133 results for Klette, Reinhard, Report

  • Topologies on the Planar Orthogonal Grid

    Klette, Reinhard (2001)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). 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.

    View record details
  • A New Algorithm for Gradient Field Integration

    Wei, Tiangong; Klette, Reinhard (2001)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). 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.

    View record details
  • Experience with Optical Flow in Colour Video Image Sequences

    Barron, John; Klette, Reinhard (2001)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). 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.

    View record details
  • Albedo Recovery Using a Photometric Stereo Method

    Chen, Chia-Yen; Klette, Reinhard (2001)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). 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.

    View record details
  • Digital Straightness

    Rosenfeld, Azriel; Klette, Reinhard (2001)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). A digital arc is called `straight' if it is the digitization of a straight line segment. Since the concept of digital straightness was introduced in the mid-1970's, dozens of papers on the subject have appeared; many characterizations of digital straight lines have been formulated, and many algorithms for determining whether a digital arc is straight have been defined. This paper reviews the literature on digital straightness and discusses its relationship to other concepts of geometry, the theory of words, and number theory.

    View record details
  • Approximation of 3D Shortest Polygons in Simple Cube Curves

    Bülow, Thomas; Klette, Reinhard (2001)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). One possible denition of the length of a digitized curve in 3D is the length of the shortest polygonal curve lying entirely in a cube curve. In earlier work the authors proposed an iterative algorithm for the calculation of this minimal length polygonal curve MLP. This paper reviews the algorithm and suggests methods to speed it up by reducing the set of possible locations of vertices of the MLP or by directly calculating MLP vertices in specific situations. Altogether the paper suggests an in depth analysis of cube curves.

    View record details
  • Hyper-resolution and Polycentric Panorama Acquisition and Experimental Data Collection

    Huang, Fay; Klette, Reinhard; Börner, Anko; Reulke, Ralf; Scheele, Martin; Scheibe, Karsten (2001)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). This report summarizes technical information regarding hyper-resolution and polycentric panoramic image acquisition and experimental data collection for a joint project between the Center for Image Technology and Robotics (CITR) in Auckland, New Zealand and the institute of space sensor technology and planetary exploration of German Aerospace Center (DLR) in Berlin, Germany.

    View record details
  • Wide-Angle Image Acquisition, Analysis and Visualisation

    Klette, Reinhard; Gimel'farb, Georgy (2001)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). 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.

    View record details
  • Analysis of Finite Difference Algorithms for Linear Shape from Shading

    Wei, Tiangong; Klette, Reinhard (2000)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). 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.

    View record details
  • A Global Surface Area Estimation Algorithm for Digital Regular Solids

    Klette, Reinhard; Sun, Hao (2000)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). 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.

    View record details
  • Digital Curves in 3D Sapce and a Linear-Time Length Estimation Algorithm

    Bülow, Thomas; Klette, Reinhard (1999)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). 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.

    View record details
  • Convergence of Calculated Features in Image Analysis

    Klette, Reinhard; Zunic, Jovisa (1999)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). 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.

    View record details
  • On the Length Estimation of Digital Curves

    Klette, Reinhard; Kovalevsky, Vladimir (1999)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original CITR web site; http://citr.auckland.ac.nz/techreports/ under terms that include this permission. All other rights are reserved by the author(s). The paper details two linear-time algorithms, one for the partition of the boundary line of a digital region into digital straight segments, and one for calculating the minimum length polygon within a simple open boundary of a digital region. Both techniques allow the estimation of the length of digital curves or the perimeter of digital regions due to known multigrid convergence theorems. The algorithms are compared with respect to convergence speed and number of generated segments.

    View record details
  • Computer Vision for the Car Industry

    Klette, Reinhard; Liu, Zhifeng (2008)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original MI_tech website http://www.mi.auckland.ac.nz/index.php?option=com_content&view=article&id=91&Itemid=76 . All other rights are reserved by the author(s). This report provides a brief and informal introduction into stereo and motion analysis for driver assistance.

    View record details
  • Shortest Path Algorithms for Sequences of Polygons

    Li, Fajie; Klette, Reinhard (2007)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original MI_tech website http://www.mi.auckland.ac.nz/index.php?option=com_content&view=article&id=91&Itemid=76 . All other rights are reserved by the author(s). In both English and Chinese Given a sequence k simple polygons in a plane, and a start point p, a target point q. We approximately compute a shortest path that starts at p, then visits each of the polygons in the specified order, and finally ends at q. So far no solution was known if the polygons are disjoint and non-convex. By applying a rubberband algorithm, we give an approximative algorithm with time complexity in κ(ε) · σ(n),where n is the total number of vertices of the given polygons, and function κ(ε) is as κ(ε)=(Lo-L)=/ε where Lo is the length of the initial path, and L is the true (i.e., optimum) path length. The given rubberband algorithm can also be applied to solve approximately three NP-complete or NP-hard 3D Euclidean shortest path (ESP) problems in time κ(ε)·σ(k), where k is the number of layers in a stack which contains the defined obstacles.

    View record details
  • An Approximate Algorithm for Solving the Watchman Route Problem

    Li, Fajie; Klette, Reinhard (2007)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original MI_tech website http://www.mi.auckland.ac.nz/index.php?option=com_content&view=article&id=91&Itemid=76 . All other rights are reserved by the author(s). The watchman route problem (WRP) was first introduced in 1988 and is defined as follows: How to calculate a shortest route completely contained inside a simple polygon such that any point inside this polygon is visible from at least one point on the route? So far the best known result for the WRP is an σ(n3logn) runtime algorithm (with inherent numerical problems of its implementation). This paper gives an κ(ε)·σ(kn) approximate algorithm for WRP by using a rubberband algorithm, where n is the number of vertices of the simple polygon, k a number of essential cuts and ε the chosen accuracy constant.

    View record details
  • The Topology of Incidence Pseudographs

    James, Thomas R; Klette, Reinhard (2008)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original MI_tech website http://www.mi.auckland.ac.nz/index.php?option=com_content&view=article&id=91&Itemid=76 . All other rights are reserved by the author(s). An incidence pseudograph models a (re exive and symmetric) incidence relation between sets of various dimensions, contained in a countable family. Work by Klaus Voss in 1993 suggested that this general discrete model allows to introduce a topol- ogy, and some authors have done some studies into this direction in the past. This paper provides a comprehensive overview about the topology of incidence pseudo- graphs. This topology has various applications, such as in modeling basic data in 2D or 3D digital picture analysis. This paper addresses especially also partially open sets which occur in common (non-binary) picture analysis.

    View record details
  • Inclusion of a Second-Order Prior into Semi-Global Matching (2008)

    Hermann, Simon; Klette, Reinhard; Destenfanis, Eduardo (2008)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original MI_tech website http://www.mi.auckland.ac.nz/index.php?option=com_content&view=article&id=91&Itemid=76 . All other rights are reserved by the author(s). Today's stereo vision algorithms and computing technology allow real-time 3D data analysis, for example for driver assistance systems. A recently developed Semi-Global Matching (SGM) approach by H. Hirschm uller became a popular choice due to performance and robustness. This paper evaluates di erent parameter settings for SGM, and its main contribution consists in suggesting to include a second order prior into the smoothness term of the energy function. It also proposes and tests a new cost function for SGM. Furthermore, some preprocessing (edge images) proved to be of great value for improving SGM stereo results on real-world sequences, as previously already shown by S. Guan and R. Klette for belief propagation. There is also a performance gain for engineered stereo data (e.g.) as currently used on the Middlebury stereo website. However, the fact that results are not as impressive as on the .enpeda.. sequences indicates that optimizing for engineered data does not neccessarily improve real world stereo data analysis.

    View record details
  • About the Calculation of Upper Bounds for Cluster Recovery Rates

    Li, Fajie; Klette, Reinhard (2008)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original MI_tech website http://www.mi.auckland.ac.nz/index.php?option=com_content&view=article&id=91&Itemid=76 . All other rights are reserved by the author(s). Obtaining a reasonable upper bound of the recovery rate of an arbitrary clustering algorithm is of importance when exploring clus- tering algorithms with respect to possible recovery rates. This paper estimates the best possible recovery rate of an arbitrary clustering algo- rithm with respect to any given input data set, based on two hypotheses. For an example of a reasonably complex data set, obtained results are veri ed and adjusted using a data visualization system.

    View record details
  • Moving Object Segmentation using Optical Flow and Depth Information

    Klappstein, Jens; Vaudrey, Tobi; Rabe, Clemens; Wedel, Andreas; Klette, Reinhard (2008)

    Report
    The University of Auckland Library

    You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the original MI_tech website http://www.mi.auckland.ac.nz/index.php?option=com_content&view=article&id=91&Itemid=76 . All other rights are reserved by the author(s). This paper discusses the detection of moving objects (being a crucial part of driver assistance systems) using monocular or stereo- scopic computer vision. In both cases, object detection is based on motion analysis of individually tracked image points (optical ow), providing a motion metric which corresponds to the likelihood that the tracked point is moving. Based on this metric, points are segmented into objects by employing a globally optimal graph-cut algorithm. Both approaches are comparatively evaluated using real-world vehicle image sequences.

    View record details