3,790 research outputs found
Phase-conjugation of the isolated optical vortex using a flat surfaces
The robust method for obtaining the helical interference pattern due to the
phase-conjugation of an isolated optical vortex by means of the non-holographic
technique is proposed. It is shown that a perfect wavefront-reversal of the
vortex in a linear polarization state via even number of reflections is
achievable due to the turn of the photon's momentum with respect to the photon's orbital angular momentum projection . The
possible experimental realization is based upon like
reflections inside the confocal optical cavity. The alternative scheme
contains the Dove prism embedded in the optical with the odd number of
reflections from mirrors. This interferometric technique is
applicable to the optical tweezers, atomic traps, Sagnac laser loops and
metamaterials fabrication.Comment: 4 pages, 3 figures, submitted to referred journa
Real-time screen space reflections and refractions using sparse voxel octrees
This thesis explores the data structure known as sparse voxel octree and how it can improve the performance of real-time ray tracing. While ray tracing is an excellent way of producing realistic effects in computer graphics it is also very computationally heavy. Its use in real-time applications such as games and simulators is therefore limited since the hardware must be able to render enough frames per second to satisfy the users. The purpose of an octree is to reduce the amount of intersection tests each ray needs significantly. This thesis will explain the many challenges when implementing and using an octree, and also how to solve them. This includes both how to build the tree using various tests and then also how to use it with a ray tracer to produce reflections and refractions in real time
ROBAST: Development of a Non-Sequential Ray-Tracing Simulation Library and its Applications in the Cherenkov Telescope Array
We have developed a non-sequential ray-tracing simulation library, ROot-BAsed
Simulator for ray Tracing (ROBAST), which is aimed for wide use in optical
simulations of cosmic-ray (CR) and gamma-ray telescopes. The library is written
in C++ and fully utilizes the geometry library of the ROOT analysis framework.
Despite the importance of optics simulations in CR experiments, no open-source
software for ray-tracing simulations that can be widely used existed. To reduce
the unnecessary effort demanded when different research groups develop multiple
ray-tracing simulators, we have successfully used ROBAST for many years to
perform optics simulations for the Cherenkov Telescope Array (CTA). Among the
proposed telescope designs for CTA, ROBAST is currently being used for three
telescopes: a Schwarzschild--Couder telescope, one of the Schwarzschild--Couder
small-sized telescopes, and a large-sized telescope (LST). ROBAST is also used
for the simulations and the development of hexagonal light concentrators that
has been proposed for the LST focal plane. By fully utilizing the ROOT geometry
library with additional ROBAST classes, building complex optics geometries that
are typically used in CR experiments and ground-based gamma-ray telescopes is
possible. We introduce ROBAST and show several successful applications for CTA.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
ROBAST: Development of a ROOT-Based Ray-Tracing Library for Cosmic-Ray Telescopes and its Applications in the Cherenkov Telescope Array
We have developed a non-sequential ray-tracing simulation library, ROOT-based
simulator for ray tracing (ROBAST), which is aimed to be widely used in optical
simulations of cosmic-ray (CR) and gamma-ray telescopes. The library is written
in C++, and fully utilizes the geometry library of the ROOT framework. Despite
the importance of optics simulations in CR experiments, no open-source software
for ray-tracing simulations that can be widely used in the community has
existed. To reduce the dispensable effort needed to develop multiple
ray-tracing simulators by different research groups, we have successfully used
ROBAST for many years to perform optics simulations for the Cherenkov Telescope
Array (CTA). Among the six proposed telescope designs for CTA, ROBAST is
currently used for three telescopes: a Schwarzschild-Couder (SC) medium-sized
telescope, one of SC small-sized telescopes, and a large-sized telescope (LST).
ROBAST is also used for the simulation and development of hexagonal light
concentrators proposed for the LST focal plane. Making full use of the ROOT
geometry library with additional ROBAST classes, we are able to build the
complex optics geometries typically used in CR experiments and ground-based
gamma-ray telescopes. We introduce ROBAST and its features developed for CR
experiments, and show several successful applications for CTA.Comment: Accepted for publication in Astroparticle Physics. 11 pages, 10
figures, 4 table
Tehnike renderiranja i računalnog osvjetljenja
This paper describes the rendering techniques, render engines and types of lighting in the Autodesk Maya software. There are many types of algorithms in the computer graphics area, but this paper describes the most commonly used or historically important ones for the development of computer graphics. Mental ray, which is used as a plug-in, enables the photorealistic rendering for Maya. Mental ray is compared with its biggest rival – V-ray. Furthermore, this paper describes the sources of direct lighting which Maya offers, as well as the options that are available from mental ray for indirect or global lighting.Ovaj rad opisuje tehnike renderiranja, render pogone, te vrste osvjetljenja scene u programu Autodesk Maya. Postoji više algoritama renderiranja koje se koriste u računalnoj grafici, a u ovom radu su opisani oni koji se najviše koriste ili oni algoritmi koji su bili važni za razvoj računalne grafike kakvu danas poznajemo. Opisan je mental ray koji je zaseban program, a u Mayi se koristi kao dodatak, pomoću kojega se Mayi omogućuje napredno i realistično renderiranje. Uz to se mental ray uspoređuje sa svojim najvećim konkurentom, V-rayom. Također su navedeni direktni izvori svjetlosti koje nam nudi Maya, te koje su to opcije za indirektno ili globalno osvjetljenje, koje nam nudi mental ray
Efficient algorithms for the realistic simulation of fluids
Nowadays there is great demand for realistic simulations in the computer graphics field. Physically-based animations are commonly used, and one of the more complex problems in this field is fluid simulation, more so if real-time applications are the goal. Videogames, in particular, resort to different techniques that, in order to represent fluids, just simulate the consequence and not the cause, using procedural or parametric methods and often discriminating the physical solution.
This need motivates the present thesis, the interactive simulation of free-surface flows, usually liquids, which are the feature of interest in most common applications. Due to the complexity of fluid simulation, in order to achieve real-time framerates, we have resorted to use the high parallelism provided by actual consumer-level GPUs. The simulation algorithm, the
Lattice Boltzmann Method, has been chosen accordingly due to its efficiency and the direct mapping to the hardware architecture because of its local operations.
We have created two free-surface simulations in the GPU: one fully in 3D and another restricted only to the upper surface of a big bulk of fluid, limiting the simulation domain to 2D. We have extended the latter to track dry regions and is also coupled with obstacles in a geometry-independent fashion. As it is restricted to 2D, the simulation loses some features due to the impossibility of simulating vertical separation of the fluid. To account for this we have coupled the surface simulation to a generic particle system with breaking wave conditions; the simulations are totally independent and only the coupling binds the LBM with the chosen particle system.
Furthermore, the visualization of both systems is also done in a realistic way within the interactive framerates; raycasting techniques are used to provide the expected light-related effects as refractions, reflections and caustics. Other techniques that improve the overall detail are also applied as low-level detail ripples and surface foam
Fluids real-time rendering
In this thesis the existing methods for realistic visualization of
uids
in real-time are reviewed. The correct handling of the interaction of light
with a
uid surface can highly increase the realism of the rendering, therefore
method for physically accurate rendering of re
ections and refractions will be
used. The light-
uid interaction does not stop at the surface, but continues
inside the
uid volume, causing caustics and beams of light. The simulation
of
uids require extremely time-consuming processes to achieve physical
accuracy and will not be explored, although the main concepts will be given.
Therefore, the main goals of this work are:
Study and review the existing methods for rendering
uids in realtime.
Find a simpli ed physical model of light interaction, because a complete
physically correct model would not achieve real-time.
Develop an application that uses the found methods and the light
interaction model
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