TY - CHAP A1 - Schmidt, Jochen A1 - Wong, C.K. A1 - Yeap, W.K. T1 - A Split & Merge Approach to Metric-Topological Map-Building T2 - International Conference on Pattern Recognition (ICPR), volume 3, pages 1069-1072, Hong Kong N2 - We present a novel split and merge based method for dividing a given metric map into distinct regions, thus effectively creating a topological map on top of a metric one. The initial metric map is obtained from range data that are converted to a geometric map consisting of linear approximations of the indoor environment. The splitting is done using an objective function that computes the quality of a region, based on criteria such as the average region width (to distinguish big rooms from corridors) and overall direction (which accounts for sharp bends). A regularization term is used in order to avoid the formation of very small regions, which may originate from missing or unreliable sensor data. Experiments based on data acquired by a mobile robot equipped with sonar sensors are presented, which demonstrate the capabilities of the proposed method. KW - Pattern Recognition KW - Metric-Topological Map-Building Y1 - 2018 ER - TY - CHAP A1 - Wong, C.K. A1 - Yeap, W.K. A1 - Schmidt, Jochen T1 - Computing a Network of ASRs Using a Mobile Robot Equipped with Sonar Sensors T2 - International Conference on Robotics, Automation, and Mechatronics (RAM), pages 57-62, Bangkok, Thailand N2 - This paper presents a novel algorithm for computing absolute space representations (ASRs) in Yeap, W.K. and Jefferies, M. (1988) for mobile robots equipped with sonar sensors and an odometer. The robot is allowed to wander freely (i.e. without following any fixed path) along the corridors in an office environment from a given start point to an end point. It then wanders from the end point back to the start point. The resulting ASRs computed in both directions are shown KW - Robotics KW - Automation and Mechatronics Y1 - 2006 ER - TY - CHAP A1 - Yeap, W.K. A1 - Wong, C.K. A1 - Schmidt, Jochen T1 - Initial Experiments with a Mobile Robot on Cognitive Mapping T2 - International Symposium on Practical Cognitive Agents and Robots (PCAR 2006), pages 221-230, Perth, Australia N2 - This paper shows how a mobile robot equipped with sonar sensors and an odometer is used to test ideas about cognitive mapping. The robot first explores an office environment and computes a "cognitive map" which is a network of ASRs [1]. The robot generates two networks, one for the outward journey and the other for the journey home. It is shown that both networks are different. The two networks, however, are not merged to form a single network. Instead, the robot attempts to use distance information implicit in the shape of each ASR to find its way home. At random positions in the homeward journey, the robot calculates its orientation towards home. The robot's performances for both problems are evaluated and found to be surprisingly accurate. KW - Mobile Robot KW - Cognitive Mapping Y1 - 2006 ER - TY - CHAP A1 - Schmidt, Jochen A1 - Vogt, F. A1 - Niemann, H. T1 - Calibration-Free Hand-Eye Calibration: A Structure-from-Motion Approach T2 - Joint Pattern Recognition Symposium N2 - The paper presents an extended hand-eye calibration approach that, in contrast to the standard method, does not require a calibration pattern for determining camera position and orientation. Instead, a structure-from-motion algorithm is applied for obtaining the eye-data that is necessary for computing the unknown hand-eye transformation. Different ways of extending the standard algorithm are presented, which mainly involves the estimation of a scale factor in addition to rotation and translation. The proposed methods are experimentally compared using data obtained from an optical tracking system that determines the pose of an endoscopic camera. The approach is of special interest in our clinical setup, as the usage of an unsterile calibration pattern is difficult in a sterile environment. KW - Translation Vector KW - Feature Tracking KW - World Coordinate System KW - Dual Quaternion Y1 - 2005 PB - Springer CY - Berlin ER - TY - CHAP A1 - Zinßler, T. A1 - Schmidt, Jochen A1 - Niemann, H. T1 - Point Set Registration with Integrated Scale Estimation T2 - Proceedings of the Eighth International Conference on Pattern Recognition and Image Processing (PRIP 2005), pages 116-119, Minsk, Republic of Belarus N2 - Wepresentaniterativeregistrationalgorithmfor aligning two differently scaled 3-D point sets. It extends the popular Iterative Closest Point (ICP) algorithm by estimating a scale factor between the two point sets in every iteration. The presented algorithm is especially useful for the registration of point sets generated by structure-frommotion algorithms, which only reconstruct the 3-D structure of a scene upto scale. LiketheoriginalICPalgorithm,thepresentedalgorithm requires a rough pre-alignment of the point sets. In order to determine the necessary accuracy of the pre-alignment, wehaveexperimentallyevaluatedthebasinofconvergence of the algorithm with respect to the initial rotation, translation, andscale factor between the two point sets. KW - Iterative Closest Point KW - Scale Estimation Y1 - 2005 ER - TY - CHAP A1 - Schmidt, Jochen A1 - Vogt, F. A1 - Niemann, H. T1 - Vector Quantization Based Data Selection for Hand-Eye Calibration T2 - Vision, Modeling, and Visualization 2004, pages 21-28, Stanford, USA N2 - The paper presents a new vectorquantization based Approach for selecting well-suited data for hand-eye calibration from a given sequence of hand and eye movements. Data selection is essential if control of the movements used for calibration is not possible, especially when using continuously recorded data. The new algorithm is compared to another method for data selection as well as to the processing of subsequent movements. Experimental results on real and synthetic data sets show the superior performance of the new approach with respect to calibration errors and computation time. Real data has been obtained from an optical tracking system and a camera mounted on an endoscope, the goal being the reconstruction of medical lightfields. KW - Vector Quantization KW - Hand-Eye Calibration KW - Data selection Y1 - 2005 ER - TY - JOUR A1 - Vogt, F. A1 - Krüger, S. A1 - Schmidt, Jochen A1 - Paulus, D. A1 - Niemann, H. A1 - Hohenberger, W. A1 - C. H., Schick T1 - Light Fields for Minimal Invasive Surgery Using an Endoscope Positioning Robot JF - Methods of Information in Medicine N2 - OBJECTIVES: To generate a fast and robust 3-D visualization of the operation site during minimal invasive surgery. METHODS: Light fields are used to model and visualize the 3-D operation site during minimal invasive surgery. An endoscope positioning robot provides the position and orientation of the endoscope. The a priori un-known transformation from the endoscope plug to the endoscope tip (hand-eye transformation) can either be determined by a three-step algorithm, which includes measuring the endoscope length by hand or by using an automatic hand-eye calibration algorithm. Both methods are described in this paper and their respective computation times and accuracies are compared. RESULTS: Light fields were generated during real operations and in the laboratory. The comparison of the two methods to determine the unknown hand-eye transformation was done in the laboratory. The results which are being presented in this paper are: rendered images from the generated light fields, the calculated extrinsic camera parameters and their accuracies with respect to the applied hand-eye calibration method, and computation times. CONCLUSION: Using an endoscope positioning robot and knowing the hand-eye transformation, the fast and robust generation of light fields for minimal invasive surgery is possible. KW - Robotics Y1 - 2004 ER - TY - CHAP A1 - Schmidt, Jochen A1 - Vogt, F. A1 - Niemann, H. T1 - Robust Hand-Eye Calibration of an Endoscopic Surgery Robot Using Dual Quaternions T2 - Pattern Recognition, Proceedings of the 25th DAGM Symposium, Magdeburg N2 - This paper presents an approach for applying a dual quaternion hand–eye calibration algorithm on an endoscopic surgery robot. Special focus is on robustness, since the error of position and orientation data provided by the robot can be large depending on the movement actually executed. Another inherent problem to all hand–eye calibration methods is that non–parallel rotation axes must be used; otherwise, the calibration will fail. Thus we propose a method for increasing the numerical stability by selecting an optimal set of relative movements from the recorded sequence. Experimental evaluation shows the error in the estimated transformation when using well–suited and ill–suited data. Additionally, we show how a RANSAC approach can be used for eliminating the erroneous robot data from the selected movements. KW - Pattern Recognition KW - Temporal Orderr KW - Numerical Stability KW - Dual Quaternion  KW - Calibration Pattern  Y1 - 2018 ER - TY - CHAP A1 - Zinßer, T. A1 - Schmidt, Jochen A1 - Niemann, H. T1 - A Refined ICP Algorithm for Robust 3-D Correspondence Estimation T2 - Proceedings of the IEEE International Conference on Image Processing, volume 2, pages 695-698, Barcelona, Spain N2 - Robust registration of two 3-D point sets is a common problem in computer vision. The iterative closest point (ICP) algorithm is undoubtedly the most popular algorithm for solving this kind of problem. In this paper, we present the Picky ICP algorithm, which has been created by merging several extensions of the standard ICP algorithm, thus improving its robustness and computation time. Using pure 3-D point sets as input data, we do not consider additional information like point color or neighborhood relations. In addition to the standard ICP algorithm and the Picky ICP algorithm proposed in this paper, a robust algorithm due to Masuda and Yokoya and the RICP algorithm by Trucco et al. are evaluated. We have experimentally determined the basin of convergence, robustness to noise and outliers, and computation time of these four ICP based algorithms KW - Iterative closest point algorithm KW - Iterative algorithms KW - Noise robustnes KW - Computer vision Y1 - 2003 ER - TY - BOOK A1 - Ernst, Hartmut A1 - Schmidt, Jochen A1 - Beneken, Gerd T1 - Grundkurs Informatik: Grundlagen und Konzepte für die erfolgreiche IT-Praxis - Eine umfassende, praxisorientierte Einführung N2 - Zahlensysteme und binäre Arithmetik – Nachricht und Information – Codierung und Datenkompression – Verschlüsselung – Schaltalgebra, Schaltnetze und Elemente der Computerhardware – Rechnerarchitekturen – Rechnernetze – Betriebssysteme – prozedurale und objektorientierte Programmierung (C und Java) – Automatentheorie und formale Sprachen – Berechenbarkeit und Komplexität – Suchen und Sortieren – Bäume und Graphen – Software-Engineering – Datenbanken – Anwendungsprogrammierung im Internet (HTML, CSS, JavaScript und PHP) – Deep Learning mit neuronalen Netzen KW - Grundlagen Informatik Y1 - 2020 SN - 978-3-658-30330-3 PB - Springer Vieweg CY - Wiesbaden ET - 7 ER - TY - BOOK A1 - Schmidt, Jochen T1 - Grundkurs Informatik - Das Übungsbuch: 148 Aufgaben mit Lösungen KW - Grundlagen Informatik Übungen Y1 - 2020 SN - 978-3-658-30332-7 PB - Springer Vieweg CY - Wiesbaden ET - 2 ER - TY - JOUR A1 - Wenninger, Marc A1 - Maier, Andreas A1 - Schmidt, Jochen T1 - DEDDIAG, a domestic electricity demand dataset of individual appliances in Germany JF - Scientific Data N2 - Real-world domestic electricity demand datasets are the key enabler for developing and evaluating machine learning algorithms that facilitate the analysis of demand attribution and usage behavior. Breaking down the electricity demand of domestic households is seen as the key technology for intelligent smart-grid management systems that seek an equilibrium of electricity supply and demand. For the purpose of comparable research, we publish DEDDIAG, a domestic electricity demand dataset of individual appliances in Germany. The dataset contains recordings of 15 homes over a period of up to 3.5 years, wherein total 50 appliances have been recorded at a frequency of 1 Hz. Recorded appliances are of significance for load-shifting purposes such as dishwashers, washing machines and refrigerators. One home also includes three-phase mains readings that can be used for disaggregation tasks. Additionally, DEDDIAG contains manual ground truth event annotations for 14 appliances, that provide precise start and stop timestamps. Such annotations have not been published for any long-term electricity dataset we are aware of. KW - Machine Learning Y1 - 2021 UR - https://doi.org/10.1038/s41597-021-00963-2 VL - 8 IS - 176 ER -