Algorithmen zur Korrespondenzschätzung und Bildinterpolation für die photorealistische Bildsynthese

Free-viewpoint video is a new form of visual medium that has received considerable attention in the last 10 years. Most systems reconstruct the geometry of the scene, thus restricting themselves to synchronized multi-view footage and Lambertian scenes. In this thesis we follow a different approach and describe contributions to a purely image-based end-to-end system operating on sparse, unsynchronized multi-view footage. In particular, we focus on dense correspondence estimation and synthesis of in-between views. In contrast to previous approaches, our correspondence estimation is specifically tailored to the needs of image interpolation; our multi-image interpolation technique advances the state-of-the-art by disposing the conventional blending step. Both algorithms are put to work in an image-based free-viewpoint video system and we demonstrate their applicability to space-time visual effects production as well as to stereoscopic content creation.3D-Video mit Blickpunktnavigation ist eine neues digitales Medium welchem die Forschung in den letzten 10 Jahren viel Aufmerksamkeit gewidmet hat. Die meisten Verfahren rekonstruieren dabei die Szenengeometrie und schränken sich somit auf Lambertsche Szenen und synchron aufgenommene Eingabedaten ein. In dieser Dissertation beschreiben wir Beiträge zu einem rein bild-basierten System welches auf unsynchronisierten Eingabevideos arbeitet. Unser Fokus liegt dabei auf der Schätzung dichter Korrespondenzkarten und auf der Synthese von Zwischenbildern. Im Gegensatz zu bisherigen Verfahren ist unser Ansatz der Korrespondenzschätzung auf die Bedürfnisse der Bilderinterpolation ausgerichtet; unsere Zwischenbildsynthese verzichtet auf das Überblenden der Eingabebilder zu Gunsten der Lösung eines Labelingproblems. Das resultierende System eignet sich sowohl zur Produktion räumlich-zeitlicher Spezialeffekte als auch zur Erzeugung stereoskopischer Videosequenzen

On the Complexity of Parameterized Local Search for the Maximum Parsimony Problem

Maximum Parsimony is the problem of computing a most parsimonious phylogenetic tree for a taxa set X from character data for X. A common strategy to attack this notoriously hard problem is to perform a local search over the phylogenetic tree space. Here, one is given a phylogenetic tree T and wants to find a more parsimonious tree in the neighborhood of T. We study the complexity of this problem when the neighborhood contains all trees within distance k for several classic distance functions. For the nearest neighbor interchange (NNI), subtree prune and regraft (SPR), tree bisection and reconnection (TBR), and edge contraction and refinement (ECR) distances, we show that, under the exponential time hypothesis, there are no algorithms with running time |I|^o(k) where |I| is the total input size. Hence, brute-force algorithms with running time |X|^?(k) ? |I| are essentially optimal. In contrast to the above distances, we observe that for the sECR-distance, where the contracted edges are constrained to form a subtree, a better solution within distance k can be found in k^?(k) ? |I|^?(1) time

Dense Corresspondence Estimation for Image Interpolation

We evaluate the current state-of-the-art in dense correspondence estimation for the use in multi-image interpolation algorithms. The evaluation is carried out on three real-world scenes and one synthetic scene, each featuring varying challenges for dense correspondence estimation. The primary focus of our study is on the perceptual quality of the interpolation sequences created from the estimated flow fields. Perceptual plausibility is assessed by means of a psychophysical userstudy. Our results show that current state-of-the-art in dense correspondence estimation does not produce visually plausible interpolations.In diesem Bericht evaluieren wir den gegenwärtigen Stand der Technik in dichter Korrespondenzschätzung hinsichtlich der Eignung für die Nutzung in Algorithmen zur Zwischenbildsynthese. Die Auswertung erfolgt auf drei realen und einer synthetischen Szene mit variierenden Herausforderungen für Algorithmen zur Korrespondenzschätzung. Mittels einer perzeptuellen Benutzerstudie werten wir die wahrgenommene Qualität der interpolierten Bildsequenzen aus. Unsere Ergebnisse zeigen dass der gegenwärtige Stand der Technik in dichter Korrespondezschätzung nicht für die Zwischenbildsynthese geeignet ist

Flexible Stereoscopic 3D Content Creation of Real World Scenes

We propose an alternative over current approaches to stereoscopic 3D video content creation based on a free-viewpoint video. Acquisition and editing is greatly simplified. Our method is suitable for arbitrary real-world scenes. From unsynchronized multi-view video footage, our approach renders high-quality stereo sequences without the need to explicitly reconstruct any scene depth or geometry. By allowing to freely edit viewpoint, slow motion, freeze-rotate shots, depth-of-field, and many more effects, the presented approach extends the possibilities in stereo 3D movie creation.In diesem Report schlagen wir eine Alternative zu gegenwärtig in der Produktion von stereoskopischen Filmen verwendeten Techniken vor. Unser Ansatz basiert auf der Verwendung eines Systems zur Blickpunktnavigation. Die Aufnahme und die Editierung der Stereodaten wird dadurch erheblich vereinfacht. Unsere Methode generiert qualitativ hochwertige Stereosequenzen ohne dabei Szenengeometrie oder Szenetiefe explizit zu rekonstruieren. Das Verfahren ermöglicht es den Blickpunkt und die Wiedergabegeschwindigkeit zu ändern und visuelle Effekte zu integrieren, wodurch neue künstlerische Möglichkeiten in der stereoskopischen Filmproduktion erschlossen werden

Eine Ghosting-Artefakt Metrik zur Qualitätsmessung von interpolierten Bildern

We present a no-reference image quality metric for image interpolation. The approach is capable of detecting ghosting artifacts, e.g., in image based rendering scenarios. Based on the assumption that ghosting artifacts can be detected locally, perceived visual quality can be predicted from the amount of regions that are affected by ghosting. Because the approach does not require any reference image, it is very suitable, e.g., for assessing quality of image-based rendering techniques in general settings.Wir präsentieren ein referenzfreies Qualitätsmaß für interpolierte Bilder. Unser Ansatz kann Ghosting-Artefakte, welche z.B. in Bildbasierten Rendering-Verfahren auftreten, detektieren. Basierend auf der Annahme, dass Ghosting-Artefakte lokal detektiert werden können, kann die subjektiv wahrgenommene Bildqualität von der Anzahl der Regionen, in denen Ghosting detektiert wurde, prädiziert werden. Aufgrund der Tatsache, dass der Ansatz keine Referenzbilder benötigt, ist dieser sehr nützlich für die Qualitätskontrolle in Bildbasierten Rendering-Systemen

Wahrnehmungsbasierte Bildinterpolation

We present a perception-based method for image interpolation, aiming for perceptually convincing transitions between real-world images. Without 3D geometry or scene motion, perception-based image interpolation enables smooth viewpoint navigation across space and time. We show how global visual effects can be created from a collection of unsynchronized, uncalibrated images. A user study confirms the perceptual quality of the proposed image interpolation approach

Renal denervation reduces atrial remodeling in hypertensive rats with metabolic syndrome

Atrial fibrillation (AF) is highly prevalent in hypertensive patients with metabolic syndrome and is related to inflammation and activation of the sympathoadrenergic system. The multi-ligand Receptor-for-Advanced-Glycation-End-products (RAGE) activates inflammation-associated tissue remodeling and is regulated by the sympathetic nervous system. Its counterpart, soluble RAGE (sRAGE), serves as anti-inflammatory decoy receptor with protective properties. We investigated the effect of sympathetic modulation by renal denervation (RDN) on atrial remodeling, RAGE/sRAGE and RAGE ligands in metabolic syndrome. RDN was performed in spontaneously hypertensive obese rats (SHRob) with metabolic syndrome compared with lean spontaneously hypertensive rats (SHR) and with normotensive non-obese control rats. Blood pressure and heart rate were measured by telemetry. The animals were killed 12 weeks after RDN. Left atrial (LA) and right atrial (RA) remodeling was assessed by histological analysis and collagen types. Sympathetic innervation was measured by tyrosine hydroxylase staining of atrial nerve fibers, RAGE/sRAGE, RAGE ligands, cytokine expressions and inflammatory infiltrates were analyzed by Western blot and immunofluorescence staining. LA sympathetic nerve fiber density was higher in SHRob (+44%) versus controls and reduced after RDN (-64% versus SHRob). RAGE was increased (+718%) and sRAGE decreased (− 62%) in SHRob as compared with controls. RDN reduced RAGE expression (− 61% versus SHRob), significantly increased sRAGE levels (+162%) and induced a significant decrease in RAGE ligand levels in SHRob (− 57% CML and − 51% HMGB1) with reduced pro-inflammatory NFkB activation (− 96%), IL-6 production (− 55%) and reduced inflammatory infiltrates. This led to a reduction in atrial fibrosis (− 33%), collagen type I content (− 72%), accompanied by reduced LA myocyte hypertrophy (− 21%). Transfection experiments on H9C2 cardiomyoblasts demonstrated that RAGE is directly involved in fibrosis formation by influencing cellular production of collagen type I. In conclusion, suppression of renal sympathetic nerve activity by RDN prevents atrial remodeling in metabolic syndrome by reducing atrial sympathetic innervation and by modulating RAGE/sRAGE balance and reducing pro-inflammatory and pro-fibrotic RAGE ligands, which provides a potential therapeutic mechanism to reduce the development of AF

Gain and Loss of Multiple Genes During the Evolution of Helicobacter pylori

Sequence diversity and gene content distinguish most isolates of Helicobacter pylori. Even greater sequence differences differentiate distinct populations of H. pylori from different continents, but it was not clear whether these populations also differ in gene content. To address this question, we tested 56 globally representative strains of H. pylori and four strains of Helicobacter acinonychis with whole genome microarrays. Of the weighted average of 1,531 genes present in the two sequenced genomes, 25% are absent in at least one strain of H. pylori and 21% were absent or variable in H. acinonychis. We extrapolate that the core genome present in all isolates of H. pylori contains 1,111 genes. Variable genes tend to be small and possess unusual GC content; many of them have probably been imported by horizontal gene transfer. Phylogenetic trees based on the microarray data differ from those based on sequences of seven genes from the core genome. These discrepancies are due to homoplasies resulting from independent gene loss by deletion or recombination in multiple strains, which distort phylogenetic patterns. The patterns of these discrepancies versus population structure allow a reconstruction of the timing of the acquisition of variable genes within this species. Variable genes that are located within the cag pathogenicity island were apparently first acquired en bloc after speciation. In contrast, most other variable genes are of unknown function or encode restriction/modification enzymes, transposases, or outer membrane proteins. These seem to have been acquired prior to speciation of H. pylori and were subsequently lost by convergent evolution within individual strains. Thus, the use of microarrays can reveal patterns of gene gain or loss when examined within a phylogenetic context that is based on sequences of core genes

Current Approaches to the Management of Sentinel Node Procedures in Early Vulvar Cancer in Germany : A Web-Based Nationwide Analysis of Practices

Background: Lymph node involvement is the most important prognostic factor for recurrence and survival in vulvar cancer. Sentinel node (SN) procedure can be offered in well-selected patients with early vulvar cancer. This study aimed to assess current management practices with respect to the sentinel node procedure in women with early vulvar cancer in Germany. Methods: A Web-based survey was conducted. Questionnaires were e-mailed to 612 gynecology departments. Data were summarized as frequencies and analyzed using the chi-square test. Results: A total of 222 hospitals (36.27%) responded to the invitation to participate. Among the responders, 9.5% did not offer the SN procedure. However, 79.5% evaluated SNs by ultrastaging. In vulvar cancer of the midline with unilateral localized positive SN, 49.1% and 48.6% of respondents, respectively, would perform ipsilateral or bilateral inguinal lymph node dissection. Repeat SN procedure was performed by 16.2% of respondents. For isolated tumor cells (ITCs) or micrometastases, 28.1% and 60.5% of respondents, respectively, would perform inguinal lymph node dissection, whereas 19.3% and 23.8%, respectively, would opt for radiation without further surgical intervention. Notably, 50.9% of respondents would not initiate any further therapy and 15.1% would opt for expectant management. Conclusions: The majority of German hospitals implement the SN procedure. However, only 79.5% of respondents performed ultrastaging and only 28.1% were aware that ITC may affect survival in vulvar cancer. There is a need to ensure that the management of vulvar cancer follows the latest recommendations and clinical evidence. Deviations from state-of-the-art management should only be after a detailed discussion with the concerned patient

Concepts and Measurement in Multimethod Research

This article argues that concept misformation and conceptual stretching undermine efforts to combine qualitative and quantitative methods in multimethod research (MMR). Two related problems result from the mismatch of qualitatively and quantitatively construed concepts. Mechanism muddling occurs when differences in the connotation of qualitatively and quantitatively construed concepts embed different causal properties into conceptual definitions. Conceptual slippage occurs when qualitatively and quantitatively construed concepts use incompatible nominal, ordinal, or radial scales. Instead of gaining leverage from the synthesis of large- and small-N analysis, these problems can push MMR in two diametrically opposed directions, emphasizing one methodological facet at the cost of the other.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline