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National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Height map compression techniques
 Lašan, Michal ; Kahoun, Martin (advisor) ; Křivánek, Jaroslav (referee)
The goal of this thesis is to design a suitable method for lossy compression of heightmap terrain data. This method should accept blocks of float samples of dimensions 2^n x 2^n as an input, for which it should be able to perform progressive decompression of mip-maps (lower-resolution representations). It should keep the reconstructed data within a certain maximum per-sample error bound for each mip-map level. This bound should be in the unit of meters and adjustable by the user. Given these constraints, it should be as efficient as possible. Our method is inspired by the second generation of progressive wavelet-based compression scheme modified to satisfy the~maximum-error constraint. We simplified this scheme by factoring out unnecessary computations in order to improve the efficiency. Our method can compress a 256x256 block in about 30 ms and decompress it in about 2 ms. Thanks to these attributes, the method can be used in a real-time planet renderer. It achieves the compression ratio of 37:1 on the whole Earth 90m/sample terrain dataset transformed and separated into square blocks, while respecting the maximum error of 5m. Powered by TCPDF (www.tcpdf.org)
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Segmentation of cells from microscopic images
 Lašan, Michal ; Soukup, Jindřich (advisor) ; Blažek, Jan (referee)
In this thesis, we present a new method for the automatic segmentation of mammalian cancer cells from time-lapse images obtained by a microscope based on phase contrast. This method is a pipeline composed of basic techniques from the field of image processing, mathematical morphology and the theory of graphs. Its main idea is to utilize the presence of halo artifacts around the cells, which cause the boundaries between the cells to be lighter than the rest of the image. It follows up to the method proposed by Jindřich Soukup which is able to separate the cells from the background. We compare this method to the watershed - a publicly available algorithm from the field of mathematical morphology. We use segmentation by a human expert as the ground truth. The presented method is implemented in MATLAB and Java with a simple and intuitive interface. We also attach a straightforward GUI editor of segmentation written in Java, with the help of which a user can correct imprecisions in the segmentation, or even create their own manual segmentation. Powered by TCPDF (www.tcpdf.org)
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