problem to an integer linear programming problem of fixed dimension within an algebraic model of computation.
Communication and Information Technology Research Technical Report 154, (2004)
1178-3591
http://hdl.handle.net/2292/2811
Digital hyperplane recognition in arbitrary fixed dimension
oai:researchspace.auckland.ac.nz:2292/26242008-08-13T04:37:30Zcom_2292_122col_2292_2623col_2292_3452
00925njm 22002777a 4500
dc
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:2292/27682008-08-29T05:00:59Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/27712008-08-29T05:01:03Zcom_2292_122col_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:2292/26852008-08-29T04:56:19Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/27082008-08-29T04:57:00Zcom_2292_122col_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:2292/28072008-08-29T05:02:21Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Rosenhahn, Bodo
author
Kersting, Uwe
author
Andrew, Smith
author
Brox, Thomas
author
Klette, Reinhard
author
Seidel, Hans-Peter
author
2005
This paper proposes a system for model based human motion estimation. We start with a human model generation system, which uses a set of input images to automatically generate a free-form surface model of a human upper torso. We subsequently determine joint locations automatically and generate a texture for the surface mesh. Following this, we present morphing and joint transformation techniques to gain more realistic human upper torso models. An advanced model such as this is used in a system for silhouette based human motion estimation. The presented motion estimation system contains silhouette extraction based on level set functions, a correspondence module, which relates image data to model data and a pose estimation module. This system is used for a variety of experiments: Different camera setups (between one to four cameras) are used for the experiments and we estimate the pose configurations of a human upper torso model with 21 degrees of freedom at two frames per second. We also discuss degenerated cases for silhouette based human motion estimation. Next, a comparison of the motion estimation system with a commercial marker based tracking system is performed to gain a quantitative error analysis. The results show the applicability of the system for marker-less human movement analysis. Finally we present experimental results on tracking leg models and show the robustness of our algorithms even for corrupted image data.
Communication and Information Technology Research Technical Report 164, (2005)
1178-3581
http://hdl.handle.net/2292/2807
A Silhouette Based Human Motion Tracking System
oai:researchspace.auckland.ac.nz:2292/26972008-08-29T04:56:44Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/27072008-08-29T04:56:59Zcom_2292_122col_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:2292/28372008-08-29T05:03:20Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Chen, Chia-Yen
author
Klette, Reinhard
author
2003
In this work, we further discuss an approach to 3D shape recovery by combining photometric stereo and shape from contours methods. Surfaces recovered by photometric stereo are aligned, adjusted and merged according to a preliminary 3D model obtained by shape from contours. Comparisons are conducted to evaluate the performances of different methods. It has been found that the proposed combination provides more accurate shape recovery than using either photometric stereo or shape from contours alone.
Communication and Information Technology Research Technical Report 130, (2003)
1178-3615
http://hdl.handle.net/2292/2837
3D Reconstruction Using Shape from Photometric Stereo and Contours
oai:researchspace.auckland.ac.nz:2292/26982008-08-29T05:16:56Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/27542008-08-29T05:00:21Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/28562009-04-08T21:15:08Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Wei, Tiangong
author
Klette, Reinhard
author
2001
This paper presents a new algorithm for height from gradients and analyzes its performance. To derive this algorithm, we combine the integrability constraint and the surface curvature and area constraints into a single functional, which is then minimized. Therefore, the changes of height 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 109, (2001)
1178-3636
http://hdl.handle.net/2292/2856
Height from Gradient with Surface Curvature and Area Constraints
oai:researchspace.auckland.ac.nz:2292/28292008-08-29T05:03:00Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Rosenhahn, Bodo
author
Sommer, Gerald
author
2004
In this report we present geometric foundations and an algorithmic approach to deal with the 2D-3D pose estimation problem for free-form surface models. This work is an extension to our former works presented in [28]. But whereas in [28] 1D contour models are treated, here the extension to 2D free-form surface models is presented. Similar to our former works we use a parametric representation of surfaces and apply Fourier transformations to gain low-pass descriptions of the object. We present an algorithm for pose estimation, which uses the silhouette of the object as image information and recovers the 3D pose of the object even for changing aspects of the object during image sequences. We further present extensions to couple surface and contour information on objects and show the potential of our chosen approach even for complex objects and scenes.
Communication and Information Technology Research Technical Report 137, (2004)
1178-3608
http://hdl.handle.net/2292/2829
Pose Estimation of Free-form Objects (Theory and Experiments)
oai:researchspace.auckland.ac.nz:2292/27462008-08-29T04:59:46Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/27292008-08-29T04:58:35Zcom_2292_122col_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:2292/27242021-06-15T02:38:21Zcom_2292_122col_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 Characterization of Image Acquisition for 3D Scene Visualization and Reconstruction Applications
oai:researchspace.auckland.ac.nz:2292/27202008-08-29T04:57:18Zcom_2292_122col_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:2292/27252008-08-29T04:58:06Zcom_2292_122col_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:2292/27512008-08-29T05:00:11Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/27262008-08-29T04:58:09Zcom_2292_122col_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:2292/27772008-08-29T05:01:11Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Tee, Garry
author
2007
Many infinite sequences of permutable rational functions and a few infinite sequences of permutable polynomials are constructed, on the basis of elliptic functions and trigonometric functions.
Communication and Information Technology Research Technical Report 193, (2007)
1178-3552
http://hdl.handle.net/2292/2777
Permutable Polynomials and Rational Functions
oai:researchspace.auckland.ac.nz:2292/26942008-08-29T04:56:30Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/26782008-08-29T04:56:01Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/27882008-08-29T05:01:32Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Torii, Akihiko
author
Klette, Reinhard
author
2006
This report provides mappings of omnidirectional images (catadioptric or dioptric images) into panoramic images on a sphere or on a cylinder, all in a single report for convenient access. The mappings are illustrated by examples (including anaglyphic panoramas generated from catadioptric image pairs).
Communication and Information Technology Research Technical Report 181, (2006)
1178-3564
http://hdl.handle.net/2292/2788
Transforms of Catadioptric or Dioptric Images into Spheric or Cylindric Panoramas
oai:researchspace.auckland.ac.nz:2292/28502008-08-29T05:16:21Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Wei, Tiangong
author
Klette, Reinhard
author
2002
This paper presents a regularization method for surface reconstruction from noisy gradient vector fields. The algorithm takes as its input a discrete gradient vector field, obtained by applying a Shape from Shading or Photometric Stereo method. To derive this algorithm, we combine the integrability constraint and the surface curvature and area constraints into a single functional, which is then minimized. Therefore, value changes in the height or depth map will be more regular. To solve the minimization problem, we employ the Fourier transform theory rather than the Variational Principle. The Fourier transform of the (unknown) surface is expressed as a function of the (given) gradient's Fourier transforms. The relative depth values can be obtained by an inverse Fourier Transform and by choosing associated weighting parameters. The method is evaluated on gradient data delivered by a Photometric Stereo algorithm.
Communication and Information Technology Research Technical Report 115, (2002)
1178-3630
http://hdl.handle.net/2292/2850
Regularization Method for Depth from Noisy Gradient Vector Fields
oai:researchspace.auckland.ac.nz:2292/27012008-08-29T04:56:52Zcom_2292_122col_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:2292/27042008-08-29T04:56:56Zcom_2292_122col_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:2292/28522008-08-29T05:16:23Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Klette, Gisela
author
2002
There are hundreds of publications on different aspects of image deformations that preserve topological properties of the original binary image. The notion of a "simple pixel" is of fundamental importance for these transformations. Simple pixels in 2D binary images have been characterized in a number of ways. This paper reviews some of these characterizations and it points out that some of them are actually equivalent.
Communication and Information Technology Research Technical Report 113, (2002)
1178-3632
http://hdl.handle.net/2292/2852
Characterizations of Simple Pixels in Binary Images
oai:researchspace.auckland.ac.nz:2292/28332008-08-29T05:03:04Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Li, Fajie
author
Zang, Qi
author
2003
Camera calibration is a necessary and critical step in 3D object analysis. The accuracy of calibration results will affect the object's position in world coordinates, especially for 3D object tracking. In this paper, we present a new camera calibration approach, and discuss its accuracy. We use 3D marks instead of 2D marks for calibration. Our experimental results show that our approach has the potential to improve the calibration accuracy.
Communication and Information Technology Research Technical Report 133, (2003)
1178-3612
http://hdl.handle.net/2292/2833
Accuracy Improvement in Camera Calibration
oai:researchspace.auckland.ac.nz:2292/28042008-08-29T05:02:16Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Wang, Xiang
author
Klette, Reinhard
author
2005
This article discusses a method for blindly removing geometric distortions in taken images of rectangular planar patterns (such as maps, pictures, or posters) in the absence of any calibration information or explicit knowledge of the imaging device. Our approach removes lens distortion form single-view images. The method is based on Least-Square-Error (LSE) approximations and Hough transforms. We approximate the lens distortion by considering only lower-order terms of the lens distortion, and additionally a single-coefficient only to model approximately the geometric distortion. The method relies on the assumption that pure radial distortion transforms straight lines into curves, and it exploits plane homography.
Communication and Information Technology Research Technical Report 167, (2005)
1178-3578
http://hdl.handle.net/2292/2804
Geometric Correction of Projected Rectangular Pictures
oai:researchspace.auckland.ac.nz:2292/28362008-08-29T05:03:19Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Chen, Johnson
author
Wei, Shou-Kang
author
2003
Object embedded stereo panoramic images have received increasing attention recently due to their numerous applications in computer vision. This article explores an approach to embed object images, both dynamic and static, into background panoramas. The approach involves three steps; namely, image acquisition, post-acquisition, and image visualization. A GUI tool is developed for image registering, merging, and pose recovering. A panoramic player is also developed for visualizing the resultant anaglyphic panorama.
Communication and Information Technology Research Technical Report 131, (2003)
1178-3614
http://hdl.handle.net/2292/2836
Authoring and Visualizing Stereo Panoramic Images with Independent Objects
oai:researchspace.auckland.ac.nz:2292/28172008-08-29T05:02:39Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Hasler, Nils
author
Klette, Reinhard
author
Agnew, Warren
author
2004
In today s pest control operations large numbers of tracking tunnels are used to estimate the number of rodents present in the target area, providing a basis for planning the required amount of poison. The marks left in the tunnels have to be interpreted by trained experts. This article introduces two methods that make a step towards automating the process of recognizing footprints of rodents and insects. Furthermore two classification methods (Principal Component Analysis, a simple Na¨?ve Bayes classifier) are studied to distinguish the four examined insect species. Here, a combination of both classifiers proved superior to using just one method.
Communication and Information Technology Research Technical Report 149, (2004)
1178-3596
http://hdl.handle.net/2292/2817
Footprint Recognition of Rodents and Insects
oai:researchspace.auckland.ac.nz:2292/28492008-08-29T05:03:01Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Huang, Fay
author
Kang, Shou
author
Gimel'farb, Georgy
author
Reulke, Ralf
author
Scheele, Martin
author
Scheibe, Karsten
author
2002
This paper reviews major steps in designing, producing and applying cylindrical panoramic cameras. Basically such a camera is characterized by rotating linear sensors capturing one image column at a time. Extremely high numbers of pixels per line allow capturing of super-high resolution panoramic images. These can be used for stereo visualisation and stereo reconstruction, as will be discussed in this paper.
Communication and Information Technology Research Technical Report 116, (2002)
1178-3629
http://hdl.handle.net/2292/2849
Cylindrical Panoramic Cameras - From Basic Design to Applications
oai:researchspace.auckland.ac.nz:2292/27002008-08-29T04:56:48Zcom_2292_122col_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:2292/27952008-08-29T05:01:45Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Li, Fajie
author
Klette, Reinhard
author
2006
We consider simple cube-curves in the orthogonal 3D grid of cells. The union of all cells contained in such a curve (also called the tube of this curve) is a polyhedrally bounded set. The curve's length is defined to be that of the minimum-length polygonal curve (MLP) contained and complete in the tube of the curve. Only one general algorithm, called rubberband algorithm, was known for the approximative calculation of such an MLP so far. An open problem in KLE_ROS_2004 is related to the design of algorithms for the calculation of the MLP of a simple cube-curve: Is there a simple cube-curve such that none of the nodes of its MLP is a grid vertex? This paper constructs an example of such a simple cube-curve, and we also characterize the class of all of such cube-curves. This study leads to a correction in Option 3 of the rubberband algorithm (by adding one missing test). We also prove that the rubber-band algorithm has linear time complexity ${\cal O}(m)$ where $m$ is the number of critical edges of a given simple cube curve, which solves another open problem in the context of this algorithm.
Communication and Information Technology Research Technical Report 175, (2006)
1178-3570
http://hdl.handle.net/2292/2795
Analysis of the Rubberband Algorithm
oai:researchspace.auckland.ac.nz:2292/28552008-08-29T05:16:36Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Wei, Tiangong
author
Klette, Reinhard
author
2001
This paper presents and analyzes four finite difference methods for linear shape from shading problem. Comparisons of accuracy, solvability, stability and convergence of these methods indicate that the weighted semi-implicit method and the box method are better than the other ones because they are easily calculated, more accurate, faster in convergence and unconditionally stable.
Communication and Information Technology Research Technical Report 110, (2001)
1178-3635
http://hdl.handle.net/2292/2855
Finite Difference Methods for Linear Shape from Shading
oai:researchspace.auckland.ac.nz:2292/27872008-08-29T05:01:23Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Hermann, Simon
author
Klette, Reinhard
author
2006
Curvature is a frequently used property in two-dimensional (2D) shape analysis, directly or for derived features such as corners or convex and concave arcs. This paper presents curvature estimators which follow approaches in differential geometry. Digital-straight segment approximation (as known from digital geometry) is used in those estimators. Results of multigrid experiments are evaluated leading to a comparative performance analysis of several curvature estimators.
Communication and Information Technology Research Technical Report 183, (2006)
1178-3562
http://hdl.handle.net/2292/2787
A Comparative Study on 2D Curvature Estimators
oai:researchspace.auckland.ac.nz:2292/28342008-08-29T05:03:16Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Reulke, Ralf
author
Wehr, Aloysius
author
Scheele, Martin
author
Scheibe, Karsten
author
2003
The fusing of panoramic camera data with laser scanner data will be discussed on measurement results obtained during verification tests using the Digital 360 Panoramic camera (M2) developed by German Aerospace Center (DLR) in cooperation with Kamera und System Technik GmbH (KST) and the imaging laser scanner (3D-LS) developed by Institute of Navigation University Stuttgart (INS). First the measurement setup will be presented. Here M2 and 3D-LS are used as independent individual sensors surveying the same target. Then the data sampling and preprocessing for each sensor will be explained and the problem of transforming both independent data sets into one common coordinate system will be addressed by discussing the results of the verification tests.
Communication and Information Technology Research Technical Report 132, (2003)
1178-3613
http://hdl.handle.net/2292/2834
Panoramic Mapping using CCD-Line Camera and Laser Scanner with Integrated Position and Orientation System
oai:researchspace.auckland.ac.nz:2292/27372008-08-29T04:59:23Zcom_2292_122col_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:2292/28232008-08-29T05:02:45Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Pan, Mian
author
Klette, Gisela
author
2004
This report is about a project that started with studying and testing an existing program by K.Palagyi et al. published in [4]. It provides several combinations of preprocessing steps with the traditional thinning approach. This study lead to a proposal of a new characterization of non-simple voxels, which has been implemented and proved to be e±cient for reducing the running time of the algorithm. Altogether, we suggest a revision of the test of voxels to be simple in the discussed 3D skeletonization algorithm.
Communication and Information Technology Research Technical Report 143, (2004)
1178-3602
http://hdl.handle.net/2292/2823
A Revision of a 3D Skeletonization Algorithm
oai:researchspace.auckland.ac.nz:2292/28122008-08-29T05:02:32Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Deng, Lea
author
Bertinshaw, Daniel
author
Klette, Gisela
author
Jeffries, Darryl
author
2004
Using tracking tunnels or tracking cards to obtain the footprints of active animals living in a specific area is useful for biosecurity research as well as environment monitoring. In the absence of human experts, a feasible computer classifier could be constructed to identify species of insects from their footprints. The essential step to develop this classifier is to obtain representative attributes on which we can perform analysis using image processing technology, geometry, etc. This paper presents procedures for an approach to build up such a classifier by discussing three different attribute heuristics.
Communication and Information Technology Research Technical Report 153, (2004)
1178-3592
http://hdl.handle.net/2292/2812
Footprint Identification of Weta and Other Insects
oai:researchspace.auckland.ac.nz:2292/27142008-08-29T04:57:06Zcom_2292_122col_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:2292/28052008-08-29T05:02:17Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Rugis, John
author
2005
In 1998 - 1999 a team of researchers from the Computer Science Departments at the University of Stanford and the University of Washington digitized a number of Michelango s sculptures, including the David statue, using a custom designed laser triangulation scanner. The resultant data has been made available to the research community. This paper explores the data structures and the inherent geometry associated with the David data set. An estimation of surface curvature that exploits the structure and geometry of the data set is described. Finally surface curvature maps are defined and several curvature maps of David are presented.
Communication and Information Technology Research Technical Report 166, (2005)
1178-3579
http://hdl.handle.net/2292/2805
Surface Curvature Maps and Michelangelo s David
oai:researchspace.auckland.ac.nz:2292/28032009-11-17T02:35:45Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Yuan, Guannan
author
Russell, James
author
Rosenhahn, Bodo
author
Stones-Havas, Steven
author
2005
Recognition of animal tracks plays an important role in environmental research and pest control. So far such track analysis can only be accurately carried out by experienced biologists. In this paper we discuss the potential of image analysis methodologies for allowing automatic identification of rat tracks. The approach is basically a refinement of template matching (as designed earlier for automated track localization), now also allowing identification of rat species.
Communication and Information Technology Research Technical Report 168, (2005)
1178-3577
http://hdl.handle.net/2292/2803
Understanding Tracks of Different Species of Rats (2005)
oai:researchspace.auckland.ac.nz:2292/26842008-08-29T04:56:11Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
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:2292/27962008-08-29T05:01:45Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
dc
Li, Fajie
author
Klette, Reinhard
author
2005
We consider simple cube-curves in the orthogonal 3D grid. The union of all cells contained in such a curve (also called the tube of this curve) is a polyhedrally bounded set. The curve's length is defined to be that of the minimum-length polygonal curve (MLP) fully contained and complete in the tube of the curve. So far only one general algorithm called rubber-band algorithm was known for the approximative calculation of such an MLP. A proof that this algorithm always converges to the correct curve, is still an open problem. This paper proves that the rubber-band algorithm is correct for the family of first-class simple cube-curves.
Communication and Information Technology Research Technical Report 174, (2005)
1178-3571
http://hdl.handle.net/2292/2796
Minimum-Length Polygons of First-Class Simple Cube-Curves
oai:researchspace.auckland.ac.nz:2292/27092008-08-29T04:57:01Zcom_2292_122col_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:2292/27282008-08-29T04:58:14Zcom_2292_122col_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:2292/27132008-08-29T04:57:06Zcom_2292_122col_2292_2623col_2292_3452
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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:2292/26952008-08-29T04:56:30Zcom_2292_122col_2292_2623
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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:2292/28512008-08-29T05:16:22Zcom_2292_122col_2292_2623
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Zang, Qi
author
Klette, Reinhard
author
2002
Video surveillance systems seek to automatically identify events of interest in a variety of situations. Extracting a moving object from background is the most important step of the whole system. There are many approaches to track moving objects in a video surveillance system. These can be classified into three main groups: feature-based tracking, background subtraction, and optical flow techniques. Background subtraction is a region-based approach where the objective is to identify parts of the image plane that are significantly different to the background. In order to avoid the most common problems introduced by gradual illumination changes, waving trees, shadows, etc., the background scene requires a composite model. A mixture of Gaussian distributions is most popular. In this paper, we classify and discuss several recently proposed composite models. We have chosen one of these for implementation and evaluate its performance. We also analyzed its benefits and drawbacks, and designed an improved version of this model based on our experimental evaluation. One stationary camera has been used.
Communication and Information Technology Research Technical Report 114, (2002)
1178-3631
http://hdl.handle.net/2292/2851
Evaluation of an Adaptive Composite Gaussian Model in Video Surveillance
oai:researchspace.auckland.ac.nz:2292/27502008-08-29T05:00:07Zcom_2292_122col_2292_2623
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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:2292/27582008-08-29T05:00:34Zcom_2292_122col_2292_2623col_2292_3452
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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:2292/28442008-08-29T05:16:14Zcom_2292_122col_2292_2623
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Klette, Reinhard
author
2003
Incidence pseudographs (or the dual model of complexes based on a bounded-by relation) are popular models for pixels or voxels and relations between these. They allow a definition of a topological space, and combinatorial formulas characterize open and closed sets in this topology. K. Voss characterized in 1993 open regions in incidence pseudographs. This article reviews these results and provides also combinatorial formulas for closed regions.
Communication and Information Technology Research Technical Report 121, (2003)
1178-3624
http://hdl.handle.net/2292/2844
Combinatorics on Incidence Pseudographs
oai:researchspace.auckland.ac.nz:2292/27982008-08-29T05:01:48Zcom_2292_122col_2292_2623
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Klette, Gisela
author
Pan, Mian
author
2005
This paper proposes algorithms for the analysis of sets of confocal microscope images of human brain tissue which constitute a 3D volume. The identification of suitable features for curve-like structures in these volumes is required for subsequent classification. The final goal is the distinction between brain tissues of patients with different degrees of neurological deceases. The given volumes show varying distributions, shapes and numbers of astrocytes (i.e., brain cells whose shape resembles that of of a star). The hypothesis is that the ``distribution'' of astrocytes in brain tissue is related to the number and distribution of branch nodes (clustered into {\it junctions}) in 3D skeletons of these cells. Segmentation is followed by an application of a modified 3D thinning algorithm. Further analysis is based on our definition of `junctions' and new methods for locating such junctions. We characterize their distribution based on subdividing the volume into subcubes, also using measures of complexity of junctions and distances between junctions (based on different metrics).
Communication and Information Technology Research Technical Report 172, (2005)
1178-3573
http://hdl.handle.net/2292/2798
Characterization of Curve-Like Structures in 3D Medical Images
oai:researchspace.auckland.ac.nz:2292/26832008-08-29T04:56:10Zcom_2292_122col_2292_2623
00925njm 22002777a 4500
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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:2292/27432008-08-29T04:59:31Zcom_2292_122col_2292_2623
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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
marc///col_2292_2623/100