National Repository of Grey Literature 55 records found  previous11 - 20nextend  jump to record: Search took 0.00 seconds. 
Physically-based Cloud Rendering on GPU
Elek, Oskár ; Wilkie, Alexander (advisor) ; Křivánek, Jaroslav (referee)
The rendering of participating media is an interesting and important problem without a simple solution. Yet even among the wide variety of participating media the clouds stand out as an especially difficult case, because of their properties that make their simulation even harder. The work presented in this thesis attempts to provide a solution to this problem, and moreover, to make the proposed method to work in interactive rendering speeds. The main design criteria in designing this method were its physical plausibility and maximal utilization of specific cloud properties which would help to balance the complex nature of clouds. As a result the proposed method builds on the well known photon mapping algorithm, but modifies it in several ways to obtain interactive and temporarily coherent results. This is further helped by designing the method in such a way which allows its implementation on contemporary GPUs, taking advantage of their massively parallel sheer computational power. We implement a prototype of the method in an application that renders a single realistic cloud in interactive framerates, and discuss possible extensions of the proposed technique that would allow its use in various practical industrial applications.
Acceleration of Ray-Casting for CSG scenes
Zajíček, Petr ; Wilkie, Alexander (advisor) ; Křivánek, Jaroslav (referee)
Ray tracing acceleration methods are usually applied to scenes defined by triangle meshes.These scenes contain a large number of triangles. In contrast, CSG scenes contain orders of magnitude less more complex primitives primitives. In this thesis we will present the Operation KD-tree. This acceleration method applies the KD-tree --- modern acceleration method developed for triangle meshes --- directly to the CSG scene. This is done on the premise, that the huge reduction in primitive count will yield enhanced performance, when rendering a scene using CSG instead of triangle meshes.
Implementation of a tone mapping operator for scotopic viewing conditions
Safko, Martin ; Wilkie, Alexander (advisor) ; Kratochvíl, Miroslav (referee)
Creating night-time images and movies that look plausible has been a problem in the industry since the creation of camera. To capture an image we need enough light to create a measurable quantity on a camera sensor. For this reason, shooting at night was not possible until sensors sensitive enough were developed and even then the captured images do not look realistic. Movie industry circumvent these issues by manually color correcting the footage in post-production. We implement an algorithm presented in a 2011 SIGGRAPH paper capable of solving this problem in a psycho-physically plausible and consistent way for spectral images and also augment it by a technique taken from a paper by INRIA. 1
Použití gyroskopů a akcelerometrů k doostření fotografií pořízených mobilním telefonem
Šindelář, Ondřej ; Šroubek, Filip (advisor) ; Wilkie, Alexander (referee)
Long exposure handheld photography is coupled with the problem of blurring, which is difficult to remove without additional information. The goal of this work was to utilize motion sensors contained in modern smartphones to detect exact motion track of the image sensor during the exposure and then to remove the blur from the resulting photograph according to this data. A system was proposed which performs deconvolution using a kernel from the recorded gyroscope data. An implementation on Android platform was proved on a test smartphone device.
Interactive Preview Renderer for Complex Camera Models
Zámečník, Bohumír ; Wilkie, Alexander (advisor) ; Pelikán, Josef (referee)
Title: Interactive Preview Renderer for Complex Camera Models Author: Bohumír Zámečník Department: Department of Software and Computer Science Education Supervisor: Dr. Alexander Wilkie Supervisor's e-mail address: Abstract: An interactive renderer was implemented that allows users to preview the effects of imaging with lenses, such as depth of field, bokeh (defocus highlights) and tilt-shift lens configurations. It is based on a state-of-the-art method which com- bines the power of GPU rasterization and ray tracing. Many models and interactive visualizations were created. A non-interactive simulation of a complex geometrical lens model has been made which is able to produce optical aberrations. Also a prototype implementation of recent fast spreading filters is available. A thorough summary of the principles of optical image formation, lens models and depth of field rendering methods used in computer graphics is given along with a comparison of the approaches and new insights. New possibilities of representing the behavior of complex lenses are suggested, which could be employed to accelerate the rendering. Keywords: image synthesis, camera models, depth of field, GPU, image-based ray tracing
Advanced halftoning methods
Zámečník, Bohumír ; Pelikán, Josef (advisor) ; Wilkie, Alexander (referee)
The goal of the thesis was to design and implement a modular library for digital halftoning methods. The aim were photorealistic methods utilizing space lling curves and blue-noise, artistic methods were considered as well. From the point of view of software design, emphasis was on modularity and extensibility, in order to support experimenting, even with new algorithms. The library along with a graphical user interface has been integrated as a plug-in with the framework of a popular image-processing application GIMP.
Simulating Hair with the Loosely-Connected Particles Method
Soták, Šimon ; Kmoch, Petr (advisor) ; Wilkie, Alexander (referee)
This thesis presents an implementation of the Loosely Connected Particles (LCP) method of hair animation proposed by Bando et al. We updated the method with several modern approaches. Firstly, we implemented two variations of parallel processing for the simulation which di er in work distribution among threads. The results indicate that work is distributed evenly, and thus dynamic distribution is not needed. Secondly, we applied the Deep Opacity Maps method of hair shadowing on the LCP and introduced alpha thresholding to eliminate artifacts. We supply a clean user interface for parameter tweaking with instant response and an easy-to-use interface for cutting hair using mouse controls. We discuss the suitability of using C# with .NET for developing a performance-heavy application.
Optimal strategy for connecting light paths in bidirectional methods for global ilumination computation
Vorba, Jiří ; Křivánek, Jaroslav (advisor) ; Wilkie, Alexander (referee)
This work introduces a method for optimal combination of light paths generated from the camera and from the light sources in the Photon Mapping algorithm used for computing global illumination. Our method is based on Multiple Importance Sampling, a general approach, introduced by Veach, for adaptive path connection in Bidirectional Path-Tracing. Our goal is to examine this method in connection with the biased algorithm of Photon Mapping and to improve the ineffective heuristic used in the original version of this algorithm. This heuristic is usually problematic when applied to the scenes where highly glossy materials prevail.
Guiding a Path Tracer with Local Radiance Estimates
Berger, Martin ; Wilkie, Alexander (advisor) ; Křivánek, Jaroslav (referee)
Path tracing is a basic, statistically unbiased method for calculating the global illumination in 3D scenes. For practical purposes, the algorithm is too slow, so it is used mainly for theoretical purposes or as a base for more advanced algorithms. This thesis explores the possibility of improving this algorithm by augmenting the sampling part, which computes outgoing directions during ray traversal through the scene. This optimization is accomplished by creating a special data structure in a preprocess step, which describes approximate light distribution in the scene and which then aids the sampling process. The presented algorithm is implemented in the PBRT library.
Advanced HDR image viewer
Wirth, Michal ; Křivánek, Jaroslav (advisor) ; Wilkie, Alexander (referee)
04.01.17 abstract.txt 1 file:///home/misa/Desktop/dp/abstract.txt The primary purpose of this thesis is to determine criteria for a high- dynamic range (HDR) image viewer accented by computer graphics artists and other users who work with HDR images produced by physically-based renderers on a daily basis. Also an overview of already existing solutions is present. Based on both of them, a new HDR viewer is designed and implemented giving an emphasis on its memory and performance efficiency. For these purposes two alternative image data layouts, Array-of-Structures (AoS) and Structure-of-Arrays (SoA), are discussed and their impact is measured on the speed of an algorithm for changing image saturation which has been selected as a representative part of whole tone mapping process of the viewer. It has turned out that the latter type of layout allows the algorithm to run about 3 times faster or more under the conditions of a defined testing environment. The thesis has two main contributions. First it gives the above users a tool which could help them when working with HDR images. Second it indicates that there may be a potential of significant speed-up of implementations of tone mapping algorithms.

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