Controlling Phase Space Caustics in the Semiclassical Coherent State Propagator

The semiclassical formula for the quantum propagator in the coherent state representation $$ is not free from the problem of caustics. These are singular points along the complex classical trajectories specified by $\mathbf{z}'$, $\mathbf{z}''$ and $T$ where the usual quadratic approximation fails, leading to divergences in the semiclassical formula. In this paper we derive third order approximations for this propagator that remain finite in the vicinity of caustics. We use Maslov's method and the dual representation proposed in Phys. Rev. Lett. {\bf 95}, 050405 (2005) to derive uniform, regular and transitional semiclassical approximations for coherent state propagator in systems with two degrees of freedom.Comment: 24 pages, to appear in Ann. of Phy

Single-pixel imaging using caustic patterns

Single-pixel imaging uses a time-varying transmission mask placed in the illumination to achieve imaging without the use of detector arrays. While most research in this field uses sophisticated masks implemented using spatial light modulators, such methods are not available at all lengthscales and wavelengths of illumination. Here we show that alternatively a sequence of projected caustic intensity patterns can be used as the basis for the single-pixel imaging of objects. Caustics can be formed using slowly varying random phase masks, such as for example the surface of a swimming pool, which potentially makes using caustics an option at a range of lengthscales and wavelengths

A Survey of Ocean Simulation and Rendering Techniques in Computer Graphics

This paper presents a survey of ocean simulation and rendering methods in computer graphics. To model and animate the ocean's surface, these methods mainly rely on two main approaches: on the one hand, those which approximate ocean dynamics with parametric, spectral or hybrid models and use empirical laws from oceanographic research. We will see that this type of methods essentially allows the simulation of ocean scenes in the deep water domain, without breaking waves. On the other hand, physically-based methods use Navier-Stokes Equations (NSE) to represent breaking waves and more generally ocean surface near the shore. We also describe ocean rendering methods in computer graphics, with a special interest in the simulation of phenomena such as foam and spray, and light's interaction with the ocean surface

Advanced 3D Rendering : Adaptive Caustic Maps with GPGPU

Graphics researchers have long studied real-time caustic rendering. The state-of-the-art technique Adaptive Caustic Maps provides a novel way to avoid densely sampling photons during a rasterization pass, and instead adaptively emits photons using a deferred shading pass. In this project, we present a variation of adaptive caustic maps for real-time rendering of caustics. Our algorithm is conceptually similar to Adaptive Caustic Maps but has a different implementation based on the general-purpose computing pipeline provided by OpenGL version 4.3. Our approach accelerates the photon splitting process using compute shaders and bypasses various other performance overheads, ultimately speeding up photon generation considerably

Adaptive optics observations of the gravitationally lensed quasar SDSS J1405+0959

We present the result of Subaru Telescope multi-band adaptive optics observations of the complex gravitationally lensed quasar SDSS J1405+0959, which is produced by two lensing galaxies. These observations reveal dramatically enhanced morphological detail, leading to the discovery of an additional object 0. 26'' from the secondary lensing galaxy, as well as three collinear clumps located in between the two lensing galaxies. The new object is likely to be the third quasar image, although the possibility that it is a galaxy cannot be entirely excluded. If confirmed via future observations, it would be the first three image lensed quasar produced by two galaxy lenses. In either case, we show based on gravitational lensing models and photometric redshift that the collinear clumps represent merging images of a portion of the quasar host galaxy, with a magnification factor of 15 - 20, depending on the model.Comment: 12 pages, 8 figures, 7 tables. Submitted to MNRA

A Precomputed Polynomial Representation for Interactive BRDF Editing with Global Illumination

The ability to interactively edit BRDFs in their final placement within a computer graphics scene is vital to making informed choices for material properties. We significantly extend previous work on BRDF editing for static scenes (with fixed lighting and view), by developing a precomputed polynomial representation that enables interactive BRDF editing with global illumination. Unlike previous recomputation based rendering techniques, the image is not linear in the BRDF when considering interreflections. We introduce a framework for precomputing a multi-bounce tensor of polynomial coefficients, that encapsulates the nonlinear nature of the task. Significant reductions in complexity are achieved by leveraging the low-frequency nature of indirect light. We use a high-quality representation for the BRDFs at the first bounce from the eye, and lower-frequency (often diffuse) versions for further bounces. This approximation correctly captures the general global illumination in a scene, including color-bleeding, near-field object reflections, and even caustics. We adapt Monte Carlo path tracing for precomputing the tensor of coefficients for BRDF basis functions. At runtime, the high-dimensional tensors can be reduced to a simple dot product at each pixel for rendering. We present a number of examples of editing BRDFs in complex scenes, with interactive feedback rendered with global illumination

Analytical Method for Reflection and Refraction

In computer graphics, ray tracing is very simple and powerful method to present physical phenomena especially light-related things such as reflection and refraction since it traces the ray from the eye to the light source; however, we cannot understand how the result image is generated. Then, this chapter describes the mechanism of reflection and refraction. It is very time-consuming to render the target object considering reflection and refraction. If the object distorted by reflection and refraction is previously obtained, it is very fast to generate the result image since all we have to do is to render the distorted object without considering reflection and refraction. In the proposed method, firstly, a virtual object, which is constructed with vertices translated from original ones by considering reflection and refraction, is generated. Then, the image with reflection and refraction is generated by rendering the virtual object. In the analysis, total reflection and attenuation of light power are also considered. At last, the proposed method is applied to two types of transparent objects: cubed glass and cylindrical glass, and the comparison between the simulation results and the real photos is performed to demonstrate that the generated images are the same as the real ones

Digital Fishes - An Interactive Virtual Aquarium

This work is supported by AUIP - Asociación Universitaria Iberoamericana de PostgradoThis work describes the creation of an interactive virtual aquarium, Digital Fishes, with a physical representation in a cubic fish tank with synchronized visual information and animated elements, such as fish and vegetation, which can be used for educational purposes. Here the solution to simulate the movement of marine flora and fauna added to our virtual Aquarium is described. An implementation of the fish behavior, to move in groups using the Boids algorithm, is created, in addition to autonomous behaviors such as chasing prey and fleeing from predators, interactive behaviors such as following the finger on the screen and going towards the food that the user may throw in the pond. The solution described in this work has managed to bring into the hands of children an interactive virtual representation of an interactive as one more learning tool at their disposal. These children who participated in the Digital Fishes Interactive Aquarium's evaluation provided positive feedback, showing great enthusiasm and positively assessed the solution

Real-time Water Waves with Wave Particles

This dissertation describes the wave particles technique for simulating water surface waves and two way fluid-object interactions for real-time applications, such as video games. Water exists in various different forms in our environment and it is important to develop necessary technologies to be able to incorporate all these forms in real-time virtual environments. Handling the behavior of large bodies of water, such as an ocean, lake, or pool, has been computationally expensive with traditional techniques even for offline graphics applications, because of the high resolution requirements of these simulations. A significant portion of water behavior for large bodies of water is the surface wave phenomenon. This dissertation discusses how water surface waves can be simulated efficiently and effectively at real-time frame rates using a simple particle system that we call "wave particles." This approach offers a simple, fast, and unconditionally stable solution to wave simulation. Unlike traditional techniques that try to simulate the water body (or its surface) as a whole with numerical techniques, wave particles merely track the deviations of the surface due to waves forming an analytical solution. This allows simulation of seemingly infinite water surfaces, like an open ocean. Both the theory and implementation of wave particles are discussed in great detail. Two-way interactions of floating objects with water is explained, including generation of waves due to object interaction and proper simulation of the effect of water on the object motion. Timing studies show that the method is scalable, allowing simulation of wave interaction with several hundreds of objects at real-time rates

Visually pleasing real-time global illumination rendering for fully-dynamic scenes

Global illumination (GI) rendering plays a crucial role in the photo-realistic rendering of virtual scenes. With the rapid development of graphics hardware, GI has become increasingly attractive even for real-time applications nowadays. However, the computation of physically-correct global illumination is time-consuming and cannot achieve real-time, or even interactive performance. Although the realtime GI is possible using a solution based on precomputation, such a solution cannot deal with fully-dynamic scenes. This dissertation focuses on solving these problems by introducing visually pleasing real-time global illumination rendering for fully-dynamic scenes. To this end, we develop a set of novel algorithms and techniques for rendering global illumination effects using the graphics hardware. All these algorithms not only result in real-time or interactive performance, but also generate comparable quality to the previous works in off-line rendering. First, we present a novel implicit visibility technique to circumvent expensive visibility queries in hierarchical radiosity by evaluating the visibility implicitly. Thereafter, we focus on rendering visually plausible soft shadows, which is the most important GI effect caused by the visibility determination. Based on the pre-filtering shadowmapping theory, wesuccessively propose two real-time soft shadow mapping methods: "convolution soft shadow mapping" (CSSM) and "variance soft shadow mapping" (VSSM). Furthermore, we successfully apply our CSSM method in computing the shadow effects for indirect lighting. Finally, to explore the GI rendering in participating media, we investigate a novel technique to interactively render volume caustics in the single-scattering participating media.Das Rendern globaler Beleuchtung ist für die fotorealistische Darstellung virtueller Szenen von entscheidender Bedeutung. Dank der rapiden Entwicklung der Grafik-Hardware wird die globale Beleuchtung heutzutage sogar für Echtzeitanwendungen immer attraktiver. Trotz allem ist die Berechnung physikalisch korrekter globaler Beleuchtung zeitintensiv und interaktive Laufzeiten können mit "standard Hardware" noch nicht erzielt werden. Obwohl das Rendering auf der Grundlage von Vorberechnungen in Echtzeit möglich ist, kann ein solcher Ansatz nicht auf voll-dynamische Szenen angewendet werden. Diese Dissertation zielt darauf ab, das Problem der globalen Beleuchtungsberechnung durch Einführung von neuen Techniken für voll-dynamische Szenen in Echtzeit zu lösen. Dazu stellen wir eine Reihe neuer Algorithmen vor, die die Effekte der globaler Beleuchtung auf der Grafik-Hardware berechnen. All diese Algorithmen erzielen nicht nur Echtzeit bzw. interaktive Laufzeiten sondern liefern auch eine Qualität, die mit bisherigen offline Methoden vergleichbar ist. Zunächst präsentieren wir eine neue Technik zur Berechnung impliziter Sichtbarkeit, die aufwändige Sichbarkeitstests in hierarchischen Radiosity-Datenstrukturen vermeidet. Anschliessend stellen wir eine Methode vor, die weiche Schatten, ein wichtiger Effekt für die globale Beleuchtung, in Echtzeit berechnet. Auf der Grundlage der Theorie über vorgefilterten Schattenwurf, zeigen wir nacheinander zwei Echtzeitmethoden zur Berechnung weicher Schattenwürfe: "Convolution Soft Shadow Mapping" (CSSM) und "Variance Soft Shadow Mapping" (VSSM). Darüber hinaus wenden wir unsere CSSM-Methode auch erfolgreich auf den Schatteneffekt in der indirekten Beleuchtung an. Abschliessend präsentieren wir eine neue Methode zum interaktiven Rendern von Volumen-Kaustiken in einfach streuenden, halbtransparenten Medien