Optimization and deep learning based multi model abundance estimation and unmixing algorithms for hyperspectral images

Özdemir, Okan Bilge
Hyperspectral unmixing aims to identify the materials within the pixels of an image and estimate the corresponding abundance values of these materials. This thesis proposes an optimizationbased abundance estimation method for the case where the spectral signatures of the materials are available, and a deep learning based hyperspectral unmixing method for the case where the spectral signatures of the materials are unavailable. The proposed abundance estimation algorithm assumes that real data can contain complex interactions that cannot be modeled with a single model, and therefore,use multiple mixing models for determining the abundance of real data. The proposed optimization-based coarse-to-fine estimation algorithm first adopts a linear mixing model for the tested pixel until the error between the reconstructed and original pixel is smaller than a threshold. The algorithm then proceeds by integrating the other nonlinear mixing modelsto the cost function. Among various utilized optimization algorithms and metrics, the proposed solution with the sequential quadratic programming and spectral angle mapper combination is found more successful than other search methods and baseline algorithms. As the second contribution of this thesis, a new 3D convolutional encoder based deep learning method is proposed for hyperspectral unmixing by observing that the local neighborhood information is not sufficiently used for the unmixing problem in hyperspectral images. Given that nonlinear mixing has not been adequately covered in deep learning based hyperspectral unmixing literature, the proposed method is especially designed to solve thenonlinear mixture models with the 3D convolutional encoder structure. The proposed method gives better performance than the well-known pure material extraction and abundance detection algorithms on synthetic and real data


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In hyperspectral images the measured spectra for each pixel can be modeled as convex combination of small number of endmember spectra. Since the measured structure contains only a few of possible responses out of possibly many materials sparsity based convex optimization techniques or compressive sensing can be used for hyperspectral unmixing. In this work varying sparsity based techniques are tested for hyperspectral unmixing problem. Performance analysis of these techniques on sparsity level and measureme...
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Image segmentation has an important role in image processing because it is a tool to obtain higher level object descriptions for further processing. In some applications such as large image databases or video image sequence segmentations, the speed of the segmentation algorithm may become a drawback of the application. This thesis work is a study to improve the run-time performance of a well-known segmentation algorithm, namely the Recursive Shortest Spanning Tree (RSST). Both the original and the fast RSST...
Citation Formats
O. B. Özdemir, “Optimization and deep learning based multi model abundance estimation and unmixing algorithms for hyperspectral images,” Ph.D. - Doctoral Program, Middle East Technical University, 2021.