John E. Ball

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—We present a semi-automated supervised hyper-spectral image segmentation algorithm based on the level set methodology. In the proposed procedure, seed pixels are automatically selected by their similarity to the training signatures, and speed functions that control the level set propagation are created based on pixel similarity to the seed signature and(More)
—This paper presents a semi-automated supervised level set hyperspectral image segmentation algorithm. The proposed method uses near-optimal speed functions (which control the level set segmentation) that are composed of a spectral similarity term and a stopping term. The spectral similarity term is used to compare pixels to class training signatures and is(More)
Image classification is an important task in the remote sensing field. In a previous study, the authors presented a semi-automated supervised level set-based hyperspectral image segmentation algorithm (LSHSA) (Ball and Bruce, 2005). The LSHSA method used specialized speed functions created using pixel similarity and class discriminator functions. The pixel(More)
—We present a supervised hyperspectral classification procedure consisting of an initial distance-based segmentation method that uses best band analysis (BBA), followed by a level set enhancement that forces localized region homogeneity. The proposed method is tested on two hyperspectral images of an urban and rural nature. The proposed method is compared(More)
In this paper, we propose a simple approach for sparse array synthesis. We employ a modified generalized alternate projection algorithm using 1-norm constrained minimization in order to achieve the excitation and the position of the elements of a sparse array. The proposed approach is very flexible, since it deals with power pattern masks and allows the(More)
OBJECTIVE Monocortical screws are commonly employed in locking plate fixation, but specific recommendations for their placement are lacking and use of short monocortical screws in metaphyseal bone may be contraindicated. Objectives of this study were to evaluate axial pullout strength of two different lengths of monocortical screws placed in various regions(More)