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Global exploration in Markov chain Monte Carlo methods for light transport simulation
Šik, Martin ; Křivánek, Jaroslav (advisor) ; Jakob, Wenzel (referee) ; Christensen, Per (referee)
Monte Carlo light transport simulation has become a de-facto standard tool for photorealistic rendering. However, the algorithms used by the current rendering systems are often ineffective, especially in scenes featuring light transport due to multiple highly glossy or specular interactions and complex visibility between the camera and light sources. It is therefore desirable to adopt more robust algorithms in practice. Light transport algorithms based on Markov chain Monte Carlo (MCMC) are known to be effective at sampling many different kinds of light transport paths even in the presence of complex visibility. However, the current MCMC algorithms often over-sample some of the paths while under-sampling or completely missing other paths. We attribute this behavior to insufficient global exploration of path space which leads to their unpredictable convergence and causes the occurrence of image artifacts. This in turn prohibits adoption of MCMC algorithms in practice. In this thesis we therefore focus on improving global exploration in MCMC algorithms for light transport simulation. First, we present a new MCMC algorithm that utilizes replica exchange to improve global exploration. To maximize efficiency of replica exchange we introduce tempering of the path space, which allows easier discovery of important...
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The analysis of limits for multimode fibre imaging
Štolzová, Hana ; Kozubek, Michal (referee) ; Dostál, Zbyněk (advisor)
Multimódová vlákna jsou zobrazovacím prostředkem s významným potenciálem v in-vivo mikroendoskopii. V poslední době tato metoda zaznamenala velký rozvoj, a to díky zdokonalování výpočetní a jiné techniky, například prostorové modulace světla. Cílem této práce bylo nalézt specifické limity zobrazování multimódovými vlákny a představit jejich počítačovou simulaci. Byl zkoumán vliv způsobu osvětlení optického systému obsahujícího multimódové vlákno na jeho schopnost fokusace a zobrazování. Analýzou dat získaných ze simulací a experimentu bylo zjištěno, že různá míra omezení Gaussovského svazku a plnění apertury multimódového vlákna má za následek významnou změnu zobrazovacích schopností systému. Při pozorování kvality fokusace bylo zjištěno, že nejlépe se projevují svazky málo omezené aperturou vlákna. Tento fakt byl potvrzen i experimentálním měřením. Zobrazování za použití svazků s podobnými hodnotami omezení (50%) projevovalo i nejlepší schopnost přenosu kontrastu. Avšak při analýze rozlišení dvou bodových objektů se jako nejvhodnější projevily svazky významně přeplňující numerickou aperturu vlákna, 100% a více. Přítomnost tohoto rozdílu poukazuje na skutečnost, že multimódové vlákno není zcela náhodné médium, ale propagace světla skrz multimódové vlákno projevuje znaky závislosti na vnějších zobrazovacích podmínkách, jako je například změna omezení osvětlovacího svazku. V této práci bylo představeno několik způsobů vyhodnocení kvality zobrazování pomocí multimódového vlákna. Každé z těchto kritérií podalo dílčí charakteristiku chování optického systému obsahujícího multimódové optické vlákno. Jednotlivé výsledky se neshodují na jednom konkrétním řešení a nutí osobu využívající zobrazovací systém obsahující multimódové vlákno ke zvážení několika aspektů, a to v jakém prostředí bude daný optický systém využívat a který parametr kvality zobrazení bude považovat za nejdůležitější.
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Atomic force microscopy in the region of biomacromolecules
Vančura, Martin ; Kopecký, Vladimír (advisor) ; Bednárová, Lucie (referee)
Atomic force microscopy (AFM) enables sample imaging at the micro and nanoscale. Recently, the method is applied to investigate biomacromolecules. Here, we describe the basic principles of AFM with a special emphasis for bioapplications. We tested experimental abilities of Alpha 300 - the Raman microscope with AFM/SNOM accessory from WITec company. The ability of AFM to study objects of cellular dimensions was demonstrated on erythrocytes and green algae Desmodesmus quadricauda. We were able to observe growing of lysozyme protein fibrils on day scale - from dimensions of seeds (~3 nm height) up to fibrils itself (3-10 nm height and 100 nm up to micrometers length). Subsequently, we observed separate protein molecules of thyroglobulin (~6 nm) and also γ-globulin (~3 nm). It seems plausible to image objects up to 2 nm dimensions by the given device with respect to the signal/noise ratio.
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Efficient rendering of fine structures on object surfaces
Brečka, Bohuš ; Křivánek, Jaroslav (advisor) ; Kondapaneni, Ivo (referee)
Current methods for realistic rendering approximate surface microstructure using a smooth normal distribution function. This approach is not sufficient for the rendering of shiny surfaces with details (such as scratches) visible under bright light in real world. It is possible to model surface structure with high-resolution normal maps, but this approach leads to unreasonable rendering times when used with modern rendering methods based on stochastic sampling. In this thesis, we explore some of the approaches specifically designed to address this problem. As a main topic we choose the algorithm proposed by Yen et al. [2016]. We analyse, implement it, compare it with other approaches and propose some improvements. As a part of this work we implement a rendering system based on the path tracing algorithm, which is used as an environment for testing and visualization of our results.
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Possibilities of three-dimensional creation in kindergarten
KIMROVÁ, Eva
The aim of the thesis is to introduce and test in practice a variety of options of threedimensional crafts on the topic "Fauna" in kindergarten. The theoretical part deals with the contribution of spatial art, its influence on the development of imagination,thinking and overall personality of the child. Social learning is of great importance, as children cooperate during the activities. The work introduces different kinds of crafts in terms of used material and the environment in which they are created. The practical part focuses on creating three-dimensional crafts of animals. The topic of fauna is very popular with children and they can be extremely enthusiastic about the activities. Individual craft projects are described and documented in detail, as well as evaluated according to the interests and abilities of children and according to educational strategies.
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Dysfunctions of interneurons in schizophrenia
Hrůzová, Karolína ; Stuchlík, Aleš (advisor) ; Weissová, Kamila (referee)
Schizophrenia is a serious neuropsychiatric disorder characterised by abnormal behaviours, perception and thoughts. It is a neurodevelopmental disease of two types of factors - genetic predispositions and environmental factors. The exact cause of schizophrenia remains, however, elusive. Interneurons are types of neurons, mostly exerting inhibitory action and their dysfunctions are associated with pathogenesis of schizophrenia. They are essential in the generation of neuronal oscillations, which play an important role in cognitive functions. Disruption of these oscillations (especially gamma band) could be paralleled by negative, positive or cognitive symptoms of schizophrenia. These interactions could be possible discerned with an innovative technique called optogenetics. Optogenetics is a combination of genetic and optical approaches to controlling activity of specific targeted neurons. With this method we can study animal models of schizophrenia with great insight, which could give us an explanation of abnormalities in behaviour caused by neuronal disruption. Keywords: schizophrenia; interneurons; animal models; neuronal oscillations; optogenetics
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Vyhodnocování dat o kvalitě veřejných prostranství
Kilnarová, Pavla
The way of the evaluating of a data from the survey for the quality of public spaces and its display can influence the interpretation of the conclusion. Currently, data collection takes place in two basic ways - from publicly available databases and in situ observations. This article describes a methodology for presenting and evaluating data acquired for this purpose. The contribution of the presented methodology is demonstrated on the case study of the square Jakubské náměstí in Brno, including the determination of the boundary conditions of individual imaging methods.
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Augmented Reality on Smartphones
Minda, Marek ; MA, Patrick Jost, BSc (referee) ; Drahanský, Martin (advisor)
Rozšířená realita je koncept doplňování reálného světa o počítačem generovaný obsah. Díky pokroku v oblasti mobilních zařízení je mnoho možností využití tohoto konceptu na chytrých telefonech. Tato práce zkoumá schopnost současných zařízení s operačním systémem Android zobrazovat fotorealistický obsah a její využití v aplikacích s rozšířenou realitou. Na základě porovnání dostupných frameworků, Wikitude SDK byl zvolen pro implementaci zobrazování budov do rozšířené reality. Pro účely trackingu je použita geolokace.
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Analysis of gender roles and stereotypes on social network Instagram
Sedláková, Veronika ; Vochocová, Lenka (advisor) ; Hladík, Radim (referee)
This diploma thesis deals with the position of women and men on the Internet social network called Instagram. The theme is first described from a theoretical point of view, explaining what web 2.0 is, what social networks are and how social networking helps with our socialization to society and our self-presentation. In this part are also explained the concepts of gender and gender stereotypes. My own research consist of three parts. The first part is a qualitative image analysis of so-called "selfie" photos of selected Instagram users, which revealed, that the women that I analyzed supported gender stereotypes in female imaginary, while analyzed men occasionally oscillated between masculinity and femininity. The second part is the analysis of the number of the likes under these "selfie" photos and the third part is the analysis of deep semi-structured interviews, which showed that women and men have much in common on Instagram. But overall, their position on this network according to my analysis is not the same.
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Drawing polytopes in various dimensions
Ondráček, Lukáš ; Šámal, Robert (advisor) ; Mareš, Martin (referee)
The thesis describes implementation of an application for drawing three- and multidimensional polytopes allowing their fluent rotation. The application Geometric Figures for Linux and Windows is written in the C language using the OpenGL library and it supports plug-ins written in the Python language. Iterated perspective projection and edges coloring according to their location is used. In addition, the application is able to generate the convex hull of a set of points, cut figures with hyperplanes, stellate figures, create geometrically dual polytopes and cut off parts of figures; all functions are independent to the number of dimensions of the polytopes. The application profits from its easy extensibility using modules and its code being open-source. Powered by TCPDF (www.tcpdf.org)
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