Relativistic Effects for Time-Resolved Light Transport

We present a real-time framework which allows interactive visualization of relativistic effects for time-resolved light transport. We leverage data from two different sources: real-world data acquired with an effective exposure time of less than 2 picoseconds, using an ultra-fast imaging technique termed femto-photography, and a transient renderer based on ray-tracing. We explore the effects of time dilation, light aberration, frequency shift and radiance accumulation by modifying existing models of these relativistic effects to take into account the time-resolved nature of light propagation. Unlike previous works, we do not impose limiting constraints in the visualization, allowing the virtual camera to explore freely a reconstructed 3D scene depicting dynamic illumination. Moreover, we consider not only linear motion, but also acceleration and rotation of the camera. We further introduce, for the first time, a pinhole camera model into our relativistic rendering framework, and account for subsequent changes in focal length and field of view as the camera moves through the scene

Visualization of Four-Dimensional Spacetimes

Dokument1.pdf enthält den Text dieser Arbeit, Dokument2.html verweist auf elektronische Filme. In dieser Arbeit werden neue und verbesserte Methoden zur Visualisierung vierdimensionaler Raumzeiten dargestellt. Der erste Teil behandelt die flache Raumzeit der speziellen Relativitätstheorie. Fragestellungen, die sich auf Beleuchtung, Farbsehen, Transformation von Eigenschaften des Lichts und die Kinematik beschleunigter Körper beziehen, werden diskutiert. Es wird gezeigt, wie relativistische Beleuchtungseffekte in bekannten Darstellungsverfahren berücksichtigt werden können. Relativistisches Radiosity und textur- und bildbasiertes relativistisches Rendering werden als neue Darstellungsmethoden vorgestellt. Interaktive virtuelle Umgebungen zur Erkundung der speziellen Relativitätstheorie werden beschrieben, einschließlich der Relativistic-Vehicle-Control-Metapher zur Navigation bei hohen Geschwindigkeiten. Der zweite Teil dieser Arbeit behandelt gekrümmte vierdimensionale Raumzeiten der allgemeinen Relativitätstheorie. Durch nichtlineares Raytracing wird die visuelle Wahrnehmung eines Beobachters in einer allgemeinrelativistischen Umgebung visualisiert. Es werden Erweiterungen des Raytracings in einer einzelnen Karte vorgeschlagen, um das differentialgeometrische Konzept eines Atlanten zu implementieren. Zudem wird gezeigt, wie die Visualisierung von Gravitationslinsen innerhalb eines Raytracing-Systems berücksichtigt werden kann. Der Caustic Finder wird eingeführt als eine numerische Methode zur Bestimmung der zweidimensionalen Kaustiken einer Gravitationslinse. Die innere Geometrie von zweidimensionalen räumlichen Hyperflächen kann durch isometrische Einbettung in den dreidimensionalen euklidschen Raum visualisiert werden. Eine Methode zur Einbettung von Flächen mit sphärischer Topologie wird beschrieben. Schließlich wird ein Algorithmus zur adaptiven Triangulierung von Höhenfeldern als eine spezielle Anwendung in der klassischen Visualisierung vorgestellt.Dokument1.pdf contains this text of the thesis, Dokument2.html is an index to accompanying electronic videos. In this thesis, new and improved methods for the visualization of four-dimensional spacetimes are presented. The first part of this thesis deals with the flat spacetime of special relativity. Issues of illumination, color vision, transformation of properties of light, and the kinematics of accelerating bodies are discussed. It is shown how relativistic effects on illumination can be included in well-known rendering techniques. Relativistic radiosity, texture-based relativistic rendering, and image-based relativistic rendering are proposed as new rendering methods. Interactive virtual environments for the exploration of special relativity are introduced, including the relativistic-vehicle-control metaphor for navigating at high velocities. The second part of the thesis deals with curved four-dimensional spacetimes of general relativity. Direct visualization of what an observer would see in a general relativistic setting is achieved by means of non-linear ray tracing. Extensions to single-chart general relativistic ray tracing are proposed to incorporate the differential-geometric concept of an atlas. Furthermore, it is shown how the visualization of gravitational lensing can be included in a ray tracing system. The caustic finder is proposed as a numerical method to identify two-dimensional caustic structures induced by a gravitational lens. The inner geometry of two-dimensional spatial hypersurfaces can be visualized by isometric embedding in three-dimensional Euclidean space. A method is described which can embed surfaces of spherical topology. Finally, an algorithm for the adaptive triangulation of height fields is presented as a specific application in classical visualization

Relativistic emission lines from accreting black holes - The effect of disk truncation on line profiles

Relativistic emission lines generated by thin accretion disks around rotating black holes are an important diagnostic tool for testing gravity near the horizon. The iron K-line is of special importance for the interpretation of the X-ray emission of Seyfert galaxies, quasars and galactic X-ray binary systems. A generalized kinematic model is presented which includes radial drifts and non-Keplerian rotations for the line emitters. The resulting line profiles are obtained with an object-oriented ray tracer operating in the curved Kerr background metric. The general form of the Doppler factor is presented which includes all kinds of poloidal and toroidal motions near the horizon. The parameters of the model include the spin parameter, the inclination, the truncation and outer radius of the disk, velocity profiles for rotation and radial drift, the emissivity profile and a multi-species line-system. The red wing flux is generally reduced when radial drift is included as compared to the pure Keplerian velocity field. All resulting emission line profiles can be classified as triangular, double-horned, double-peaked, bumpy and shoulder-like. Of particular interest are emission line profiles generated by truncated standard accretion disks (TSD). It is also shown that the emissivity law has a great influence on the profiles. The characteristic shoulder-like line profile observed for the Seyfert galaxy MCG-6-30-15 can be reproduced for suitable parametersComment: 20 pages, 24 figures, accepted for publication in A&

Virtual tour

Interactive 3D Visualization of Architectural models might be the best way to get some idea about an Architecture Plan. Photo-realistic visualization often attracts the investors and customers for whom the architectural blueprints are obscure. Architectural Visualization is considered to have a bright future ahead of it as more and more architects and real estate developers are using this technology. Virtual Walk-through can give not only ideas about your building but its interiors and design too. The Architectural Virtual Environment also most widely used in Gaming and Entertainment Industry in creating a complex movie scenes or a game environment

A trillion frames per second: the techniques and applications of light-in-flight photography

Cameras capable of capturing videos at a trillion frames per second allow to freeze light in motion, a very counterintuitive capability when related to our everyday experience in which light appears to travel instantaneously. By combining this capability with computational imaging techniques, new imaging opportunities emerge such as three dimensional imaging of scenes that are hidden behind a corner, the study of relativistic distortion effects, imaging through diffusive media and imaging of ultrafast optical processes such as laser ablation, supercontinuum and plasma generation. We provide an overview of the main techniques that have been developed for ultra-high speed photography with a particular focus on `light-in-flight' imaging, i.e. applications where the key element is the imaging of light itself at frame rates that allow to freeze it's motion and therefore extract information that would otherwise be blurred out and lost.Comment: Published in Reports on progress in Physic

Photon-induced near-field electron microscopy (PINEM): theoretical and experimental

Electron imaging in space and time is achieved in microscopy with timed (near relativistic) electron packets of picometer wavelength coincident with light pulses of femtosecond duration. The photons (with an energy of a few electronvolts) are used to impulsively heat or excite the specimen so that the evolution of structures from their nonequilibrium state can be followed in real time. As such, and at relatively low fluences, there is no interaction between the electrons and the photons; certainly that is the case in vacuum because energy–momentum conservation is not possible. In the presence of nanostructures and at higher fluences, energy–momentum conservation is possible and the electron packet can either gain or lose light quanta. Recently, it was reported that, when only electrons with gained energy are filtered, near-field imaging enables the visualization of nanoscale particles and interfaces with enhanced contrast (Barwick et al 2009 Nature 462 902). To explore a variety of applications, it is important to express, through analytical formulation, the key parameters involved in this photon-induced near-field electron microscopy (PINEM) and to predict the associated phenomena of, e.g., forty-photon absorption by the electron packet. In this paper, we give an account of the theoretical and experimental results of PINEM. In particular, the time-dependent quantum solution for ultrafast electron packets in the nanostructure scattered electromagnetic (near) field is solved in the high kinetic energy limit to obtain the evolution of the incident electron packet into a superposition of discrete momentum wavelets. The characteristic length and time scales of the halo of electron–photon coupling are discussed in the framework of Rayleigh and Mie scatterings, providing the dependence of the PINEM effect on size, polarization, material and spatiotemporal localization. We also provide a simple classical description that is based on features of plasmonics. A major part of this paper is devoted to the comparisons between the theoretical results and the recently obtained experimental findings about the imaging of materials and biological systems