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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.
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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.
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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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Live-cell tracking in time-lapse sequences
Zámečník, Tomáš ; Šorel, Michal (advisor) ; Křivánek, Jaroslav (referee)
Title: Live-cell tracking in time-lapse sequences Author: Tomáš Zámečník Department: Department of Software and Computer Science Education Supervisor: RNDr. Michal Šorel Ph.D., Oddělení zpracování obrazu ÚTIA AV ČR Abstract: This diploma thesis deals with methods of tracking particles in image sequences. It's goal is to design and implement a complete system for tracking of live cells, their motion and division. The thesis uses conclusions of published scientific papers, studies their application and analyzes possibilities for their mo- difications or improvement. As a result, there are two applications. First of them is a demonstrational pro- gram, provided as an attachment of this thesis. Second implementation is a mo- dule of commercial software NIS-Elements, by Laboratory Imaging, Ltd., which is used by both scientific and commercial institutions in the whole world. Keywords: cell tracking, particle tracking, cell division 1
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Generování vlasů interpolací
Šik, Martin ; Křivánek, Jaroslav (advisor) ; Kolomazník, Jan (referee)
This thesis describes a procedural hair generator that is able to generate hair from just a few hairs, called hair guides, which are directly modeled by a 3d artist. The procedural hair generator is a part of Stubble project -- a tool for hair modeling in Autodesk Maya. The procedural hair generator can generate hair during rendering, thus avoiding storage of hair geometry in a scene file, which makes the rendering process very efficient. Furthermore, hair can be generated interactively and displayed by OpenGL during modeling in Maya. Generated hair geometry is mainly defined by interpolation from the mentioned hair guides; however it is also influenced by many hair properties. These properties can change hair geometry using noise functions, define hair color, width and more. To determine hair root positions on a given triangular mesh I use my own mesh sampling algorithm that generates random samples on a triangular mesh according to a density defined by a 2-dimensional texture. My sampling algorithm uses an innovative way of sampling from a discrete probability distribution, which can be used in other applications than mesh sampling.
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GPU implementation of the irradiance and radiance caching algorithms
Bulant, Martin ; Křivánek, Jaroslav (advisor) ; Šik, Martin (referee)
The objective of this work is to create software implementing two algorithms for global ilumination computation. Iradiance and radiance caching should be implemented in CUDA framework on a graphics card (GPU). Parallel implementation on the GPU should improve algoritm speed compared to CPU implementation. The software will be written using an already done framework for global illumunation computation. That allows to focus on algorithm implementation only. This work should speed up testing of new or existing methods for global illumination computing, because saving and reusing of intermediate results can be used for other algorithms too. Powered by TCPDF (www.tcpdf.org)
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Data structures for rendering non-polygonal geometry
Kuckir, Ivan ; Křivánek, Jaroslav (advisor) ; Vorba, Jiří (referee)
In modern 3D graphics, scenes made of triangles are usually used, combined with methods based on ray tracing. Hierarchical data structures, called accelerating trees, are often used to speed up the search for intersection between ray and the scene. When testing the best current methods with non-polygonal geometry (line segments), we have found out that those structures cannot build an effective tree in many cases. The aim of this work is to formulate the problem mathematically. Thanks to this, the whole subject becomes more transparent and we can see the shortcomings of current methods, which have not yet been pointed out. At the result, we develop an algorithm which generalizes all current methods, which is not dependent on geometry and directly shows the space for improvement.
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Real-time Global Illumination Computation
Šváb, Tomáš ; Křivánek, Jaroslav (advisor) ; Vorba, Jiří (referee)
Thesis examines the current research and development in the field of real-time global illumination. It concentrates on techniques that are capable of simulating dynamic environments and require only limited precomputation. It contains a theoretical as well as practical part. In the theoretical part the basics of rendering and selected global illumination methods are described, namely reflective shadow mapping, light propagation volumes and voxel cone tracing. The practical part includes implementation of selected methods, which are then tested, compared and improved. A program called R-GITE (Real- Time Global Illumination Testing Environment) was created to provide a foundation for prototyping these rendering algorithms. There are two main criteria in the testing - accuracy of the result and speed of computation. In the end we used the data from the tests to determine both the strong and the weak points of the methods and discuss usability of the methods for specific scenarios. Powered by TCPDF (www.tcpdf.org)
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Realistic hair rendering in Autodesk Maya
Svoboda, Tomáš ; Křivánek, Jaroslav (advisor) ; Vorba, Jiří (referee)
This thesis describes a real-time hair rendering in 3D animation and modeling software Autodesk Maya. The renderer is part of the Stubble project a - Maya plug-in for hair modeling. The presented renderer provides a high-quality interactive preview that allows fast hair modeling without the need for rendering in slow off-line renderers. The goal of this work is to create a renderer that can generate images in real-time that are as close as possible to the output of the 3Delight renderer - a plug-in for Maya that is based on RenderMan standards.
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Colour reproduction accuracy of stochastic spectral sampling: an experimental evaluation.
Hencz, Attila ; Wilkie, Alexander (advisor) ; Křivánek, Jaroslav (referee)
Title: Colour reproduction accuracy of stochastic spectral sampling: an experi- mental evaluation Author: Bc. Attila Hencz �attila.hencz@matfyz.cz� Department: Department of Software and Computer Science Education Supervisor: doc. Alexander Wilkie, Dr. �wilkie@cgg.mff.cuni.cz�, Department of Software and Computer Science Education Abstract: We investigate the colorimetric accuracy of stochastic sampling in the wavelength domain for realistic rendering purposes. In particular, we consider the impact of three specific design choices in a rendering system on the accuracy of the overall result: how exactly spectral samples are splatted into the final result spectrum, how many spectral channels one uses in the result images, and the impact of Hero Wavelength Spectral Sampling (HWSS) compared to the stand- ard monochrome technique. We provide experimental results, comparisons and evaluation of sampling high-resolution spectra that originate from measurements of real paint samples found in colour atlases, and normed light sources defined by the CIE. The latter include both smooth and spiky spectra, so the used com- bination of reflectances and light spectra provides a representative body of input values that allows to draw conclusions that are relevant for practical rendering work. Keywords: physically based image...
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