National Repository of Grey Literature 62 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Adjoint-Driven Importance Sampling in Light Transport Simulation
Vorba, Jiří ; Křivánek, Jaroslav (advisor) ; Keller, Alexander (referee) ; Wann Jensen, Henrik (referee)
Title: Adjoint-Driven Importance Sampling in Light Transport Simulation Author: RNDr. Jiří Vorba Department: Department of Software and Computer Science Education Supervisor: doc. Ing. Jaroslav Křivánek, Ph.D., Department of Software and Computer Science Education Abstract: Monte Carlo light transport simulation has recently been adopted by the movie industry as a standard tool for producing photo realistic imagery. As the industry pushes current technologies to the very edge of their possibilities, the unprecedented complexity of rendered scenes has underlined a fundamental weakness of MC light transport simulation: slow convergence in the presence of indirect illumination. The culprit of this poor behaviour is that the sam- pling schemes used in the state-of-the-art MC transport algorithms usually do not adapt to the conditions of rendered scenes. We base our work on the ob- servation that the vast amount of samples needed by these algorithms forms an abundant source of information that can be used to derive superior sampling strategies, tailored for a given scene. In the first part of this thesis, we adapt general machine learning techniques to train directional distributions for biasing scattering directions of camera paths towards incident illumination (radiance). Our approach allows progressive...
Synthesis of digital landscape surface data
Šebesta, Michal ; Kahoun, Martin (advisor) ; Křivánek, Jaroslav (referee)
A procedural generation of landscapes often meets a need for real spatial data at finer resolution that data available at the moment. We introduce a method that refines the spatial data at the coarse resolution into the finer resolution utilizing other data sources which are already at the better resolution. We construct weighted local linear statistical models from both the coarse and utility data and use the by- models-learned dependencies between the data sources to predict the needed data at better resolution. To achieve higher computational speed and evade utility data imperfection, we utilize truncated singular value decomposition which reduce a dimensionality of the data space we work with. The~method is highly modifiable and its application shows plausible real-like results. Thanks to this, the method can be of practical use for simulation software development. Powered by TCPDF (
Procedurální generování měst
Beneš, Jan ; Wilkie, Alexander (advisor) ; Křivánek, Jaroslav (referee)
This thesis proposes a novel method for procedural generation of urban street networks. A simple traffic simulation, based on observations made about the social-geographic nature of cities, that is able to drive the temporal evolution of city road networks by creating new major roads, as well as a modified generation algorithm for minor roads, are described. The presented method is highly automated.
Efficient visibility calculation for light transport simulation in participating media
Houška, Čestmír ; Křivánek, Jaroslav (advisor) ; Karlík, Ondřej (referee)
Title: Efficient visibility calculation for light transport simulation in participating media Author: Čestmír Houška Department / Institute: Department of Software and Computer Science Educa- tion Supervisor of the master thesis: doc. Ing. Jaroslav Křivánek, Ph.D. Abstract: This thesis investigates the use of acceleration methods for the testing of visibility in light transport calculation algorithms with the emphasis on conser- vativeness and low accelerated query overhead. Several published non-directional and directional distance field methods are presented with the description of their characteristic properties. Two of these methods are then implemented and thor- oughly tested in an existing rendering framework on a path tracing volumetric integrator as well as on an own implementation of a ray marching single scattering integrator. A method that further accelerates the original distance field methods by pre-caching results of some of the queries is also proposed, implemented and tested. Furthermore, several possible extensions to this method are outlined. Keywords: computer graphics, rendering, participating media, visibility
Segmentation of images with leaves of woody species
Valchová, Ivana ; Suk, Tomáš (advisor) ; Křivánek, Jaroslav (referee)
The thesis focuses on segmentation of images with leaves of woody species. The aim was to investigate existing image segmentation methods, choose suitable method for given data and implement it. The chosen method should segment existing datasets, photographs from cameras as well as photographs from lower-quality mobile phones. Inputs are scanned leaves and photographs of various quality. The thesis summarizes the general methods of image segmentation and describes own algorithm that gives us the best results. Based on the histogram, the algorithm decides whether the input is of sufficient quality and can be segmented by Otsu algorithm or is not and should be segmented using GrowCut algorithm. Next, the image is improved by morphological closing and holes filling. Finally, only the largest object is left. Results are illustrated using generated output images. Powered by TCPDF (
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.
Design and evaluation of a user inteface for cinematic lighting
Růžička, Martin ; Křivánek, Jaroslav (advisor) ; Vorba, Jiří (referee)
This diploma thesis deals with global illumination and generally with the process of illumination of prepared scenes. A program for illumination management was written for this purpose. It can manage both direct and indirect illumination in interactive time. Simple and comfortable user interface allows for addition, deletion and change in light settings. Different types of both point and area lights are supported. In the course of all work, the program displays current illumination of the scene. With the help of this application, a series of different experiments will be carried out. We will explore the way users work during illumination, the way they perceive different properties of global illumination, various options of its control and its comparison with common direct illumination.
CSG modeling for polygonal objects
Václavík, Jiří ; Křivánek, Jaroslav (advisor) ; Beneš, Jan (referee)
This work deals with an efficient and robust technique of performing Boolean operations on polygonal models. Full robustness is achieved within an internal representation based on planes and BSP (binary space partitioning) trees, in which operations can be carried out exactly in mere fixed precision arithmetic. Necessary conversions from the usual representation to the inner one and back, including their consequences are analyzed in detail. The performance of the method is optimized by a localization scheme in the form of an adaptive octree. The resulting implementation RazeCSG is experimentally compared with implementations used in practice Carve and Maya, which are not fully robust. For large models, RazeCSG shows only twice lower performance in the worst case than Carve, and is at least 130 times faster than Maya.
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.

National Repository of Grey Literature : 62 records found   1 - 10nextend  jump to record:
See also: similar author names
7 Křivánek, Jan
2 Křivánek, Jaromír
2 Křivánek, Jindřich
4 Křivánek, Jiří
Interested in being notified about new results for this query?
Subscribe to the RSS feed.