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Tessellation of trimmed NURBS surfaces.
Safko, Martin ; Šír, Zbyněk (advisor) ; Pelikán, Josef (referee)
Tessellation of trimmed NURBS surfaces is classical problem in CAD/CAM, with long history and huge amount of research developed so far. We present and describe a tessellation algorithm suitable for visualization purposes in either offline or online setting and present our results. We also provide pointers to litera- ture and to tessellation algorithms for simulation. We discuss relevant definitions and procedures necessary to work with CAD data and try to familiarize it for people outside the industry. 1
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Tessellation of trimmed NURBS surfaces.
Safko, Martin ; Šír, Zbyněk (advisor) ; Pelikán, Josef (referee)
Tessellation of trimmed NURBS surfaces is classical problem in CAD/CAM, with long history and huge amount of research developed so far. We present and describe a tessellation algorithm suitable for visualization purposes in either offline or online setting and present our results. We also provide pointers to litera- ture and to tessellation algorithms for simulation. We discuss relevant definitions and procedures necessary to work with CAD data and try to familiarize it for people outside the industry. 1
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Best View of 3D Scene
Jankovič, Ivan ; Pelikán, Josef (advisor) ; Wilkie, Alexander (referee)
The computation of good viewpoints is useful in many fields: exploration of virtual worlds, global illumination, robot motion, radiosity, imagebased modeling, etc. The main goal of the thesis was to implement several methods for computing the optimal viewpoint of a 3D scene. Two methods have been implemented - Heuristic Measure and Viewpoint Entropy. In addition, a modification of the first method, Weighted Heuristic Measure, was created and tested to find the values that give the best results. For the purpose of method evaluation, a simple application was developed, which loads a 3D scene and runs the implemented methods.
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Perfusion studies
Ulman, Attila ; Pelikán, Josef (advisor) ; Horáček, Jan (referee)
Perfusion data (dynamic contrast-enhanced image data) are used to characterize regional tissue perfusion. Perfusion data consist of a sequence of images, acquired after a contrast agent is applied. Perfusion studies are used for diagnostic purposes in oncology, ischemic stroke assessment, or myocardial ischemia. The diagnostic evaluation of perfusion data is challenging, because the data is very complex and exhibits various artifacts (e.g. motion). Important aspect in the diagnosis of perfusion data is the correlation between perfusion data and derived time-intensity curves (TIC) as well as with other image data, in particular with high-resolution morphologic image data. The present work is focused mainly on cerebral, brain perfusion studies. The thesis studies their medical background as well as the process and possibilities of their examination. Discusses different ways of processing of perfusion series and designs own approach. The work also includes an overview of possibilities for every single step of the processing procedure (registration, segmentation, analysis and visualization) and selection of the most suitable approach for the particular part of processing in the context of cerebral perfusion studies. Results of the work also include a multiplatform application enabling study and analysis of...
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Terrain Processing on Modern GPU
Margold, Roman ; Pelikán, Josef (advisor) ; Maršálek, Lukáš (referee)
Recent development in graphics hardware opened the possibility for new terrain rendering techniques. Former techniques are based on rapid geometry reduction performed on CPU. Recent approaches are moving the load from CPU to GPU, thus keeping CPU available for other tasks, which is especially important for game development. A majority of these approaches is restricted to static datasets or limited data size. We introduce a novel approach which is capable of modifying data during runtime and is easily applicable to potentially infinite landscapes. It is implemented entirely on GPU, except view frustum culling, which is still performed by CPU. However, thanks to the proposed terrain sampling scheme it is trivial and extremely efficient. Employed two-level data representation offers simple implementation without loss of functionality such as sudden change of visual angle or view direction. Those are common problems of other approaches. We also adopted block compression to keep memory consumptions low. Further, a general loading mechanism has been designed and implemented in order to allow asynchronous data read from external medium. This system has been optimized for reading with serial access, although data demands are processed in parallel. The system has been used for continuous terrain data retrieval and...
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Volumetric data processing for CT enterography
Horáček, Jan ; Pelikán, Josef (advisor) ; Czanner, Silvester (referee) ; Schier, Jan (referee)
Title: Volumetric data processing for CT enterography Author: Jan Horáček Department: Department of Software and Computer Science Education Supervisor: RNDr. Josef Pelikán, Department of Software and Computer Sci- ence Education Abstract: The overall goal of our work is to develop algorithms for efficient processing, segmentation and tracking of the small intestine in CT enterography scans. The small intestine is a complex organ, the shape of which can vary con- siderably between patients: and in addition to this, its location and shape can change significantly between subsequent scans of the same person. The CT en- terography process uses contrast agents to improve the visibility of the intestine, so that various potentially problematic features, such as inflammations, obstruc- tions and so on, can be properly seen. However, due to the convoluted shape of the organ, manual diagnosis of raw CT enterography data is still a difficult and time-consuming task, and is prone to diagnostic errors. We have prepared a set of methods for automatic preprocessing, segmentation and tracking of such data that aims at providing a much clearer data visualization: such tools can greatly improve the diagnostic process. Our first contribution is to make a high quality denoising method for volumet- ric data practically usable: so...
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Contour lines to heightfield conversion
Klimeš, Jonáš ; Pelikán, Josef (advisor) ; Dupej, Ján (referee)
Title: Contour lines to heightfield conversion Author: Jonáš Klimeš Department: Department of Software and Computer Science Education Supervisor: RNDr. Josef Pelikán, Department of Software and Computer Science Education Abstract: The task of this project is to design and test algorithms for semiautomatic contour lines conversion to height field. This work tries to solve following problems: automatic connection of disconnected contour lines, adjacent paths finding, semiautomatic ordering of contour lines with user assistance, creating of terrain height field using Catmull-Rom splines or radial basis functions. A part of this thesis is an experimental application, which implements these algorithms and displays the process of conversion. Program input are in form of contour lines in SVG vector format. Output 3D meshes are in Wavefront OBJ format. Keywords: contour lines, height field, terrain
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Robust feature curve detection in 3D surface models
Hmíra, Peter ; Dupej, Ján (advisor) ; Pelikán, Josef (referee)
Most current algorithms typically lack in robustness to noise or do not handle T-shaped curve joining properly. There is a challenge to not only detect features in the noisy 3D-data obtained from the digital scanners. Moreover, most of the algorithms even when they are robust to noise, they lose the feature information near the T-shaped junctions as the triplet of lines ``confuses'' the algorithm so it treats it as a plane. Powered by TCPDF (www.tcpdf.org)
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Digital Reconstructed Radiography
Chovanec, Andrej ; Pelikán, Josef (advisor) ; Krajíček, Václav (referee)
X-ray examination is an important part of the medical treatment. Despite all the advantages it introduces, it brings some limitations as well. In the present work we describe a technique that from the acquired CT data reconstructs a digital x-ray image and removes some drawbacks of traditional x-ray screening. Among the most significant improvements over the classical radiography belong generation of the screen from very arbitrary angle and interactive rotation of the image in real-time. In order to obtain the most realistic final image, we put the emphasis on the accurate simulation of physical properties of the x-ray radiation. We also try to get as low computational time needed to gain one image as possible. For this purpose we present a parallelization model that decomposes the required work of some components into several processors' cores and thus noticeably decreases the running time of the algorithm.
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BRDF workshop
Matějka, Jiří ; Pelikán, Josef (advisor) ; Karlík, Ondřej (referee)
This thesis develops an application for interactive experiments with BRDF functions. Arbitrary BRDF function may be specified with an analytic formula, including arbitrary number of parameters. A simple scene is displayed, using specified BRDF. The parameters can be modified which has an immediate impact to the scene's appearance. The application can utilize a programmable GPU for high speed of rendering.
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