@phdthesis{Voelske, author = {V{\"o}lske, Michael}, title = {Retrieval Enhancements for Task-Based Web Search}, doi = {10.25643/bauhaus-universitaet.3942}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20190709-39422}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {The task-based view of web search implies that retrieval should take the user perspective into account. Going beyond merely retrieving the most relevant result set for the current query, the retrieval system should aim to surface results that are actually useful to the task that motivated the query. This dissertation explores how retrieval systems can better understand and support their users' tasks from three main angles: First, we study and quantify search engine user behavior during complex writing tasks, and how task success and behavior are associated in such settings. Second, we investigate search engine queries formulated as questions, and explore patterns in a large query log that may help search engines to better support this increasingly prevalent interaction pattern. Third, we propose a novel approach to reranking the search result lists produced by web search engines, taking into account retrieval axioms that formally specify properties of a good ranking.}, subject = {Information Retrieval}, language = {en} } @article{KleinerRoesslerVogtetal., author = {Kleiner, Florian and R{\"o}ßler, Christiane and Vogt, Franziska and Osburg, Andrea and Ludwig, Horst-Michael}, title = {Reconstruction of calcium silicate hydrates using multiple 2D and 3D imaging techniques: Light microscopy, μ-CT, SEM, FIB-nT combined with EDX}, series = {Journal of Microscopy}, volume = {2021}, journal = {Journal of Microscopy}, publisher = {John Wiley \& Sons Ltd}, address = {Oxford}, doi = {10.1111/jmi.13081}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220106-45458}, pages = {1 -- 6}, abstract = {This study demonstrates the application and combination of multiple imaging techniques [light microscopy, micro-X-ray computer tomography (μ-CT), scanning electron microscopy (SEM) and focussed ion beam - nano-tomography (FIB-nT)] to the analysis of the microstructure of hydrated alite across multiple scales. However, by comparing findings with mercury intrusion porosimetry (MIP), it becomes obvious that the imaged 3D volumes and 2D images do not sufficiently overlap at certain scales to allow a continuous quantification of the pore size distribution (PSD). This can be overcome by improving the resolution and increasing the measured volume. Furthermore, results show that the fibrous morphology of calcium-silicate-hydrates (C-S-H) phases is preserved during FIB-nT. This is a requirement for characterisation of nano-scale porosity. Finally, it was proven that the combination of FIB-nT with energy-dispersive X-ray spectroscopy (EDX) data facilitates the phase segmentation of a 11 × 11 × 7.7 μm3 volume of hydrated alite.}, subject = {Zementklinker}, language = {en} } @unpublished{GrundhoeferBimber2006, author = {Grundh{\"o}fer, Anselm and Bimber, Oliver}, title = {Real-Time Adaptive Radiometric Compensation}, doi = {10.25643/bauhaus-universitaet.784}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-7848}, year = {2006}, abstract = {Recent radiometric compensation techniques make it possible to project images onto colored and textured surfaces. This is realized with projector-camera systems by scanning the projection surface on a per-pixel basis. With the captured information, a compensation image is calculated that neutralizes geometric distortions and color blending caused by the underlying surface. As a result, the brightness and the contrast of the input image is reduced compared to a conventional projection onto a white canvas. If the input image is not manipulated in its intensities, the compensation image can contain values that are outside the dynamic range of the projector. They will lead to clipping errors and to visible artifacts on the surface. In this article, we present a novel algorithm that dynamically adjusts the content of the input images before radiometric compensation is carried out. This reduces the perceived visual artifacts while simultaneously preserving a maximum of luminance and contrast. The algorithm is implemented entirely on the GPU and is the first of its kind to run in real-time.}, subject = {Maschinelles Sehen}, language = {en} } @misc{Wetzstein2006, type = {Master Thesis}, author = {Wetzstein, Gordon}, title = {Radiometric Compensation of Global Illumination Effects with Projector-Camera Systems}, doi = {10.25643/bauhaus-universitaet.810}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-8106}, school = {Bauhaus-Universit{\"a}t Weimar}, year = {2006}, abstract = {Projector-based displays have been evolving tremendously in the last decade. Reduced costs and increasing capabilities have let to a widespread use for home entertainment and scientific visualization. The rapid development is continuing - techniques that allow seamless projection onto complex everyday environments such as textured walls, window curtains or bookshelfs have recently been proposed. Although cameras enable a completely automatic calibration of the systems, all previously described techniques rely on a precise mapping between projector and camera pixels. Global illumination effects such as reflections, refractions, scattering, dispersion etc. are completely ignored since only direct illumination is taken into account. We propose a novel method that applies the light transport matrix for performing an image-based radiometric compensation which accounts for all possible lighting effects. For practical application the matrix is decomposed into clusters of mutually influencing projector and camera pixels. The compensation is modeled as a linear equation system that can be solved separately for each cluster. For interactive compensation rates this model is adapted to enable an efficient implementation on programmable graphics hardware. Applying the light transport matrix's pseudo-inverse allows to separate the compensation into a computational expensive preprocessing step (computing the pseudo-inverse) and an on-line matrix-vector multiplication. The generalized mathematical foundation for radiometric compensation with projector-camera systems is validated with several experiments. We show that it is possible to project corrected imagery onto complex surfaces such as an inter-reflecting statuette and glass. The overall sharpness of defocused projections is increased as well. Using the proposed optimization for GPUs, real-time framerates are achieved.}, subject = {Association for Computing Machinery / Special Interest Group on Graphics}, language = {en} } @incollection{Bimber2006, author = {Bimber, Oliver}, title = {Projector-Based Augmentation}, series = {Emerging Technologies of Augmented Reality: Interfaces \& Design}, booktitle = {Emerging Technologies of Augmented Reality: Interfaces \& Design}, doi = {10.25643/bauhaus-universitaet.735}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-7353}, year = {2006}, abstract = {Projector-based augmentation approaches hold the potential of combining the advantages of well-establishes spatial virtual reality and spatial augmented reality. Immersive, semi-immersive and augmented visualizations can be realized in everyday environments - without the need for special projection screens and dedicated display configurations. Limitations of mobile devices, such as low resolution and small field of view, focus constrains, and ergonomic issues can be overcome in many cases by the utilization of projection technology. Thus, applications that do not require mobility can benefit from efficient spatial augmentations. Examples range from edutainment in museums (such as storytelling projections onto natural stone walls in historical buildings) to architectural visualizations (such as augmentations of complex illumination simulations or modified surface materials in real building structures). This chapter describes projector-camera methods and multi-projector techniques that aim at correcting geometric aberrations, compensating local and global radiometric effects, and improving focus properties of images projected onto everyday surfaces.}, subject = {Erweiterte Realit{\"a}t }, language = {en} } @techreport{GrossOemig2008, author = {Gross, Tom and Oemig, Christoph}, title = {Presence, Privacy, and PRIMIFaces: Towards Selective Information Disclosure in Instant Messaging}, doi = {10.25643/bauhaus-universitaet.1275}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20080314-13452}, year = {2008}, abstract = {Efficient distant cooperation often requires spontaneous ad-hoc social interaction, which is only possible with adequate information on the prospective communication partner. This often requires disclosing and sharing personal information via tools such as instant messaging systems and can conflict with the users' wishes for privacy. In this paper we present an initial study investigating this trade-off and discuss implications for the design of instant messaging systems. We present the functionality and design of the PRIMIFaces instant messaging prototype supporting flexible identity management and selective information disclosure.}, subject = {Angewandte Informatik}, language = {en} } @article{VakkariVoelskePotthastetal., author = {Vakkari, Pertti and V{\"o}lske, Michael and Potthast, Martin and Hagen, Matthias and Stein, Benno}, title = {Predicting essay quality from search and writing behavior}, series = {Journal of Association for Information Science and Technology}, volume = {2021}, journal = {Journal of Association for Information Science and Technology}, number = {volume 72, issue 7}, publisher = {Wiley}, address = {Hoboken, NJ}, doi = {10.1002/asi.24451}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210804-44692}, pages = {839 -- 852}, abstract = {Few studies have investigated how search behavior affects complex writing tasks. We analyze a dataset of 150 long essays whose authors searched the ClueWeb09 corpus for source material, while all querying, clicking, and writing activity was meticulously recorded. We model the effect of search and writing behavior on essay quality using path analysis. Since the boil-down and build-up writing strategies identified in previous research have been found to affect search behavior, we model each writing strategy separately. Our analysis shows that the search process contributes significantly to essay quality through both direct and mediated effects, while the author's writing strategy moderates this relationship. Our models explain 25-35\% of the variation in essay quality through rather simple search and writing process characteristics alone, a fact that has implications on how search engines could personalize result pages for writing tasks. Authors' writing strategies and associated searching patterns differ, producing differences in essay quality. In a nutshell: essay quality improves if search and writing strategies harmonize—build-up writers benefit from focused, in-depth querying, while boil-down writers fare better with a broader and shallower querying strategy.}, subject = {Information Retrieval}, language = {en} } @techreport{FoecklerZeidlerBimber2005, author = {F{\"o}ckler, Paul and Zeidler, Thomas and Bimber, Oliver}, title = {PhoneGuide: Museum Guidance Supported by On-Device Object Recognition on Mobile Phones}, doi = {10.25643/bauhaus-universitaet.650}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-6500}, year = {2005}, abstract = {We present PhoneGuide - an enhanced museum guidance approach that uses camera-equipped mobile phones and on-device object recognition. Our main technical achievement is a simple and light-weight object recognition approach that is realized with single-layer perceptron neuronal networks. In contrast to related systems which perform computational intensive image processing tasks on remote servers, our intention is to carry out all computations directly on the phone. This ensures little or even no network traffic and consequently decreases cost for online times. Our laboratory experiments and field surveys have shown that photographed museum exhibits can be recognized with a probability of over 90\%. We have evaluated different feature sets to optimize the recognition rate and performance. Our experiments revealed that normalized color features are most effective for our method. Choosing such a feature set allows recognizing an object below one second on up-to-date phones. The amount of data that is required for differentiating 50 objects from multiple perspectives is less than 6KBytes.}, subject = {Neuronales Netz}, language = {en} } @article{BrunsBimber2008, author = {Bruns, Erich and Bimber, Oliver}, title = {Phone-to-Phone Communication for Adaptive Image Classification}, doi = {10.25643/bauhaus-universitaet.1296}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20080722-13685}, year = {2008}, abstract = {In this paper, we present a novel technique for adapting local image classifiers that are applied for object recognition on mobile phones through ad-hoc network communication between the devices. By continuously accumulating and exchanging collected user feedback among devices that are located within signal range, we show that our approach improves the overall classification rate and adapts to dynamic changes quickly. This technique is applied in the context of PhoneGuide - a mobile phone based museum guidance framework that combines pervasive tracking and local object recognition for identifying a large number of objects in uncontrolled museum environments.}, subject = {Peer-to-Peer-Netz}, language = {en} } @article{WiegmannKerstenSenaratneetal., author = {Wiegmann, Matti and Kersten, Jens and Senaratne, Hansi and Potthast, Martin and Klan, Friederike and Stein, Benno}, title = {Opportunities and risks of disaster data from social media: a systematic review of incident information}, series = {Natural Hazards and Earth System Sciences}, volume = {2021}, journal = {Natural Hazards and Earth System Sciences}, number = {Volume 21, Issue 5}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, doi = {10.5194/nhess-21-1431-2021}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210804-44634}, pages = {1431 -- 1444}, abstract = {Compiling and disseminating information about incidents and disasters are key to disaster management and relief. But due to inherent limitations of the acquisition process, the required information is often incomplete or missing altogether. To fill these gaps, citizen observations spread through social media are widely considered to be a promising source of relevant information, and many studies propose new methods to tap this resource. Yet, the overarching question of whether and under which circumstances social media can supply relevant information (both qualitatively and quantitatively) still remains unanswered. To shed some light on this question, we review 37 disaster and incident databases covering 27 incident types, compile a unified overview of the contained data and their collection processes, and identify the missing or incomplete information. The resulting data collection reveals six major use cases for social media analysis in incident data collection: (1) impact assessment and verification of model predictions, (2) narrative generation, (3) recruiting citizen volunteers, (4) supporting weakly institutionalized areas, (5) narrowing surveillance areas, and (6) reporting triggers for periodical surveillance. Furthermore, we discuss the benefits and shortcomings of using social media data for closing information gaps related to incidents and disasters.}, subject = {Katastrophe}, language = {en} }