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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

Range Data Recognition: Segmentation, Matching, And Similarity Retrieval

Yalcin Bayramoglu, Neslihan 01 September 2011 (has links) (PDF)
The improvements in 3D scanning technologies have led the necessity for managing range image databases. Hence, the requirement of describing and indexing this type of data arises. Up to now, rather much work is achieved on capturing, transmission and visualization / however, there is still a gap in the 3D semantic analysis between the requirements of the applications and the obtained results. In this thesis we studied 3D semantic analysis of range data. Under this broad title we address segmentation of range scenes, correspondence matching of range images and the similarity retrieval of range models. Inputs are considered as single view depth images. First, possible research topics related to 3D semantic analysis are introduced. Planar structure detection in range scenes are analyzed and some modifications on available methods are proposed. Also, a novel algorithm to segment 3D point cloud (obtained via TOF camera) into objects by using the spatial information is presented. We proposed a novel local range image matching method that combines 3D surface properties with the 2D scale invariant feature transform. Next, our proposal for retrieving similar models where the query and the database both consist of only range models is presented. Finally, analysis of heat diffusion process on range data is presented. Challenges and some experimental results are presented.
2

2.5D Feature Based Correspondence Matching for Part Localization

Asplund, Hugo January 2024 (has links)
In the area of automation, object localization stands as a fundamental functionalitywith widespread applicability. This master’s thesis focuses on a specificapplication involving robot object picking. Given recent advancements in depthcamera technology, there is a high interest in exploring the synergistic integrationof both 2D and 3D data to address challenges such as missing data, occlusion,varying viewing angles, and diverse lighting conditions. This master’s thesis presents the development of two distinct algorithms for arbitraryshaped template matching using 2D image features. Both algorithms leveragefeatures detected by the GoodFeaturesToTrack algorithm and described withScale-invariant feature transform (SIFT) descriptors. While an initial sliding windowmatcher was developed, it was ultimately discarded due to extensive timerequirements. Instead, a correspondence matcher was created, offering two variations:one exclusively employing 2D image data for matching and another utilizing3D coordinates to enhance matching accuracy. The correspondence matchingalgorithms showed similar strengths and weaknesses. They demonstrated proficiencyin handling scenarios characterized by occlusion, minor tilt, and varyingscaling. Both variations struggled with objects 90-degrees rotated and could inmany cases not find them. The findings suggest that the developed feature-based correspondence matchingalgorithm holds promise for object localization in industrial picking applications,although with limitations concerning objects with substantial rotationdifferences. Addressing the challenge of large rotations is recommended for enhancingthe algorithm’s robustness, followed by comprehensive testing to ascertainits efficacy in diverse scenarios.iii

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