2,279 results for Report

  • An In-Depth Robustness Evaluation of Stereo Algorithms on Long Stereo Sequences

    Morales, Sandino; Vaudrey, Tobi; Klette, Reinhard (2008)

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    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 presents an approach to test stereo algorithms against long stereo sequences (100+ image pairs). Stereo sequences of this length have not been quantitatively evaluated in the past. Using stereo sequences allows one to exploit the temporal information, which is in general not well used currently. Furthermore, the presented approach focuses on evaluating the robustness of algorithms against differing noise parameters (Gaussian noise, brightness differences, and blurring).

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  • Robust Calculation of Ego-Vehicle Corridors

    Jiang, Ruyi; Klette, Reinhard; Wang, Shigang; Vaudrey, Tobi (2009)

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    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=127&Itemid=113 . All other rights are reserved by the author(s). An important component of driver assistance systems (DAS) is lane detection, and has been studied since the 1990s. However, improving and generalizing lane detection solutions remains to be a challenging task until recently. A (physical) lane is defined by road boundaries or various kinds of lane marks, and this is only partially applicable for modeling the space an ego-vehicle is able to driving in. This paper proposes a concept of a (virtual) corridor for modeling this space. A corridor depends on information available about the motion of the ego-vehicle, as well as about the (physical) lane. This paper suggests robust corridor detection using hypothesis testing based on maximum a posterior (MAP) estimation. Then, boundary selection and road patch extension are applied as post-processing. Furthermore, a simple but efficient corridor tracking method is also discussed. This paper also informs the readers about experiments using images of some challenging road situations illustrating the usefulness of the proposed corridor detection and tracking scheme.

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  • Prediction Error Evaluation

    Morales, Sandino; Klette, Reinhard (2009)

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    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=127&Itemid=113 . All other rights are reserved by the author(s). Prediction errors are commonly used when analyzing the performance of a multi-camera stereo system using at least three cameras. This paper discusses this methodology for performance evaluation on long stereo sequences (in the context of vision-based driver assistance systems). Three cameras are calibrated in an ego-vehicle, and prediction error analysis is performed on recorded stereo sequences. They are evaluated using various common stereo matching algorithms, such as belief propagation, dynamic programming, semi-global matching, or graph cut. This performance evaluation is demonstrated on synthetic and real data.

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  • A Methodology for Evaluating Illumination Artifact Removal for Corresponding Images

    Vaudrey, Tobi; Wedel, Andreas; Klette, Reinhard (2009)

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    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=127&Itemid=113 . All other rights are reserved by the author(s). Robust stereo and optical flow disparity matching is essential for computer vision applications with varying illumination conditions. Most robust disparity matching algorithms rely on computationally expensive normalized variants of the brightness constancy assumption to compute the matching criterion. In this paper, we reinvestigate the removal of global and large area illumination artifacts, such as vignetting, camera gain, and shading reflections, by directly modifying the input images. We show that this significantly reduces violations of the brightness constancy assumption, while maintaining the information content in the images. In particular, we define metrics and perform a methodical evaluation to firstly identify the loss of information in the images, and secondly determine the reduction of brightness constancy violations. Thirdly, we experimentally validate that modifying the input images yields robustness against illumination artifacts for optical flow disparity matching.

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  • Low-level Image Processing for Lane Detection and Tracking

    Jiang, Ruyi; Klette, Reinhard; Wang, Shigang; Vaudrey, Tobi (2009)

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    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=127&Itemid=113 . All other rights are reserved by the author(s). Lane detection and tracking is a significant component of vision-based driver assistance systems (DAS). Low-level image processing is the first step in such a component. This paper suggests three useful techniques for low-level image processing in lane detection situations: bird’s-eye view mapping, a specialized edge detection method, and the distance transform. The first two techniques have been widely used in DAS, while the distance transform is a method newly exploited in DAS, that can provide useful information in lane detection situations. This paper recalls two methods to generate a bird’s-eye image from the original input image, it also compares edge detectors. A modified version of the Euclidean distance transform called real orientation distance transform (RODT) is proposed. Finally, the paper discusses experiments on lane detection and tracking using these technologies.

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  • Lane Detection on the iPhone

    Ren, Feixiang; Huang, Jinsheng; Jiang, Ruyi; Klette, Reinhard (2009)

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    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=127&Itemid=113 . All other rights are reserved by the author(s). A robust and efficient lane detection system is an essential component of Lane Departure Warning Systems, which are commonly used in many vision-based Driver Assistance Systems (DAS) in intelligent transportation. Various computation platforms have been proposed in the past few years for the implementation of driver assistance systems (e.g., PC, laptop, integrated chips, play station, and so on). In this paper, we propose a new platform for the implementation of lane detection, which is based on a mobile phone (the iPhone). Due to physical limitations of the iPhone w.r.t. memory and computing power, a simple and efficient lane detection algorithm using a Hough transform is developed and implemented on the iPhone, as existing algorithms developed based on the PC platform are not suitable for mobile phone devices (currently). Experiments of the lane detection algorithm are made both on PC and on iPhone.

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  • Discrete Driver Assistance

    Klette, Reinhard; Jiang, Ruyi; Morales, Sandino; Vaudrey, Tobi (2009)

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    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=127&Itemid=113 . All other rights are reserved by the author(s). Applying computer technology, such as computer vision in driver assistance, implies that processes and data are modeled as being discretized rather than being continuous. The area of stereo vision provides various examples how concepts known in discrete mathematics (e.g., pixel adjacency graphs, belief propagation, dynamic programming, max- ow/min-cut, or digital straight lines) are applied when aiming for efficient and accurate pixel correspondence solutions. The paper reviews such developments for a reader in discrete mathematics who is interested in applied research (in particular, in vision-based driver assistance). As a second subject, the paper also discusses lane detection and tracking, which is a particular task in driver assistance; recently the Euclidean distance transform proved to be a very appropriate tool for obtaining a fairly robust solution.

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  • Estimating 3D Flow for Driver Assistance Applications

    Sanchez, Jorge; Klette, Reinhard; Destenfanis, Eduardo (2008)

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    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 proposes a technique for estimating 3D flow vectors, by combining a KLT tracker with subsequent scale-space analysis of tracked points. A tracked point defines a 2D vector, which is mapped into 3D space based on ratios of maxima of scale-space characteristics. The approach is tested for night-vision sequences as recorded (at Daimler A.G., Germany) for driver assistance projects. Those image sequences (at 25Hz) are characterized by being slightly blurry and of low contrast.

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  • Approximated Ground Truth for Stereo and Motion Analysis on Real-World Sequences (Technical Report)

    Liu, Zhifeng; Klette, Reinhard (2008)

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    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 approximates ground truth for real-world stereo sequences and demonstrates its use for the performance analysis of a few selected stereo matching and optical flow techniques.

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  • Integrating Disparity Images by Incorporating Disparity Rate

    Vaudrey, Tobi; Bandino, Hernan; Gehrig, Stefan (2007)

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    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). Intelligent vehicle systems need to distinguish which objects are moving and which are static. A static concrete wall lying in the path of a vehicle should be treated differently than a truck moving in front of the vehicle. This paper proposes a new algorithm that addresses this problem, by providing dense dynamic depth information, while coping with real-time constraints. The algorithm models disparity and disparity rate pixel-wise for an entire image. This model is integrated over time and tracked by means of many pixel-wise Kalman filters. This provides better depth estimation results over time, and also provides speed information at each pixel without using optical flow. This simple approach leads to good experimental results for real stereo sequences, by showing an improvement over previous methods.

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  • Belief-Propagation on Edge Images for Stereo Analysis of Image Sequences

    Guan, Shushi; Klette, Reinhard (2007)

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    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 history of stereo analysis of images dates back more than one hundred years, but stereo analysis of image sequences is a fairly recent subject. Sequences allow time-propagation of results, but also come with particular characteristics such as being of lower resolution, or with less contrast. This article discusses the application of belief propagation (BP), which is widely used for solving various low-level vision problems, for the stereo analysis of night-vision stereo sequences. For this application it appears that BP often fails on the original frames for objects with blurry borders (trees, clouds, . . . ). In this paper, we show that BP leads to more accurate stereo correspondence results if it is applied on edge images, where we have decided for the Sobel edge operator, due to its time efficiency. We present the applied algorithm and illustrate results (without, or with prior edge processing) on seven, geometrically rectified night-vision stereo sequences (provided by Daimler AG, Germany).

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  • Shortest Path Algorithms for Sequences of Polygons

    Li, Fajie; Klette, Reinhard (2007)

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    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.

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

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

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    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.

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  • About the Calculation of Upper Bounds for Cluster Recovery Rates

    Li, Fajie; Klette, Reinhard (2008)

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    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.

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  • Differences Between Stereo and Motion Behaviour on Synthetic and Real-World Stereo Sequences

    Vaudrey, Tobi; Rabe, Clemens; Klette, Reinhard; Milburn, James (2008)

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    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). Performance evaluation of stereo or motion analysis techniques is commonly done either on synthetic data where the ground truth can be calculated from ray-tracing principals, or on engineered data where ground truth is easy to estimate. Furthermore, these scenes are usually only shown in a very short sequence of images. This paper shows why synthetic scenes may not be the only testing criteria by giving evidence of con icting results of disparity and optical ow estimation for real-world and synthetic testing. The data dealt with in this paper are images taken from a moving vehicle. Each real-world sequence contains 250 image pairs or more. Synthetic driver assistance scenes (with ground truth) are 100 or more image pairs. Particular emphasis is paid to the estimation and evaluation of scene ow on the synthetic stereo sequences. All image data used in this paper is made publicly available at http: // www. mi. auckland. ac. nz/ EISATS .

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  • The Naked Truth about Cost Functions

    Hermann, Simon; Klette, Reinhard (2009)

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    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=127&Itemid=113 . All other rights are reserved by the author(s). This paper reports about the performance of various cost functions as common or possible for stereo matching, within a `purist's matching strategy', which does not integrate any further optimization approach such as a continuity term, coarse-to- ne, left/right consistency checks, or others. The performed experiments support a few general conclusions, such as about the relation between 1D- or 2D-window based cost functions, the use of zero-mean normalization, the census cost function, or the use of B-splines for subpixel accurate cost calculation.

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  • An Approximate Algorithm for Solving Shortest Path Problems for Mobile Robots or Driver Assistance

    Li, Fajie; Klette, Reinhard; Morales, Sandino (2009)

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    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=127&Itemid=113 . All other rights are reserved by the author(s). Finding a shortest path between two given locations is of importance for mobile robots, but also (e.g.) for identifying unique paths in a given surrounding region II when (e.g.) evaluating vision software in test vehicles, or for calculating the free-space boundary in vision-based driver assistance. We assume that II is given as a triangulated surface which is not necessary simply connected.

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  • Lane Detection and Tracking Using a New Lane Model and a Distance Transform

    Jiang, Ruyi; Klette, Reinhard; Wang, Shigang; Vaudrey, Tobi (2009)

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    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=127&Itemid=113 . All other rights are reserved by the author(s). Lane detection is an important component of driver assistance systems (DAS), and highway-based lane departure solutions have been in the market since the mid 1990s. However, improving and generalizing vision-based lane detection solutions remains to be a challenging task. Particle filtering of boundary points is a robust way to estimate lanes. This paper introduces a new lane model in correspondence to this particle filter-based approach. Furthermore, a modified version of an Euclidean distance transform is applied on an edge map to provide information for boundary point detection. In comparison to the edge map, properties of the distance transform support improved lane detection including a novel initialization method. Two lane tracking methods are also discussed while focusing on efficiency and robustness, respectively. Finally, the paper reports about experiments on lane detection and tracking.

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  • Stock Price Response to New CEO Earnings News

    Geertsema, Paul; Lont, DH; Lu, Helen (2016-08-15)

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    The University of Auckland Library

    Stock prices on average rise more on good earnings news announced by new CEOs compared with established CEOs. This new-CEO attributes effect is more pronounced for CEOs appointed during challenging situations. By contrast, stock prices tend to drop less on bad earnings news for new CEOs. This honeymoon effect is robust to negative accruals. The new-CEO attributes effect is stronger for firms followed by fewer analysts but the honeymoon effect is stronger for firms followed by more analysts.

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