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Krause, Tom; Dolereit, Tim; Vahl, Matthias

Nutzung von Stereo-Hochkontrast-Aufnahmen für eine bodengestützte, automatische Bestimmung von Schüttgutmaterialien und für die Erkennung der Belegung von Außenlagerflächen in Häfen

2017

Lukas, Uwe von (Ed.) et al.: Go-3D 2017: Mit 3D Richtung Maritim 4.0 : Tagungsband zur Konferenz Go-3D 2017. Stuttgart: Fraunhofer Verlag, 2017, pp. 157-166

Go-3D <8, 2017, Rostock, Germany>

In diesem Artikel wird ein Stereokameraaufbau vorgeschlagen, welcher es ermöglicht, über weite Distanzen einen Schüttguthaufen freizustellen und seine Art (Sand, Kies, Roheisen) zu bestimmen. Durch Aufnahme von Belichtungsreihen werden Hochkontrastbilder gewonnen. Somit ist das System für Außenaufnahmen bei jedem Wetter geeignet. Der vorgestellte Ansatz arbeitet in fünf Schritten: Aufnahme von Stereo- Hochkontrastbildern, Bildvorverarbeitung, Semi-global Blockmatching, Segmentierung/Rücktransformation und Materialerkennung. Es wird in diesem Artikel gezeigt, dass dieses Verfahren robust gegenüber Wetterbedingungen ist, eine zuverlässige Segmentierung auf Basis der Tiefeninformationen erreicht und die korrekte Materialbestimmung ermöglicht.

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Dolereit, Tim; Lukas, Uwe von

Calibration of Shared Flat Refractive Stereo Systems

2016

Aurélio, Campilho (Ed.) et al.: Image Analysis and Recognition : ICIAR 2016. Switzerland: Springer International Publishing, 2016. (Lecture Notes in Computer Science (LNCS) 9730), pp. 433-442

International Conference on Image Analysis and Recognition (ICIAR) <13, 2016, Póvoa de Varzim, Portugal>

The calibration of underwater camera systems differs significantly from calibration in air due to the refraction of light. In this paper, we present a calibration approach for a shared flat refractive stereo system that is based on virtual object points. We propose a sampling strategy in combination with an efficiently solvable set of equations for the calibration of the refractive parameters. Due to the independence of calibration targets of known dimensions, the approach can be realized by using stereo correspondences alone.

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Schulz, Jan; Möller, Klas Ove; Bracher, Astrid; Hieronymi, Martin; Cisewski, Boris; Zielinski, Olver; Voss, Daniela; Gutzeit, Enrico; Dolereit, Tim; Niedzwiedz, Gern; Kohlberg, Gesche; Schories, Dirk; Kiko, Rainer; Körtzinger, Arne; Falldorf, Claas; Fischer, Philipp; Nowald, Nicolas; Beisiegel, Kolja; Martinez-Arbizu, Pedro; Rüssmeier, Nick; Röttgers, Rüdiger; Büdenbender, Jan; Jordt-Sedlazeck, Anne; Koch, Reinhard; Riebesell, Ulf; Hvitfeldt Iversen, Morten; Köser, Kevin; Kwasnitschka, Tom; Wellhausen, Jens; Thoma, Christoph; Barz, Christina; Rohde, Sven; Nattkemper, Tim W.; Schoening, Timm; Peeters, Frank; Hofmann, Hilmar; Busch, Julia A.; Hircher, Hans-Jürgen; Niehoff, Barbara; Hildebrandt, Nicole; Stohr, Erik; Winter, Christian; Herbst, Gabriel; Konrad, Christian; Schmidt, Mark; Linke, Peter; Brey, Thomas; Bange, Hermann W.; Nolle, Lars; Krägefsky, Sören; Gröger, Joachim; Sauter, Eberhard; Schulz, Miriam; Müller, Jens; Rehder, Gregor; Stepputtis, Daniel; Beszteri, Bank; Kloster, Michael; Kauer, Gerhard; Göritz, Anna; Gege, Peter; Lukas, Uwe von; Bathmann, Ulrich

Aquatische Optische Technologien in Deutschland

2015

2015

Meereswissenschaftliche Berichte 97

Optische Technologien und Verfahren sind sowohl in der limnischen als auch marinen Forschung Deutschlands über alle Bereiche und Skalen etabliert und entwickeln sich rasant weiter. Die Arbeitsgruppe ,Aquatische Optische Technologien" (AOT) will Forschern und Anwendern eine Plattform bieten, die Wissenstransfer fördert, der nationalen Entwicklergemeinschaft ein synergistisches Umfeld eröffnet und die internationale Sichtbarkeit der deutschen Aktivitäten in diesem Forschungsfeld erhöht. Diese Zusammenfassung dokumentiert erstmalig die AOT-Verfahren und -Technologien, die von nationalen Forschungsinstitutionen eingesetzt werden. Wir erwarten, dass die Dokumentation einen Trend in Richtung institutsübergreifender Harmonisierung initiiert. Dies wird die Etablierung offener Standards, eine Verbesserung im Zugang zu Dokumentationen und gegenseitige technischer Hilfestellung bei (System-) Integrationen ermöglichen. Effizienz und Leistungsfähigkeit der AOT-Entwicklung und Anwendung auf nationaler Ebene werden von diesen Bestrebungen profitieren. Weitere Arbeitsgruppen und Entwickler werden ausdrücklich ermutigt, Kontakt aufzunehmen, um in einer späteren Auflage berücksichtigt zu werden.

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Dolereit, Tim

Concepts for Underwater Stereo Calibration, Stereo 3D-Reconstruction and Evaluation

2015

Schulz, Hans-Jörg (Ed.) et al.: Proceedings of the International Summer School on Visual Computing 2015. Stuttgart: Fraunhofer Verlag, 2015, pp. 71-80

International Summer School on Visual Computing <1, 2015, Rostock, Germany>

Handling refractive effects in computer vision disciplines like underwater stereo camera system calibration or 3D-reconstruction is a major challenge. Refraction occurs at the borders between different media on the way of the light and introduces non-linear distortions, that are dependent on the imaged scene. In this paper, concepts will be proposed for the calibration of a stereo camera system including a set of additional refractive parameters, for underwater stereo 3D-reconstruction and for evaluation of the computations.

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Dolereit, Tim; Lukas, Uwe von; Kuijper, Arjan

New Constraints for Underwater Stereo Calibration

2015

Loncaric, Sven (Ed.) et al.: ISPA 2015 : 9th International Symposium on Image and Signal Processing and Analysis. Zagreb: University of Zagreb, 2015, pp. 176-181

International Symposium on Image and Signal Processing and Analysis (ISPA) <9, 2015, Zagreb, Croatia>

In this paper we present new constraints for calibration of underwater stereo-camera-systems and 3Dreconstruction. These constraints are both intuitive and simple to realize. We show that additionally needed refractive parameters in such a system can be calibrated simultaneously. Our constraints partially build upon each other. A subset of them even enables the calibration from stereo-correspondences alone, making known calibration targets unnecessary.

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Lukas, Uwe von; Quarles, John; Kaklis, Panagiotis; Dolereit, Tim

Underwater Mixed Environments

2015

Brunnett, Guido (Ed.) et al.: Virtual Realities : International Dagstuhl Seminar, Dagstuhl Castle, Germany, June 9-14, 2013, Revised Selected Papers. Schweiz: Springer International Publishing, 2015. (Lecture Notes in Computer Science (LNCS) 8844), pp. 56-76

International Dagstuhl-Seminar <2013, Dagstuhl Castle, Germany>

In this chapter we give a systematic overview over Virtual Reality (VR) and Augmented Reality (AR) in underwater settings and suggest several future applications. Based on a novel classification scheme we illustrate the broad range of available and future implementation options. Whilst we find a variety of previous work on creating and using virtual underwater worlds, quite few examples of real underwater settings exist up to now. Thus, we concentrate on this new category, sketch attractive application areas that go beyond entertainment, and derive requirements for Underwater Mixed Environments (UWME). Combined with a short summary on relevant aspects of underwater optics, we formulate potential topics of future research to overcome current limitations of UWME.

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Dolereit, Tim; Lukas, Uwe von; Kuijper, Arjan

Underwater Stereo Calibration Utilizing Virtual Object Points

2015

Marine Technology Society (MTS): OCEANS 2015 MTS/IEEE Washington. The Institute of Electrical and Electronics Engineers (IEEE), 2015, 7 p.

MTS/IEEE Oceans Conference and Exhibition (OCEANS) <2015, Genova, Italy>

For 3D-reconstruction of underwater scenes, a camera calibration handling refractive effects is indispensable. We present a novel geometry-based approach for calibration of stereo-camera-systems in a single underwater housing with a flat interface. Our approach consists of three steps. First, we show a hypothesis on how to relate the location of virtual object points non-ambiguously to the true object location in water. Secondly, axis determination and thirdly, distance determination of a refractive interface towards the cameras is performed with the aid of this hypothesis. We propose, that the calibration can be done with just one stereo-view of a known calibration pattern, that axis determination can be done from stereo correspondences alone and that our hypothesis is a valid constraint for stereo 3d-reconstruction. We evaluated our approach on simulated data with ground truth and real data.

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Gutzeit, Enrico; Scheel, Christian; Dolereit, Tim; Rust, Matthias

Contour Based Split and Merge Segmentation and Pre-classification of Zooplankton in Very Large Images

2014

Battiato, Sebastiano (Ed.) et al.: VISAPP 2014 - Volume I : Proceedings of the International Conference on Computer Vision Theory and Applications. SciTePress, 2014, pp. 417-424

International Conference on Computer Vision Theory and Applications (VISAPP) <9, 2014, Lisbon, Portugal>

Zooplankton is an important component in the water ecosystem and food chain. To understand the influence of zooplankton on the ecosystem a data collection is necessary. In research the automatic image based recognition of zooplankton is of growing interest. Several systems have been developed for zooplankton recognition on low resolution images. For large images approaches are seldom. Images of this size easily exceed the main memory of standard computers. Our novel automatic segmentation approach is able to handle these large images. We developed a contour based Split & Merge approach for segmentation and, to reduce the nonzooplankton segments, combine it with a pre-classification of the segments in reference to their shape. The latter includes a detection of quasi round segments and a novel one for thin segments. Experimental results on several large images show that we are able to handle them satisfactorily.

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Dolereit, Tim; Kuijper, Arjan

Converting Underwater Imaging into Imaging in Air

2014

Battiato, Sebastiano (Ed.) et al.: VISAPP 2014 - Volume I : Proceedings of the International Conference on Computer Vision Theory and Applications. SciTePress, 2014, pp. 96-103

International Conference on Computer Vision Theory and Applications (VISAPP) <9, 2014, Lisbon, Portugal>

The application of imaging devices in underwater environments has become a common practice. Protecting the camera's constituent electric parts against water leads to refractive effects emanating from the water-glassair transition of light rays. These non-linear distortions can not be modeled by the pinhole camera model. For our new approach we focus on flat interface systems. By handling refractive effects properly, we are able to convert the problem to imaging conditions in air. We show that based on the location of virtual object points in water, virtual parameters of a camera following the pinhole camera model can be computed per image ray. This enables us to image the same object as if it was situated in air. Our novel approach works for an arbitrary camera orientation to the refractive interface. We show experimentally that our adopted physical methods can be used for the computation of 3D object points by a stereo camera system with much higher precision than with a naive in-situ calibration.