Interactive raytraced caustics

technical reportIn computer graphics, bright patterns of light focused onto matte surfaces are called ?caustics?. We present a method for rendering dynamic scenes with moving caustics at interactive rates. This technique requires some simplifying assumptions about caustic behavior allowing us to consider it a local spatial property which we sample in a pre-processing stage. Storing the caustic locally limits caustic rendering to a simple lookup. We examine a number of ways to represent this data, allowing us to trade between accuracy, storage, run time, and precomputation time

Interactive caustics using local precomputed irradiance

Journal ArticleBright patterns of light focused via reflective or refractive objects onto matte surfaces are called "caustics". We present a method for rendering dynamic scenes with moving caustics at interactive rates. This technique requires some simplifying assumptions about caustic behavior allowing us to consider it a local spatial property which we sample in a pre-processing stage. Storing the caustic locally limits caustic rendering to a simple lookup. We examine a number of ways to represent this data, allowing us to trade between accuracy, storage, run time, and precomputation time

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Prof. Dr. N. NavabTo my familyAcknowledgements I am deeply grateful that I had the opportunity to write this thesis while working at the Chair for Pattern Recognition within the project B6 of the Sonderforschungsbereich 603 (funded by Deutsche Forschungsgemeinschaft). Many people contributed to this work and I want to express my gratitude to all of them

Liminal Surfaces

The poet Ben Okri wrote: “Stories are the secret reservoir of values: change the stories individuals and nations live by and tell themselves, and you change the individuals and nations.” (Stibbe) In the early 21st Century we are facing numerous environmental problems that are being caused by human activity. This era is termed the Anthropocene , a time when accumulated pollutants are causing detrimental ecological change. Ocean creatures are threatened by increasing seawater temperature, acidifying pH levels and melting ice. On land we are experiencing droughts, alteration of biomes, extinctions and an atmosphere that contains less oxygen per breath than it used to. I wondered how humanity had allowed this to happen. What tales have we told ourselves that led to this situation, and how might we devise new tales that might lead to a less polluted future? I see our environment as a structure of surfaces. Material surfaces on which we live, existential surfaces that enfold our thoughts, and liminal surfaces that transition awareness of these through experiential learning. I researched non-toxic printmaking techniques to attach images to surfaces, both physical and cognitive, as a way to bring about recognition that we are part of the natural world, and need to reconnect to it. if we are to begin to solve human-caused environmental damage. The textured surfaces and prints I created in my thesis work are intended to be visually compelling, yet unsettling. An audience for my work would need to articulate new language if they are to assimilate the educable moments it offers. The research presented here uses the concept of surface to unify information about language, cognition, biology and art history as they give context to my artwork about the Anthropocene. I present research that indicates humanity\u27s present difficulty is not a sudden occurrence. Rather, it is the continuance of centuries of behavior built on faulty assumptions derived from metaphorical language and imagery that gave rise to generational practices of acquisitiveness and economic expansion at the expense of the environment. I present a real-world consequence of our actions: the invention of plastic, useful in many ways, but like the sorcerer\u27s apprentice with too many water buckets, is now a profound danger to aquatic ecosystems

A Study of the Interactions of Lipid Bilayers and Dendrimers Using Small Angle X-Ray Scattering and Freeze Fracture Transmission Electron Microscopy

Lipids are fundamental to all life forms, a key component of cell walls, and essential to proper respiratory function. They are amphiphilic molecules and readily form bilayers. Dendrimers are designer molecules that can be tailored to provide a variety of endgroup moieties, sizes, and charges. The interaction of liposomes and dendrimers can provide information on how medicine interacts with cells and an array of unique structures can be imagined from their assembly into superstructures. Polypropylenimine tetraamine (DAB-Am) and 1-directional arborol dendrimers have been studied in different molar concentrations with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers. One-directional arborols are amphiphilic dendrimers with a hydrophilic head group composed of 9 hydroxyl groups and a short alkyl chain for the hydrophobic tail while DAB-Am is a uniform, hydrophilic dendrimer. Designing, building, and repairing equipment added instrumentation to Louisiana State University’s research infrastructure and provided capabilities to perform experiments without traveling to distant laboratories. Small angle X-ray scattering (SAXS) was installed at the Center for Advanced Microstructures and Devices (CAMD) in 2002 and has begun to produce useful information about the size and structure of molecules. Its versatility and availability makes it a powerful tool for researchers and the user base is growing. The Balzers BAF 400 Freeze Etching equipment, or FF, was reintroduced after about 10 years of inactivity and, if properly maintained, will provide scientists the ability to explore samples in situ for years to come. These techniques have been used to study dendrimers’ interactions with lipid bilayers. The liposome decreases in size upon the addition of 1 × 10-6 moles per liter of dendrimer or less. As the dendrimer concentration increases, the lipid bilayer increases until it is no longer visible in SAXS spectra. FF-TEM shows the formation of large aggregates at high dendrimer concentration, 5 × 10-6 moles per liter

Simulation and rendering of light field data in the Mitsuba renderer

Light fields offer the opportunity to change properties of pictures, even after they were shot. There is no possibility of recording all four necessary dimensions of a light field with a 4D camera, but many different techniques for generating light fields from normal 2D pictures exist. Comparing the quality and usability of these techniques is however difficult, because they often only rely on prototypes or are complex and costly to reproduce. Virtual simulations of theses techniques offer an easy and fast method for such comparisons. The rendering of light fields can be done with normal render software, but which render method is best suited for it, is unclear. This thesis wants to answer the question if the Mitsuba renderer is capable of simulating the acquisition of light fields and rendering light field data. In several simulations, Mitsuba will be used to create light fields from multiple test scenes. In addition, virtual light field data will be rendered with Mitsuba in different ways. Each time it will be evaluated, which of Mitsubas rendering methods are well suited for the task and which are not. In each case the required time and image quality of the results will be assessed. Because Mitsuba does not support light fields by default, a custom software framework was implemented for simulations and tests. The framework allows to use Mitsuba for light field acquisition and adds the functionality to render light field data to Mitsuba. The thesis will show that Mitsubas methods of rendering are absolutely capable of creating synthetic light fields or rendering them. Depending on the use case however, the choice for the right rendering technique differs. For example, some methods are not capable of creating light fields of specific scenes, while other methods can not be used for rendering.Lichtfelder ermöglichen es Eigenschaften von Bildern auch nach der Aufnahme zu ändern. Es gibt zwar keine Möglichkeit die vier notwendigen Dimensionen eines Lichtfeldes direkt mit einer 4D Kamera aufzunehmen, aber es gibt zahlreiche und sehr unterschiedliche Techniken um Lichtfelder aus normalen 2D Bildern zu generieren. Diese Aufnahmetechniken miteinander auf Qualität oder Nutzbarkeit zu vergleichen, gestaltet sich allerdings schwierig, da sie größtenteils nur auf Prototypen basieren oder sehr aufwendig und teuer zu reproduzieren sind. Virtuelle Simulation solcher Techniken bietet eine einfache und schnelle Möglichkeit für solche Vergleiche. Das Rendern von Lichtfeldern kann durch normale Rendersoftware erfolgen, aber hier stellt sich die Frage, welche Rendermethoden am besten dafür geeignet sind. Diese Arbeit soll klären, ob der Mitsuba Renderer dazu genutzt werden kann, um Lichtfeldaufnahmen zu simulieren und Lichtfelddaten zu rendern. Dabei wird Mitsuba in mehreren Simulationen dazu benutzt werden, um Lichtfelder von verschiedenen Testszenen zu erzeugen. Außerdem werden anschließend virtuell erzeugte Lichtfelder mit Hilfe von Mitsuba auf mehrere Arten gerendert werden. Dabei wird jeweils evaluiert, welche Rendermethoden von Mitsuba sich gut oder gar nicht für die Aufnahme oder das Rendern eignen. Dabei wird sowohl die Laufzeit als auch die erzeugte Bildqualität bewertet werden. Da Mitsuba den Umgang mit Lichtfeldern nicht standardmäßig unterstützt, wurde speziell ein Software Framework erstellt, um die Simulationen und Tests durchzuführen. Das Framework ermöglicht die Lichtfeldaufnahme mit Mitsuba und erweitert Mitsuba um die Funktion Lichtfelddaten zu rendern. Es wird sich zeigen, dass sich die Rendermethoden von Mitsuba im allgemeinen durchaus dafür eignen Lichtfelder synthetisch aufzunehmen oder zu rendern. Welche Rendermethode dabei allerdings zu bevorzugen ist, unterscheidet sich von Anwendungsfall zu Anwendungsfall. Einige Methoden sind zum Beispiel nicht dazu geeignet Lichtfelder von bestimmten Szenen aufzunehmen, während andere nicht zum Rendern genutzt werden können