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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Low-Cost Design of a 3D Stereo Synthesizer Using Depth-Image-Based Rendering

Cheng, Ching-Wen 01 September 2011 (has links)
In this thesis, we proposed a low cost stereoscopic image generation hardware using Depth Image Based Rendering (DIBR) method. Due to the unfavorable artifacts produced by the DIBR algorithm, researchers have developed various algorithms to handle the problem. The most common one is to smooth the depth map before rendering. However, pre-processing of the depth map usually generates other artifacts and even degrades the perception of 3D images. In order to avoid these defects, we present a method by modifying the disparity of edges to make the edges of foreground objects on the synthesized virtual images look more natural. In contrast to the high computational complexity and power consumption in previous designs, we propose a method that fills the holes with the mirrored background pixel values next to the holes. Furthermore, unlike previous DIBR methods that usually consist of two phases, image warping and hole filling, in this thesis we present a new DIBR algorithm that combines the operations of image warping and hole filling in one phase so that the total computation time and power consumption are greatly reduced. Experimental results show that the proposed design can generate more natural virtual images for different view angles with shorter computation latency.
2

Topographie 3D par approche segmentation : application au microscope électronique à balayage / 3D topography by image segmentation approach : application to scanning electron microscopy

Drouyer, Sébastien 01 December 2017 (has links)
Le but de ce travail est de fournir une méthode de reconstruction stéréoscopique capable d'estimer la topographie des catalyseurs à partir d'images MEB. Les méthodes stéréo standard ne permettent pas d'évaluer des reconstructions 3D de bonne qualité en raison de la surface homogène de ces échantillons. Bien que particulièrement prononcé sur nos catalyseurs, le manque de texture est un problème courant dans la reconstruction stéréo, et aucune solution idéale n'a encore été trouvée.Notre approche principale à ce problème est de combiner les méthodes stéréo existantes avec la segmentation hiérarchique des images de l’échantillon. En effet, la morphologie mathématique fournit des outils efficaces permettant de diviser une image en régions et sous-régions. Nous avons utilisé ces outils pour affiner et compléter les reconstructions 3D.La méthode que nous avons développé estime des reconstructions 3D moins bruitées et plus précises que les méthodes existantes. L'approche fournit également des informations supplémentaires: la segmentation finalement retenue ainsi que la carte indiquant l’orientation de chaque région sont des données intéressantes qui peuvent être utilisées pour affiner la compréhension des catalyseurs.Bien que le but de cette thèse soit très spécifique, l'approche proposée est généraliste. Elle a été notamment testée sur la base Middlebury et les résultats obtenus sont comparables et parfois meilleurs que les méthodes de pointe.L’approche pourrait aussi être étendue à d’autres cas d’utilisation. Tant que des données spatiales sont combinées avec une image, notre méthode TDSR peut être utilisée pour améliorer et compléter ces données spatiales. Les images RGBD et la segmentation sémantique sont quelques exemples d'applications potentielles. / The aim of this work is to provide a stereo reconstruction method able to estimate the topography of catalysts from SEM images. Standard stereo methods fail to evaluate adequate 3D reconstructions because of the homogeneous surface of these samples. Though particularly pronounced on our catalysts, the lack of texture is a common issue in stereo reconstruction, and no ideal solution has yet been found.Our main approach to this issue is to combine existing stereo methods with the hierarchical segmentation of the sample's images. Indeed, Mathematical Morphology provides efficient tools that divide an image into regions and subregions. We have used these tools to refine and complete the 3D reconstructions.The method we have developed estimates 3D reconstructions that are less noisy and more precise than state of the art methods. The approach also provides additional information: the final segmentation as well as the normal map are interesting data that can be used to refine the understanding of the catalysts.Though this thesis' purpose is very specific, the proposed approach is general.It has been notably used in the Middlebury database which contains images of in-door scenes, and obtained results were comparable and sometimes better than state of the art methods.It could also be extended to other uses. As long as spatial data is combined with an image, our TDSR method can be used to refine it. RGBD images and semantic segmentation are a few potential applications.

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