Enhancment of dense urban digital surface models from VHR optical satellite stereo data by pre-segmentation and object detection

The generation of digital surface models (DSM) of urban areas from very high resolution (VHR) stereo satellite imagery requires advanced methods. In the classical approach of DSM generation from stereo satellite imagery, interest points are extracted and correlated between the stereo mates using an area based matching followed by a least-squares sub-pixel refinement step. After a region growing the 3D point list is triangulated to the resulting DSM. In urban areas this approach fails due to the size of the correlation window, which smoothes out the usual steep edges of buildings. Also missing correlations as for partly – in one or both of the images – occluded areas will simply be interpolated in the triangulation step. So an urban DSM generated with the classical approach results in a very smooth DSM with missing steep walls, narrow streets and courtyards. To overcome these problems algorithms from computer vision are introduced and adopted to satellite imagery. These algorithms do not work using local optimisation like the area-based matching but try to optimize a (semi-)global cost function. Analysis shows that dynamic programming approaches based on epipolar images like dynamic line warping or semiglobal matching yield the best results according to accuracy and processing time. These algorithms can also detect occlusions – areas not visible in one or both of the stereo images. Beside these also the time and memory consuming step of handling and triangulating large point lists can be omitted due to the direct operation on epipolar images and direct generation of a so called disparity image fitting exactly on the first of the stereo images. This disparity image – representing already a sort of a dense DSM – contains the distances measured in pixels in the epipolar direction (or a no-data value for a detected occlusion) for each pixel in the image. Despite the global optimization of the cost function many outliers, mismatches and erroneously detected occlusions remain, especially if only one stereo pair is available. To enhance these dense DSM – the disparity image – a pre-segmentation approach is presented in this paper. Since the disparity image is fitting exactly on the first of the two stereo partners (beforehand transformed to epipolar geometry) a direct correlation between image pixels and derived heights (the disparities) exist. This feature of the disparity image is exploited to integrate additional knowledge from the image into the DSM. This is done by segmenting the stereo image, transferring the segmentation information to the DSM and performing a statistical analysis on each of the created DSM segments. Based on this analysis and spectral information a coarse object detection and classification can be performed and in turn the DSM can be enhanced. After the description of the proposed method some results are shown and discussed

Wiederholungs-, Varianten- und Neuplanung bei der Fertigung rotationssymmetrischer Drehteile

Diese Arbeit beschreibt eine empirische Studie zum Planungsverhalten menschlicher Experten bei der Fertigungsplanung im Maschinenbau. Im Rahmen der Studie wurden zwei Teiluntersuchungen durchgeführt. In der ersten Untersuchung waren eine Reihe von Planungsaufgaben für die Herstellung eines Werkstückes (definiert durch die Geometrie und den Werkstoff) in einer bestimmten Werkstatt (Drehmaschine) zu bearbeiten. Dabei wurden verschiedene Geometrien, Werkstoffe und Drehmaschinen einbezogen. Es wurde gezeigt, daß Experten bei der Fertigungsplanung zunächst eine erste Lösung auf einem abstrakteren Niveau, die als Planskelett (sceletal plan) bezeichnet wird, erarbeiten. Bei der Erstellung solcher wird auf bereits vorliegende Lösungen zurückgegriffen, die gegebenenfalls modifiziert werden. In einer zusammenfassenden Strukturierung. der Variantenplanungen konnten verschiedene Vorgehensweisen bei der Übertragung vorhandener Planskelette auf neue Fertigungsaufgaben unterschieden werden. In der zweiten Untersuchung war im Paarvergleich von Planungsaufgaben einzuschätzen, wie ähnlich deren resultierende Fertigungspläne sind. Dabei sollte Aufschluß darüber gewonnen werden, wie das Ähnlichkeitsurteil von den Faktoren Geometrie, Werkstoff und Drehmaschine abhängt

Intelligent documentation as a catalyst for developing cooperative knowledge-based systems

In the long run, the development of cooperative knowledge-based systems for complex real world domains such as production planning in mechanical engineering should yield significant economic returns. However, large investments have already been made into the conventional technology. Intelligent documentation, which abstracts the current practice of the industry, is suggested as a stepping stone for developing such knowledge-based systems. A set of coordinated knowledge acquisition tools has been developed by which intelligent documents are constructed as an intermediate product, which by itself is already useful. Within the frame of the conventional technology, the task- and domain specific hypertext structures allow the reuse of production plans while simultaneously starting the development process for knowledge based systems

COLREGs-Informed RRT* for Collision Avoidance of Marine Crafts

The paper proposes novel sampling strategies to compute the optimal path alteration of a surface vessel sailing in close quarters. Such strategy directly encodes the rules for safe navigation at sea, by exploiting the concept of minimal ship domain to determine the compliant region where the path deviation is to be generated. The sampling strategy is integrated within the optimal rapidly-exploring random tree algorithm, which minimizes the length of the path deviation. Further, the feasibility of the path with respect to the steering characteristics of own ship is verified by ensuring that the position of the new waypoints respects the minimum turning radius of the vessel. The proposed sampling strategy brings a significant performance improvement both in terms of optimal cost, computational speed and convergence rate.Comment: Accepted for publication at ICRA'2

Benchmarking and quality analysis of DEM generated from high and very high resolution optical stereo satellite data

The Working Group 4 of Commission I on ¿Geometric and Radiometric Modelling of Optical Spaceborne Sensors¿ provides on its website several stereo data sets from high and very high resolution spaceborne sensors. Among these are data from the 2.5 meter class like ALOS-PRISM and Cartosat-1 as well as, in near future, data from the highest resolution sensors (0.5 m class) like GeoEye-1 and Worldview-1 and -2. The region selected is an area in Catalonia, Spain, including city areas (Barcelona), rural areas and forests in flat and medium undulated terrain as well as steeper mountains. In addition to these data sets, ground truth data: orthoimages from airborne campaigns and Digital Elevation Models (DEM) produced by laser scanning, all data generated by the Institut Cartogràfic de Catalunya (ICC), are provided as reference for comparison. The goal is to give interested scientists of the ISPRS community the opportunity to test their algorithms on DEM generation, to see how they match with the reference data and to compare their results within the scientific community. A second goal is to develop further methodology for a common DEM quality analysis with qualitative and quantitative measures. Several proposals exist already and the working group is going to publish them on their website. But still there is a need for more standardized methodologies to quantify the quality even in cases where no better reference is available. The data sets, the goal of the benchmarking and first evaluation results are presented within the paper. Algorithms using area-based least squares matching are compared to those using additionally feature-based matching or newly developed algorithms from the Computer Vision community. The main goal though is to motivate further researchers to join the benchmarking and to discuss pros and cons of the methods as well as to trigger the process of establishing standardized DEM quality figures and procedures.JRC.DG.G.2-Global security and crisis managemen

Wiederholungs-, Varianten- und Neuplanung bei der Fertigung rotationssymmetrischer Drehteile

Diese Arbeit beschreibt eine empirische Studie zum Planungsverhalten menschlicher Experten bei der Fertigungsplanung im Maschinenbau. Im Rahmen der Studie wurden zwei Teiluntersuchungen durchgeführt. In der ersten Untersuchung waren eine Reihe von Planungsaufgaben für die Herstellung eines Werkstückes (definiert durch die Geometrie und den Werkstoff) in einer bestimmten Werkstatt (Drehmaschine) zu bearbeiten. Dabei wurden verschiedene Geometrien, Werkstoffe und Drehmaschinen einbezogen. Es wurde gezeigt, daß Experten bei der Fertigungsplanung zunächst eine erste Lösung auf einem abstrakteren Niveau, die als Planskelett (sceletal plan) bezeichnet wird, erarbeiten. Bei der Erstellung solcher wird auf bereits vorliegende Lösungen zurückgegriffen, die gegebenenfalls modifiziert werden. In einer zusammenfassenden Strukturierung. der Variantenplanungen konnten verschiedene Vorgehensweisen bei der Übertragung vorhandener Planskelette auf neue Fertigungsaufgaben unterschieden werden. In der zweiten Untersuchung war im Paarvergleich von Planungsaufgaben einzuschätzen, wie ähnlich deren resultierende Fertigungspläne sind. Dabei sollte Aufschluß darüber gewonnen werden, wie das Ähnlichkeitsurteil von den Faktoren Geometrie, Werkstoff und Drehmaschine abhängt

Sequential (gemcitabine/vinorelbine) and concurrent (gemcitabine) radiochemotherapy with FDG-PET-based target volume definition in locally advanced non-small cell lung cancer: first results of a phase I/II study

BACKGROUND: The aim of the study was to determine the maximal tolerated dose (MTD) of gemcitabine every two weeks concurrent to radiotherapy, administered during an aggressive program of sequential and simultaneous radiochemotherapy for locally advanced, unresectable non-small cell lung cancer (NSCLC) and to evaluate the efficacy of this regime in a phase II study. METHODS: 33 patients with histologically confirmed NSCLC were enrolled in a combined radiochemotherapy protocol. 29 patients were assessable for evaluation of toxicity and tumor response. Treatment included two cycles of induction chemotherapy with gemcitabine (1200 mg/m(2)) and vinorelbine (30 mg/m(2)) at day 1, 8 and 22, 29 followed by concurrent radiotherapy (2.0 Gy/d; total dose 66.0 Gy) and chemotherapy with gemcitabine every two weeks at day 43, 57 and 71. Radiotherapy planning included [(18)F] fluorodeoxyglucose positron emission tomography (FDG PET) based target volume definition. 10 patients were included in the phase I study with an initial gemcitabine dose of 300 mg/m(2). The dose of gemcitabine was increased in steps of 100 mg/m(2 )until the MTD was realized. RESULTS: MTD was defined for the patient group receiving gemcitabine 500 mg/m(2 )due to grade 2 (next to grade 3) esophagitis in all patients resulting in a mean body weight loss of 5 kg (SD = 1.4 kg), representing 8% of the initial weight. These patients showed persisting dysphagia 3 to 4 weeks after completing radiotherapy. In accordance with expected complications as esophagitis, dysphagia and odynophagia, we defined the MTD at this dose level, although no dose limiting toxicity (DLT) grade 3 was reached. In the phase I/II median follow-up was 15.7 months (4.1 to 42.6 months). The overall response rate after completion of therapy was 64%. The median overall survival was 19.9 (95% CI: [10.1; 29.7]) months for all eligible patients. The median disease-free survival for all patients was 8.7 (95% CI: [2.7; 14.6]) months. CONCLUSION: After induction chemotherapy, the maximum tolerated dose and frequency of gemcitabine was defined at 500 mg/m(2 )every two weeks in three cycles during a maximum of 7 weeks of thoracic radiotherapy for the phase II study. This regimen represents an effective and tolerable therapy in the treatment of NSCLC